
    384 F. 2d 391
    AUTOGIRO COMPANY OF AMERICA v. THE UNITED STATES
    [No. 50328.
    Decided October 13, 1967]
    
      
      J. E(hoard Shinn, attorney of record, for plaintiff. Syn-nestvedt <& Lechner, Raymond H. Synnestvedt, and 0. Willard Hayes, of counsel.
    
      Acting Assistant Attorney General J. 'William Doolittle, for defendant. Francis H. Fassett and Howard B. Rochman, of counsel.
    Before CoweN, Chief Judge, Laramore, Durfee, Davis and ColliNS, Judges.
    
   Durfee, Judge,

delivered the opinion of the court:

The Autogiro Company of America, a Delaware corporation owning all patents involved in this litigation, sues, under 28 U.S.C. § 1498, to recover the “reasonable and entire compensation” for the Government’s allegedly unauthorized use of its patented inventions. Only the question of liability is now before the court. The determination of any amount of recovery is reserved for further proceedings before the trial commissioner.

Plaintiff initiated suit in this court on September 21,1951, with a Petition Pending Motion for Call which claimed the infringement of twenty-sis patents. The petition was amended on March 10, 1954; twelve patents were dropped from the suit and six were added. Four years of pre-trial proceedings reduced the number of patents to sixteen. During that period, fourteen witnesses appeared, over one thousand exhibits were presented, and almost fifteen thousand pages of transcript were taken. The trial commissioner issued a 232-page report containing 415 findings of fact. Fifteen of the sixteen patents in suit and eighty-five of their eighty-six claims in suit were found valid and infringed by various Government structures. One patent and its one claim were found not infringed.

Plaintiff has not excepted to any findings of fact. Defendant has excepted to findings concerning the fifteen patents found valid and infringed. We find claims of eleven patents to be valid and infringed.

Patent Infringement

Like many patent infringement suits, this case presents no novel legal questions. Absent are any issues not found in the run-of-the-mine case. This does not mean that the law involved should go unstated. The complexity of the inventions in suit, the length of the trial, and the basic disagreement of the parties on legal issues are considerations that dictate a recital of this court’s law of patent infringement.

I

The Patent Act of 1952, 35 U.S.C. § 1 et seq., which applies to all patents granted on or before January 1, 1953, is the controlling law in this case. No previous patent act contained a section on infringement. Congress had always allowed the courts to settle the issue without any legislative guidelines. Rich, Infringement Under Section 271 of the Patent Act of 1952, 21 Geo. Wash. L. Rev. 521 (1953). Section 271(a) which, covers the type of infringement alleged here was not inserted in the Act to clarify any legal problems, but only as a codification of existing judicial determinations. As one commentator has stated: “We got along without it for 162 years and we could again. Its omission would change nothing.” Id at 537.

The claims of the patent provide the concise formal definition of the invention. They are the numbered paragraphs which “particularly [point] out and distinctly claim the subject matter which the applicant regards as his invention.” 35 U.S.C. § 112. It is to these wordings that one must look to determine whether there has been infringement. Courts can neither broaden nor narrow the claims to give the patentee something different than what he has set forth. No matter how great the temptations of fairness or policy making, courts do not rework claims. They only interpret them. Although courts are confined by the language of the claims, they are not, however, confined to the language of the claims in interpreting their meaning.

Courts occasionally have confined themselves to the language of the claims. When claims have been found clear and unambiguous, courts have not gone beyond them to determine their content. Keystone Bridge Co. v. Phoenix Iron Co., supra, at 278; Borg-Warenr Corp. v. Mall Tool Co., 217 F. 2d 850 (7th Cir. 1954); Zonolite Co. and Insulating Concrete Corp. v. United States, 138 Ct. Cl. 114, 149 F. Snpp. 953 (1957). Courts have also held that the fact that claims are free from ambiguity is no reason for limiting the material which may be inspected for the purpose of better understanding the meaning of claims. Warner & Swasey Co. v. Universal Marion Corp., supra, at 737.

We find both approaches to be hypothetical. Claims cannot be clear and unambiguous on their face. A comparison must exist. The lucidity of a claim is determined in light of what ideas it is trying to convey. Only by knowing the idea, can one decide how much shadow encumbers the reality.

The very nature of words would make a clear and unambiguous claim a rare occurrence. Writing on statutory interpretation, Justice Frankfurther commented on the inexactitude of words:

They are symbols of meaning. But unlike mathematical symbols, the phrasing of a document, especially a complicated enactment, seldom attains more than approximate precision. If individual words are inexact symbols, with shifting variables, their configuration can hardly achieve invariant meaning or assured definiteness.

Frankfurter, Some Reflections on the Reading of Statutes, 47 Col. L. Rev. 527, 528 (1947). See, also, A Re-Evaluation of the Use of Legislative History in the Federal Courts, 52 Col. L. Rev. 125 (1952).

The inability of words to achieve precision is none the less extant with patent claims than it is with statutes. The problem is likely more acute with claims. Statutes by definition are the reduction of ideas to print. Since the ability to verbalize is crucial in statutory enactment, legislators develop a facility with words not equally developed in inventors. An invention exists most importantly as a tangible structure or a series of drawings. A verbal portrayal is usually an afterthought written to satisfy the requirements of patent law. This conversion of machine to words allows for unintended idea gaps which cannot be satisfactorily filled. Often the invention is novel and words do not exist to describe it. Tbe dictionary does not always keep abreast of the inventor. It cannot. Things are not made for the sake of words, but words for things. To overcome this lag, patent law allows the inventor to be his own lexicographer. Chicago Steel Foundry Co. v. Burnside Steel Foundry Co., 182 F. 2d 812 (7th Cir. 1943); Stuart Oxygen Co. Ltd. v. Josephian, 162 F. 2d 857 (9th Cir. 1947); Universal Oil Products Co. v. Globe Oil & Refining Co., 137 F. 2d 3 (7th Cir. 1943), aff'd 322 U.S. 471 (1944).

Allowing the patentee verbal license only augments the difficulty of understanding the claims. The sanction of new words or hybrids from old ones not only leaves one unsure what a rose is, but also unsure whether a rose is a rose. Thus we find that a claim cannot be interpreted without going beyond the claim itself. No matter how clear a claim appears to be, lurking in the background are documents that may completely disrupt initial views on its meaning.

The necessity for a sensible and systematic approach to claim interpretation is axiomatic. The Alice-in-Wonderland view that something means whatever one chooses it to mean makes for enjoyable reading, but bad law. Claims are best construed in connection with the other parts of the patent instrument and with the circumstances surrounding the inception of the patent application. Doble Engineering Co. v. Leeds & Northrup Co., 134 F. 2d 78 (1st Cir. 1943). In utilizing all the patent documents, one should not sacrifice the value of these references by the “unimaginative adherence to well-worn professional phrases.” Frankfurter, supra, at 529. Patent law is replete with major canons of construction of minor value which have seldom provided useful guidance in the unraveling of complex claims. Instead, these canons have only added confusion to the problem of claim interpretation. Doble Engineering Co. v. Leeds & Northrup, supra, at 84.

ii

In deriving the meaning of a claim, we inspect all useful documents and reach what Justice Holmes called the “felt meaning” of the claim. In seeking this goal, we make use of three parts of the patent: the specification, the drawings, and the file wrapper.

Specification.—Section 112 of the 1952 Patent Act requires the specification to describe the manner and process of making and using the invention so that any person skilled in the patent’s art may utilize it. In serving its statutory purpose, the specification aids in ascertaining the scope and meaning of the language employed in the claims inasmuch as words must be used in the same way in both the claims and the specification. U.S. Pat. Off. Eule 75(d). The use of the specification as a concordance for the claims is accepted by almost every court, and is a basic concept of patent law. Most courts have simply stated that the specification is to be used to explain the claims; others have stated the proposition in different terms, but with the same effect. The following expressions are indicative of this latter approach: (1) “* * * [A] patentee’s broadest claim can be no broader than his actual invention.” Kemart Corp. v. Printing Arts Research Laboratories, Inc., 201 F. 2d 624, 629 (9th Cir. 1953), (2) “* * * [E]ecourse must be had to the specification to see how far the means there disclosed correspond with those made by the defendant.” Perry v. United States, 112 Ct. Cl. 1, 30, 76 F. Supp. 503, 505 (1948); Grubman Engi neering & Mfg. Co. v. Goldberger, 47 F. 2d 151, 152 (2d Cir. 1931), (3) “While the specification may be referred to in order to limit the claim, it can never be available to expand it.” Hanovia Chemical Mfg. Co. v. David Buttrick Co., 39 F. Supp. 646 (D. Mass. 1941), aff'd 127 F. 2d 888 (1st Cir. 1942).

The specification “set[s] forth the best mode contemplated by the inventor of carrying out his invention.” 35 U.S.C. § 112. This one embodiment of the invention does not restrict the claims. Claim interpretation must not make use of “best mode” terms inasmuch as the patentee need not guard against infringement by listing every possible infringing device in the specification. Adams v. United States, 165 Ct. Cl. 576, 330 F. 2d 622 (1964), aff'd 383 U.S. 39 (1966); Grant Paper Box Co. v. Russell Box Co., 154 F. 2d 729 (1st Cir. 1946), cert. denied 329 U.S. 741. But where the specification does not refer to an embodiment or a class of embodiments in terms of “best mode,” such reference may be of value in claim interpretation. This would be where the patentee describes an embodiment as being the invention itself and not only one way of utilizing it.

Drawings.—The patent may contain drawings. 35 U.S.C. § 113. In those instances where a visual representation can flesh out words, drawings may be used in the same manner and with the same limitations as the specification. Permutit Co. v. Graver Corp., 284 U.S. 52 (1931); Cameron Iron Works, Inc. v. Stekoll, 242 F. 2d 17 (5th Cir. 1957) ; Binks Mfg. Co. v. Ransburg Eleotro-Coating Corp., 281 F. 2d 252 (7th Cir. 1960), cert. dismissed 366 U.S. 211 (1961); Foxboro Co. v. Taylor Instrument Companies, 157 F. 2d 226 (2d Cir. 1946), cert. denied 329 U.S. 800 (1947).

File wrapper.—The file wrapper contains the entire record of the proceedings in the Patent Office from the first application papers to the issued patent. Since all express representations of the patent applicant made to induce a patent grant are in the file wrapper, this material provides an accurate charting of the patent’s pre-issuance history. One use of the file wrapper is file wrapper estoppel, which is the application of familiar estoppel principles to Patent Office prosecution and patent infringement litigation. The patent applicant must convince the patent examiner that his invention meets the statutory requirements; otherwise, a patent will not be issued. When the application is rejected, the applicant will insert limitations and restrictions for the purpose of inducing the Patent Office to grant his patent. When the patent is issued, the patentee cannot disclaim these alterations and seek an interpretation that would ignore them. He cannot construe the claims narrowly before the Patent Office and later broadly before the courts. File wrapper estoppel serves two functions in claim interpretation; the applicant’s statements not only define terms, but also set the barriers within which the claim’s meaning must be kept. These results arise when the file wrapper discloses either what the claim covers or what it does not cover.

The file wrapper also has a broader and more general use. This is its utilization, like the specification and drawings, to determine the scope of claims. For example, the prior art cited in the file wrapper is used in this maimer. In file wrapper estoppel, it is not the prior art that provides the guidelines, but the applicant’s acquiescence with regard to the prior art. In its broader use as source material, the prior art cited in the file wrapper gives clues as to what the claims do not cover. Westinghouse Electric &Mfg. Co. v. Formica In sulation Co., 266 U.S. 342 (1924); Remington Rand, Inc. v. Meilink Steel Safe Co., 140 F. 2d 519 (6th Cir. 1944). Moto-Mower Co. v. E. G. Stearns & Co. Inc., 126 F. 2d 854 (2d Cir. 1942).

Ill

The use of the various parts of the patent to determine the meaning of the claims is only half the process of determining patent infringement. The other half is “reading the claims on the accused structures.” If the claims read literally on the accused structures, an initial hurdle in the test for infringement has been cleared. The race is not over; it has only started. To allow literality to satisfy the test for infringement would force the patent law to reward literary skill and not mechanical creativity. And since the law is to benefit the inventor’s genius and not the scrivener’s talents, claims must not only read literally on the accused structures, but also the structures must “do the same work, in substantially .the same way, and accomplish substantially the same result.” Dominion Magnesium Ltd. v. United States, 162 Ct. Cl. 240, 252, 320 F. 2d 388, 396 (1963). This approach of making literal overlap only a step and not the entire test of infringement has been consistently applied by the courts since Westinghouse v. Boyden Power Brake Co., 170 U.S. 537 (1898), where Justice Brown stated at 568:

* * * The patentee may bring the defendant within the letter of his claims, but if the latter has so far changed the principle of the device that the claims of the patent, literally construed, have ceased to represent his actual invention, he is as little subject to be adjudged an in-fringer as one who has violated the letter of a statute has to be convicted, when he has done nothing in conflict with its spirit and intent. * * *

If the claims do not read literally on the accused structures, infringement is not necessarily ruled out. The doctrine of equivalence casts around a claim a penumbra which also must be avoided if there is to be no infringement. It provides that a structure infringes, without there being literal overlap, if it performs substantially the same function in substantially the same way and for substantially the same purpose as the claims set forth. Equivalence is the obverse of the discounting of literal overlap. The latter is to protect the accused; the former to protect the patentee. The rationale behind equivalence was set forth by the Supreme Court in Graver Tank Mfg. Co. v. Linde Air Products Co., sufra, at 607:

[T]o permit imitation of a patented invention which does not copy every literal detail would be to convert the protection of the patent grant into a hollow and useless thing. Such a limitation would leave room for— indeed encourage — the unscrupulous copyist to make unimportant and unsubstantial changes and substitutions in the patent which, though adding nothing, would, be enough to take the copied matter outside the claim, and hence outside the reach of the law. * * *

Checking the subordination of substance to form and not depriving the inventor of the benefit of his invention cannot be standardized. The range of equivalence varies with each patent; however, some general guidelines can be drawn. One important guide is whether persons reasonably skilled in the art would have known of the interchangeability of an ingredient not contained in the patent with one that was. Id. at 609. Another guide is the notion that pioneer patents are to be given wider ranges of equivalence than minor improvement patents. Pratt & Whitney v. United States, sufra, Aluminum Co. of America v. Thompson Products, Inc., 122 F. 2d 796 (6th Cir. 1941). This statement is less a canon of construction and more a shorthand expression for the dictates of the law and the patents themselves. The doctrine of equivalence is subservient to file wrapper estoppel. It may not include within its range anything that would vitiate limitations expressed before the Patent Office. Exhibit Supply Co. v. Ace Patents Corp., supra; Smith v. Magic City Kennel Club, supra. Thus a patent that has been severely limited to avoid the prior art will only have a small range between it and the point beyond which it violates file wrapper estoppel. Similarly a patent which is a major departure from the prior art will have a larger range in which equivalence can function. The scope of the patents also influences the range of equivalence. A pioneer patent which occupies symbolically a six-inch circle will have three inches of equivalence if its range is fifty percent. An improvement patent occupying a two-inch circle has only one inch of equivalence with the same range. Thus with relatively identical ranges, the scope of the patent provides the pioneer patent with absolutely a larger range of equivalence.

IV

In summary, the determination of patent infringement is a two-step process. First, the meaning of the claims in issue must be determined by a study of all relevant patent documents. Secondly, the claims must be read on the accused structures. In doing this, it is of little value that they read literally on the structures. What is crucial is that the structures must do the same work, in substantially the same way, and accomplish substantially the same result to constitute infringement. This is the general approach which this court uses to determine the infringement of all the patent claims properly before it in this case.

The Patents

The patents in suit are concerned with rotor structures and control systems on rotary wing aircraft. The two principal types of rotary wing aircraft are the helicopter and the gyroplane (also referred to by plaintiff’s trademark Autogiro) . The autogiro has both fixed wings and rotary blades, and resembles a cross between an airplane and a helicopter. The helicopter has only rotary blades. The auto-giro is propeller-powered; the helicopter, rotary blade-powered. The autogiro cannot achieve under normal circumstances a vertical take-off like the helicopter with rotary blade power; it must taxi on takeoffs like the airplane with propeller power. The two types of aircraft do have several common characteristics. They both rise and descend and control horizontal movements through the operation of the same control systems—respectively, the collective and cyclic pitch control system.

I

Stanley Patent No. 2,302,068.—Neither party has excepted to the trial commissioner’s finding of fact on this patent and its single claim; therefore, it is adopted as part of this opinion. The ’068 patent is concerned with rotor blade construction. Since they have routed and not apertured rotor blades, the accused structures, the Vertol HUP-1 and the Vertol H-21B helicopters, do not infringe the one claim of this patent.

II

Court of Claims Rule 58(c) requires that “* * * [appropriate references shall be made at the end of each exception to the parts of the record relied upon in support thereof.” Otherwise, in determining the merit of the exceptions, the court would be required to go through the entire record without benefit of a Baedeker. Such a task relegates the court to making the parties’ case rather than deciding it. Thus it has been strict in enforcing Rule 58(c). For example, a party has not been allowed to set forth only its own extended narrative version of the facts with an appendix of its own proposed findings of fact. Hunt and Willett, Inc. v. United States, 168 Ct. Cl. 256, 351 F. 2d 980 (1964). See, also, Societe Anonyme des Ateliers Brillie Freres v. United States, 160 Ct. Cl. 192 (1963); Schmoll v. United States, 105 Ct. Cl. 415, 63 F. Supp. 753, cert. denied 329 U.S. 724 (1946).

For eight of the patents and their claims, defendant has excepted .to the trial commissioner’s opinion by only listing the numbers of the findings of fact with which it finds fault. No briefs have been submitted in support of these exceptions. No references to the trial record or exhibits have been made to underpin the allegation that the trial commissioner erred in his findings. This method of excepting is a hollow gesture and has the same effect that failure to except has. See, Harrington v. United States, 161 Ct. Cl. 432 (1963); Batchelor v. United States, 169 Ct. Cl. 180, cert. denied 382 U.S. 870 (1965). This failure to meet the burden of Rule 58(c) results in this court’s adoption of the trial commissioner’s findings of fact on the following patents:

Larsen Patent No. 1,948,457.—The ’457 patent relates to rotary wing aircraft sustaining rotors and particularly to improved blade damper mechanisms for controlling the pivotal movement of rotor blades about their vertical pivots. Claims 9, 12, 13, 14 and 18 of this patent are infringed by the Vertol HUP-1 helicopter and particularly the construction of its fore and aft rotors.

Cierva Patent No. 1,994,465.—The ’465 patent relates to the mechanism for folding the rotor blades of rotary wing aircraft equipped with vertical pivots and to the mechanism for controlling the movement of the blades about these pivots. Claims 1, 5, 6, 7, 10 and 13 are infringed by the Vertol HUP-l helicopter and particularly the construction of its fore and aft rotors.

Larsen Patent No. 1,990,291.—The ’291 patent relates to a method for adjusting the effective incidence of flappingly-pivoted rotor blades in their tracking. Claim 4 is infringed by the Hiller H-23A helicopter and particularly its sustaining rotor construction, the Vertol HUP-l helicopter and particularly the construction of its fore and aft rotors, and the Bell HTL-4 helicopter and particularly its sustaining rotor construction. Claim 5 is infringed by the rotor blade tracking procedures of the Vertol HUP-1. Claim 6 is infringed by the rotor blade tracking procedures of the Hiller H-23A, the Vertol HUP-1, and the Bell HTL-4.

Larsen Patent No. 2,151,215.—The ’215 patent relates to displaceable droop support mechanism for sustaining rotary wing aircraft rotors. Its purpose is to prevent rotor blades from striking the ground or the aircraft when the rotor is either not rotating or rotating at substantially less than normal flight speed. Claims 1,2, 3, 5, 6, 8 and 9 are infringed by the Kaman HOK-1 helicopter.

Campbell Patent No. 2,339,836.—The ’836 patent relates to aircraft with twin rotors arranged side-by-side so that when viewed from above, the left hand rotor rotates counterclockwise, and the right hand rotor rotates clockwise. Claim 1 is infringed by the Kaman HOK-1 helicopter.

Campbell Patent No. 2,321,572.—The ’572 patent relates to aircraft with side-by-side rotors and flappingly-pivoted blades. Claims 8, 9, 28 and 29 are infringed by the Kaman HOK-1 helicopter.

Campbell Patent No. 2,344,966.—The ’966 patent relates to the control of aircraft with side-by-side rotors and flap-pingly-pivoted blades. In particular, this is the turn control which functions by having the rotors so positioned to provide for differential shifting of the rotors’ lift lines both fore and aft of the aircraft’s center of gravity. This allows the craft to turn or bank in a certain direction. Claim 1 is infringed by the Kaman HOK-1 helicopter.

Bennett Patent No. 2,344,967.—The ’967 patent relates to the control of aircraft with side-by-side rotors and flap-pingly-pivoted blades. In particular, this is the longitudinal and lateral attitude control which functions by the conjoint tilting of the lift lines of the rotors both fore and aft and laterally of the craft. The ’967 patent also relates to the rotor phasing which minimizes the bouncing effects which rotors experience in translational flight. Claims 1, 2, 3, 4, 13 and 18 are infringed by the Kaman HOK-1 helicopter.

Ill

Findings of fact for the following patents were properly excepted to either in whole or in part:

Cierva Patent No. 1,947,901.—The trial commissioner found Claim 3 infringed by the Vertol HUP-1 helicopter and particularly the rotor construction of its fore and aft rotors, the Hiller H-23A helicopter and its sustaining rotor construction, and the Bell HTL-4 helicopter and its sustaining rotor construction.

The claim.—Claim 3 is a combination claim containing several elements, each considered to be essential and equal to all others. Aro Mfg. Co. v. Convertible Top Replacement Co., supra, at 345. For there to be infringement, it is necessary that every element or its substantial equivalent be found in the accused structures. E.g., McCullough, Tool Co. v. Well Surveys, Inc., 343 F. 2d 381 (10th Cir. 1965), cert. denied 383 U.S. 933 (1966); Texas Co. v. Anderson-Prichard Refining Corp., 122 F. 2d 829 (10th Cir. 1941); Alex Lee Wallau, Inc. v. J. W. Landenberger & Co., 121 F. Supp. 555 (S.D.N.Y. 1954); Vollink v. Holland Celery Planter Co., 33 F. Supp. 203 (W.D. Mich. 1938), aff'd 112 F. 2d 576 (6th Cir. 1940). Therefore, only one element of the claim is to be discussed. This is the element which states:

In an aircraft, a sustaining rotor construction having blades mounted for movement with respect to an axis member and so proportioned that, under the influence of air currents, the blades have an average autorota-tional speed at the tip substantially in excess of the maximum flight speed of which the craft is capable. * * * [Emphasis added.]

The claim, on its surface, defines “so proportioned” in terms of function or result; however, a reading of the term in light of the patent documents shows “so proportioned” to include a means of accomplishing its function. See 35 U.S.C. § 112. The specification shows that the proportioning is a relationship between rotor blades and a fixed wing. In the beginning, it states that:

* * * the present invention contemplates certain novel features of proportioning and disposition of the blades and blade system, and the relation thereof to the fixed lifting surfaces * * *. ’901 Specification 1, Is, 46-50.

The invention is later described in the following manner:

According to the most complete development of the invention, however, I contemplate combining, in the same construction, fixed wings of a certain positive incidence in conjunction with a rotor having freely swinging air-rotated blades, each of which blades is itself set at positive incidence with relation to a no-lift setting on the axis * * *.Id. at 2, ls. 3-9.

In a section which discusses embodiments of the ’901 patent, the specification expressly discusses proportioning. The embodiments referred to in this section are not means of proportioning the rotor blades, but various relationships between the rotor blades and a fixed wing. The rotor blade-fixed wing relationship is constant throughout this section. No other relationship is suggested, only various ratios of this relationship.

Plaintiff contends that “so proportioned” refers to the construction of the individual blades. It cites specification references to “a thin or medium-thick section of substantially fixed center of pressure” (id. at 3, Is. 46-18) and a blade “of uniform symmetry from end to end of its effective lifting portion” (id. at 3, Is. 28-30). Neither of these references was made in the company of the term proportioning. Furthermore, these references are to embodiments inasmuch as the specification states that “[t]he foregoing are cited to show that different types of blade construction may be employed in carrying out the present invention.” Id. at 3, Is. 51-53.

The file wrapper does not compel a different interpretation of the claim. Claim 3 was initially rejected three times on the strength of the prior art. Referring to its rejection, along with other claims, the applicant remarked about “the entirely novel cooperative relationships of the rotor and the particular type and arrangement of fixed wing employed * * *.” ’901 File Wrapper 124. The novelty of this relationship between rotor blades and fixed wings is recited in other parts of the file wrapper dealing with the inadequacy of the prior art to meet the spirit of his claims. See, e.g., id at 46,60 and 82.

The above interpretation of “so proportioned” does not ignore the concept of claim differentiation which states that claims should be presumed to cover different inventions. This means that an interpretation of a claim should be avoided if it would make the claim read like another one. Claim differentiation is a guide, not a rigid rule. If a claim will bear only one interpretation, similarity will have to be tolerated.

Claims 4r-7 of the ’901 patent refer to a substantially fixed aerofoil (i.e. wing). And Claims 8-17 refer to a relatively fixed lifting aerofoil surface. Interpreting Claim 3 to refer to a fixed wing would not render any of those claims redundant. Claims 4 and 5, the ones with which 3 has the greatest similarity, are markedly different. Claim 3 refers to “maximum flight speed of which the craft is capable;” Claims 4 and 5 refer to the “translational flight of which the craft is capable.” Also, Claim 3 does not have the specificity of these claims — for example, their limitation to an aircraft “with a substantially fixed aerofoil of an effective area approximately 50 percent to 100 percent of the area of the ro-tative blades.” These differences are not to be undervalued because of their slightness since claims covering the same invention in varying degrees of breadth or scope usually have only slight differences.

The accused structures.—The Vertol, Hiller, and Bell helicopters found iby the trial commissioner to infringe Claim 3 do not have a fixed wing; therefore, they cannot have their rotors proportioned in the manner called for by the claim as explained by its supporting documents. Since they do not operate in substantially the same way as the claim requires, they do not infringe it.

Prewitt Patent No. 2,380,581.—The trial commissioner found: (1) Claim 28 infringed by the Hiller H-23A helicopter, and (2) Claims 29, 36, 37, 38 and 42 infringed by the Hiller H-23A and the Bell HTL-4 helicopter. Infringement by these helicopters included their collective pitch systems having both manually and centrifugally actuated pitch governing mechanisms.

The claims.—Each claim contains an element which defines a nonmanual mechanism for regulating the rotational speed of rotary wing aircraft rotors. Such changes are achieved through the use of movable weights mounted in each rotor and attached to the collective pitch control system. As the rotor speeds up, the concomitant increase in centrifugal force causes the weights to move outboard. Such movement increases the pitch angle of the rotor blades and slows the blades by presenting a greater blade surface to the air flow.

In listing the patent’s purposes, the ’581 specification states at 1, col. 2, Is. 1-5: “A further object is to provide governing means in cooperation with my blade incidence control which will tend to maintain constant rotational speed of the rotor.” Since the term “governing means” is only used in the specification in this way, it is proper to presume that it is being used in the same way in Claims 29 and 87. op. cit. supra at footnote 8. The other claims (28, 36, 38 and 42) use the term “centrifugal means.” Since it is centrifugal means which produces the governing means, these terms are interchangeable. See ’581 Specification at 2, col. 2, ls. 10-17.

Plaintiff contends that only Claim 28 provides a means for governing rotational speed of the rotor. It claims that centrifugal means and governing means are not the same. To obtain governing means, it says that there must be centrifugal means plus a resilient means and that only Claim 28 provides this combination. This combination is only a preferred embodiment in that the resilient means (usually a spring) is not necessary for the maintenance of a constant rotational speed; it only acts as an aid to such an end. Id. at 4, col. 1, Is. 8-30. Without the resilient means, the centrifugal means will still “tend to maintain constant rotational speed of the rotor.”

In prosecuting Claims 28,29, 36 and 37 of the ’581 patent before the Patent Office, the applicant based their validity on novel non-manual governing means which tended to maintain constant rotor speed. After the claims had been so narrowed, the Patent Examiner allowed Claims 28, 29 and 36; Claim 37 was rejected for not distinguishing the prior art. It was then allowed when amended to be in accord with its companion claims. ’581 File Wrapper at 73. After the allowance of the ’581 patent, Claims 38 and 42 were entered under Patent Office Eule 78 which permits the entry of additional claims after the allowance of the application. This rule is not intended to provide a way for the continued prosecution of an approved application; an additional claim that is not “obviously allowable” is usually not accepted. See Manual of Patent Examining Procedure 714.16. A claim will most likely be “obviously allowable” if it is no broader in scope than claims already allowed. Thus the file wrapper raises the presumption that Claims 38 and 42 are subject to the same limitations on governing means as 28, 29, 36 and 37.

The file wrapper supports the idea that the resilient means is not a necessary ingredient in the governing means by stating:

As additional factors in the control situation the provision of the spring 113 with or without its variable control (wing nut 114) is a variant on the automatic governor to change the rotative speed at which the governor becomes effective, and thus to change the predetermined E.P.M. and pitch angle. This has been pointed out in certain of the new claims which are urged for allowance as not anticipated by any of the art of record, notably and illustratively [claim 28] * * *.” ’581 File Wrapper at 59.

Furthermore, when claiming the governing means to be an advance over the prior art, the applicant made no distinction between Claims 28, 29, 36 and 37; even though only 28 contained a resilient means, all were grouped together in discussing advances over the prior art.

The accused structures.—On the Bell HTL-4 helicopter, the accused structures are upright counterweights attached to the inboard trailing edges of the rotor blades. These counterweights balance and counteract aerodynamic forces (rotor loads and collective pitch loads) operating on the blades that otherwise would have to be absorbed by the control systems and the pilot. They produce twisting moments approximately balancing those created by centrifugal force which would normally make pitch change possible only with an undesirably large force. The weights do not perform a rotor speed governing function. The HTL-4 has no non-manual rotor speed governor; rotor speed is always controlled by the pilot.

On the Hiller H-23A helicopter, the accused structures are flyweight ballast arms attached to the rotor blades. They serve the same function that the counterweights on the Bell HTL-4 helicopter do. Rotor speed control is also a manual operation on this craft.

Since the accused structures on these two helicopters do not achieve the same or a substantially similar result as the claims, they do not infringe the ’581 patent.

Cierva Patent No. 2,380,583.—The trial commissioner found: (1) Claim 56 infringed by the straight and twisted wooden rotor blades of the Vertol HUP-1 helicopter and the tandem-disposed rotors with wooden or metal blades of the Vertol H-21B helicopter, (2) Claim 59 infringed by the Vertol HUP-1, the Vertol H-21B, the sustaining rotor construction of the Bell HTL-4 helicopter, and the sustaining rotor construction of the Hiller H-23A helicopter, (3) Claim 60 infringed by the Vertol HUP-1 and the Vertol H-21B, (4) Claim 62 infringed by the rotor construction of the fore and aft rotors and rotor blades of the McCulloch MC-4C helicopter, (5) Claims 64 and 65 infringed by the Vertol HUP-1, the Vertol H-21B, the McCulloch MC-4C, the Bell HTL-4, and the Pliller H-23A. Only Claims 59, 64 and 65 have been properly excepted to; therefore, we adopt the trial commissioner’s findings of infringement on Claims 56, 60 and 62.

Claim, 64.—An element of this claim states that the rotor blade’s sectional mass center be at least as far forward as its aerodynamic center. “Sectional” only appears once in the specification. In explaining that movable weights may be built into a rotor blade to permit the shifting of the mass center of the blade both forwardly and outwardly, it states:

[adjustment of the weight as well as of the sectional and longitudinal location of the center of gravity of the blade may thus also be obtained. ’583 'Specification at 8, col. 1, Is 70-73.

This context gives “sectional” a directional meaning. Its juxtaposition with “longitudinal” indicates that it refers to the front-rear (or chordwise) direction, and the other word refers to the inboard-outboard (or spanwise) direction of the blade. Thus “sectional” is used in the sense of “cross-sectional” and not some constituent section.

Not only is there no mention of “sectional” as meaning “part” in the specification, but also there is the problem that such a meaning might lead to invalidation of the claim for indefiniteness. No leads as to what section is involved can be found in any of the patent documents. Yet, if a particular section is intended in the claim, it must be pointed out so that people skilled in the art can make use of the patent. 35 U.S.C. § 112. Failure to meet this requirement can result in the claim’s invalidation. See, e.g., Bullard Co. v. General Electric Co., 348 F. 2d 985 (4th Cir. 1965); Locklin v. Switzer Bros. Inc., 299 F. 2d 160 (9th Cir. 1961), cert. denied 369 U.S. 861 (1962) ; Societe Anonyme des Anciens Etablissements Cail v. United States, 43 Ct. Cl. 25 (1907), aff'd 224 U.S. 309 (1912).

Use of “sectional” to mean “cross-sectional” does not violate the doctrine of claim differentiation. Claims 56 and 57 use mass center in the same way that we have interpreted sectional mass center as to Claim 64. Claim differentiation would normally have different expressions in different claims read differently. But in these claims (56, 57 and 64), the two phrases are meant to be interchangeable. Claims 56 and 57 use references to the chord to convey what 64 achieves by using “sectional” and not making any references to the chord. Thus, the difference between these phrases is intended to be one of style and not content.

The accused structures.—Exceptions have only been taken to the trial commissioner’s findings of infringement on the Bell HTL-4, the Hiller H-23A, and the McCulloch MC-4C. On the Vertol HUP-1 and H-21B helicopters, we adopt his findings of infringement.

The mass center generates forces that push downwardly on the blade when it is producing lift. The aerodynamic center generates upward forces. The effect of these forces depends upon their relative placement along the blade’s cross-section. If the two centers occupy tbe same spot, their forces balance out. This is called neutral pitching moment. With the aerodynamic center forward, the forces push upward and there is a positive pitching moment. With the mass center forward, the leading edge is forced downward and a negative pitching moment results. A negative pitching moment reduces blade flapping and increases rotor efficiency. This is the result Claim 64 seeks, in part, to achieve. ’583 Specification at 3, col. 2, ls. 20-33.

None of the three excepted to structures infringes Claim 64. Neither the Bell IITL-4 nor the Hiller H-23A has a cross-sectional negative pitching moment. The Bell helicopter has a mass center one to two percent behind the aerodynamic center. The Hiller helicopter has the mass center one to three percent behind the aerodynamic center. Without the negative pitching moment, these structures cannot achieve the desired result the way the claim sets it forth. The same holds for the McCulloch MC-4C which has a neutral pitching moment.

Claim 65.—It is dependent upon Claim 64 and can only be infringed if 64 is infringed. Application of Schutte, 244 F. 2d 323 (C.C.P.A. 1957).

The accused structures.—We make the same holding on 65 that we made on 64. We adopt the trial commissioner’s findings that the Vertol HUP-1 and H-21B helicopters infringe Claim 65. And we find that all other accused structures do not infringe Claim 65.

Claim 59.—This claim provides, in part, for the placement of weights along the leading edge of the blade near the tip. This placement helps bring the mass center of the blade forward of the aerodynamic center so as to achieve negative pitching moment. Id. at 4, col. 1, ls. 19-22. It also increases the total moment of inertia of the rotor in an economical manner in that a lesser weight out near the tip is as effective in increasing inertia as a greater weight inboard. Id. at 4, col. 1, Is. 14-19 and 9, col. 1, ls. 63-78.

The accused structures.—Exceptions have only been taken to the trial commissioner’s findings of infringement on the Bell HTLf-4 and the Hiller H-23A. On the Vertol HUP-1 and H-21B helicopters, we adopt his findings of infringement.

The Bell and Hiller helicopters have a steel bar on their rotor blades which is close to the leading edge. It is not, however, concentrated near the tip of the blade since it extends the full length of the blade, and is of uniform cross section. The bar aids in achieving negative pitching moment, but not in economically increasing the moment of inertia. Since the bar does not operate in a way substantially similar to the teachings of Claim 59 and with a substantially similar result, the Bell and Hiller helicopters are not infringing structures.

Oierva Patent No. 2,216,162.—The trial commissioner found: (1) Claims 7 and 22 infringed by the Bell HTL-2 and HTL-1 helicopters, and (2) Claim 8 infringed by the HTL-2.

The claims.—The claims of the ’162 patent teach a means of obtaining a measure of vertical rise capacity. They propose the conjoint operation of the rotor drive controls and the blade pitch controls to bring about a simultaneous increase in rotor pitch and a disconnection of rotor power. Power is applied to the rotor only when the craft is on the ground and has its rotor blades at a no-lift pitch. When the rotor is rotating at a sufficient speed, the pilot activates a mechanism that simultaneously increases the collective pitch of the rotor blades and disconnects the power from the rotor. This sudden increase in lift will cause a rotary wing aircraft to literally jump off the ground and thus achieve a semblance of vertical take-off. ’162 Specification at 1, col. 1, ls. 6-18.

The conjoint operation of rotor drive and pitch change controls to effect a vertical take-off is not an embodiment of the invention, but is a statement of its desired result. The vertical take-off result is referred to as “the invention.” Id. at 1, col. 1, l. 6. And id. at 3, col. 2, ls. 72-74, it is referred to as “the purpose” of the invention. The specification does discuss embodiments, but as means of implementing the vertical take-off and not additional uses for the conjoint operation of the controls. The following supports this statement:

The invention is susceptible of a number of constructional embodiments. For example, a control lever regulating the pitch angle and a control lever actuating the clutch release may be arranged side by side, similarly to the throttle control levers of twin-engined aircraft in such a way that either lever can be operated independently but both levers can be operated by one hand of the pilot for the purpose of simultaneously releasing the starter clutch and increasing the pitch angle. To obtain this result the two levers must register with one another when the clutch releasing lever is in the “clutch engaged position” and the pitch control lever is in the minimum pitch position. Id. at 1, col. 2, Is. 16-30. See, also id. at 2, col. 2, ls. 67-75 and at 3, col. 2, 1. 72—4, col. 1,1. 5.

References to the fact that the conjoint operation should allow for separate control of the rotor and pitch mechanisms does not show that functions other than vertical take-offs are contemplated by the invention. They only show that the linkage between the two controls should be constructed to allow each control to also serve its normal function.

The accused structures. — Since its rotor is autorotatively operated, an autogiro cannot use the rotor to achieve vertical take-offs unless it is equipped with some additional mechanism such as that taught by the ’162 patent. The accused structures, being helicopters, do not require vertical take-off assistance. With a powered rotor, they have the ability to rise vertically as a matter of normal operating procedure. Since the patentee has limited his patent’s result to only vertical take-off assistance, the accused structures do not achieve the same or a substantially similar result. They also do not operate in the same way that the claims teach since at no time would the pitch of a helicopter’s rotors be increased simultaneously with disconnection of the rotor power. Claims 7, 8 and 22 are not infringed.

Cierva Patent No. 2,421,364—The trial commissioner found: (1) Claims 33, 44, and 45 infringed by the Kaman HOK-1 helicopter, and particularly the construction of its rotors, (2) Claims 53 and 54 infringed by the Bell HTL-4 helicopter, and particularly its sustaining rotor construction, the Hiller H-23A helicopter and its rotor construction, and the McCulloch MC-4C helicopter and its fore and aft rotors, (3) Claims 55, 56 and 60 infringed by the Bell HTL-4 and the Hiller H-23A. Claims 33, 44 and 45 have not been properly excepted to; therefore, we adopt the trial commissioner’s findings of infringement on these claims.

The claims.—Where the ’162 patent provided manual means to accomplish a vertical take-off, the ’364 patent provides nonmanual means.

Claims 54, 55 and 60 were first presented to the Patent Office on February 26,1947; Claim 53, on May 6,1947. This was some eleven years after the filing of the patent application. ’364 File Wrapper 224, 235-238. It was four years after the first successful helicopter flight using the accused structures and more than one year after the completion of the first production helicopter using the accused structures. Claims which have been first filed more than one year after public usage may be invalid. 35 U.S.C. § 102(b) . Where the late-filed claim only makes express what would have been regarded as the equivalent of earlier claims or where it merely incorporates into one claim what was to be gathered from the perusal of all, if read together, it is to be allowed. These exceptions are permitted since the rule is designed to protect the public against abuses of the patent law and not to deprive inventors of what they plainly never meant to put into the public domain. Engineering Development Laboratories v. Radio Corp. of America, 153 F. 2d 523 (2d Cir. 1946); Binks Mfg. Co. v. Ransburg Electro-Coating Corp., supra.

The applicant’s late-filed claims were allowed since he limited them to the scope of previously allowed claims. Claim 54 was stated to be “a combination of features within the general purview of claims heretofore allowed * * ’364 File Wrapper at 249. Claim 55 was called “a combination similar to subject-matter heretofore allowed to applicant.” Ibid. Similar comments were made about Claims 56 and 60. Id. at 250 and 251. The claims already allowed had limitations regarding vertical take-offs and the nonmanual means of achieving them. They cited specific components needed for the take-off and/or the take-off itself.

Claim 53 was originally entered on the basis of its similarity to Claims 54 and 60. Id. at 300-302. By depending upon 54 and 60 to sanction its late filing, 53 must bear their limitations and be considered no broader in scope than previously allowed claims.

The specification states that “[a]n object of this invention is to provide an improved and more efficient rotor particularly adapted for obtaining the most efficient direct take-off possible.” ’364 Specification at col. 2, 1. 54—col. 3, 1.1. It also refers to the object of the invention as obviating the disadvantages of prior vertical take-off devices. Id. at col. 3, ls. 7-32.

The way the ’364 patent reaches its desired result is quite simple. When power is connected to the rotor hub, the blades will lag behind the hub because of the resistance of the air to the movement of the blades. When, the power is stopped, the blades’ inertia force will swing them in advance of the hub. These lead-lag tendencies can be translated into actual blade movement if the blade is mounted on an axis that permits it to move back and forth without restriction. And if the free axis is inclined where the blade swings back and forth, the blade will also change pitch in its movements. When it lags, the pitch angle will decrease. When it leads or swings forward, the pitch angle will increase. The sudden change in pitch angle that will arise when the power is removed from the rotor provides the impetus for a non-manual vertical take-off in a way similar to that provided manually by the ’162 patent.

The necessary free axis that allows the blade to swing back and forth without restriction as well as the inclination of the axis are set forth in both the specification and the drawings. The specification provides at col. 10, ls. 50-70:

The axis of the drag pivot pin (termed alpha axis) is shown in Fig. 13 at [x-x] and it will be seen that this axis is inclined upwardly and outwardly at an acute angle to the longitudinal blade axis b-b.
The result of this arrangement is that movement of the blade on the drag pivot is associated with a change in blade pitch angle such that when the blade lags behind its normal mean radial position, the pitch angle is decreased and vice versa. By this means an automatic control of pitch angle during the starting of the rotor and the take-off is obtained, the effect of the application of the starting torque to the rotor causing the blade to lag and therefore decrease its pitch angle, whereas when the starting torque vanishes on the disengagement of tin. starter clutch, the blade swings about its drag pivot approximately into its normal radial position with a consequent increase of pitch angle to about the value obtaining in autorotational flight.

For the drawings, see 9 in Appendix II.

In summary, the teaching of the ’364 patent and its claims is the means of achieving vertical take-offs. This result is reached by the non-manual jump in pitch angle which in turn is the product of an inclined, free axis taking advantage of a rotor blade’s lead-lag tendencies.

The accused structures.—The Bell HTL-4 and the Hiller H-23A do not have a free axis on which their blades can swing back and forth; their blades are unyieldingly affixed to the rotor hub with no lead-lag flexibility. Also, they have no inclination which would permit the blades, if they did swing, to change pitch. The McCulloch MC-4C’s blades have limited lead-lag flexibility, 'but there is no inclination that would produce pitch change. All three helicopters achieve vertical take-offs by the power directed to their rotors and have no use for a non-manual take-off as taught in the ’364 patent. The accused structures do not do the same work, in the same way, and for the same result as the claims in issue. Nor is their operation substantially similar; therefore, they do not infringe Claims 53, 54, 55, 56 and 60.

Cierva Patent No. 2,380,580.—The trial commissioner found: (1) Claims 1, 3 and 4 inf ringed by the Bell HTL-4 helicopter and its rotor control system, the Hiller H-23A helicopter and its rotor and rotor control system, and the Kaman HOK-1 helicopter and its rotor and rotor control system, (2) Claim 8 infringed by the Vertol HUP-1 helicopter, the McCulloch MC-4C helicopter, and the Vertol H-21B helicopter, (3) Claims 10,11,12,14 and 15 infringed by the Bell HTL-4 and the Hiller H-23A, (4) Claim 13 infringed by the Bell HTL-4, and (5) Claim 36 infringed by the Vertol HUP-1 and the Vertol H-21B.

The claims.—Notary wing aircraft are steered in a horizontal plane by a cyclic pitch control system. This system imposes pitch changes on the rotor blades which cause the rotor to revolve in an inclined plane and which concomitantly produce horizontal movement. Its control device must be a non-rotating mechanism even though the rotor upon which it acts is a rotating mechanism. Generally, there are two types of cyclic pitch control systems. There may be a tilting of the real axis of the rotor or the virtual axis. In tilting the real axis, control is linked directly to a non-rotating part of the rotor hub. The application of control to this part will also tilt tlie rotating part. In tilting the virtual axis, control is applied directly to the blades. This is usually done by a swashplate which is two concentric rings encircling the rotor mast and separated by bearings. Only one ring revolves. The pilot’s control is linked to the non-rotating ring and the rotating ring is linked by rods to the blades. When control is applied, the entire swashplate tilts and the rods attached to the blades bring about cyclic pitch changes.

The ’580 patent and its claims teach cyclic pitch control by tilting the real axis. In the specification the invention is so limited:

Broadly, this stabilizing and controlling action is effected by controlling the effect of the lift line of the rotor, as by causing a shifting of the lift line thereof. Specifically, the invention contemplates mounting the common rotational axis of the rotor for tilting and/or bodily displacement longitudinally and laterally of the craft.
Still more specifically, the invention contemplates mounting the hub or rotational axis of the rotor on a pair of transverse pivots, one of which extends generally longitudinally of the craft and the other of which extends generally transversely of the craft. The preferred arrangement further involves the dual articulation of each wing of the rotor to its hub or axis by means of individual horizontal and vertical pivots.

’580 Specification at 2, col. 2, Is. 20-35. See, also id. at 4, col. 1, 1.7—col. 2, 1.14.

In discussing “certain of the more specific objects and advantages of the invention,” the specification only discusses the invention in terms of tilting the real axis, id at 6, col. 2, 1. 50—7, col. 1,1. 2. The possibility of controlling cyclic pitch by affecting the virtual axis is mentioned, id. at 2, col. 2, ls. 13-15 and 5, col. 2, ls. 56-66. The specification goes no further than acknowledging the existence of the other approach; nowhere does it teach such tilting of the virtual axis. Such a casual reference seems sufficient in that the patentee covered this approach in his ’582 patent which is discussed hereafter.

The embodiments discussed in the specification (id. at 7, col. 2, 1. 50-12, col. 1, 1. 5-) are not embodiments of cyclic pitch control in general, but of cyclic pitch control by tilting the real axis. This lends support to the view that the patentee has limited his invention to the one form of cyclic pitch control. The fact that he might have claimed more is irrelevant. Courts go through the patent documents to find what has been claimed, not what might have been claimed. Keystone Bridge Co. v. Phoenix Iron Co., supra at 278.

The accused structures.—The Kaman HOK-1, the Mc-Culloch MC-4C, the Vertol HUP-1, and the Vertol H-21B helicopters do not achieve cyclic pitch control by tilting the real axis; instead, their control is the result of bodily moving their blades relative to the hub. The Bell HTL-4 and the Hiller H-23A helicopters impose control through various linkages (i.e., a swashplate) on the rotor blades. A member of the real axis of these two crafts may tilt when control is achieved. This tilting is not by itself cyclic pitch control; instead, it is a coincidental accompaniment to the imposition of cyclic pitch control. That this tilting is the result and not the cause of such control is supported by the fact that the ’580 patent’s approach creates major problems when used on helicopters. When power is applied through the rotor hub, a high degree of friction is created between the hub parts. This friction is so great that it would take a force of Brobdingnagian proportions to apply control by tilting the real axis.

Even though all the accused structures achieve horizontal movement by cyclic pitch control as the ’580 claims teach, they do not do it in the same or substantially the same way; therefore, they do not infringe.

Cierva Patent No. 2,380,58%.—The trial commissioner found: (1) Claims 1, 2, 3, 4, 5, 7, 8, 9, 12,13,16,17,18,19, 20 and 21 infringed by the Yertol HUP-1 helicopter, the Vertol H-21B helicopter, and the McCulloch MC-4C helicopter, (2) Claims 6, 7, 8, 9, 12, 13, 16 and 17 infringed by the Bell HSL-1 helicopter, and (3) Claims 16 and 17 infringed by the Bell HTL-4 helicopter. Only the findings of infringement on the Bell HTL-4 have been properly excepted to; therefore, we adopt the trial commissioner’s findings of infringement on all other accused structures.

The claims.—This patent teaches cyclic pitch control by tilting the virtual axis. Claim 16 calls for:

* * * a pitch change pivot operatively interposed between the flapping pivot and the blade mounting member whereby the pitch of the blade may be altered as a unit without shifting the position of the flapping pivot.

In the file wrapper, the applicant limited this claim to cyclic pitch control in defending the patent as an improvement over the prior art. ’582 File Wrapper at 149. See, also at 148. At 148-149, he stated:

* * * This claim involves generally the cyclic pitch control system of the present case and includes specifically the flapping pivot, the pitch change pivot opera-tively interposed between the flapping pivot and the blade root end mounting member * * *. As pointed out in interview, applicant’s attorneys are unaware of any available art showing any such specific arrangement of blade root mounting and cyclic pitch control.

Claim differentiation adds support to the idea that the pitch control in Claim 16 is only the cyclic variety. Claim 17 was offered under Patent Office Rule 78. op. cit. supra, footnote 26 and p. 77. In seeking its acceptance by the Patent Examiner, the applicant stated:

Claim [17] is based on allowed claim [16], but includes the added feature of control means adapted to alter the mean blade pitch and being operatable independently of the cyclic pitch control. This should be allowable (as dependent from allowed Claim [16]) for reasons similar to the basis for allowance of certain other claims * * *.

’582 File Wrapper at 163. If Claim 16 referred to collective pitch control as well as cyclic pitch control, there would have been no need for Claim 17 which adds collective pitch control to a base of Claim 16. But since claim differentiation would have 16 and 17 cover different materials, it follows that 16 only includes cyclic pitch control.

The accused structures.—The cyclic pitch system of Claim 16 is interposed between the flapping pivot and the blade mounting. The Bell IITL-4’s cyclic pitch control pivot is located at a point higher in the rotor hub assembly than either the blade mounting member or the longitudinal axis of the blade. Claim 16 can be read on a combination of the helicopter cyclic and collective pitch control systems since the latter control is interposed between the flapping pivot and the blade mounting member. A combination of these two systems seems to infringe since they achieve horizontal movement by a cyclic pitch system operating in a way taught by the claim. These systems, however, do not interact or contribute together to produce the result taught by the claim. The fact that they can be operated simultaneously has no bearing on whether they have the operative relationship needed to label them an infringing combination. There must be an essential correlation or coordination of the systems which mutually contributes to a common result. The systems need not mechanically interact with one another. They need only act together for the same result; that is to say, they must be part of the same unit which serves a single purpose. E.g., Beecher Mfg. Co. v. Atwater Mfg. Co., 114 U.S. 523 (1885); Sachs v. Hartford Electric Supply Co., 47 F. 2d 743 (2d Cir. 1931); Application of Worrest, 201 F. 2d 930 (COPA 1953); Vollink v. Holland Celery Planter Co., supra. The cyclic and collective pitch control systems are not such a combination; they are each a unit, each serving a single purpose. Therefore, the cyclic pitch control system of the Bell IiTL-4 does not operate in the same or substantially the same way as Claim 16, and does not infringe it.

Since Claim 17 is dependent upon 16, it can only be infringed by a structure that also infringes 16. Application of Schutte, supra. Therefore, it is not infringed by the Bell HTL-4.

IV

In summary, we make the following findings of infringement :

(1) Larsen Patent No. 1,948,457

Claims 9,12,13,14 and 18 infringed by the Vertol HUP-1 helicopter.

Opinion of the Court

(2) Cierva Patent No. 1,994,465

Claims 1, 5, 6, 7, 10 and 13 infringed by the Yertol HUP-1.

(3) Larsen Patent No. 1,990,291

Claims 4 and 6 infringed by the Hiller H-23A, the Bell HTL-4, and the Vertol HUP-1 helicopters; Claim 5, by the Vertol HUP-1.

(4) Larsen Patent No. 2,151 215

Claims 1, 2, 3, 5, 6, 8 and 9 infringed by the Kaman HOK-1 helicopter.

(5) Campbell Patent No. 2,339,836

Claim 1 infringed by the Kaman HOK-1.

(6) Campbell Patent No. 2,321,572

Claims 8, 9, 28 and 29 infringed by the Kaman HOK-1.

(7) Campbell Patent No. 2,344,966

Claim 1 infringed by the Kaman HOK-1.

(8) Bermeit Patent No. 2,344,967

Claims 1, 2, 3, 4, 13 and 18 infringed 'by the Kaman HOK-1.

(9) Cierva Patent No. 2,380,583

Claims 56, 59, 60, 64 and 65 infringed by the Vertol HUP-1 and the Vertol H-21B; Claim 62, by the McCulloch MC-4C.

(10) Cierva Patent No. 2,421,364.

Claims 33, 44 and 45 infringed by the Kaman HOK-1.

(11) Cierva Patent No. 2,380,582

Claims 6, 7, 8, 9,12,13,16 and 17 infringed by the Bell HSL-1 helicopter; Claims 1, 2, 3, 4, 5, 7, 8, 9,12,13, 16, 17, 18, 19, 20 and 21 by the McCulloch MC-4C, the Vertol HUP-1, and the Vertol H-21B.

Patent Validity

All claims found infringed by the trial commissioner were also found valid. Neither party has properly excepted to any findings of fact on validity. Only on claims found infringed is it necessary to reach a decision on validity. This results from the fact that infringement of an invalid patent is the same as noninfringement. Therefore, we adopt the trial commissioner’s findings of validity on all claims found infringed.

On all claims found not infringed, we do not reach the question of validity. We take this approach notwithstanding the argument that the validity issue should be reached whether or not there has been a finding of infringement. See concurring opinion of Judge Frank in Aero Spark Plug Co. v. B. G. Corp., 130 F. 2d 290, 292 (2d Cir. 1942). The argument for deciding validity is based on the ground that there is more at stake than only the issue of validity between the two parties. There is a public interest that must be served—an interest that should know the state of a patent so that onerous and unnecessary license and royalty arrangements could be avoided. Unlike this case, the issue of validity was squarely raised on appeal in the Aero Spark Plug Co. case. Ibid. This distinction is important; otherwise, this court would be required to do the same work we felt outside our scope on the unexcepted-to infringement issues. The Supreme Court has recognized this practice of not treating the issue of validity when it is not properly raised. Exhibit Supply Co. v. Ace Patents Corp., supra. Furthermore, we find that deciding validity does not substantially serve the public interest. A finding of invalidity might have some psychological value in that a patentee with a court’s holding against validity might not be able to exert the pressure against an alleged infringer that a patentee with an unblemished court record might. There is scant legal value to be derived from a holding of invalidity. Only the defendant may collaterally use the holding in a subsequent action against plaintiff. No third party not in a privy relationship with the parties may avoid litigation by the use of collateral estoppel. See Teehnograph Printed Circuits Ltd. v. United States, 178 Ct. Cl. 543, 372 F. 2d 969 (1967). Although the patentee might be, in Judge Frank’s terms, “wiped out” in this suit, he is not, at least in this court, “wiped out” for good.

In summary, we find valid all claims found infringed. Of. ait. supra, section IY.

Oonolusion

Since plaintiff is the lawful owner of all claims found valid and infringed, it is entitled to recover “reasonable and entire compensation” for the unauthorized use of these claims. Judgment is entered to that effect. The extent of liability will be determined in further proceedings before the trial commissioner, pursuant to Rule 47 (c).

Affendix I

CIERVA PATENT NO. 1,947,901

3. In an aircraft, a sustaining rotor construction having blades mounted for movement with respect to an axis member and so proportioned that, under the influence of air currents, the blades have an average autorotational speed at the tip substantially in excess of the maximum flight speed of which the craft is capable, the blades of the rotor being of an aerofoil section of substantially fixed center of pressure, and arranged, with respect to the axis member, in such manner as to be free to assume positions of equilibrium between inertia and lift forces at various points in their general path of rotative travel and said blades being set at a positive incidence calculated with respect to the no-lift position relative to a plane perpendicular to the axis of rotation.

PREWITT PATENT NO. 2,380,581

28. Aircraft comprising a hub, blades mounted on the hub and arranged for variable pitch angles and comprising with the hub a rotor, means manually actuated to govern the pitch angles of the blades, centrifugal means operatively associated with the rotor and responsive to increase of rotational speed to urge the blades toward increased pitch angles, and adjustable resilient means operatively associated with the centrifugal means to vary the speed at which such urge is neutralized.

29. Aircraft comprising a rotatable wing system, the blades of which have variable pitch angles, said system being adapted to accommodate differential flight forces, means for manually changing said pitch angles, governing means for changing said pitch angles, and means modifying the effectiveness of the governing means to change the speed at which the pitch angles are affected.

36. Aircraft comprising a hub, blades mounted on the hub and 'arranged for variable pitch angles and comprising with the hub a rotor, means manually actuated to govern the pitch angles of the blades, and centrifugal means operatively associated with the rotor and responsive to increase of rotational speed to urge the blades toward increased pitch angles.

37. In aircraft, a rotatable wing system comprising a rotor having blades which have variable pitch angles, means for manually changing said pitch angles, and supplemental governing means in part at least mounted on the rotor for changing the pitch angles of said blades.

3-8. Aircraft comprising a hub, blades mounted on the hub and arranged for variable pitch angles and comprising with the hub a rotor, centrifugal means operatively associated with the rotor and responsive to variations of rotational speed to urge the blades toward changed pitch angles, and means manually actuated to override the centrifugal governor means to provide for positive manual setting of the pitch angle.

42. A rotative winged aircraft having a sustained rotor comprising a rotatable hub and a blade pivotally connected therewith for upward and downward swinging movement to compensate for differential lift effects in translational flight, the blade mounting on the hub further incorporating means providing for variation of blade pitch angle, means manually actuated to govern the pitch angle of the blades, and centrifugal means operatively associated with the rotor and responsive to variations of rotational speed to urge the blade toward changed pitch angle.

CIERVA PATENT NO. 2,380,583

59. For an autorotatable sustaining rotor for aircraft, a rotary wing or blade having a flapping pivot mounting and incorporating mass elements additional to structural requirements, said mass elements being concentrated along tbe leading edge of the blade near the tip thereof.

64. In an aircraft, an autorotatable sustaining rotor adapted to accommodate differential flight forces and comprising a plurality of aeroform blades with means for varying the effective pitch of the blades, each of said blades being of substantially fixed center of pressure section and having its sectional mass center at least as far forward as its aerodynamic center.

65. A variable-pitch flapping rotor blade having the blade features set forth in Claim 64.

CIERVA PATENT NO. 2,216,162

7. In an aircraft having a sustaining rotor comprising a hub, a plurality of autorotatable blades and pivot mechanism mounting said blades on said hub, independently operatable disconnectible drive means for the rotor and independently operatable means for raising and lowering the effective pitch of the blades of the rotor, and an interlock between said two independent means mounted for movement betwen operative and inoperative positions.

8. In an aircraft having a sustaining rotor comprising a hub, a plurality of autorotatable blades and pivot mechanism mounting said blades on said hub, independently operatable disconnectible drive means for the rotor and independently operatable means for raising and lowering the effective pitch of the blades of the rotor, and a movable flight control for the craft adapted in at least one position to interlock said two independent means.

22. The combination, in an aircraft, of a power plant, an autorotatable sustaining rotor including a generally upright hub and blades pivotally secured thereto including mechanism for varying the effective pitch of the blades, mechanism for driving said rotor from said power plant, a separately op-eratable control for each of said mechanisms, and means for interconnecting said controls at will for common operation.

CIERVA PATENT NO. 2,421,364

53. In an aircraft capable of substantially vertical take-off and descent, a sustaining rotor rotatable about a generally upright axis and adapted to accommodate or compensate for differential flight forces and having means of direct rotor control effective in vertical flight, comprising an elongated aeroform sustaining blade, capable of autorotation at positive pitch, said blade having a root connection adapted to mount the blade at a point on its longitudinal axis, said connection incorporating means for varying the effective pitch of the blade by movement about an axis approximately intersecting the axis of rotation, said blade having a biconvex profile and a construction providing flexibility in the direction transverse to its rotational path with freedom to yield under varying thrust, the blade further having its mass center substantially on said longitudinal axis1.

54. In an aircraft sustaining rotor rotatable about an upright axis and constructed for yielding in the flapping sense sufficiently to accommodate differential lift effects due to translational flight, an elongated aeroform sustaining blade, capable of autorotation, having a root connection adapted to mount the blade at a point on its longitudinal axis, said connection including a pitch varying pivot whose axis approximately intersects the axis of rotation, said blade having a bi-convex profile and being of a construction providing flexibility in the flapping sense and having its sectional mass center located on said longitudinal axis.

55. In an aircraft sustaining rotor adapted to accommodate or compensate for differential flight forces, an elongated aeroform sustaining blade, capable of autorotation, having a blade-swinging pivot whose axis intersects the general axis of rotation to provide for up and down blade-swinging and a pitch-varying pivot disposed in a plane approximately containing the longitudinal axis of the blade and the axis of rotation, and being of a profile and structure providing a mass center location for the blade substantially on said longitudinal axis.

56. In an aircraft sustaining rotor adapted to accommodate or compensate for differential flight forces, an elongated aeroform sustaining blade, capable of autorotation, having a blade-swinging pivot whose axis intersects the general axis of rotation to provide for up and down-blade swinging and a pitch-varying pivot disposed in a plane approximately containing the longitudinal axis of the blade and tbe axis of rotation, and having a bi-convex profile and being of a structure providing a mass center location for the blade substantially on said longitudinal axis.

60. In an aircraft, a sustaining rotor adapted to accommodate or compensate for differential flight forces, an elongated aeroform sustaining blade, capable of autorotation, having a blade-swinging pivot whose axis intersects the general axis of rotation to provide for up and down blade-swinging and a pitch-varying pivot disposed in a plane approximately containing the longitudinal axis of the blade and the axis of rotation, and being of a profile and structure providing a mass center location for the blade substantially on said longitudinal axis, and means for controllably varying the path of rotation of the blade to maneuver the aircraft.

CIERVA PATENT NO. 2,380,580

1. In an aircraft, a principal means of support in flight comprising a sustaining rotor of the autorotatable-wing type having a substantial vertical rotational axis hereinafter referred to as the rotor axis, means for controllably tilting said rotor axis in relation to the body of the aircraft in at least one generally vertical plane about at least one real or virtual pivot axis, characterized in that any such pivot axis is located above the center of gravity of the aircraft, that the point of intersection of the rotor axis with the projection of the line of resultant aerodynamic reaction of the rotor on a plane containing both the rotor axis and the shortest distance between the rotor axis and said pivot axis is above said pivot axis, and that the said pivot axis is offset from the rotor axis in the direction of the aerodynamic reaction line so that in no condition of forward flight does the rotor axis lie between the aerodynamic reaction line and the said pivot axis, the limiting case in which the said pivot axis passes through the said point of intersection being included.

3. An aircraft in accordance with Claim 1, in which the pivot axis is arranged for longitudinal tilting of the rotor and extends generally transversely of the craft.

4. An aircraft in accordance with. Claim 1, in which, the pivot axis is arranged for lateral tilting of the rotor and extends generally longitudinally of the craft.

8. In an aircraft, a rotative sustaining system including an upright axis structure, blade or wing means adapted to be aerodynamically rotated about said axis structure as a center and mounted for movement with respect to said structure about an axis substantially intersecting the axis of said structure, and control mechanism for the wing means providing for controllable shifting of the lift line of said system, the mounting of each wing including two individual articulations angled to each other and to the longitudinal axis of the wing, whereby to minimize control loads.

10. In an aircraft, a sustaining and controlling rotor blade system comprising a rotatable aeroform blade normally positioned in flight at positive-lift incidence relative to its general rotational path, pivot mechanism for said blade system incorporating a plurality of pivot axes which provide for blade movements for control purposes as well as to compensate for differential flight forces and minimize gyroscopic effects, said mechanism providing an axis of blade oscillation transverse to the general axis of rotation and a rocking axis approximately intersecting said axis of oscillation, both of said axes substantially intersecting the general axis of rotation, and mechanism for controlling said rotor blade system comprising a pilot’s control member mounted for movement in a plurality of planes and coupled with pivoted parts of said system by control connections adapted to effect blade movements which tilt the lift line of said system in like sense to the direction of movement of said member by the pilot.

11. In an aircraft, a sustaining and controlling rotor blade system comprising a rotatable aeroform blade normally positioned in flight at positive-lift incidence relative to its general rotational path, power drive means for said system adapted to provide also for autorotational operation of said system, pivot mechanism for said rotor blade system incorporating a plurality of pivot axes which provide for blade movements for control purposes as well as to compensate for differential flight forces and minimize gyroscopic effects, said mechanism providing an axis of blade oscillation transverse to the general axis of rotation and a rocking axis approximately intersecting said axis of oscillation, both of said axes substantially intersecting the general axis of rotation, and mechanism for controlling said rotor blade system comprising a pilot’s control member mounted for movement in a plurality of planes and coupled with pivoted parts of said system by control connections adapted to effect blade movements which tilt the lift line of said system in like sense to the direction of movement of said member by the pilot, said power drive means being constructed and arranged to permit free blade pivotal movements and operation of the control mechanism under all flight conditions.

12. A construction according to Claim 10 incorporating means by which the system acts to stabilize the craft at a certain flight attitude for a given flight speed.

13. A construction according to Claim 10 incorporating non-rebounding damping means exerting a restraint upon the controllable operations of said system.

14. A construction according to Claim 10, together with resistive means acting to restore said blade to a given general path of rotation relative to the aircraft when their relationship is aerodynamically disturbed.

15. In an aircraft, a sustaining and controlling rotor comprising elongated rotatable blade means, a centrally open rotor hub member, a rotor supporting member projecting upwardly into the central opening of the hub member, pivot mechanisms for respectively mounting the blade means on the hub member and the hub member on the supporting member having pivotal axes intersecting each other and the axis of rotation of the rotor to provide both for rocking movement of the blade means for control purposes and for swinging movement of the blade means to accommodate differential flight forces, and manually regulable means for controlling rocking movement of the blade means, whereby to control the attitude of the aircraft laterally and longitudinally.

38. In an aircraft, a body having toward the rear thereof normally fixed vertical and horizontal tail surfaces for directional and longitudinal stability, a streamlined rotor mounting pylon above the- body, an antorotatably actuable sustaining rotor connected to the body by said pylon and having flappingly pivoted wings, means acting upon the rotor for shifting the path of rotation of the wings so as to shift the rotor lift-line both laterally and longitudinally for control purposes, said streamlined pylon housing the control connections to the rotor and being positioned as upright for surfacing for coaction above the center of gravity with the controllable rotor in laterally stabilizing and controlling the craft.

CIERVA PATENT NO. 2,380,582

16. In an aircraft, a rotor comprising a hub member adapted to rotate about a generally upright axis and a radially extending blade having a root end mounting member, mechanism for pivotally interconnecting the hub and said mounting member to provide for pivotal movements of the blade as a whole with respect to the hub, said pivot mechanism including a flapping pivot providing freedom for upward and downward swinging movement of the blade during normal flight maneuvering, and the pivot mechanism further including a pitch change pivot operatively interposed between the flapping pivot and the blade mounting member whereby the pitch of the blade may be altered as a unit without shifting the position of the flapping pivot, and controllable means for cyclically varying the pitch angle of the blade in synchronism with rotation of the rotor including a pilot’s control and connections coupled with the pilot’s control and extended therefrom beyond the flapping pivot to the root end blade mounting member, said connections being flexibly-jointed adjacent the flapping pivot axis to accommodate the swinging movements of the blade on the flapping pivot without introducing extensive pitch change movements as a result of said blade swinging movements.

17. A construction according to the preceding claim, with control means adapted to alter the mean blade pitch, said control means and the controllable means for cyclically varying the pitch being independently operatable.

Cowen, Chief Judge,

concurring in part and dissenting in part:

With deference to the majority and with due recognition of the time and study which Judge Durfee and my associates who join with him have devoted to the consideration of this case, I am unable to agree with that portion of the court’s opinion which relates to Cierva Patent No. 1,947,901, referred to as the ’901 patent.

As the trial commissioner pointed out in his opinion, helicopters with power-driven rotary wings and gyroplanes with wind-driven (autorotation) rotary wings are both broadly old and both types are rotary wing aircraft. In resolving the issue, it is important to bear in mind that throughout the history of the prosecution and issuance of the ’901 patent, claims of two different kinds were present in the application for the patent — first, claims which are concerned only with rotary wing aircraft and, second, claims which relate to aircraft containing both rotary wings and fixed aerofoils or wings. The original application (def. ex. 94) filed in 1930 presented more than 30 claims, including 14 claims which did not refer to or include a fixed wing and a number of others which recited a fixed wing as an element of the combination. Moreover, of the 30 claims included in the ’901 patent, 14 do not recite or refer to fixed wings or aerofoils. These are Claims 1,2, 3,18, 19 and 24 through 32.

The first sentence of the ’901 patent application states that the invention relates to improvements in rotary wing aircraft disclosed in the applicant’s earlier Patent No. 1,590,497. That patent, which was issued in 1926, disclosed a rotary wing aircraft without a fixed wing.

As shown in the trial commissioner’s finding 25, Claim 3 of the ’901 patent involved here, does not define relationships between the rotary wing system and a supplemental fixed wing. Instead, it pertains to a sustaining rotor construction having features of proportioning and disposition of the rotor blades, which are of airfoil section in a swingingly-pivoted arrangement and with the rotor blades having a positive incidence setting. Claim 3, tabulated to show the elements thereof, reads as follows:

In an aircraft,
1. a sustaining rotor construction having blades
(a) mounted for movement with respect to an axis member
(b) and so proportioned that, under the influence of air currents, the blades have an average autorotational speed at the tip substantially in excess of the maximum flight speed of which the craft is capable,
(c) the blades of the rotor being of an aerofoil section of substantially fixed centre of pressure,
(d) and arranged, with respect to the axis member, in such manner as to be free to assume positions of equilibrium between inertia and lift forces at various points in their general path of rotative travel
(e) and said blades being set at a positive incidence calculated with respect to the no-lift position relative to a plane perpendicular to the axis of rotation. [Indentation and numbering added.]

In describing the improvement of the invention covered by the ’901 patent over the earlier ’907 patent, the inventor states:

I have further found that I can best attain these desirable results, at least when employing substantially symmetrical blade sections, with an individual positive-incidence setting of the blades on their common axis, of preferably around 2° or 3°, but not more than 5°, as compared with the substantially neutral setting illustrated in my said Patent No. 1,590,497. This is productive of two rather striking results: first, that at rather slow speeds of translational movement of the craft, the rotor operates at a somewhat slower speed of rotation than one with blades set at no-lift or at a slight negative incidence, but with increased lifting efficiency and decreased frictional resistance; and second, at higher speeds of the craft, the rotor tends to run materially faster than its rotational speeds at low speeds of the craft, rather than slower or substantially constant as is respectively the case with rotors, in which the effective blade incidence is negative or neutral; all of which produces an important result, later to be considered.

Eeference to the positive incidence setting of the rotor blades is made in six separate paragraphs of the specifications dealing with the purposes and advantages of the ’901 invention.

The decision of the majority is based upon its conclusion that the term “so proportioned” in Claim 8 means a relationship between rotor blades and fixed wings. Since the accused helicopters have no fixed wings, the court holds that Claim 3 has not been infringed. In reaching that result, the majority relies primarily upon three quotations from the specifications. The first of these refers to a proportioning and disposition of the blades and blade system and the “relation thereof” to the fixed lifting surfaces. I interpret the first portion of the quotation as a reference to a proportioning of the rotor blades themselves in an aircraft without fixed wings for the purpose of achieving the results described in Claim 3. I read the second portion of the quotation as a statement that for other claims including both fixed and rotary wings, there is a relationship between the rotor blades and the fixed wing. There is no statement that the rotor blades are proportioned to the fixed wings.

The second quotation from the specifications in the court’s opinion is no more than an illustrative embodiment of what the inventor conceived to be the best mode of using his invention, i.e., by employing it in an aircraft having both fixed and rotary wings. There is no reference in this second quotation to “proportioning” of the rotor blades.

The third quotation from the specifications appears in footnote 19 of the court’s opinion. Here again is an illustrative embodiment of what the inventor considered the most advantageous use of Ms invention—a use to wMch tlie patent does not confine him. The quotation does not mention proportioning of the rotor blade system. Instead, the specification states that if one uses an aircraft combining both fixed and rotary wings in the particular embodiment of the invention there described, the total area of the fixed wings should be proportioned to the area of rotor blades within a range of 50 percent to 100 percent. When read in connection with the other claims, it is perfectly clear that Claim 3 covers only a sustaining rotor construction. In that context, the claim refers to a proportioning of the rotor blades to achieve the tip speed described. Therefore, I find no basis in the quotation for reading into Claim 3 a limitation that pertains only to a proportioning of the fixed wings to the rotor blades in aircraft where both types of wings are employed.

In my view, the court has utilized certain illustrative embodiments in the patent specifications for the purpose of engrafting on Claim 3, which does not involve fixed wing aircraft, a limitation which pertains only to fixed wing aircraft. It seems to me that such an interpretation is contrary to the holding of this court in Zonolite Co. v. United States, 138 Ct. Cl. 114, 123, 149 F. Supp. 953, 958 (1957), wherein the court stated:

Patent specifications and drawings are not to be read so as to limit the scope of the claim recital where the claim recital is clear and unambiguous. WMle claims should be construed in the light of the specifications and drawings to obtain an understanding thereof, the illustrative embodiments specified are not to be read into the claims. See White v. Dunbar, 119 U.S. 47, 51-52 (1886). The claims alone define what is covered by the patent. See Kuhne Identification Systems, Inc. v. United States, 82 C. Cls. 237, 258 (1936).

The reason for the rule, particularly in cases where an illustrative embodiment that represents the inventor’s conception of the best use of the invention is offered as a defense to infringement, was set forth by the Supreme Court in Continental Paper Bag Co. v. Eastern Paper Bag Co., 210 U.S. 405 (1908) :

We think it is clear that the court considered that Liddell sought to comply with § 4888 of the Revised Statutes. In other words, he filed a description of his invention, explained its principle and the best mode in which he “contemplated applying that principle,” and did not intend to give up all other modes of application. An inventor must describe what he conceives to be the best mode, but he is not confined to that. If this were not so most patents would be of little worth. [Footnote omitted]

Id. at 418.

It is my conclusion that Claim 8 of the ’901 patent defines an invention in which the rotor blades are so proportioned in shape, area, and incidence with relation to the weight of the aircraft as to produce a tip speed that gives greater efficiency in the operation of a rotary wing aircraft. That conclusion is based upon a consideration of the file wrapper, a study of the entire ’901 patent, the prior art, and the testimony of expert witnesses — all as reflected in the trial commissioner’s findings of fact.

In determining the meaning of the term “so proportioned,” I would turn first to the application file. Connecticut Valley Enterprises v. United States, 172 Ct. Cl. 468, 475, 348 F. 2d 949 (1965); Mastini v. American Telephone & Telegraph Co., 236 F. Supp. 310, 314 (S.D.N.Y. 1964), aff'd, 369 F. 2d 378 (1966).

The term “so proportioned” was used in several of the original claims in the ’901 patent. For example, original Claim 22 referred to a proportioning of the rotor blades so that under the influence of air currents, the blades would have a rotational speed as described. No reference was made to fixed wings. Claim 22 was amended to state that the blades were “so proportioned with respect to the weight of the craft.” (def. ex. 49, p. 24). In seeking the allowance of Claim 22, the applicant argued (def. ex. 49, p. 122) that “the claim as amended brings out the proportioning of the blades with respect to the weight of the craft in such manner that even with a positive-lift incidence setting the tip speed will have the relationship set forth in the claim.” Thus, it is clear that the term “so proportioned” has been in the ’901 patent disclosure since the application was filed in 1930. Since the definition given by the applicant was not questioned by the Patent Office, it seems to me that the inventor’s interpretation should be controlling. It should also be noted that in the application, Claims 1-4 (def. ex. 49, pp. 16-17), Claims 18-20 (def. ex. 49, pp. 23-24), and Claim 30 (def. ex. 49, pp. 28-29) included no references to fixed wing aircraft.

It is proper to look at other claims in the patent to determine the interpretation of a particular claim involved in a case. United States v. Adams, 383 U.S. 39, 49 (1966). In reaching its interpretation, the majority has compared Claim 3 with Claims 4-7 and 8-17, all of which refer to a fixed wing or fixed aerofoil. However, I would contrast Claim 3 with Claim 4 and compare Claim 3 with Claim 18. Claim 4, which relates to aircraft having both rotary and fixed wings, reads as follows:

4. In an aircraft, a sustaining rotor construction having blades mounted for movement with respect to an axis member and so proportioned that, under the influence of air currents, the blades have an average rotational speed at the tip substantially in excess of the translational flight speed of which the craft is capable, the blades of the rotor being arranged, with respect to the axis member, in such manner as to be free to assume positions of equilibrium between inertia and lift forces at various points in their general path of rotative travel, together with a substantially -faced aerofoil of an effective area approximating 60% to 100% of the area of the rotative blades. [Emphasis supplied.']

It is noteworthy that the first portion of Claim 4, like Claim 3, refers to a proportioning of the rotor blades to attain the tip speed described. By contrast, the last clause in Claim 4, which includes a fixed wing, recites a specific percentage of the area of the fixed wing to the area of the rotative blades.

Claim 18, which covers rotary wing aircraft, states in part as follows:

* * *; said wings having in flight, when at an intermediate position of pivotation, an average autorota-tional incidence which is at positive-lift with relation to a plane perpendicular to the axis of rotation; the elongated form, the area and the average incidence of said rotative wings being so proportioned with relation to the weight of the craft that with the full burden of sustention falling upon said rotor the wings thereof have an average rotational speed at the tip greater than the top forward speed of which the craft is capable under the influence of said forward propulsion means. [Emphasis supplied.]

Since Claim 3 recites no fixed wing, I would utilize the underlined statement in Claim 18 for determining the proper interpretation of the term “so proportioned” as it is used in Claim 3.

The defendant contends that the trial commissioner’s ultimate findings of fact and recommended conclusions of law are based entirely upon the language of Claim 3 without regard to other pertinent evidence. A mere reading of the findings demonstrates the complete inaccuracy of that contention and shows that the findings on validity and infringement resulted from a two-step process:

First, a determination of the meaning of Claim 3 from a consideration of all the relevant evidence, including the patent, the application file, the prior art, and the testimony of many witnesses.

Second, a determination that the accused helicopters do substantially the same work in substantially the same way and accomplish the same result as the invention recited in Claim 3.

In its relatively few exceptions that comply with the rules of this court, defendant has relied upon certain parts of the patent specifications to support its argument that Claim 3 is concerned exclusively with rotary wing aircraft having supplemental fixed wings. In my judgment, the trial commissioner’s findings 11-23, 362, 364, 366, 368, 380 and 381 effectively dispose of the fixed wing defense. His findings 24r-45, inclusive, deal with the features of the invention disclosed in Claim 3, and are based upon the specifications, the drawings, the file wrapper, and the testimony of the witnesses. Such findings, both evidentiary and ultimate, sustain a conclusion that the subject matter of Claim 3 is not limited to fixed wing aircraft. In his findings 48 to 56, inclusive, 57 to 65, inclusive, and 66 to 74, inclusive, the trial commissioner has shown in clear detail how the accused helicopters incorporate the combination of elements defined in Claim 3 of the ’901 patent, operate in the same manner, and produce the same result. Since each of the findings enumerated above is well supported by the record, I would adopt them as separate findings of fact and as the basis for a conclusion of law.

Under our rules and especially in a case like this where a vast amount of evidence is offered by both parties and where there is conflicting testimony of expert witnesses, the trial commissioner’s findings are presumed to be correct. In my opinion, the defendant has not made the strong affirmative showing that would justify the rejection of such findings. Davis v. United States, 164 Ct. Cl. 612, 616-17 (1964); Dodge Street Building Corp. v. United States, 169 Ct. Cl. 496, 501, 341 F. 2d 641, 644 (1965). It seems to me that a careful adherence to our rule is called for in this case. The record is one of the most voluminous that has ever been presented in litigation in this court. The determination of the many factual issues requires not only a balancing of the credibility of the witnesses and an assessment of the weight to be accorded to the documentary evidence but a knowledge and understanding of the scientific principles so extensively involved in this action. In view of the training and experience of the trial commissioner in such matters, I would not disturb his findings of fact with respect to the ’901 patent on the basis of what I regard as an inadequate showing to the contrary.

For the reasons stated above, I would hold that Claim 3 of the ’901 patent is valid and has been infringed. As to the other patents involved in this action, I concur in the court’s decision.

Collins, Judge, joins in the foregoing opinion concurring in part and dissenting in part.

FINDINGS OP PACT

The following are the findings of fact for all claims and infringing structures not properly excepted to. All other findings of fact are stated in the opinion. See, e.g., Oro Fino Consolidated Mines, Inc. v. United States, 118 Ct. Cl. 18, 92 F. Supp. 1016 (1950), cert. denied 341 U.S. 948 (1951); Farnsworth and Chambers Co. v. United States, 171 Ct. Cl. 30, 346 F. 2d 577 (1965); United Contractors v. United States, 177 Ct. Cl. 151, 368 F. 2d, 585 (1966); Williamsburg Drapery Co. v. United States, 177 Ct. Cl. 776, 369 F. 2d, 729 (1966); Beckham v. United States, 179 Ct. Cl. 539, 375 F. 2d 782 (1967), petition for cert. filed Oct. 30, 1967 (No. 774).

LARSEN PATENT NO. 1,948,457

1. Larsen patent 1,948,457, hereinafter referred to as the '457 patent, issued to plaintiff February 20, 1934, on an application filed June 29, 1931. The '457 patent relates to rotating-wing aircraft sustaining rotors and particularly to improved mechanisms or devices for restricting and controlling pivotal movement of rotor blades about their vertical or drag pivots. Such devices may be referred to as blade damper mechanisms. Vertical or drag pivots of blades of rotating-wing aircraft are pivots which allow fore-and-aft or lead-lag motion of the blades in their plane of rotation.

2. The '457 patent specification states in part:

* * * sustaining rotors of the character here involved generally include means whereby the individual blades thereof may be free to assume various positions, under the influence of inertia, lift, drag and antidrag and other forces to which they are subjected in flight operation. To this end each rotor blade is preferably pivoted or articulated to a central axis or hub mechanism to provide for individual movement of the blades both within as well as transversely of their general path of rotative travel about the central axis mechanism. At least under certain conditions or with craft of certain characteristics, it is desirable to control or partially restrict some individual blade movement.
* jji tje $
The present invention is primarily concerned with an improved mechanism or device which is adapted to restrict or control certain individual blade movements in rotors of the character here involved. Among the motor important objects of the invention might be mentioned : Generally improved operation of devices of this type; reduction of parasite drag and the like in the rotor as a whole; simplification of construction and operation of the parts employed; and the provision of means for conveniently and readily adjusting the reaction or resistance of the device to blade movement.

3. Plaintiff relies on claims 9,12,13,14 and 18 of the '457 patent. These claims read as follows: (Indentation and numbering added.)

Patent Claim 9 of '¡¡57
An aircraft including
1. sustaining blades mounted for rotation about a common axis,
2. pivot joints for the blades providing for movement thereof in addition to their common rotation,
3. and means for controlling pivotal blade movement, said means including
(a) opposed abutment means associated with blade parts at each side of a pivot joint
(b) and a fluid pressure device arranged to react between the opposed abutment means.
Patent Claim 1% of '¡¡57
An aircraft including
1. sustaining blades mounted for rotation about a common substantially vertically disposed axis,
2. an axis structure,
3. pivot joints interconnecting the blades and the axis structure,
4. and non-rebounding means for resisting pivotal blade movements,
(a) said means being 'disposed adjacent said pivot joints.
Patent Claim 13 of '457
A rotatably mounted multi-bladed sustaining unit for aircraft including
1. articulations for the blades providing for blade movement in addition to the rotational movement,
2. and mechanism for controlling additional blade movement,
(a) said mechanism including a non-rebounding damping device operative between blade articulation parts.
Patent Claim 14 of '457
In an aircraft of the rotative blade type,
1. a head structure including an axis mechanism for a plurality of blades,
2. the blades being provided with pivot joints disposed near the head structure,
8. and non-rebounding means for resisting pivotal blade movements,
(a) said means also being disposed, at least in large part, near the head structure.
Patent Claim 18 of '457
An aircraft including
1. sustaining blades mounted for rotation about a common axis,
2. pivot joints for the blades providing for movement thereof in addition to their common rotation,
3. and means for controlling pivotal blade movement, said means including
(a) opposed abutment means associated with blade parts at each side of a pivot j oint
(b) and a non-rebounding movement resisting device arranged to react between the opposed abutment means.

4. The terms restricting and controlling used in describing the operation and effect of the blade damper mechanisms disclosed in the '457 patent refer to resisting or restraining the pivotal movements of the rotor blades about their vertical or drag pivots, rather than to absolutely limiting or manually controlling such lead-lag movements.

5. The '457 patent drawings show several modifications of the Larsen invention. Figs. 1-8 and 12-14 taken with portions of the '457 patent specification illustrate the subject matter of the claims in suit. As shown in fig. 1, which is a top plan view of the gyroplane type of rotating wing aircraft with reference to which the subject matter of the '457 patent is described and illustrated, the rotor, having a plurality of blades 27, is mounted above the body of the aircraft and affords the major portion of the lift at all times and substantially the entire lift when making a vertical or substantially vertical descent. The blades of such a rotor are sustaining rotor blades. The central hub or axis member 28 as indicated in fig. 1 is rotatably mounted to the top of a pyramid or pylon structure having upwardly converging supporting legs 29. A fragmentary showing of the rotative portion of the central hub member is also indicated at 28 in fig. 2 and has pro-j ecting forks 31 apertured to receive the flapping pivot pins 33 which pins connect blade links 32 to the hub structure. The other ends of the blade links 32 are forked and have holes to receive the vertical or drag pivot pins 36 which pivotally connect to the blade links 32 apertured lugs 34 of the blade spars 35. The attachment of the blades to the links 32 through the pins 36 constitutes drag pivot joints, and each of the rotor blades as illustrated in fig. 1 has its own drag pivot joint, which provides for blade movement substantially within the general path of travel thereof. Said pivotal mounting of the rotor blades allows the blades freedom to move fore-and-aft in their plane of rotation and to seek positions of equilibrium between centrifugal and drag forces, including aerodynamic drag forces and components of inertia and lift forces which act on the blades in their plane of rotation. Such an equilibrium position or condition of an auto-rotatively operating rotor blade about its drag pivot is also a condition of equilibrium of a helicopter rotor blade having a drag pivot and being power driven.

6. The blade damper mechanism in figs. 2 and 3 includes the lever or arm 63 which is rigidly fastened to the top of the drag pivot pin 36, and the outer end of arm 63 is connected to the blade spar 35 by a clamp structure 65 having adjustable bolts 66. In figs. 3, 7 and 8, the drag pivot pin 36 extends into a casing 37 and is mounted therein so as to turn within the casing as arm 63 moves with the blade in the lag-lead sense. The casing 37 has hydraulic mechanism which resists movement of the pin 36 which carries at its lower enlarged end 45 vanes 46 that move within separated hydraulic fluid chambers a-c and b-d in the bottom of casing 37. The casing is fixedly attached by bolts 39 to the blade link 32. The attachment of casing 37 to the blade link 32 forms one of the reaction points or abutments against which the blade damper mechanism reacts, and is located on the hub side of the drag pivot joint. The other reaction point or abutment for the blade damper mechanism is provided 'by the attachment of arm 63 through the clamp 65 to the blade spar 35 and is located on the blade side of the drag pivot joint. These two reaction points provide opposed abutments on the hub and blade sides respectively of the drag pivot joint against which the blade damper mechanism reacts. Under the pressure applied to the fluid by the rotation of the pivot pin vanes 46 when they move within the chambers a-c and b-d the fluid is forced through channels 56 and 57, and the resistance to flow of the fluid through those restricted channels provides the resistance or the restraining action of the damper mechanism for resisting or controlling the pivotal movements of each blade about its drag pivot. A control valve 59 extends downwardly through pin 36 into a central chamber 55 with which the channels 56 and 57 communicate. By adjusting the valve 59, the restriction to flow of fluid through the channels may be regulated and thus adjust the amount of restricting force or restriction that the fluid pressure device of the damper mechanism will give to the blade in its lag-lead motions.

7. Another form of mechanism for restraining the pivotal lag-lead motions of a rotor blade is in figs. 12-14 of the '457 patent drawings. In this embodiment the damper mechanism reacts between articulation parts of an individual blade. In fig. 12, which is a top plan view, the blade spar 35 is secured to the joint part or link 81 by a drag pivot pin 83 which is journaled in the outer forked end of link 81 and passes through an aperture ear 84 connected to the blade spar. The inner portion of link 81 is pivotally connected to a bearing block 79 by the flapping pivot pin 80, the blocks 79 extending from and forming a part of the rotative portion of the rotor hub or axis structure 78. Web members 85 extend laterally from the spar ear 84 and are connected through pins 93 to slotted ears 92 of the casing or cylinder 87 of each damping device 86. The construction of this damping device is shown in longitudinal section in fig. 14. The piston 88-91 of the damping device has an apertured ear 89 at its outer end which is attached by a pin 90 to- a laterally extending flange 82 of the blade link 81. A pair of the damping devices 86 are connected between the blade link flanges 82 and the spar ear webs 85 on opposite sides of the drag pivot joint. The connection of each damping device to the blade link flanges 82 forms the reaction point or abutment for the damping device on the hub side of the drag pivot joint, and the connection of the damping device to the spar ear webs 85 forms the reaction point or abutment for the damping device on the blade side of the drag pivot pin. The damping device 86 is a hydraulic mechanism and operates in a maimer similar to that explained above with reference to the hydraulic unit in figs. 7 and 8.

8. The hydraulic mechanism as disclosed in embodiments of the '457 patent provides a non-rebounding or non-resilient type of damping motion to the pivotal movement of the rotor blades about their drag pivots. This is described in the '457 patent specification as follows:

* j*« # $
It should be noted in connection with this device that the blade-movement control or resistance is non-rebounding or non-resilient in character, this being desirable, for example, as it reduces the tendency to set up more or less violent, and sometimes undesirably synchronized, blade movements.

9. The undesirably synchronized blade movements mentioned above here refer to lag-lead motions of the rotor blade which may become synchronized with the r.p.m. of the rotor or with the natural vibration frequency of the aircraft itself. When such synchronization occurs, a condition of resonance results, and such condition produces uncomfortable and undesirable vibrations in the aircraft and can cause material damage to or destruction of the aircraft.

10. The advantages of the structures disclosed in the '457 patent are summarized in the '457 patent specification as follows:

# * * * *
According to the foregoing the present invention makes provision for control or restriction of individual blade movements, especially on their vertically disposed pivot pins, by the use of devices which are simple as well as effective in operation. Blade interconnecting cables such as those employed heretofore for this purpose become unnecessary, with the result that a more efficient rotor structure, from the standpoint of parasite drag and the like, is provided.
The use of hydraulic damping devices in structures of this character is advantageous as relatively great resistance values may 'be obtained even when employing only relatively small and compact parts and short lever arms from the center of rotation.
Note also that the disposition of the blade-movement control mechanism adjacent to the rotor head structure results in the elimination of parts projecting from and secured to the blades except in the immediate vicinity of the hub. In view of this, the surfaces of the effective lift producing sections or portions of the blades, i.e., their outer portions, remain entirely smooth and regular. The structures of the present invention are also conveniently located for purposes of inspection, repair or adjustment. *****
Finally, all forms keep the damper operating means closely adjacent the blade spar so as to minimize tendency to twist the blades on their pivots.
As to the form of the invention shown in Figures 1 to 8, it will be observed that this has the advantages of a minimum number of parts, a single damping device and operating arm for each blade, independence of the device from the rotor hub and from other blades, and the utilization of the damping device itself as an articulation for the blade.
:fe * # $ *
The construction shown in Figures 12 to 14, in common with the construction of Figures 1 to 8, provides the advantage of having the damping devices move with the blades, during swinging on the horizontal blade pivots, which avoids the necessity of pivoting the operating arms on supplemental transverse pivots such as the pivots 74 which are required in the construction of Figures 9 to 11. Furthermore, this form entirely eliminates any reaction tending to twist the blades with respect to their pivots, since the reaction of the arms is in a central horizontal plane through the longitudinal blade axis.

11. These advantages are of practical significance and importance to the safety and efficiency of operation of sustaining rotor systems having rotor blade drag pivots in both the gyroplane and helicopter types of aircraft. The claims in suit, i.e., claims 9, 12, 13, 14 and 18, of the '457 patent find complete support in the disclosure of the specification and drawings of the patent as issued and also in the application for the patent as filed. The specification and the claims in suit of the '457 patent are sufficiently definite and certain, and are not vague or indefinite.

12. The subject matter as well as the language of the claims in suit of the '457 patent is not limited to aircraft of the gyroplane type, with reference to which the invention is described and illustrated, nor is either the subject matter or language of the claims in suit limited to aircraft sustaining rotors which are air-rotated or autorotatively actuated only or usually. Instead, the invention as defined in the claims in suit is equally applicable to aircraft of the helicopter type, such as defendant’s Vertol helicopters, and including the sustaining rotors thereof, and whether operating under power drive or autorotatively. The definitions of the invention in the claims in suit of the '457 patent were not so limited during the course of the prosecution of the application therefor that said claims can not properly 'be construed to cover defendant’s Vertol helicopters and particularly their sustaining rotors. The date of invention by Larsen of the subject matter of the claims in suit of the '457 patent was at least as early as June 29,1931, the filing date of the United States patent application.

13. Plaintiff has submitted proofs of infringement of the five claims in suit of the '457 patent by defendant’s HUP-1 Vertol helicopter and particularly the construction of both its fore-and-aft rotors. The pertinent mechanism of defendant’s HUP-1 helicopter is described and illustrated in plaintiff’s exhibits 80, 84, 86, 87, 88, 90,108,109,110 and 112. These exhibits are portions of manuals pertaining to the HUP-1 and similar models of defendant’s Vertol helicopters.

14. The HUP-1 helicopter and particularly the construction of both its fore-and-aft rotors incorporates each of the elements of the combination defined in each of claims 9, 12, 13, 14 and 18 of the '457 patent, and each such combination of elements in the HUP-1 helicopter operates in the same manner and produces the same result as disclosed in the '457 patent. The HUP-1 helicopter and particularly the construction of both its fore-and-aft rotors comes within the meaning and within the principle of each of claims 9,12, 13, 14 and 18 of the '457 patent, and infringes said claims.

15. With respect to the '457 patent in suit, defendant has asserted that the '457 patent does not involve invention unless restricted to the specific structure shown in the patent drawings and that it does not provide an unexpected result in view of the following patents:

United States Patents dxno.

1, 859, 584 Cierva. 1932 114.6

1,884,597 Cierva-1932 114.11

1, 894,673 Cierva 1933 114.20

1, 899,096 Larsen 1933 114.24

1, 948,458 Cierva. 1934 115.20

16. The sole purpose of damping or controlling the lead-lag motion of the rotor blade as referred to in the '457 patent is to prevent vibration conditions occurring because of the lead-lag or oscillating movement of the rotor blade in its path of rotation. The five patents listed in finding 15 disclose blade damping mechanisms comprising cables interconnecting adjacent blades of the rotor at about one-half of the blade radius, the cables incorporating flexible, elastic or resilient elements or weights. The patents listed do not disclose the elements or features specifically defined in the '457 patent claims in suit, reproduced in finding S, nor do they disclose damper means adjacent to the pivot joints, articulations, or head structures. The '457 patent claims in suit recite a new combination of elements.

17. The '457 patent claims in suit are not invalidated by either the patents or the theories advanced by the defendant. The '457 patent claims in suit are neither ambiguous nor indefinite.

CIERVA PATENT NO. 1,994,465

18. The subject matter of the Cierva patent 1,994,465 (hereinafter referred to as the '465 patent) relates to rotary wing aircraft, and particularly to mechanism for folding the rotor blades of such aircraft in which the blades are equipped with vertical or drag pivots and with mechanism closely associated with the drag pivots for controlling or partially restricting and also for limiting the movement of the blades about their drag pivots. The subject matter of this patent also relates to the folding of fixed wings in a rotary wing aircraft which is equipped with fixed wings, but the claims in suit do not pertain to this latter subject. The vertical or drag pivots of the blades of a rotary wing aircraft are pivots which provide for the fore-and-aft or lead-lag (also lag-lead) motion of the blades within their plane of rotation. The purpose in so mounting the blades is to allow them freedom to seek positions of equilibrium between centrifugal and drag forces, including aerodynamic drag forces and components of inertia and lift forces which act on the blades in their plane of rotation. Such an equilibrium condition of a rotor blade about its drag pivot is also a condition of equilibrium of a helicopter rotor blade which has a drag pivot and when being power driven in flight.

19. Devices for controlling or partially restricting the lag-lead pivotal movement of rotor blades about their vertical or drag pivots are generally referred to as blade damper mechanisms. The subject matter of the '465 patent is described as relating to aircraft of the type having, as a primary means of sustention, a system of rotatively mounted sustaining blades or wings arranged for normally free rotation under the influence of relative airflow; namely the gyro-plane type of rotary wing aircraft. However, the claimed subject matter as well as the language of the six claims in suit of the '465 patent is not limited to aircraft of the gyro-plane type, nor is either the subject matter or language of the claims in suit limited to aircraft sustaining rotors which are air-rotated or autorotatively actuated only or usually. The invention as defined in the '465 patent claims in suit is equally applicable to aircraft of the helicopter type, such as defendant’s Vertol helicopters, including the sustaining rotors thereof, and whether operating under power drive or autorotatively.

20. The '465 patent specification states in part:

* * * * *
One important general object of this invention is involved in the provision of a novel construction which provides for folding of the rotor blades or wings for purposes of storage m a relatively small space.
* * * * ‡
In addition to the foregoing general objects and advantages, this invention has in view the provision of means for folding the blades or wings of the rotor generally longitudinally of the body of the craft regardless of the number of blades incorporated in the rotor.
♦ # * * *
The pivot or joint means by which the individual blades or wings of the rotor are provided freedom for swinging movements within as well as transversely of their general path of rotative travel, ordinarily include pivot joints having substantially vertically extending axes, and it is an object of the present invention to utilize these vertical pivot joints as a means of folding the blades to a position in which they all extend in one direction from the rotor mount to overlie the body of the craft in a group.
A further object of the invention will appear more clearly if it be borne in mind that, during normal flight operation, it is desirable to limit as well as yieldingly control blade movements about their substantially upright pivots. According to a feature of this invention, stop means for limiting pivotal blade movement, as well as means for cushioning such movement are associated with the joint parts providing the upright pivot axis referred to, and readily removable and replaceable locking means are provided, so as to disconnect or release the blade from the action of the movement limiting and control devices and thus permit the blade to be swung through a relatively large angle about its upright pivot joint. By associating the movement controlling devices with the upright pivot itself, and further by utilizing this upright pivot as the means to effect folding of the rotor, the number, weight and size of parts is materially reduced, this being of especial importance, since it reduces skin friction, parasite drag and the like, all of which impair the efficiency of the rotor.

In the above quotation, “cushioning” refers to the effect of the damper mechanism as it operates to yieldingly resist or control the lag-lead motion of the rotor blades.

21. Plaintiff relies on claims 1, 5, 6,7,10 and 13 of the '465 patent. These claims read as follows: (Indentation and numbering added.)

Patent Claim 1 of '465
In an aircraft,
1. a sustaining rotor including a common axis structure,
2. sustaining blades or wings mounted to rotate about the axis structure,
3. pivot means for the blades arranged to provide freedom for force-compensating blade movements of each blade substantially independently of the other blades in flight, said pivot means being positioned to serve also as a means to provide freedom for blade folding movements when the rotor is at rest,
4. and releasable means located adjacent the axis structure and arranged to prevent unintentional folding movements of the blades on said pivot means.
Patent Olaim 5 of 'J±65
In an aircraft sustaining rotor,
1. a central mounting or hub structure,
2. a rotor blade or wing attached to said structure on a substantially upright pivot joint,
3. means reacting between pivot joint parts at opposite sides of the pivot axis for restricting blade pivotal movements,
4. and manually operable means for providing substantially unrestricted blade pivotal movement about the pivot axis.
Patent Olaim 6 of 'J¡B5
In an aircraft sustaining rotor,
1. a central hub and mounting structure,
2. a sustaining blade,
3. a pivot joint for attaching the blade to said structure including a substantially upright pivot pin,
4. means for yieldingly resisting pivotal blade movements about said pin including a movement damping device connected to and reacting between joint parts at opposite sides of said pin,
5. and means for disconnecting said damping device at least at one side of said pin, whereby to permit substantially unrestricted blade movement about the pin, to facilitate folding of the rotor for storage purposes.
Patent Claim 7 of 'J¡.65
In an aircraft sustaining rotor,
1. a central mounting or hub structure,
2. a rotor blade or wing attached to said structure on a substantially upright pivot joint,
3. means reacting between pivot joint parts at opposite sides of the pivot axis for yieldingly resisting pivotal blade movements,
4. means for limiting pivotal blade movements,
5. and means operable at will to provide substantially unrestricted pivotal blade movement, about said pivot axis, beyond the limits imposed by the limiting means.
Patent Claim 10 of 'lj.65
In an aircraft sustaining rotor,
1. a central bub and mounting structure,
2. a sustaining blade,
3. a pivot joint part connected with said structure,
4. a substantially upright pivot pin for connecting the blade and said part,
5. means for resisting relative rotation of said part and the blade about said pivot pin having connection with the joint part and with the blade to react there-between,
6. spaced stop means connected and movable with said joint part and the blade for limiting relative pivotal movement thereof,
7. and a readily removable locking device operative to disconnect the stop means and the resistive means, whereby to permit substantially unrestricted relative rotation of the joint part and the blade beyond the limits imposed by the stop means.
Patent Claim IS of '1¡¿65
In an aircraft sustaining rotor,
1. a central mounting or hub structure,
2. rotative blades or wings each attached to said structure on a substantially upright pivot joint providing for force compensating movements of the wmgs in flight and for folding movements of the wings when the rotor is at rest,
3. and separate releasable means for each wing arranged to prevent unintentional folding movement of the wings on their pivot joints.

22. The subject matter of the above claims in suit is illustrated by the mechanism shown in figs. 1-6 of the patent drawings in the '465 patent.

23. Fig. 1 of the '465 patent drawings shows in diagrammatic side elevation an aircraft of the gyroplane type, but with the two rotor blades shown as being folded rearwardly over the fuselage. In fig. 2, which is a plan view of the central portion of the rotor, the hub member 20 is rotably mounted on the axis structure 18 which is supported above the fuselage by means of pylon legs 10. In fig. 2, two of the rotor blades have been folded about their drag pivots to bring them parallel to the central blade which has been positioned, by turning the rotor, so as to extend lengthwise back over the fuselage. Hub member 20 has apertured ears 21 which, provide for the pivotal attachment, through flapping pivot pins 22, of blade links 23. These pivotal connections provide for the flapping action of the blade. In fig. 3, the outer end of each blade link 23 is apertured and carries a bearing sleeve 28 through which the upright or drag pivot pin 25 is received for pivotally connecting to the blade link the apertured forks 24 of the blade spar 17a. Fig. 3 is a vertical sectional view showing parts of the inboard portions of a rotor blade and its attachment to the rotor hub and also showing certain portions of a blade movement controlling mechanism. Fig. 4 is a plan view of fig. 3; and fig. 5 is a detailed view of certain attachments and fittings in figs. 2-4.

24. The damper mechanism for yieldingly controlling or resisting the lag-lead motion of the rotor blade, in the upper portion of fig. 3, comprises an assembly of friction discs with friction material interposed between the discs, and with one set of discs attached to and arranged to move with the blade spar and with the other set of discs attached to and arranged to move with the blade link. The friction discs are at 35 and 36 in fig. 3. Discs 36 have projecting lips 41 which extend toward the hub and are held between lugs 40 on the inner portion of blade link 23 in figs. 3 and 4. Discs 35 have projecting lips 42 which extend toward the blade and are held between lugs 43 which project upwardly from plate 38. Plate 38 is connected by rivets or bolts 39 to the retainer plate 28 for the drag pivot 25. The friction discs 35 and 36 and plate 38 are centrally open to fit around the drag pivot retainer plate 28. The portion of plate 38 adjacent the blade spar is connected through a bolt 46 to a bracket block 44 and tie plate 48. The block 44 is shaped to fit around one side of the blade spar 17a. The other side of the blade spar 17a is attached, as by welding 45a, to a bracket 45. A removable locking pin or bolt 49, having an operating handle 52, passes through apertures formed in plate 38, block 45 and tie plate 48. This construction provides for the connection of plate 38 through bracket blocks 44 and 45 to the blade spar 17a. With the plate 38 thus connected to the blade spar, as the blade moves about the drag pivot joint, plate 38 and discs 35 move with the blade, while the discs 36 remain fixed to and move with the blade link 23. This friction type damper, which is closely associated with and reacts between the drag pivot joint parts 23 and 24 on opposite sides of the drag pivot axis, provides for yieldingly controlling or resisting the pivotal movement of the blade in its lag-lead motion about the drag pivot. The amount of friction produced between discs 35 and 36 may be varied by adjusting nuts 56 which are threaded to the top of the pivot spindle 29 which extends upwardly to accommodate a plate 33 overlying the friction damper assembly, and with a rubber compression ring 55 being interposed between plate 33 and the upper friction disc 35. Flanges 38a attached to plate 38 support abutments or stop members 53 which have rubber bumpers 54 affixed thereto. The stop members 53 are adjacent the axis structure and are spaced laterally of the projecting lips 41 of the friction discs 36 for cooperating with the edges of those lips to ultimately limit the lag-lead motion of the rotor blade and to prevent unintentional folding movement of the blade about the drag pivot.

25. In the normal operating position of the blade, the blade spar is connected through bracket blocks 44, 45 and bolts 46, 49 to plate 38. When the pin 49 is removed, block 45 and the attached blade spar is then free to move out from between plates 38 and 48 so that the blade may be turned substantially without restriction about its drag pivot to permit folding the blade about the drag pivot. This operation of the blade folding mechanism is described in the patent as follows:

Thus, by the mere removal of a single locking device, the friction damper as well as the abutments for limiting blade movements are both disconnected so that substantially no resistance to the desired folding movement remains.

The folding of the blade about its drag pivot, as permitted upon withdrawal of pin 49 and the release of plate 38 and limiting stops 53 from the spar, is effected relative to the damper and limiting stop mechanism which remain in their normal position.

26. The construction disclosed in the '465 patent provides for folding of rotor blades about their drag pivots and thus eliminates additional parts which would be required if the blades were folded about some auxiliary pivot or pivots. This construction also provides a blade folding mechanism not requiring additional parts which necessarily would be subjected to the centrifugal loads on the rotor blades. This construction also permits folding of the blades about their drag pivots, still accommodating structure closely associated with the drag pivots for damping and limiting motions of the blades about those pivots, and with the attendant advantages thereof. These advantages are summarized in the '465 patent specification as follows:

By associating the movement controlling devices with the upright pivot itself, and further by utilizing this upright pivot as the means to effect folding of the rotor, the number, weight and size of parts is materially reduced, this being of especial importance, since it reduces skin friction, parasite drag and the like, all of which impair the efficiency of the rotor.

27. The six patent claims of the '465 patent involved in this suit find complete support in the disclosure of the specification and drawings of the patent as issued and also in the application for the patent as filed in the United States Patent Office. The specification and claims in suit of the '465 patent are sufficiently definite and certain, and are not vague or indefinite. The definitions of the '465 patent invention set forth in the claims in suit were not so limited during the course of prosecution of the application therefor that said claims cannot properly be construed to cover defendant’s Vertol helicopters and particularly their sustaining rotors. The date of invention by Cierva of the subject matter of the claims in suit of the '465 patent was at least as early as May 31, 1932, the filing date of the United States application for letters patent.

28. Plaintiff has submitted proofs of infringement of the six claims in suit of the '465 patent by defendant’s HUP-1 Vertol helicopter, and particularly the construction of both its fore-and-aft rotors. The pertinent mechanism of the HUP-1 Vertol helicopter is described and illustrated in plaintiff’s exhibits 80, 84, 86, 87, 88, 90, 112 and 125. These exhibits are portion's of manuals pertaining to the HUP-1 and similar models of defendant’s Vertol helicopters.

29. The HUP-1 helicopter and particularly the construction of both its fore-and-aft rotors incorporate each of the elements of the combination defined in each of claims 1, 5,6,7,10 and 13 of the '485 patent, and each such combination of elements hi the HUP-1 helicopter operates in the same manner and produces the same result as disclosed hi the '465 patent. The HUP-1 helicopter and particularly the construction of both its fore-and-aft rotors comes within the meaning and within the principle of each of claims 1, 5, 6,7,10 and 13 of the '465 patent, and infringes said claims.

30. With respect to the '465 patent in suit, defendant has asserted that the patent claims are invalid in view of the following patents:

United States Patents DXNo.
1,673,233 Cierva _ 1928 113.10
1,948,457 Larsen _ 1934 (PX-4)
1,989,544 Campbell _ 1935 116.8

31. The important features of the '465 patent claims in suit, set forth in finding 21, involve utilizing the drag or lag-lead pivots as means for folding the rotor blades to a position in which they all extend in one direction from the rotor mount to overlie the body of the aircraft in a group. The Larsen '457 patent, one of the patents involved in this suit, contains no disclosure regarding the folding of rotor blades. The Cierva '233 patent was considered by the Patent Office examiner during the prosecution of the '465 patent application and does not disclose drag pivots to serve also for blade folding, nor does it disclose mechanism adjacent the rotor axis to prevent unintentional blade folding, nor mechanism between parts of the pivot joints to resist blade pivotal movements, nor removable locking mechanisms. The Campbell '544 patent is mentioned in the '465 patent specification as filed and issued and discloses folding the blades about special pivot pins other than the drag pivots. The '465 patent claims in suit clearly distinguish from the disclosures of the three patents noted in the preceding finding and are found valid.

32. Defendant has asserted that the '465 patent claims must be limited to the particular form of mechanism illustrated in the patent drawings. The recitals of the '465 patent claims in suit are not limited to the specific structural embodiment illustrated in the '465 patent drawings.

LARSEN PATENT NO. 1,990,291

33. The subject matter of the Larsen Patent 1,990,291 (hereinafter referred to as the '291 patent) relates to a method of adjusting the effective incidence of flappingly-pivoted rotor blades for tracking the blades, and is especially adapted for rotor systems of rotary wing aircraft. The '291 patent also relates to a blade construction for adjusting the effective incidence of rotor blades in air-rotors to accomplish tracking of the blades, being especially adapted for rotor systems of rotary wing aircraft. The patent states:

* * * * *
* * * it has been found desirable to provide means for adjustably setting the individual blades, particularly as to incidence, at least for equalization of the settings of the several individual blades, or to correct for variations or inaccuracies in manufacture as between blades, so that all blades of an assembled rotor may have equivalent aerodynamic characteristics, especially to prevent out-of-track running and to obtain smooth operation of the rotor and thus of the aircraft; * * *
¡it $ :f! * $
For smooth rotor operation, for greatest efficiency, for minimum vibration, and for the best equilibrium and the most desirable conditions generally, the structural and aerodynamic characteristics and the individual effective blade incidence setting should be exactly uniform for all the blades of the rotor.
*****

34. The blades of a multi-bladed fiappingly-pivoted rotor are said to be in track when each blade passes a given point in the rotative path at exactly the same flapping position as every other blade of the rotor. The flapping position of a rotor blade, i.e., its position about its flapping pivot, is dependent on the aerodynamic lift forces and on the inertia forces acting on the blade. The aerodynamic lift forces acting on a rotor blade are determined principally by the effective incidence of the blade and by the velocity of air which the blade encounters. The inertia forces acting on a rotor blade are determined principally by tbe centrifugal force acting on tbe blade and tbe inertia due to tbe upward-and-downward flapping of the blade. When the blades of a rotor are adjusted to have the same effective blade incidence setting, each blade will have the same lift (for a given air flow thereover), and thus the blades will be in track as they rotate.

35. The three claims in suit of the '291 patent, i.e., claims 4,5 and 6, are set forth below:

Patent Claim I¡, of '891
In an aircraft,
1. a rotatable sustaining wing or blade,
2. pivot means whereby the blade may take an irregular rotative path,
3. and means for altering the path of movement which the blade will take during rotation,
(a) said means including a blade-surface-contour element bendable to different positions
(b) and composed of a material adapted to take a set.
Patent Claim 5 of '891
The method of adjusting individually-freely-pivoted wings or blades of an autorotative air-rotor which includes
1. setting up rotation of the rotor to substantially its normal autorotational speed,
2. contacting a marker with the blades as they rotate,
3. and ascertaining irregular aerodynamic tracking of the blades, as occurs in their free pivotation, by variations in the markings on the blades,
4. and adjusting blade incidence to substantially equalize the aerodynamic tracking of the blades, by shifting a trailing edge portion of the blade in a direction toward one side or the other of the rotary path of movement thereof,
(a) the general direction of shifting being the same as the general direction in which it is desired the blade shall be shifted in its operation.
Patent Claim 6 of '291
The method of correcting an out-of-track blade of a pivoted-blade air-rotor which includes
1. shifting a trailing edge portion of the blade in a direction toward one side or the other of the rotary path of movement thereof,
(a) the general direction of shifting being the same as the general direction in which it is desired the blade shall be shifted in its operation.

36. The '291 patent is entitled “Air-Rotor for Aircraft” and the specification of the patent begins:

This invention relates to air-rotors, particularly aero-foil systems normally actuated by relative air flow, and is especially adapted to the rotary wing systems of aircraft; and I herein describe and illustrate the invention as applied to an aircraft having a normally freely wind driven, hinged-wing sustaining rotor and a separate or independent means of forward propulsion.
Broadly, the invention contemplates substantial improvements in the aerodynamic and structural characteristics of such an air-rotor, and particularly of the individual wings or blades thereof, and certain novel methods of adjustment and operation; the simplification of the manufacture, mounting, adjustment, and repair of the rotor blades or wings; the increase of the safety factor in the making of adjustments and in the operation of the machine as a whole; and the considerable reduction of costs of manufacture, assembly, adjustment, inspection and repair.
* * * * *
The foregoing objects and advantages may be accomplished, in accordance with the present invention, by rendering the blade itself, at least in part, adjustable or deformable, or by applying an adjustable or deformable flap, trailing edge, or other element to the blade, preferably adjacent its outer end, or in a zone where the blade action with respect to the air is the most effective.
I further contemplate the convenient application of the invention to existing blades as well as its incorporation in new blades built for the purpose.
Another object of the invention involves the attainment of very fine adjustments of the aerodynamic characteristics of the blade, especially by minute adjustments in its effective incidence (even to small fractions of a degree) without the necessity for equally fine movements or adjustments of the adjusting means itself or the necessity for employing accurate gauges, sights, or other instruments or the necessity of having the work supervised by experts. In fact, a very fine adjustment of the lift, incidence, contour, tracking, and operation in general, of any given blade, may be made by a relatively coarse adjustment of a small part of the trailing edge adjacent the tip thereof, for example, by an ordinary mechanic, using a screw driver or a pair of pliers, and this without the necessity for dismantling the rotor or the blades, or returning the machine or any part of it to the factory.
Still another object of the invention is to alter the blade contour, or effective incidence, at least of a portion of the blade, in such a manner as to alter the center of pressure, particularly with respect to its center of gravity, either at a given section of the blade, or along a considerable portion of its length; * * *
* * £ # #

37. The '291 patent illustrates and describes several forms of rotor blade construction, and also the steps in a method of rotor blade tracking and tracking correction. Figs. 1, 2, 3, 4, 5, 6 and 9 of the patent drawings, taken with descriptive portions of the specification, fully support the subject matter of the three claims in suit.

38. The aircraft in fig. 1 includes the air-rotor 7 which is described as being actuable by relative air flow, so as to sustain the craft in forward flight and allow it to settle gently in vertical descent. Such a rotor is an autorotatable or auto-rotative sustaining rotor. In figs. 1 and 2, the sustaining rotor blades or wings 8 are pivoted to their common rotative hub 9 by horizontal and vertical articulations 10 and 11, and the motions of the blades on these articulations accommodate variations in forces of lift, inertia, etc. The rotor blade in fig. 2 of the patent drawings has a bendable or deformable member 13 mounted with its rear edge flush with the trailing edge of the blade. In this form of construction the deformable member 13 is built into the trailing edge of the blade-covering material 8a and replaces a portion of the trailing edge structure of the blade. The deformable or 'bendable element 13 is provided for varying the average effective incidence of the blade in order to effect proper blade tracking. The bendable element 13 may take the form of a V-shaped metallic strip such as aluminum which can be readily bent up or down, but which will take a “set” so as to retain its shape as against any air pressure encountered. Figs. 4 and 5 are enlarged elevational and plan views, respectively, of portions of the blade in fig. 2.

39. Fig. 3 illustrates a modified construction having the deformable trailing edge 20 which may be applied to a blade with no change whatever in the blade construction itself. On this form of construction the specification states:

The dotted line 22 indicates the trailing edge of the blade as built, the element 20 being a single fiat plate, secured to the trailing edge stringer as by rivets 23.

A detail of the form of trailing edge construction of fig. 3 is in fig. 9 which shows the deformable trailing edge 20 as being applied on the upper surface of the blade.

40. Fig. 1 of the patent drawings illustrates steps in the method of blade tracking and tracking correction in accordance with the invention. The aircraft is shown in forward flight with the rotor operating autorotatively. The blades are tested for their tracking pattern by gradually moving a marking stick upwardly until its upper end, which carries a marking material, makes contact with the undersurface of the blades as they rotate. The further steps in the blade tracking procedures and the adjustment of the effective incidence of the blades for effecting correct blade tracking are described in detail in the specification of the '291 patent.

41. Although the adjustment of the effective blade incidence in accordance with the invention of the '291 patent is described and illustrated with reference to fig. 6 of the patent drawings in relation to a rotor blade, which has its center of pressure located ahead (chordwise) of its center of gravity, the effective incidence adjustments by means of a deformable trailing edge member as disclosed in the patent, and the rotor blade tracking procedures as disclosed in the patent, are equally applicable to rotor blades having their center of pressure located rearwardly (chordwise) of their center of gravity. With either type of blade, bending the deformable trailing edge upwardly or downwardly (respectively) will shift the center of pressure chordwise in that portion of the blade, causing the blade to twist so as to increase or decrease (respectively) its effective incidence angle, thus producing more or less (respectively) lift on the blade, and thereby causing the blade to fly or ride higher or lower (respectively) on its flapping pivot in its path of rotation.

42. In accordance with the disclosure of the '291 patent, both the deformable element 13 of figs. 2, 4 and 5, and the deformable element 20 of figs. 3 and 9 constitute a blade-surface-contour element, as specified in item 3(a) of claim 4. The three claims in suit, i.e., claims 4, 5 and 6, of the '291 patent, find complete support in the disclosure of the specification and drawings of the patent as issued and also in the application for the patent as filed. The specification and the claims in suit of the '291 patent are sufficiently definite and certain, and are not vague or indefinite. The subject matter as well as the language of the claims in suit of the '291 patent is not limited to the rotor construction of gyroplanes, or to the blade tracking or blade tracking correction of gyro-plane rotors, with reference to which the invention is described and illustrated, nor is either the subject matter or language of the claims in suit limited to the rotor construction, or to the blade tracking or blade tracking correction, of rotors which are air-rotated or autorotatively actuated only or usually. Instead, the invention as defined in the claims in suit is equally applicable to the rotor construction, and to the blade tracking and blade tracking correction, in aircraft of the helicopter type, and whether operating under power drive or autorotatively.

43. The definitions of the invention in the claims in suit of the '291 patent were not so limited during the course of the prosecution of the application therefor that said claims can not properly be construed to cover defendant’s Bell, Hiller and Vertol helicopters, and particularly their sustaining rotor constructions and the rotor blade tracking procedures employed therewith. The date of invention by Larsen of the subject matter of the claims in suit of the '291 patent was at least as early as December 5, 1931, the date of filing of the application for United States Letters Patent.

44. Plaintiff has submitted proofs of infringement of the '291 patent by defendant’s HTL-4 Bell, H-23A Hiller and HUP-1 Vertol helicopters, and by the blade tracking procedures as utilized by defendant with said helicopters.

45. Plaintiff has submitted proofs of infringement of claims 4 and 6 of the '291 patent by the HTL-4 helicopter and particularly its main rotor construction, and by the blade tracking procedures employed therewith.. The pertinent mechanism and the blade tracking procedures of defendant’s HTL-4 helicopter are described and illustrated in plaintiff’s exhibits 51, 54, 56, 58, 60, 61, 62,143 and 144. These exhibits are portions of manuals pertaining to the HTL-4 and similar models of defendant’s Bell helicopters; and those manuals were published by defendant.

46. The blade tracking procedures for the HTL-4 rotor blades are described as follows in plaintiff’s exhibit 143, a portion of the HTL-4 manual:

4-11. Tracking Main Rotor Blades
* * # * *
a. Attach a small piece of sponge rubber % to ^4 inch thick to the end of a light wooden pole. Coat upper surface of rubber with a compound made from a small amount of prussian blue. * * * Bun engine at 3000 rpm, apply collective pitch to the maximum allowable without permitting helicopter to become airborne.
*****
b. Slowly raise marking device into disc, of rotor blades j ust far enough to mark low blade near tip. (Figure 4-6.) When low blade is marked, stop engine (refer to paragraph 3-32) and allow rotor to stop. Alternately adjust trim tabs on blades by bending to raise low blade, or lower high blade, until rotor blades track. Bending the tab up will raise blade and bending it down will lower blade.

47. The HTL-4 helicopter and particularly its sustaining rotor construction incorporates each of the elements of the combination defined in claim 4 of the '291 patent, and such combination of elements in the HTL-4 helicopter operates in the same manner and produces the same result as disclosed in the '291 patent. The HTL-4 helicopter and particularly its sustaining rotor construction comes within the meaning and within the principle of claim 4 of the '291 patent, and infringes said claim.

48. The blade tracking procedures employed with the HTL-4 helicopter include each of the steps of the method of correcting an out-of-track rotor blade as defined in claim 6 of the '291 patent, and in the HTL-4 helicopter blade tracking procedures such steps are carried out in the same manner and produce tlie same result as disclosed in the '291 patent. The blade tracking procedures employed with the HTL-4 helicopter come within the meaning and within the principle of claim 6 of the '291 patent, and infringe said claim.

49. Plaintiff has submitted proofs of infringement of claims 4 and 6 of the '291 patent by the H-23A Hiller helicopter and particularly its main rotor construction, and by the blade tracking procedures employed therewith. The pertinent mechanism and the blade tracking procedures of defendant’s H-23A helicopter are described and illustrated in plaintiff’s exhibits 67, 71, 72, 73, 76, 78,148 and 209. These exhibits are portions of manuals pertaining to the H-23A and the other models of defendant’s Hiller helicopters; and those manuals were published by the defendant.

50. The blade tracking procedures for the H-23A rotor blades are described as follows in plaintiff’s exhibit 148, a portion of the H-23A manual:

2-111. Tracking of Main Rotor Blades. It is important that both blades of the rotor assembly pass through the same point during their rotation, otherwise vibration will result.
$ $ ‡ $
a. * * * Color each blade tip with a different color using slow-drying paint, chalk, grease pencil or other marking agent.
b. Load helicopter to a sufficient gross weight so it will not fly when take-off power and collective pitch are applied. Tracking can be done, usually with less satisfactory results, when ship is loaded lighter than this weight. With a lighter loading it is more difficult to track rotor over a wide rpm spread, or to obtain track at a high collective pitch setting, both of which are desirable.
*****
d. Move flag SLOWLY toward the helicopter until both rotating blade tips just nick the folded edge of the flag, leaving their color mark at the level where they nick the flag.
e. Using flag, track blades at 2000 and 3000 engine rpm maintaining the same collective pitch setting. Apply enough collective pitch to make ship light on its wheels.
2-112. TeaokiNG Corrections.
a. * * * A mark spread of greater than % inch requires adjustment of trim tabs, or collective pitch push rods, or both.
2-113. Adjusting Trim Tabs.
*****
a. Bend tabs by hand, applying pressure with thumbs. When bending tab, be sure trailing edge of tab is straight, and parallel to trailing edge of blade. Check by sighting along trailing edge of tab.
b. Raising trailing edge of tab causes that blade to fly higher; the opposite action results when trailing edge of tab is lowered.
NOTE
Tab adjustments have little or no effect on auto-rotation rpm.

51» The H-23A helicopter and particularly its sustaining-rotor construction incorporates each of the elements of the combination defined in claim 4 of the '291 patent, and such combination of elements in the H-23A helicopter operates in the same manner and produces the same result as disclosed in the '291 patent. The H-23A helicopter and particularly its sustaining rotor construction comes within the meaning and within the principle of claim 4 of the '291 patent, and infringes said claim.

52. The blade tracking procedures employed with the H-23A helicopter include each of the steps of the method of correcting an out-of-tract rotor blade as defined in claim 6 of the '291 patent, and in the H-23A helicopter blade tracking procedures such steps are carried out in the same maimer and produce the same result as disclosed in the '291 patent. The blade tracking procedures employed with the H-23A helicopter come within the meaning and within the principle of claim 6 of the '291 patent, and infringe said claim.

53. Plaintiff has submitted proofs of infringement of claims 4, 5 and 6 of the '291 patent by the HUP-1 helicopter and particularly the construction of both its fore-and-aft rotors, and by the blade tracking procedures employed therewith. The pertinent mechanism and the blade tracking procedures of defendant’s HUP-1 Vertol helicopter are described and illustrated in plaintiff’s exhibits 80, 82, 84, 86, 87, 88, 90, 92, 135 and 137. These exhibits are portions of manuals pertaining to the HUP-1 and similar models of defendant’s Vertol helicopters; and those manuals were published by defendant.

54. The HUP-1 helicopter and particularly the construction of both its fore and aft rotors incorporates each of the elements of the combination defined in claim 4 of the '291 patent, and such combination of elements in the HUP-1 helicopter operates in the same manner and produces the same result as disclosed in the '291 patent. The HUP-1 helicopter and particularly the construction of both its fore and aft rotors comes within the meaning and within the principle of claim 4 of the '291 patent, and infringes said claim.

55. The blade tracking procedures employed with the HUP-1 helicopter, for each of its rotors, include each of the steps of the method of correcting an out-of-track rotor blade as defined in claim 6 of the '291 patent, and in the HUP-1 helicopter blade tracking procedures such steps are carried out in the same manner and produce the same result as disclosed in the '291 patent. The blade tracking procedures employed with the HUP-1 helicopter, for each of its rotors, come within the meaning and within the principle of claim 6 of the '291 patent, and infringe said claim.

56. The blade tracking procedures employed with the HUP-1 helicopter, for each of its rotors, include each of the steps, or the equivalent of each of the steps of the method defined in claim 5 of the '291 patent, and in the HUP-1 helicopter blade tracking procedures such steps are carried out in the same or equivalent manner and produce the same result as disclosed in the '291 patent. The blade tracking procedures employed with the HUP-1 helicopter, for each of its rotors, come within the meaning and within the principle of claim 5 of the '291 patent, and infringe said claim.

57. With respect to the '291 patent in suit, defendant has asserted that the claims are invalid and not infringed. Defendant has relied upon the following patents:

United States Patents DX No-

1,449,129 Pescara_ 1923 112.21

1,454,944 Pescara_ 1923 112.22

1,526,230 Pescara_ 1925 112.31

1,697,009 Isacco _ 1929 113.16

1,789,240 Leitner et al_ 1931 113.29

1,813,852 Isacco_ 1931 113.33

1,948,455 Cierva_ 1934 115.18

1,949,785 Cierva_ 1934 115.24

1,960,141 d’Ascanio_ 1934 115.29

Reissue

22,595 Upson _ 1945 199

Foreign Patents

British 146,257 Pescara_ 1921 (PX-536)

British 293,932 Pescara _ 1928 118.23

British 410,532 Cierva _ 1934 118.35

58. The important features of the '291 pat ant claims in suit, set forth in finding 85, include the provision in a flap-pingly-pivoted rotor blade of a blade-surface-contour element bendable to different positions and composed of material adapted to take a permanent set, and methods of blade-tracking-correction including shifting the trailing edge portion of a flappingly-pivoted rotor blade in the direction in which it is desired to shift the blade in its tracking path. These features are not disclosed in or taught by the several patents listed in the preceding finding. British patent 410,-532 was filed subsequent to the filing date of the '291 patent in suit. The '291 patent claims in suit are not invalidated by the several patents listed. The arguments presented before the Patent Office in obtaining the grant of the '291 patent claims in suit do not require that these claims be limited to the structural matter specifically depicted in the patent drawings.

STANLEY PATENT NO. 2,302,068

59. During the trial plaintiff introduced evidence as to the disclosure of Stanley patent 2,302,068, hereinafter referred to as the '068 patent, and as to its single claim. The subject matter of the '068 patent relates to sustaining rotors for aircraft, and is more particularly concerned with features of rotor blade construction. During the trial plaintiff submitted proofs of infringements of the claim of the '068 patent by both the straight and the twisted wooden rotor blades for defendant’s HUP-1 Yertol helicopter, and also by the wooden blades for defendant’s H-21B Vertol helicopter. The Commissioner’s Order dated April 16, 1962, received in evidence certain plaintiff’s exhibits showing that the blade ribs in both the HUP-1 and H-21B Yertol rotor blades are not apertured but are routed. In view of the routed construction of the ribs of the Yertol HUP-1 and H-21 wooden rotor blades, those rotor blades do not infringe the claim of Stanley patent 2,302,068.

LARSEN PATENT NO. 2,151,215

60. The subject matter of the Larsen patent 2,151,215, hereinafter referred to as the '215 patent, relates to displace-able droop support mechanism in sustaining rotors of rotary wing aircraft, for preventing the rotor blades from striking the ground or portions of the aircraft when the rotor is not rotating or when it is rotating at substantially less than normal flight speed. The invention provides a droop support mechanism for the blades of an aircraft sustaining rotor, in which mechanism centrifugally operated means are employed for restricting downward drooping of the blades to a smaller angle when the rotor is rotating at low speeds than when the rotor is rotating at the normal flight speeds. Drooping of such sustaining rotor, blades is caused by downward movement of the blades about their flapping pivot and also by downward bending of the blades due to their flexibility. Under the effect of gravity acting on the blades they droop downwardly when they are not rotating or when they are turning at slow speeds.

61. Seven claims of the '215 patent are in suit, namely, claims 1, 2, 3, 5, 6, 8, and 9. Claims 3 and 8 are reproduced herein. [Indentation and numbering added.]

Patent Claim 3 of '215
In an aircraft sustaining rotor having a hub and a blade, 1. pivot means for connecting the blade with the hub providing freedom for upward and downward swinging movement of the blade,
2. a droop stop on the hub for, arresting downward movement of the blade,
3. and an element mounted for movement into and out of a position between said droop stop and the blade,
a. said element being operative under the influence of centrifugal force to move out of said position when the blade is rotating at a substantial speed.
Patent Claim 8 of '215
In an aircraft having a sustaining rotor incorporating a hub and a blade,
1. pivot mechanism connecting the blade with the hub and including a pivot axis providing freedom for upward and downward swinging of the blade, which pivot axis makes an acute angle with the longitudinal blade axis at the leading side thereof, whereby upward and downward swinging movements of the blade are accompanied by pitch change movements thereof,
2. and mechanism for limiting downward drooping of the blade about said pivot axis and providing freedom for greater angular drooping when the rotor, is rotating at flight speeds than when the rotor is rotating substantially below flight speeds.

62. Fig. 2 of the patent drawings is an enlarged side view of the hub structure, the root spars of the two blades, and the inner portion of one blade, with certain parts being shown in vertical section; fig. 3 is a top plan view of the hub and blade structure as shown in fig. 2; and fig. 4 is a fragmentary side elevation showing the mounting of one blade on the hub, but with certain parts occupying different positions than as shown in fig. 2. Referring again to fig. 2 of the patent drawings, the rotor blade 24 to the right of the figure is connected through its blade spar 27 and drag pivot 28 to the blade link 25. The blade links for the two blades are each pivotally momited through the single flapping pivot pin 23 to the hub block 22 which is formed at the upper end of the hub spindle 14 journaled through bearings 15 in the tiltably-mounted casing 13. The mounting of the rotor blades to the hub 22 through the blade links 25 and the flapping pivot pin 23 provides for up-and-down angular swinging or oscillation of the rotor blades transverse their mean rotative path of travel.

63. In figs. 2 and 4, an abutment or stop member 30 is provided on each blade mounting link 25, and cooperating stops 29' are located on the lower portion of hub member 22, sufficient clearance between the stops 29 and 30 being provided to allow for the full downward range of swinging or flapping of the rotor blades as required in translational flight and for flight maneuvers. A yoke 31 is mounted through a pivot 32 on each blade link 25, providing for swinging of each yoke with its attached arm 33 toward and away from the axis of the hub, and thus permitting the arm 33 to swing in and out between the stops 29 and 30. In fig. 2, when the rotor is not rotating or when it is rotating at low speed, the downward drooping of the blades is limited by the interposition of the arms 33 between the stops 29 and 30. When the rotor is rotating at substantial speeds so that the stops 30 have been raised upwardly with their rotor blades due to the lift and centrifugal force acting on the rotor blade, the arms 33 are released from between stops 29 and 30, and then under the effect of centrifugal force acting on the yokes 31 and arms 33 they are pivoted outwardly so that arms 33 are moved out from between stops 29 and 30. In this condition a substantially greater angular range of pivotal movement of the blades about the flapping pivot is permitted before the downward movement of a blade will be arrested by the stop 29. Referring again to fig. 3 of the patent drawings, the axis of the flapping pivot 23 makes an acute angle with the leading edge of the rotor blade, and thus with the longitudinal axis of the blade. In blades equipped with such an inclined flapping pivot, the pitch angle of the blade decreases when the blade flaps upwardly, and increases when the blade flaps downwardly.

64. In accordance with findings 61-62, the seven claims in suit of the '215 patent, i.e., claims 1, 2, 3, 5, 6, 8, and 9, find complete support in the disclosure of the specification and drawings of the patent as issued, and also in the application for the patent as filed. The specification and the claims in suit of the '215 patent are sufficiently definite and certain, and are not vague or indefinite. The claimed subject matter as well as the language of the claims in suit of the '215 patent is not limited to the sustaining rotor construction of any particular type of rotary wing aircraft, and the invention as defined in the claims in suit is applicable to the rotor construction of aircraft of the helicopter type. The definitions of the invention in the claims in suit of the '215 patent were not so limited during the course of the prosecution of the application therefor that said claims can not properly be construed to cover defendant’s Kaman helicopters and particularly their sustaining rotors. The date of invention by Larsen of the subject matter of the claims in suit of the '215 patent was at least as early as April 30, 1938, the filing date of the U.S. patent application.

65. Plaintiff has submitted proofs of infringement of the seven claims in suit of the '215 patent by defendant’s HOK-1 Kaman helicopter and particularly the construction of both of its rotors. The pertinent mechanism of the HOK-1 Kaman helicopter is described and illustrated in plaintiff’s exhibits 159, 160, 161, 163, 165, 166, 168, 220, 221, and 224. These exhibits are portions of manuals pertaining to defendant’s HOK-1 helicopters.

66. In accordance with findings 61-65, inclusive, the HOK-1 and particularly the construction of both of its rotors incorporates each of the elements of the combination defined in each of claims 1, 2, 3, 5, 6, 8, and 9 of the '215 patent, and each such combination of elements in the HOK-1 operates in the same manner and produces the same result as disclosed in the '215 patent. The HOK-1 Kaman helicopter and particularly the construction of both of its rotors comes within the meaning and within the principle of each of claims 1,2,3, 5, 6, 8, and 9 of the '215 patent, and infringes said claims.

67. With respect to the validity of the '215 patent in suit, defendant’s requested findings refer to Cierva '893, '584, '042, '456, and Von Baumhauer British 265,272, and Cierva 1,980,169 which is DX 116.4. During the prosecution of the '215 patent application, no references were cited by the Patent Office examiner. The several patents referred to by defendant do not disclose the drop stop mechanisms and elements defined in patent claims 1, 2, 3, 5, 6, 8, and 9 of the '215 patent in suit and do not invalidate said claims.

CAMPBELL PATENT NO. 2,339,830

68. The subject matter of tlie Campbell patent 2,339,836, hereinafter referred to as the '836 patent, relates to twin rotor aircraft having the rotors arranged side-by-side so that when viewed from above the left hand rotor rotates counterclockwise and the right hand rotor rotates clockwise. The '836 patent specification discloses that the invention is applicable to a machine of the helicopter type incorporating a pair of side-by-side rotors adapted to be mechanically driven in flight as well as applicable to a machine in which the rotors are adapted to be autorotationally or aerodynamically rotated. The specification also discloses that the invention is applicable to a composite aircraft having rotors adapted for power-driven operation and for autorotational operation under different conditions.

69. The '836 patent contains two claims, but only claim 1 is in suit. Claim 1 is reproduced below. ['Indentation and numbering added.]

Patent Claim 1 of '836
An aircraft having
1. a pair of side-by-side sustaining rotors,
a. each rotor incorporating a hub and blades connected thereto with freedom for flapping movement,
b. the direction of rotation of the rotors being such that when viewed in top plan from adjacent the rear of the machine, the left-hand rotor rotates counterclockwise and the right-hand rotor clockwise.

70. Fig. 1 of the patent drawings is a top plan view of a rotating-wing aircraft having two side-by-side rotors; and fig. 2 is a front view of the aircraft shown in fig. 1, but showing the left-hand or left side rotor only, deferring to the patent drawings, the two side-by-side sustaining rotors are supported on out-rigger struts 11, 12, and 13 which extend outwardly and upwardly from the fuselage 7, and each rotor is mounted in a member 14 through a supporting hub spindle 15. A hub member 16 is journaled on each hub spindle 15, and the rotor blades 17 are connected to the hub member 16 through flapping pivots 18 as indicated in fig. 2. The flapping pivots provide freedom for flapping movement of the rotor blades. Referring to fig. 1, as indicated by the arrows R the rotor on the right side of the aircraft, i.e., to the pilot’s right, rotates clockwise looking down, and the rotor on the left side of the aircraft rotates counterclockwise looking down.

71. In translational flight of a rotor having flappingly pivoted rotor blades, as the blades move upwardly and downwardly in their path of rotation to compensate for differential lift effects, the rotor blades reach a high position in their movement about the flapping pivot when they are generally forward and on the retreating side, and the blades reach a maximum downward position in their movement about the flapping pivot when they are generally rearward and on the advancing side of the rotor, with the low and high points being approximately 180 degrees apart. With the high position of the rotor blades in their movement about the flapping-pivot being on the retreating side of the rotor, the average position of the rotor blades, when moving on the retreating side, will be higher than the average position of the blades when moving on the advancing side. This is indicated by the dot-and-dash lines in fig. 2 of the patent drawings, the line labeled 17b representing an average position of the rotor blades about the flapping pivot, with reference to the horizontal, when moving on the retreating side of the rotor, and the dot-and-dash lines labeled 17a representing the average position of the rotor blades about the flapping pivot when moving on the advancing side of the rotor. As the plane of rotation of each rotor is thus tilted due to the flapping action of tlhe rotor blades in compensating for differential lift effects in translational flight, being higher on the retreating side, i.e., on the outer side of each rotor, and being lower on the advancing side, i.e., on the inner side of each rotor, and having the direction or rotation as in fig. 1, the aerodynamic reaction or lift line of each rotor is tilted inwardly at the top toward the fuselage. Accordingly, the lift lines of the two rotors are tilted inwardly at the top toward each other, and this is referred to as a dihedral effect.

72. In accordance with findings 68-71 inclusive, claim 1 of the '836 patent finds complete support in the disclosure of the specification and the drawings of the patent as issued and also in the application for the patent as filed. The specification and claim 1 of the '836 patent are sufficiently definite and certain, and are not vague or indefinite. The claimed subject matter as well as the language of claim 1 of the '836 patent is not limited to any particular type of rotary wing aircraft, and the invention as defined in the '836 patent claim in suit is applicable to aircraft of the helicopter type in which the sustaining rotors are adapted for power-driven operation and autorotational operation under different conditions. The definition of the invention in claim 1 of the '836 patent was not so limited during the course of the prosecution of the application therefor that said claim cannot properly be construed to cover defendant’s Kaman helicopters. The date of conception by Campbell of the subject matter of the claim in suit of the '836 patent was at least as early as April 19,1934, the date of a sketch with description and comprising a part of an affidavit filed May 31,1941, in Campbell patent application Ser. No. 324, 248 of March 16, 1940, on which application the '836 patent issued.

73. Plaintiff has submitted proofs of infringement of claim 1 of the '836 patent by defendant’s HOK-1 Kaman helicopter. The pertinent mechanism of the HOK-1 is described and illustrated in plaintiff’s exhibits 160, 163, 166, 168,220,221, and 224. These exhibits are portions of manuals pertaining to defendant’s PIOK-1 helicopters.

74. In accordance with findings 69-73,. inclusive, the HOK-1 incorporates each of the elements of the combination defined in claim 1 of the '836 patent, and such combination of elements in the PIOK-1 operates in the same manner and produces the same result as disclosed in the '836 patent. The HOK-1 Kaman helicopter comes within the meaning and within the principle of claim 1 of the '836 patent, and infringes said claim.

75. With respect to the validity of the '836 patent in suit, defendant has relied upon some twenty prior art items as invalidating patent claim 1, the only claim of the '836 patent involved in this suit. Defendant has specifically cited the following items together with certain Cierva patents, Beur-rier '982, de Bothezat '228, Focke German 588,391, Focke Flight Publication and also:

United States Patents DX No-

1,957,813 Wilford_ 1934 115.27

1,961,996 Williams_ 1934 115.30

Foreign Patents

British 14,445 Wojciechowski_ 1910 190

French 406,796 Wojciechowski_ 1910 121.2

British 499,073 Focke_ 1939 119.8

76. Beurrier, de Bothezat, Wilford and Wojciechowski 14,445, noted in the preceding finding all show rotors having rigidly braced rotor blades. None of the prior art items urged by defendant against claim 1 of the '836 patent discloses both the direction of rotation of the two rotors and the flapping mounting of the rotor blades in a side-by-side rotor arrangement as defined in said patent claim. The prior art does not invalidate claim 1 of the '836 patent in suit.

CAMPBELL PATENT NO. 2,321,572

77. The Campbell patent 2,321,572, hereinafter referred to as the '572 patent, and also the Campbell patent 2,344,966 and the Bennett patent 2,344,967 all of which are patents in suit relate to aircraft having side-by-side rotors with flap-pingly-pivoted blades and to the special problems of control in such aircraft. In the '572 patent the control system is described for use in aircraft having autorotatively driven rotors and also in power-driven rotors. The side-by-side rotors of the rotating-wing aircraft of the '572 patent sustain the aircraft in flight and are sustaining rotors. The '572 patent describes and illustrates an overall control system for maneuvering and trimming a rotating-wing aircraft having side-by-side rotors. Longitudinal attitude control is provided by conjoint or similar tilt of the lift lines of the two rotors in longitudinal planes. Lateral attitude control is provided by differentially changing the collective pitch of the two rotors. Directional control is provided by differentially tilting the lift lines of the two rotors in longitudinal planes. Control for ascending or descending is provided by increasing or decreasing the collective pitch of the two rotors together. Trimming control for the attitude of the aircraft to maintain the body level in translational or vertical flight is provided by tilting the rotors about an axis close to the center of gravity of the aircraft.

78. The '572 patent contains 32 claims, four of which, namely claims 8,9, 28, and 29, are in suit. "While other claims in the '572 patent not in suit define features of the trimming control, the claims in suit do not pertain to the trimming control but rather to features of the longitudinal and lateral attitude controls and of the directional control. Claims 9 and 28 are reproduced herein. [Indentation and numbering added.]

Patent Olaim 9 of '572
An aircraft including
1. a pair of side-by-side sustaining rotors,
2. mechanism providing for shirt of the lift lines of said rotors for control purposes in a plurality of senses,
3. a foot operated control organ,
4. a manually operated control organ,
5. means connecting the manually operated control organ with said mechanism and providing for conjoint shift of the lift lines of the two rotors in the same sense,
6. and means connecting the foot operated control organ with said mechanism and providing for differential shift of the lift lines of the two rotors in opposite directions.
Patent Claim 28 of '572
In an aircraft,
1. a pair of bladed sustaining rotors positioned in side-by-side relation and arranged for rotation in opposite directions, and
. 2. a flight control system for the craft operating by means of said rotors, the rotors having means providing for blade flapping, said system comprising
a. separate control mechanisms for tilting the two rotor lift lines whereby they may be given inclinations relative to each other, and
b. separate pitch-varying mechanisms for the two rotors whereby their mean pitches may be varied relative to each other, and
c. connections from the pitch-varying mechanisms of the two rotors coupled to a common control organ for unified operation.

79. Figs. 1 and 2 of the patent drawings are side elevation and front views of a side-by-side twin rotor helicopter. Fig. 4 is a diagrammatic perspective view of portions of a control system, and also a vertical section, looking from the rear, of the right-hand rotor hub and portions of the control and drive mechanisms. Fig. 5 is a diagrammatic perspective view of a portion of a modified control system. Referring to fig. 4, the root end member of a rotor blade is at 17 and has a pitch-bearing housing 18 mounted on a pitch-bearing shaft 19 to provide for turning of the blade about its longitudinal axis. Each pitch shaft is flappingly-pivoted to lugs 21 at the upper part of hub member 13 which is mounted by bearings to the support 23; and a large bevel gear 44 is attached to the lower end of the hub member 13 and meshes with a pinion 43 carried by a shaft 41 mounted by bearings in the upper part of the outrigger 14. The two rotors are interconnected through a shaft and are driven to rotate in opposite directions, the right-hand rotor turning in the clockwise direction and the left-hand rotor in the counterclockwise direction looking in plan view on the rotors.

80. The parts of the collective pitch control system in fig. 4 are fully described in the '572 patent specification. The parts of the rotor structure for shifting the lift lines of the rotors are also in fig. 4 and described in the specification. Referring to figs. 4 'and 5 of the '572 patent, longitudinal attitude control of the aircraft is achieved by fore- and-aft movement of the control column 96 which is mounted for such fore-and-aft pivotal movement by means of transverse rocking Shafts 97a which carry double ended levers 100 having pulleys at their upper and lower ends with cable runs 103R and 107R associated with the pulleys on the right-hand lever 100 and with cable runs 103L and 107L associated with the pulleys on the left-hand lever 100; and the cable runs 107L and 107R are interconnected. Cable runs 103L and 107L extend to the left side rotor and cable runs 103R and 107R extend to the right side rotor. Cable runs 103R and 107R extend to a pulley 94 attached to a shaft 93 which is joined to shaft 88 through shafts 90 and 89; and shaft 88 carries a pulley 86 with which a closed circuit cable 85 is associated, said cable also being associated with pulley 84 which has an arm 83 pivotally connected to the link 82, for the right side rotor. There are corresponding parts and connections for cable runs 103L and 107L to a pulley 94 for the left side rotor, and similar shafts and cable 85 extended to a pulley 84 for the left side rotor. Directional control is attained by movement of the foot pedals 101 which are mounted at 102 and to the lower ends of which cable runs 104 and 106 are connected, these runs being interconnected by cable ran 105. Cable run 104 which is attached to the right foot pedal passes around pulleys on the right-hand lever 100 and joins cable ran 103R, and cable ran 106 which is attached to the left foot pedal passes around pulleys on the left-hand lever 100 and joins cable ran 103L. Lateral attitude or banking control is obtained by turning the control wheel 95 to which a pulley is attached and from which pulley cable runs 72L and 72R extend, these cable runs being joined at said pulley. Cable ran 72L passes around a pulley just below the yoke 98 and then through the left-hand transverse rocking shaft 97a and then around and beyond pulleys including pulley 117L which is mounted on the slide bar 118. The run of the cable 72R which comes down the right side of the control column 96 passes around a pulley just below the yoke 98 and then through the right-hand transverse rocking shaft 97a and then around and beyond pulleys including pulley 116R which is mounted on the slide bar 118. Another cable ran numbered 73R is interconnected with cable ran 73L and these interconnected cable runs pass around pulleys including pulleys 117R and 116L which are mounted on the slide bar 118. Cable runs 72R and 73R which are for the right side rotor extend through the outrigger 14 for the right side rotor and these cable runs join around pulley 71 which has an arm 76 to which is pivotally connected the link 69 and by which the collar 64 is moved upwardly and downwardly to change the collective pitch of the rotor blades. Corresponding connections are provided from cable runs 72L and 73L for the left side rotor, for changing the collective pitch of the rotor blades of that rotor.

81. In accordance with findings 77-80, inclusive, claims 8, 9, 28, and 29 of the '572 patent find complete support in the disclosure of the specification and the drawings of the patent as issued and also in the application for the patent as filed. The specification and claims 8, 9, 28, and 29 are sufficiently definite and certain, and are not vague or indefinite. The claimed subject matter as well as the language of claims 8, 9,28, and 29 is not limited to any particular type of rotary wing aircraft, and the invention as defined in the claims in suit is applicable to aircraft of the helicopter type in which the sustaining rotors are adapted for power-driven rotation and autorotational operation under different conditions. The definition of the invention in claims 8, 9, 28 and 29 was not so limited during the course of the prosecution of the application therefor that said claims cannot properly be construed to cover defendant’s Kaman helicopters. The date of conception by Campbell of the subject matter of the claims in suit was at least as early as April 19, 1934, the date of a sketch with description and comprising a part of an affidavit filed May 31, 1941, in Campbell patent application Ser. No. 324,248 of March 16, 1940, on which application the Campbell patent in suit, 2,339,836 issued.

82. Plaintiff has submitted proofs of infringement of claims 8, 9, 28, and 29 of the '572 patent by defendant’s HOK-1 Kaman helicopter. The general construction and operation of the HOK-1 and the structure and operation of the parts of particular pertinence to the claims in suit of the Campbell '572 patent are described and illustrated in plaintiff’s exhibits 160, 163, 166, 168, 218 to 224 and 383 to 386. These exhibits are portions of manuals pertaining to the HOK-1 and similar models of defendant’s Kaman helicopters.

83. In accordance with finding 82, the HOK-1 incorporates each of the elements of the combination defined in each of claims 8, 9, 28, and 29 of the '572 patent and each such combination of elements in the HOK-1 operates in the same maimer and produces the same result as disclosed in the '572 patent. The HOK-1 Kaman helicopter comes within the meaning and within the principle of each of claims 8, 9, 28, and 29 of the '572 patent, and infringes said claims.

84. With respect to the validity of the '572 patent in suit, defendant has referred to some eighteen prior art items including Nash '261, Beurrier '982, Perrin '310, de Bothezat '228, Pitcairn '762, Breguet '089, Wilford '813, Williams '996, Smith '105, Cierva '230, Wojciechowski British 14,445, Focke British 499,073, Laroche French 736,223, Focke Flight Article, Yierva British 264,286 and also:

United States Patents DXNo.

982,700 Appley_ 1911 112.4

1,849,766 McGuire _ 1932 114.2

2,380,580 Cierva_ 1945 PX-6

2,380,582 Cierva_ 1945 PX-7

Foreign Patent

French 767,068 Yannay- 1934 120.7

Patent claims 8, 9, 28, and 29' of the '572 patent are involved in this suit. In urging invalidity, defendant refers to patent claim 5, a claim not in suit. The patent claims in suit are concerned with other control features than those defined in claim 5. Appley '700, Nash '251, Beurrier '982, Perrin '310, McGuire '766, Wilford '813, Williams '996, Wojciechowski British 14,445, Laroche French 736,223, and Yannay French 767,068 each fail to disclose the mechanisms for shifting the lift lines of the rotors for control purposes in a plurality of senses, or two separately operatable control organs for shifting the rotor lines or the other means specifically defined in claims 8 and 9 of the '572 patent. Likewise said patents fail to disclose all of the means and mechanisms specifically defined in claims 28 and 29 of the '572 patent. The other patents listed in finding 411, but not specifically applied by defendant to the '572 patent claims in suit, do not disclose the structures defined in said claims. The '572 patent claims in suit are found to be valid over such prior art items.

CAMPBELL PATENT NO. 2,344,966

85. The Campbell patent 2,344,966, hereinafter referred to as the '966 patent, relates to control of aircraft having side-by-side rotors with fiappingly-pivoted blades, and particularly to control mechanism used in making a turn, the rotors being so positioned and the control arranged to provide for differential shifting of the lift lines of the two side-by-side rotors fore and aft of the center of gravity of the aircraft in longitudinal planes to cause the aircraft to turn or bank in one direction or the other.

86. The '966 patent contains seven claims, but only claim 1 is relied upon in this suit. Claim 1 is set forth below. [Indentation and numbering added.]

Patent Olaim 1 of '966
An aircraft having
1. a pair of pivoted-blade sustaining rotors arranged in side-by-side relation in positions where the rotor lift lines may be shifted forwardly or rearwardly of the center of gravity location,
2. and control mechanism for use in making a turn including
a. a manually operable control member and
b. means coupling said member to both rotors for differentially tilting the rotors in longitudinal vertical planes by a single movement of said control member.

87. Figs. 1 to 5 of the '966 patent illustrate a twin side-by-side rotor gyroplane, the rotors being autorotatively operated and having flappingly-pivoted blades, and these figures also illustrate the mounting of the hub of one of the rotors and some of the controls of the aircraft; and fig. 6 illustrates a portion of the control system of fig. 5 modified for aircraft where the rotors are power driven. The rotor mechanism includes a member 14 at the outer end of each outrigger which serves to mount and enclose the lower portion of a hub support 15. The hub support is pivotally connected with a pair of apertured lugs 16 — 16 by means of a pivot pin 17 disposed with its axis extended transversely of the aircraft so as to provide for tilting movement of the associated rotor in a fore-and-aft direction. A hub spindle 18 projects upwardly above the pivot 17, and the hub member proper, at 19, is rotatively mounted on the spindle. Each rotor incorporates a plurality of blades 20, three being illustrated in the drawings, each blade being connected with the hub 19 by pivot means including at least a flapping pivot 21 providing freedom for individual flapping movement of the blades in a direction generally transverse their mean rotative path of travel, in order to compensate for differential lift effects in translational flight. A drag or lag-and-lead pivot 22 is also desirably employed in the connection of each blade to the hub. The lower extension 23 of the tiltable hub supporting member lies within the mounting casing 14 and is provided with a yoke 24 embracing the sleeve 25, the legs of the yoke being slotted to engage the pins 26 which project in opposite directions from the sleeve 25. Sleeve 25 is internally threaded to receive and cooperate with the threaded spindle 27 which is journaled in the supporting casing 14 and restrained as against axial movement. This mechanism provides for tilting of the hub support and the rotor carried thereby upon rotation of the spindle 27 which effects movement of the sleeve 25. Notation of the spindle, in turn, is accomplished by the control system.

88. Neferring to fig. 5, which is a view of the control connections to the right side rotor, the spindle 27 is rotated by pulley 33 and through the threaded connection with sleeve 25 causes the lower portion 23 of the hub support 15 and also the hub spindle 18 to tilt in a longitudinal plane about the tilting pivot 17. Pulley 33 is actuated by cable runs c and b. Nun c passes around a pulley at the top of the double arm 35 and then in a run d through an aperture in the rocking shaft 31 to the lower extension arm 37 of the control column 28 and up to a pulley at the top of double arm 36, thus joining cable run e for the left side rotor, Which run e is similar to the run c for the right side rotor, and the run e extends to a pulley for the left side rotor corresponding to pulley 33 for the right side rotor; and cable run b from pulley 33 for the right side rotor passes around a pulley at the lower end of double arm 35 and then up through an aperture in the rocking shaft 31 and attaches to the control stick 28, and a similar cable run f for the left side rotor passes around a pulley at the bottom of the double arm 36 and upwardly for attachment to the control stick 28. The control stick 28 attaches to a yoke 29 which is pivoted at 30 to the rocking shaft 31 and at its ends the rocking shaft 31 is provided with trunnions 32 mounted in bearings on the aircraft structure, and the pivoting at 30 and the mounting of trunnions 32 provide for universal movement of the stick.

89. Fig. 6 of the '966 patent drawings shows a modification of the control system of fig. 5 for use with side-by-side rotors which are power driven. The effect or result of the differential tilting of the rotors is to cause a banking or rolling of the aircraft so that for a left movement of the control stick the aircraft will roll to the left and for a right movement of the control stick the aircraft will roll to the right, and that rolling is a motion of the aircraft used in making a turn to the left or right. For a left movement of the control stick the lift line of the right rotor will tilt forwardly and the lift line of the left rotor will tilt rearwardly causing the aircraft to turn to the left, and conversely for a right movement of the control stick the lift line of the right rotor will tilt rearwardly and the lift line of the left rotor will tilt forwardly causing the aircraft to turn to the right. The rotors of the aircraft of the '966 patent sustain the aircraft in flight whether the rotors are autorotatively actuated or power driven.

90. In accordance with findings 85 — 89, inclusive, claim 1 of the '966 patent finds complete support in the disclosure of the specification and the drawings of the patent as issued and also in the application for the patent as filed. The specification and claim 1 of the '966 patent are sufficiently definite and certain, and are not vague or indefinite. The claimed subject matter as well as the language of claim 1 of the '966 patent is not limited to any particular type of rotary wing aircraft, and the invention as defined in the '966 patent claim in suit is applicable to aircraft of the helicopter type in which the sustaining rotors are adapted for power-driven rotation and autorotative operation under different conditions, such as defendant’s Kaman helicopters. The definition of the invention in claim 1 of the '966 patent was not so limited during the course of the prosecution of the application therefor that said claim cannot properly be construed to cover defendant’s Kaman helicopters. The date of conception by Campbell of the subject matter of the claim in suit of the '966 patent was at least as early as April 19, 1934, the date of a sketch with description and comprising a part of an affidavit filed May 31, 1941, in Campbell patent application Ser. No. 324,248 of March 16,1940, on which application the Campbell patent in suit 2,339,836 issued.

91. Plaintiff has submitted proofs of infringement of claim 1 of the '966 patent by defendant’s HOK-1 Kaman helicopter. The general construction and operation of the HOK-1, and the structure and operation of the parts of particular pertinence to the claim in suit of the Campbell '966 patent are described and illustrated in plaintiff’s exhibits 160,168,166, 168, 219 to 224 and 383 to 385. These exhibits are portions of manuals pertaining to the HOK-1 and similar models of defendant’s Kaman helicopters.

92. In accordance with finding 91, the HOK-1 incorporates each of the elements of the combination defined in claim 1 of the '966 patent and such combination of elements in the HOK-1 operates in the same manner and produces the same result as disclosed in the '966 patent. The HOK-1 Kaman helicopter comes within the meaning and within the principle of claim 1 of the '966 patent, and infringes said claim.

93. With respect to the validity of the '966 patent in suit, defendant has relied upon most of the items noted in finding 84. The Appley '700, Beurrier '982, McGuire '766, Smith '105, Wojciechowski British 14,445, Focke British 499,073, Focke Flight Article, Laroche French 736,223, and Vannay French 767,068 patents and publication do not disclose structure such as pivoted blade sustaining rotors, rotors arranged where the lift lines may be shifted forwardly or rearwardly of the center of gravity, control mechanisms coupled to both rotors, and means for differentially tilting the rotors in longitudinal planes, as defined in claim 1 of the '966 patent. The Focke British Patent and Article were considered by the Patent Office examiner during the prosecution of the '966 patent application. Said claim is found to be valid.

BENNETT PATENT NO. 2,344,967

94. The Bennett patent 2,344,967, hereinafter referred to as the '967 patent, relates to control of aircraft having side-by-side rotors with flappingly-pivoted blades, and particularly to longitudinal and lateral attitude control by conjointly shifting or tilting the lift lines of the two rotors fore and aft and laterally of the aircraft, and also to collective or mean pitch change of the rotor blades. The '967 patent also relates to the phasing of the rotors to minimize bouncing effects which rotors experience in translational flight.

95. The '967 patent contains 20 claims, six of which, namely claims 1, 2, 3, 4,13,'and 18 are in suit. Claims 1 and 13 are reproduced below. (Mentation and numbering added.)

Patent Claim 1 of '967
In an aircraft,
1. a sustaining system including a pair of rotors lying substantially in a common horizontal plane,
2. flight control mechanism for the aircraft comprising means associated with the rotors and providing for shifting of the lift lines of the rotors to control the attitude of the aircraft in flight,
(la) the rotors comprising generally upright rotational hubs and blades pivotally mounted thereon for free aerodynamically-induced swinging in directions generally transverse to planes perpendicular to the hub axes and through a range comprehending that position in which the blade is perpendicular to its rotational axis, to compensate for differential lift effects in all normal flight operations including actuation of the flight control mechanism,
(1)_ the pivotal blade mountings being constructed to provide clearance for said range of swinging movement throughout the entire circle of rotation,
(2) the axes of said hubs being arranged in spaced side-by-side relation,
(lb) the rotors incorporating the same number of blades and the blades being equi-spaced and being aero-foils respectively oriented to rotate in opposite senses,
3. and mechanism interconnecting said rotors for rotation in such phase relationship that when the axis of a blade of one rotor extends fore and aft ¡of the craft, the axis of a blade of the other rotor extends at an angle to said first blade axis, which angle is substantially equal to one-half of the inter-blade spacing angle.
Patent Claim 13 of '967
In an aircraft,
1. a pair of pivoted wing sustaining rotors arranged in side-by-side relation,
2. and flight control mechanism comprising, for eaph rotor, controllable means for angularly shifting the lift line of the rotor fore and aft and laterally of the aircraft,
3. and, for each rotor, controllable means for increasing or decreasing the mean rotor blade pitch.

96. The '967 patent discloses a number of embodiments and a total of 19 figures in the drawings only a few of which embodiments and figures need be considered in connection with the claims in suit. Figs. 1 to 4 and figs. 9 and 10 illustrate two different embodiments of rotary wing aircraft having side-by-side rotors; figs. 13, 13a, and 14 illustrate details of the hub mounting structure and control mechanism for the embodiment of figs. 9 and 10; and fig. 15 is a view of a rotor hub similar to those of fig. 3 but illustrating a modified arrangement. The rotary wing aircraft of figs. 1 to 4 of the '967 patent has power-driven spaced non-intermeshing side-by-side laterally disposed rotors mounted on outriggers 18 and 18a, with the axes of the rotor hubs and the rotors located in a transverse plane passing through the center of gravity indicated at eg in fig. 2; and the rotors being driven in opposite directions, as indicated by arrows in fig. 2, by drive mechanism in fig. 3, which interconnects the rotors and assures that they rotate together. The two rotors have generally upright rotational hubs in spaced side-by-side relation as is indicated by the dot-dash lines on fig. 1, and the two rotors lie substantially in a common horizontal plane. The rotors sustain the aircraft in flight.

97. In a flappingly-pivoted sustaining rotor, bouncing effects are caused by variations in lift encountered by the blades especially in relatively high speed translational flight, such bouncing being an axial vibration experienced by a sustaining rotor and derived from the periodic variation of the thrust of the blades, having frequencies which are integral multiples of the revolutions per second of the rotor multiplied by the number of blades. This vibration, if not otherwise prevented, inhibited, compensated or absorbed, is transmitted to the body of the craft as a vertical vibration having a particularly undesirably physiological and psychological effect on the occupants, being in a direction parallel to their spinal columns. The '967 patent provides a solution for the problem of bouncing effects in sustaining rotors by operation of spaced side-by-side rotors in a phase relation so that the bouncing effect of one rotor is out of phase with the bouncing effect of the other rotor. This minimizes the bouncing effect of a single rotor, and the remaining vibration, because of the side-by-side relation of the rotors is a rolling effect rather than a direct up-and-down vibratory effect. The desired compensation for bouncing is obtained by so gearing the rotors together that when the blade of one of the rotors lies in the direction of forward flight of the aircraft, a blade of the other rotor lies in a direction making an angle with the first named direction equal or approximately equal to half the blade-spacing angle

98. Figs. 9' and 10 illustrate a configuration of rotors sometimes referred to as the eggbeater type, having two oppositely rotating rotors each having two equi-spaced aerofoil blades, the rotors lying substantially in a common horizontal plane in closely spaced intermeshing side-by-side relationship with the axes of the rotor hubs and of the rotors lying in a plane approximately containing the center of gravity of the aircraft and separated by a distance less than one-half the rotor diameter and with the rotor axes upwardly divergent so that the blades of one rotor will pass over or clear the hub structure of the other rotor even when the blades are in the lowest positions of swinging on their flapping pivots. The ge'aring interconnecting the two rotors provides for rotation of the two rotors in that phase relationship referred to in finding 97.

99. In fig. 14 and in fig. 9, the two rotors are mounted for tilting longitudinally and laterally for control at the top of a single central mast support 48. At the top of the mast are overhung bearings 53 which journal a longitudinal pivot pin 54 carrying a housing member 55, also shown in fig. 13, which mounts the rotor mounting beam 49 through bearing 56, providing for longitudinal and lateral tilting of both rotor hub spindles. As an alternative to the use of control mechanism for actually tilting the hubs of the paired rotors, either as a unit or on separate universal mountings, the rotor lift lines may be tilted by control mechanism for periodically varying the pitch angles of the rotor blades. In the arrangement in fig. 15, each of the two rotors is separately mounted for tilting in longitudinal and lateral planes. In rotating-wing aircraft having flappingly mounted rotor blades and having rotor control the flapping motion of the blades due to actuation of the controls is superimposed upon the flapping motion of the blades in compensating for differential lift effects in translational flight; and in the '967 patent as in figs. 1 and 2 and also in figs. 9 and 10, the flapping mounting of the blades provides a range of flapping motion for the blades including blade positions perpendicular to the rotor axis and even below the perpendicular, and permits blade flapping to compensate for differential lift effects in all normal flight operations including operation of the flight control mechanisms, and that range of flapping is available throughout the entire circle of rotation of the rotor blades.

100. In accordance with findings 96-99, inclusive, claims 1, 2, 8, 4,13, and 18 of the '967 patent find complete support in the disclosure of the specification and the drawings of the patent as issued and :also in the application for the patent as filed. The specification 'and claims 1, 2, 3, 4, 13, and 18 of the '967 patent are sufficiently definite and certain, and are not vague and indefinite.

101. The claimed subject matter as well as the language of claims 1, 2, 3, 4, 13, and 18 of the '967 patent is not limited to any particular type of rotary wing aircraft, and the invention as defined in the '967 patent claims in suit is applicable to aircraft of the helicopter type in which the sustaining rotors are adapted for power-driven rotation and auto-rotational operation 'Under different conditions, such as defendant’s Eaman helicopters. The definition of the invention in claims 1, 2, 3, 4,13, and 18 of the '967 patent was not so limited during the course of the prosecution of the application therefor that said claims cannot properly be construed to cover defendant’s Kaman helicopters. So far as the subject matter of the '967 patent claims in suit is concerned, U.S. Patent application, Ser. No. 242,057, filed November 23, 1938, and on which the '967 patent issued, was based upon and corresponds to the provisional and complete specification of Bennett’s British application 32,731 dated November 26, 1937. The date of invention by Bennett of the subject matter of the claims in suit of the '967 patent was at least as early as November 26, 1937, the application date in Great Britain of Bennett’s British, application No. 32,731.

102. Plaintiff has submitted proofs of infringement of claims 1, 2, 3, 4, 13, and 18 of the '967 patent by defendant’s HOK-1 Kaman helicopter. The general construction and operation of the HOK-1, and the structure and operation of the parts of particular pertinence to the claims in suit of the Bennett "967 patent are described and illustrated in plaintiff’s exhibits 160, 163, 166, 168, 218 to 224, 382, and 384 to 386. These exhibits are portions of manuals pertaining to the HOK-1 and similar models of defendant’s Kaman helicopters.

103. In accordance with findings 101-102, inclusive, the HOK-1 incorporates each of the elements of the combination defined in each of claims 1, 2, 3, 4, 13, and 18 of the '967 patent and each such combination of elements in the HOK-1 operates in the same manner and produces the, same result as disclosed in the '967 patent. The HOK-1 Kaman helicopter comes within the meaning and within the principle of each of claims 1,2, 3,4,13, and 18 of the '967 patent, and infringes said claims.

104. With respect to the '967 patent in suit, defendant has urged that the patent claims are limited by the patentee’s British patent 506,404, that the claims are invalid as being based on new matter, and that the claims are invalid in view of prior art items. Certain statements inserted by the patentee in his British patent application relate to constructions already proposed and shown, for example, in prior patents considered by the U.S. Patent Office examiner during the prosecution of the '966 application for patent. The statements in the British patent do not limit the patent claims here in suit. With regard to the new matter contention, it is found that the additional drawing added to the '966 patent application was not new matter. It is found that the applicant in obtaining the '966 patent did not disclaim certain rotor control features as alleged by defendant.

105. With regard to the validity of claims 1, 2, 3, 4, 13, and 18 of the '967 patent, defendant apparently relies upon the numerous prior art items urged against the '572, '836, and '966 patents and noted in findings 75, 76, 84, and 93. The Appley '700, Beurrier '982, Pitcairn '762, Perrin '310, de Bothezat '228, McGuire '766, Wilford '813, Williams '996, Smith '105, Wojciechowski British 14,445, Focke British 499,073, Focke Flight Article, Laroche French 736,223, Van-nay French 767,068, Nash '361, Breguet '089, Cierva '230, '580 and '582 patents and publication do not disclose the specific flight control mechanisms defined in claims 1, 2, 3, 4, 13, and 18 of the '967 patent. The record shows that at least seven of the above-listed items were considered by the Patent Office examiner during the prosecution of the '967 application for patent. The '967 patent claims in suit are found to be valid over the listed items.

CIERVA PATENT NO. 2,380,583

106. Plaintiff has submitted proofs of infringement of claims 56, 59, 60, 64, and 65 of the '583 patent by the HUP-1 Vertol helicopter and its rotor blades. The pertinent mechanism of the HUP-1 helicopter and of both its straight wooden and twisted wooden rotor blades is described and illustrated in plaintiff’s exhibits 80, 84, 86, 87, 88, 90, 92,140, 141, 340, and 341. These exhibits are portions of manuals pertaining to the HUP-1 and similar models of defendant’s Vertol helicopters.

107. The HUP-1 helicopter and particularly the rotor construction of both its fore-and-aft rotors, with straight and also with twisted wooden rotor blades, incorporates each of the elements of the combination defined in claim 64 of the '583 patent and such combination of elements in the HUP-1 operates in the same manner and produces the samé result as disclosed in the '583 patent, and comes within the meaning and within the principle of claim 64 of the '583 patent, and infringes said claim. Both the straight and twisted wooden rotor blades for the HUP-1 incorporate each of the elements of the combination defined in each of claims 56, 59, 60, and 65 of the '583 patent, and each such combination of elements in said straight and twisted wooden rotor blades operates in the same manner and produces the same result as disclosed in the '583 patent, and comes within the meaning and within the prill-ciple of each of claims 56, 59, 60, and 65 of the '583 patent, and infringes said claims.

108. Plaintiff has submitted proofs of infringement of claims 56, 59, 60, 64, and 65 of the '583 patent by the H-21B Vertol helicopter and its rotor blades. The pertinent mechanism of the H-21B and of both its wooden and metal blades is described and illustrated in plaintiff’s exhibits 247, 249, 250, 253, 254, 255, 257, 258, 259, 344, 345, 346, and 347. These exhibits are portions of manuals pertaining to the H-21B and similar models of defendant’s Vertol helicopters.

109. The H-21B Vertol helicopter and particularly its tandem-disposed rotors, with wooden and also with metal rotor blades, incorporates each of the elements of the combinations defined in claims 56, 59, 60, 64, and 65 of the '583 patent, and such combinations of elements in the H-21B operate in the same manner and produce the same results disclosed in the '583 patent. The constructions used in the H-21B come within the meaning and principle of each of claims 56, 59, 60, 64, and 65 of the '583 patent and infringe said claims.

110. Plaintiff has submitted proofs of infringement of claim 62 of the '583 patent by the MC-4C McCulloch helicopter and its rotor blades. The pertinent mechanism of the ]VEO — 40 is described and illustrated in plaintiff’s exhibits 235, 236, 238, 239, 240, 242, 245, 348, 349, and 350. These exhibits are portions of manuals pertaining to the MC-4C helicopter as manufactured by the McCulloch Motors Corporation and used by defendant.

111. The MC-4C McCulloch helicopter and particularly the rotor construction of both its fore-and-aft rotors and rotor blades incorporates each of the elements of the combinations defined in claim 62 of the '583 patent, and each such combination operates in the same maimer and produces the same results as disclosed in the '583 patent. The constructions used in the MC-4C come within the meaning and principle of claim 62 of the '583 patent and infringes said claim.

112. In its requests for findings of fact relative to the infringement and validity of the '583 patent claims, defendant has referred to about forty patents and publications and to a number of patent application files. These include Cof-felt '486, Hewitt '454 and '455, Martin '518, Cierva '497, '282 and '081, Isacco '009, Pitcairn '427, Cierva '584, Smith '928, Bleecker '450, Cierva '520, Breguet et al. '089, Bordoni '805, Cierva '785, Avery '701, d’Ascanio '141, Pecker '986, Myers '090, Upson '595, Cierva British '748, '963 and'965, Oehmichen British '871, Andres French '650, Isacco French 'Oil, and Cierva French '347, all being patents fully identified in findings 367, 390 and 398 of the Commissioner’s report, and also the following additional patents and publication:

United States Patents DXNo.

1,685,029 Kelley_ 1928 -

1,688,188 Humphrey _ 1928 -

1,692,082 Cierva_ 1928 113.15

1,777,630 Vaughn_ 1930 113.27

1,884,598 Cierva_ 1932 114.12

1,897,042 Cierva_ 1933 114.21

2,216,163 Ray_ 1940 117.29

2,216,768 Cierva_ 1940 207

2,333,364 Dyer et al_ 1943 245

Foreign Patent

British 274,973 Muir_’ 1927 118.21

Publication

North American Review, pp. 530-535_ Nov. 1929 165

113. It is specifically found that the teachings of the Bor-doni '805, d’Ascanio '141, Oehmichen British '871, and Cierva British '983 patents particularly relied upon by the defendant do not invalidate the '583 patent claims 56, 59, 60, 62, 64, and 65.

CIERVA PATENT NO. 2,421,364

114. Plaintiff has submitted proofs of infringement of claims 33, 44, and 45 of the '364 patent by defendant’s HOK-1 Kaman helicopter. The pertinent mechanism of the HOK-1 is described and illustrated in plaintiff’s exhibits 160, 163, 166, 168, 218, 220, 221, and 224. These exhibits are portions of manuals pertaining to defendant’s HOK-1 helicopters.

115. The HOK-1 Kaman helicopter and particularly the construction of both of its rotors incorporates each of the elements of the combination defined in each of claims 33, 44, and 45 of the '364 patent, and each such combination of elements in the HOK-1 helicopter operates in the same manner and produces the same result as disclosed in the '364 patent. The HOK-1 helicopter and particularly the construction of both of its rotors comes within the meaning and within the principle of each of claims 33, 44, and 45 of the '364 patent, and infringes said claims.

116. In its request for findings of fact relative to infringement and validity of the '364 patent, defendant has referred to some 25 patents and patent application files including Degn '756, Perrin '513, Cierva '497, '232, '893, '081, '082, '303, '584, and '598, Breguet et al. '089, Bordoni '805, Larsen '411, Cierva '819 and '785, Avery '701, Pitcairn '600, Stanley '417, d’Ascanio '141, Upson '595, Pollacsek British '621, Cierva British '965, Oehmichen British '871, Isacco French 'Oil, and Breguet French '756, patents all fully identified in findings 367, 390, 395, and 401 of the Commissioner’s report, and also Nagler British patent 476,597, 1937, DX No. 119.6, and Cierva U.S. patent 1,985,819,1934, DX No. 116.5.

117. It is found specifically that the '364 patent claims 33, 44, and 45 are not invalidated by Perrin '513, Bordoni '805, Oehmichen British '871 and d’Ascanio '141 patents.

CIERVA PATENT NO. 2,380,582

118. Plaintiff has submitted proofs of infringement of claims 1, 2, 3, 4, 5, 7, 8, 9, 12, 13, 16, 17, 18, 19, 20, and 21 of the '582 patent by the HUP-1 Yertol helicopter. The pertinent mechanism of the HUP-1 is described and illustrated in plaintiff’s exhibits 80, 81, 84, 86, 87, 90, 227, 229, 230, 282, 283, and 284. These exhibits are portions of manuals pertaining to the HUP-1 and similar models of defendant’s Yertol helicopters.

119. The HUP-1 Yertol helicopter incorporates each of the elements of the combination defined in each of claims 1, 2, 3, 4, 5, 7, 8, 9, 12, 13, 16, 17, 18, 19, 20, and 21 of the '582 patent, and in the HUP-1 each such combination of elements operates in the same manner and produces the same result as disclosed in the '582 patent. The HUP-1 Vertol helicopter comes within the meaning and within the principle of each of claims 1, 2, 3, 4, 5, 7, 8, 9,12,13,16,17,18, 19,20, and 21 of the '582 patent, and infringes said claims.

120. Plaintiff has submitted proofs of infringement of claims 1, 2, 3, 4, 5, 7, 8, 9,12,13,16,17,18,19, 20, and 21 of the '582 patent by the H-21B Vertol helicopter. The pertinent mechanism of the H-21B is described and illustrated in plaintiff’s exhibits 247, 248, 249, 250, 251, 253, 254, 255, 256, 257, 258, and 259. These exhibits are portions of manuals pertaining to the H-21B and similar models of defendant’s Vertol helicopters.

121. The H-21B Vertol helicopter incorporates each of the elements of the combination defined in each of claims 1, 2, 3, 4, 5, 7, 8, 9, 12, 13, 16, 17, 18, 19, 20, and 21 of the '582 patent, and in the H-21B each such combination of elements operates in the same manner and produces the same result as disclosed in the '582 patent. The H-21B Vertol helicopter comes within the meaning and within the principle of each of claims 1, 2, 3, 4, 5, 7, 8, 9, 12, 13,. 16, 17, 18, 19, 20, and 21 of the '582 patent, and thereby infringes said claims.

122. Plaintiff has submitted proofs of infringement of claims 1-5, 7, 8, 9, 12, 13, and 16-21 of the '582 patent by the MC-4C McCulloch helicopter. The pertinent mechanism of defendant’s MC-4C helicopter is described and illustrated in plaintiff’s exhibits 235, 236, 238 to 245, and 291. These exhibits are portions of manuals pertaining to the MC-4C helicopter as manufactured by the McCulloch Motors Corporation and used by defendant.

123. The MC-4C McCulloch helicopter incorporates each of the elements of the combination defined in each of claims 1, 2, 3, 4, 5, 7, 8, 9, 12, 13, 16, 17, 18, 19, 20, and 21 of the '582 patent and in the MC-4C each such combination of elements operates in the same manner and produces the same result as disclosed in the '582 patent. The MC-4C McCulloch helicopter comes within the meaning and within the principle of each of claims 1, 2, 3, 4, 5, 7, 8, 9, 12, 13, 16, 17, 18, 19, 20, and 21 of the '582 patent and infringes said claims.

124. Plaintiff has submitted proofs of infringement of claims 6, 7, 8, 9, 12, 13, 16, and 17 of the '582 patent by the HSL-l Bell helicopter. The general configuration and construction and the parts of the HSL-l helicopter of particular pertinence to the claims referred to above are described and illustrated in plaintiff’s exhibits 296 to 300, 302 to 306, 308, and 310. These exhibits are portions of manuals pertaining to the HSL-l helicopter and these manuals were published by defendant.

125. The HSL-l Bell helicopter incorporates each of the elements of the combination defined in each of claims 6, 7, 8, 9, 12, 13, 16, and 17 of the '582 patent and in the HSL-l each such combination of elements operates in the same manner and produces the same result as disclosed in the '582 patent. The HSL-1 helicopter comes within the meaning and within the principle of each of claims 6, 7, 8, 9, 12, 13, 16, and 17 of the '582 patent, and infringes said claims.

126. The numerous prior patents and publications mentioned by defendant as invalidating the several '582 patent claims in suit do not disclose the various combinations of means providing for flapping or blade swinging transverse the rotative path to accommodate differential flight forces, means providing for bodily shift of each blade as an entirety for cyclic variation of pitch with respect to the hub, a pilot’s control member and control connections coupled with the rotor to provide instinctive control response, control connections flexibly jointed adjacent flapping axis, an autorotatable sustaining rotor, and/or means for varying the average or collective geometrical pitch settings of the rotor blades, as defined in the '582 patent claims. It is found specifically that such combinations are not present in the constructions disclosed in Upson '470 and '595, Breguet '089, Sweet '108, Oehmichen '783, '871 and '752, Fabre '263, Pes-cara '716, '944, '257 and '932, Cierva '935 and '286, Isacco '758, Pitcairn '762, Pollacsek '621, Perrin '573, Cierva '497, '232, '303, '584 and '963, Bordoni '805, Perry '846, Pescara '129 and '739, Pitcairn '427 and '577, Nagler et al. '845, Bleecker '450, Yon Baumhauer '272, Breguet '756, Cierva '748, '893 and '965, and Avery '701 patents, nor in the Aerophile publication.

127. Defendant’s attempted modifications and combinations of certain prior art disclosures against the claims in suit of the '582 patent, in the light of established legal principles, are not effective against those claims, either because the disclosures individually contain errors, or are ambiguous, vague, indefinite, contradictory, impractical or inoperative, or because the suggested modifications or combinations are not practicable, proper or obvious, and/or are not suggested by any one of the prior art disclosures which the defendant attempts to so modify or combine; or because the defendant has not presented any clear-cut application thereof specifically to any claim of the '582 patent. The patent claims in suit of the '582 patent are found to be valid.

CONCLUSION OF LAW

Upon the foregoing findings of fact and opinion, which are adopted by the court and made a part of the judgment herein, the court concludes as a matter of law that plaintiff is the lawful owner of all claims found valid and infringed, and is entitled to recover “reasonable and entire compensation” for the unauthorized use of these claims. Judgment is entered to that effect with the determination of the amount of recovery to be reserved for further proceedings before the trial commissioner pursuant to Rule 47(c). 
      
       28 U.S.C. § 1498 states in part:
      “Whenever an invention described in and covered by a patent of the United States is used or manufactured by or for the United States without license of the owner thereof or lawful right to use or manufacture the same, the owner’s remedy shall be by action against the United States in the Court of Claims for the recovery of his reasonable and entire compensation for such use and manufacture.”
      See Western Electric Co. v. Hammond, 135 F. 2d 283 (1st Cir. 1943).
     
      
      
         Lyon v. Bausch & Lomb Optical Co., 224 F. 2d 530, 536 (2d CIr. 1955), cert. denied 350 U.S. 911; Fairchild Engine & Airplane Corp. v. United States, 152 Ct. Cl. 352, 285 F. 2d 131 (1961).
     
      
       Section 271(a) states: “Except as otherwise provided in this title, whoever without authority makes, uses or sells any patented invention, within the united States during the term of the patent therefor, infringes the patent.”
     
      
      
         E.g., Yale Lock Mfg. Co. v. Greenleaf, 117 U.S. 554 (1886) ; Merrill v. Yeomans, 94 U.S. 568 (1876) ; Keystone Bridge Co. v. Phoenix Iron Co., 95 U.S. 274 (1877) ; Smith v. Snow, 294 U.S. 1 (1935) ; Altoona Public Theatres, Inc. v. American Tri-Ergon Corp., 294 U.S. 477 (1935) ; Ethyl Gasoline Corp. v. United States, 309 U.S. 436 (1940) ; Sontag Chain Stores Co. Ltd. v. National Nut Co., 310 U.S. 281 (1940) ; Scott Paper Co. v. Marcalus Mfg. Co., 326 U.S. 249 (1945) ; Milcor Steel Co. v. George A. Puller Co., 316 U.S. 143 (1942) ; Marconi Wireless Telegraph Co. of America v. United States, 320 U.S. 1 (1943) ; Aro Mfg. Co. v. Convertible Top Replacement Co., 365 U.S. 336 (1961) ; Graver Tank & Mfg. Co. v. Linde Air Products Co., 339 U.S. 605 (1950) ; Perry v. United States, 112 Ct. Cl. 1, 76 F. Supp. 503 (1948) ; Chesterfield v. United States, 141 Ct. Cl. 838, 159 F. Supp. 371 (1958) ; Yosemite Chemical Co. v. United States, 175 Ct. Cl. 623, 360 F. 2d 948 (1966) ; Soundscriber Corp. v. United States, 175 Ct. Cl. 644, 360 F. 2d 954 (1966).
     
      
      
         E.g., Brooks v. Piske, 56 U.S. (15 How.) 212 (1853) ; White v. Dunbar, 119 U.S. 47 (1886) ; Cimiotti Unhairing Co. v. American Fur Refining Co., 198 U.S. 399 (1905) ; Hutzler Bros. v. Sales Affiliates, Inc., 164 F. 2d 260 (4th Cir. 1947) ; Warner & Swasey Co. V. Universal Marion Corp., 237 F. Supp. 719 (D. Colo. 1964) ; Morrill v. Automatic Industries, Inc., 93 F. Supp. 697 (W. D. Mo. 1950).
     
      
       Pin Berkey v. United States, 176 Ct Cl. 1, 361 W. 2d 983 (1960), a case involving veterans’ benefits, a supposedly clear and unambiguous section of a statute read on tbe surface to bar certain payments to tbe survivors of an incompetent veteran. Tbe court went below tbe surface and found that Congressional intent was tbe opposite of tbe surface manifestation.
     
      
      
        United States v. Johnson, 221 U.S. 488, 496 (1911).
     
      
       Rule 75(d) : “The claim or claims must conform to the Invention as set forth in the remainder of the specification and the terms and phrases used in the claims must find clear support or antecedent basis in the description so that the meaning of the terms in the claims may be ascertainable by reference to the description.”
     
      
      
         E.g., Topliff v. Topliff, 145 U.S. 156 (1892) ; Marconi Wireless Co. v. United States, supra; Bates v. Coe, 98 U.S. 31 (1878) ; Cimiotti Unhairing Co. v. American Fur Refining Co., supra; Schriber-Schroth Co. v. Cleveland Trust Co., 311 U.S. 211 (1940) ; United States v. Adams, 383 U.S. 39 (1966) ; Fauber v. United States, 93 Ct. Cl. 11, 37 F. Supp. 415 (1941) ; Stearns v. Tinker & Rasor, 252 F. 2d 589 (9th Cir. 1957) ; Carl Braun, Inc. v. Kendall-Lamar Corp., 116 F. 2d 663 (2d Cir. 1941) ; Hutsler Bros. Co. v. Sales Affiliates, supra; Scherbatskoy v. U.S. Steel Corp., 287 F. 2d, 552 (7th Cir. 1961) ; National Transformer Corp. v. France Mfg. Co., 215 F. 2d 343 (6th Cir. 1954) ; Standard Duplicating Machines Co. v. American Business Machines Corp., 174 F. 2d 101 (1st Cir. 1949), cert. denied 338 U.S. 827.
     
      
       35 U.S.C. § 103 requires that: “A patent may not he obtained though the invention is not identically disclosed or described as set forth in section 102 of this title, if the differences between the subject matter sought to be patented and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary shill in the art to which said subject matter pertains.”
     
      
      
        E.g., I.T.S. Rubber Co. v. Essex Rubber Co., 272 U.S. 429 (1926) ; Morgan Envelope Co. v. Albany Perforated Wrapping Paper Co., 152 U.S. 425 (1894) ; Exhibit Supply Co. v. Ace Patents Corp., 315 U.S. 126 (1942) ; Powers-Kennedy Contracting Corp. v. Concrete Mixing and Conveying Co., 282 U.S. 175 (1930) ; Keystone Driller Co. v. Northwest Engineering Corp., 294 U.S. 42 (1935) ; Smith v. Magic City Kennel Club, Inc., 282 U.S. 784 (1931) ; Also, Pine, “File Wrapper Estoppel” in Encyclopedia of Patent Practice and Patent Management, 295 (Calvert ed.).
     
      
       The use of the file wrapper as “legislative history” has been condoned by most courts. E.g., Goodyear Dental Vulcanite Co. v. Davis, 102 U.S. (12 Otto) 222 (1880) ; Crawford v. Heysinger, 123 U.S. 589 (1887) ; Lavelle Aircraft Corp. v. United States, 175 Ct. Cl. 325, 358 F. 2d 1005 (1966) ; Jones v. United States, 120 Ct. Cl. 747, 100 F. Supp. 628 (1951) ; Moon v. Cabot Shops, 270 F. 2d 539 (9th Cir. 1959), cert. denied 361 U.S. 965 (1960) ; Westinghouse Electric Corp. v. Hanovia Chem. & Mfg. Co., 179 F. 2d 293 (3d Cir. 1949) ; Mall Tool Co. v. Quaker Vilbrators, Inc., 30 F. Supp. 841 (E.D. Pa. 1939). Contra; A. G. Spalding & Bros. v. John Wanamaker, 256 Fed. 530 (2d Cir. 1919) ; Zenith Radio Corp. v. Lehman, 121 F. Supp. 69 (S.D.N.Y. 1954), aff’d 217 F. 2d 954 (2d Cir. 1955).
     
      
      
         E.g., Singer Mfg. Co. v. Cramer, 192 U.S. 265 (1904) ; Graver Tank Mfg Co. v. Linde Air Products Co., supra; Perry v. United. States, supra; Independent Pneumatic Tool Co. v. Chicago Pneumatic Tool Co., 194 F. 2d 945 (7th Cir. 1952) ; Grubman v. Goldberger, supra; S. S. Kresge Co. v. Davies, 112 F. 2d 708 (8th Cir. 1940) ; Standard Oil Development Co. v. James B. Berry Sons Co., 92 F. 2d 386 (3d Cir. 1937) ; Mattel, Inc. v. Louis Marx & Co., 200 F. Supp. 593 (S.D. Calif. 1961) ; U.S. Gypsum Co. v. Rock Wool Insulating Co., 212 F. Supp. 1 (D. Colo. 1962).
     
      
      
         E.g., Machine Co. v. Murphy, 97 U.S. 120 (1877) ; Graver Tank Mfg. Co. v. Linde Air Products Co., supra; Pratt & Whitney Co., Inc. v. United States, 170 Ct. Cl. 829, 345 F. 2d 838 (1965) ; Dwyer v. United States, 174 Ct. Cl. 1064, 357 F. 2d 978 (1966) ; Badowski v. United States, 135 Ct. Cl. 93, 140 F. Supp. 544 (1956) ; Chicago Pneumatic Tool Co. v. Hughes Tool Co., 97 F. 2d 945 (10th Cir. 1938), cert denied 305 U.S. 643 ; Powder Power Tool Corp. v. Powder Actuated Tool Co., Inc., 230 F. 2d 409 (7th Cir. 1956).
     
      
      
         “Autogiro” was coined by tie inventor, Juan de la Cierva, as a proprietary name. When spelled with a lower ease a, it is used as a generic term. Other generic terms include autogyro, rotorplane, and giro. In this opinion “autogiro” will be used to cover this group of aircraft.
     
      
       A more detailed analysis of the operation of these two types of rotary wing aircraft appears in the discussion of the various patents. For background on helicopters and autogiros, see, generally, Gablehouse, Helicopters and Autogiros, Chaps. I—III and at 210-212, 218, 222-224, and 227-230; Cierva, Wings of Tomorrow; Canby, A History of Flight; Francis, The Story of the Helicopter.
      
     
      
       For this and all other patents mentioned in this opinion, identification will be made by reference to the last three digits of the patent’s number.
     
      
       The complete text of this claim and all other claims properly excepted to is in Appendix I.
     
      
      
         The '901 Specification states at 3, 1. 149-4, 1. 20:
      “Still further, to obtain to the fullest extent the advantages hereinbefore discussed, especially as to the combined effects of the positive-incidence rotor blades and positive-ineidence fixed wings, such as: increased lifting efficiency, increased top speed of the craft, and maintenance of the closest possible uniformity of rotor speed, it is preferable to make the total area of the fixed wings equal to about 75% to 100% of the amount of area of the four rotor blades, although in certain craft, for constructional reasons, it is desirable that the fixed wings be proportioned somewhat smaller, say 50% of rotative blade area. With fixed wing area proportioned in that range (especially between the 75 % and 100 % limits) and with positive incidence settings of both fixed and rotary wings, the rotor may be made to operate at a substantially uniform speed of rotation through the range of flight speeds of the craft, and such rotational speed, computed at the blade tip, will approximate 140% to 200% of the top speed of the craft."
     
      
      
        E.g., Kemart Corp. v. Printing Arts Research Laboratories, Inc., 201 F. 2d 624 (9th Cir. 1963) ; Western States Machine Co. v. S. S. Hepworth Co., 147 F. 2d 345 (2d Cir. 1945), cert. denied 325 U.S. 873 (1945) ; Cameron Iron Works v. Stekoll, 242 F. 2d 17 (5th Cir. 1957) ; Kennedy v. Trimble Nurseryland Furniture, Inc., 99 F. 2d 786 (2d Cir. 1938) ; Baker-Cammack Hosiery Mills, Inc. v. Davis Co., 181 F. 2d 550 (4th Cir. 1950). cert. denied 340 U.S. 824.
     
      
       These elements are: (28) “centrifugal means operatively associated with the rotor and responsive to increase of rotational speed to urge the blades toward increased pitch angles, and adjustable resilient means operatively associated with the centrifugal means to vary the speed at which such urge is neutralized” ; (29) “governing means for changing said pitch angles, and means modifying the effectiveness of the governing means to change the speed at which the pitch angles are affected”; (36) “centrifugal means operatively associated with the rotor and responsive to increase of rotational speed to urge the blades toward increased pitch angles”; (37) “supplemental governing means in part at least mounted on the rotor for changing the pitch angles of said blades”; (38) “centrifugal means operatively associated with the rotor and responsive to variations' of rotational speed to urge the blades toward changed pitch angles, and means manually actuated to override the centrifugal governor means to provide for positive manual setting of the pitch angles”; and (42) “centrifugal means operatively associated with the rotor and responsive to variations of rotational speed to urge the blade toward changed pitch angle.”
     
      
       See id. at 1, col. 1, 1. 29 — col. 2, 1. 11.
      
     
      
       In support of this, it cites id. at 2, col. 2, Is. 17-29 :
      “For my governing device, I have weights located in the blades which are acted upon by centrifugal forces resulting from the rotation of the rotor.
      “The weights are attached to the corresponding block incidence adjustment through cables in such manner as to tend to increase the incidence angle of the blade by the action of the centrifugal tension in the cables. Biased against the action of the centrifugal weight is an adjustable spring or elastic means. By this arrangement, the rotor tends to rotate at a constant speed until disturbed by the pilot.”
     
      
       When first entered, the claims were numbered 32, 33, 39 and 40. To avoid confusion, claims will be referred to at all times' by their final numbers.
     
      
       At 58 of the ’581 File Wrapper, the applicant stated that “the system disclosed in the instant specification and drawings automatically tends to return the blade pitch angles to a predetermined value without the attention of the pilot.” And id. at 59 : “* * * applicant has provided control devices in the form of an automatic governor so arranged as to urge the pitch angles of the blades or the R.P.M. of the rotor, to a substantially normal value used in level flight, which is completely foreign to any of the art of record. Illustratively only, the centrifugal weights disclosed provide a function of governing which is not present in Ethe prior artX”
     
      
       Rule 78 which Is now Rule 312 states:
      “Amendment alter tlie notice of allowance of an application will not be permitted as a matter of right, but may be made, if the printing of the specification has not begun, on the recommendation of the primary examiner, approved by the Commissioner, without withdrawing the case from issue.”
     
      
       See drawing 1 in Appendix II.
     
      
       See drawings 2, 3 and 4 in Appendix II.
     
      
       See drawing 5 in Appendix II for a depletion of this as found in the patent drawings.
     
      
       The specification states :
      “The invention refers to the method of ‘taking-off’ which consists in over-speeding the rotor by means of the starter transmission, the latter having a suitable gear ratio for this purpose, with the rotor blades set at a small pitch angle, preferably zero, and increasing the blade pitch angle to a value at least as great as that utilized in autorotative flight substantially at the same time as the starter transmission is disengaged, in order to utilize the excess kinetic energy of the overspeeded rotor to raise the aircraft substantially vertically from the ground.”
     
      
      
        Id. at 1, col. 1, ls. 19-27 and col. 2, ls. 45-46.
     
      
      
         E.g., Muncie Gear Works, Inc. v. Outboard Marine & Mfg. Co., 315 U.S. 759 (1942) and Railway Co. v. Sayles, 97 U.S. 554 (1878) which says at 563 and 564 : “* * * Courts should regard with jealousy and disfavor any attempts to enlarge the scope of an application once filed, or of a patent once granted, the effect of which would be to enable the patentee to appropriate other inventions made prior to such alteration, or to appropriate that which has, in the meantime, gone into public use.” Also, Coats Loaders & Stackers, Inc. v. Henderson, 233 F. 2d 915 (6th Cir. 1956) ; R.U.V. Engineering Corp. v. Borden Co., 170 F. 2d 688 (2d Cir. 1948) ; Jacquard Knitting Machine Co. v. Ordnance Gauge Co., 95 F. Supp. 902 (E.D. Pa. 1951), aff’d 213 P. 2d 503 (3d Cir. 1954).
     
      
       The specification states:
      “In the process of accomplishing a direct take-off, from the instant at which the pitch increase begins until autorotation is established, the rotor operates under a continuously changing regime, characterized by varying inflow, which, starting at zero, has at first a rapidly increasing positive (downward) value, reaching a peak and thereafter declining more slowly to zero again and finally reversing its sign as autorotation establishes itself.
      “If, for take-off, the blade pitch angle is increased almost instantaneously from about zero to an autorotative value of say 5 or 6 degrees, the thrust of the rotor immediately jumps from nothing to a large (peak) value much exceeding the weight of the aircraft, on account of the initial absence of inflow, and as the (downward) inflow builds up the thrust falls sharply and continues to fall as the rotational speed falls. Thus at the beginning of the take-off there is a violent upward acceleration which is followed by a relatively rapid falling off of lifting effort, which may give rise to a loss of height from the maximum attained, before autorotative flight is established.
      “An object of the present invention is to obviate the above-mentioned disadvantages.”
     
      
       See drawing 6 in Appendix II.
     
      
       See drawing 7 in Appendix II.
     
      
       See drawing 8 in Appendix II.
     
      
       After the take-off, the pitch decreases to an autorotational angle due to a contain construction of the rotor blade which is taught by the ’364 patent at col. 11, ls. 56—60 and col. 12, ls. 17— 28 of the specification.
     
      
       See drawing 10 in Appendix II.
     
      
       See drawing 11 in Appendix II.
     
      
       gee drawing 12 in Appendix II.
     
      
       See drawing 13 in Appendix II.
     
      
      
        E.g., Miehle Printing Press & Mfg. Co. v. Publications Corp., 166 F. 2d 615 (7th Cir. 1948) ; M. Swift & Sons v. W. H. Coe Mfg. Co., 102 F. 2d. 391 (1st Cir. 1939) ; Cummings v. Moore, 202 F. 2d 145 (10th Cir. 1953) ; Breeden V. Attwood Brass Works, 105 F. Supp. 876 (W.D. Mich. 1952).
     