Pee Curiam:
In this suit under 28 U.S.C. § 1498, plaintiff seeks reasonable and entire compensation for the alleged unauthorized use by defendant of an invention described and claimed in his U.S. Patent No. 2,601,104, entitled “Jet Propulsion and Control Means Therefor,” issued June 17, 1952. Jurisdiction is acknowledged and ownership of the patent is uncontested.
The suit involves jet-propelled airplanes. Accused to infringe are six British-made airplanes (called the Kestrel) and 11 replacement engines (called the Pegasus) that were brought to this country by defendant in late 1965. In addition, plaintiff alleges infringement by reason of the production version of the Kestrel (renamed the Harrier) being demonstrated by the British in this country in May, 1969. Defendant asserts invalidity of the patent on the grounds of lack of utility under 35 U.S.C. § 101, insufficient disclosure under 35 U.S.C. § 112 and obviousness under 35 U.S.C. § 103. In addition, defendant urges the defenses of noninfringement and absence of liability by reason of “experimental use.” During pretrial proceedings, claims 1-3, 5 and 8 were [99]*99alleged, to be infringed.1 However, plaintiff’s brief and proposed findings are restricted to claim 1. Accordingly, only that claim will be considered herein.
For the reasons stated hereinafter, we find that claim 1 is invalid for reasons of obviousness. It is not necessary for this court to rule on the defenses of noninfringement and absence of liability by reason of “experimental use” urged by the defendant.
Jet engines employ a jet pipe or tube through which hot combustion gases are directed to produce the thrust required to propel an airplane. Normally, the jet pipe opens rear-wardly of the plane so that the propelling gases issue from the jet pipe in a direction opposite to the line of forward flight of the airplane. This suit is concerned with the manner in which the thrust generated by a jet engine may be used, in addition to propelling the aircraft in the normal forward direction, to alter the conventional mode of takeoff and landing. Eeference will be made to VTOL, STOL and Y/STOL. The term VTOL indicates “vertical takeoff and landing” and refers to the takeoff or landing of a fixed-wing aircraft by only vertical movement of the aircraft. The term STOL indicates “short takeoff and landing” and refers to a fixed-wing aircraft that either takes off or lands with only a short horizontal run of the aircraft. The term V/STOL indicates “vertical and/or short takeoff and landing” and refers to an aircraft that is capable of operating in both the VTOL and STOL modes. The term “vectored thrust” will be used herein. That term refers to the directional control of the thrust generated by the jet engine whereby the thrust may be directed to a desired angle other than directly rearward of the plane.
The Douglas patent proposes a mechanism for selectively diverting the combustion gases of a jet engine to a direction other than that of their normal flow so that the thrust may be utilized for braking the airplane, or for assisting takeoff or landing, or for control purposes. Three embodiments are disclosed in the patent. The first (Figs. 1 and 2) employs a [100]*100baffle for diverting at least a portion of the combustion gases from the jet tube to a pivotally mounted conduit. By pivoting the conduit, the thrust of the engine may be directed toward the ground and either forward (to brake the airplane) or backward (for increasing the lift of the plane). The second embodiment (Figs. 3-5) employs, at the exit end of the jet tube, a number of arcuate members nested together and supported on a common pivot to form a curved conduit for directionally controlling the flow of combustion gases for the same purposes as the embodiment of Fig. 1. The third embodiment (Figs. 6 and 7) has the engine mounted transversely of the aircraft with a pivotally mounted L-shaped conduit for directing the thrust of the engine in the desired direction.
In all three embodiments, directional control of the thrust is achieved by some form of a pivotally mounted conduit movable in a plane substantially perpendicular to the wing. By, for example, pivoting the conduit of any one of the three embodiments downwardly and rearwardly, the thrust of the engine produces two rectilinear components, one acting horizontally to move the plane forward and the other acting vertically to provide lift for the plane. This is the concept of “vectored thrust,” i.e., the thrust generated by the engine has both magnitude and direction and is resolvable into rectilinear components.
The advantages of vectoring the thrust, as stated in the patent and during the prosecution of the application, are several. By directing the thrust downward and rearward, the forward speed of the airplane may be decreased while the engine is maintained at full power. This has particular advantages during landing in that the increased lift generated by the downward component of the thrust decreases both the plane’s landing speed and the length of the landing run. Moreover, by maintaining the engine at full power, it is immediately available in the event of an emergency. During takeoff, the downward component of thrust decreases the speed at which the plane becomes airborne and thus decreases the length of the takeoff run. In short, and as Douglas stated it in his patent, “a slow running aircraft and a fast running engine is thus made possible.”
[101]*101
The sufficiency and operability of the Douglas disclosure
At the outset, defendant argues that tbe patent is invalid by reason of an inadequate disclosure under 35 U.S.C. § 112. Defendant’s attack is based primarily on the absence of any disclosure in the patent regarding the many technological problems encountered and solved by the British company in producing the accused Kestrel and Harrier airplanes. However, a patent specification is not required to be a production blueprint for constructing a jet airplane. Trio Process Corp. v. L. Goldstein's Sons, Inc., 461 F. 2d 66, 74 (3d Cir. 1972), cert. denied, 409 U.S. 997 (1972). Nor can a patentee be expected to foresee every technological problem that may be encountered in adapting his idea to a particular use. Some experimentation and exercise of judgment is to be expected. Binks Manufacturing Co. v. Ransburg Electro-Coating Corp., 281 F. 2d 252, 257 (7th Cir. 1960), appeal dismissed, 366 U.S. 211 (1961); International Nickel Co. v. United States, 175 U.S.P.Q. 209, 214-15 (Trial Div. Ct. Cl. No. 330-68, Aug. 10, 1972, settled by stipulation). Giving due regard to the subject matter involved and the circumstances existing in 1945 when the application was filed, Bowser, Inc. v. United States, 181 Ct. Cl. 834, 388 F. 2d 346 (1967), the disclosure adequately describes a mechanism for directionally controlling the thrust of a jet engine.
Defendant’s argument that the patent fails to disclose a device that is sufficiently operative to satisfy the “useful” requirements of 35 U.S.C. § 101 is equally without merit. Plainly, the disclosed device is capable of performing the function attributed to it, that is, directionally controlling the thrust of a jet engine. The mere fact that problems may be encountered in adapting the device to a particular airplane having particular characteristics or that in one mode of its operation some additional controls would be required does not detract from the overall operativeness of the device. Hildreth v. Mastoras, 257 U.S. 27, 34 (1921).
Obviousness of claim 1
Defendant’s principal attack on the validity of the patent is the contention that claim 1 merely defines subject matter that would have been obvious within the meaning of 35 [102]*102U.S.C. § 103. Although the resolution of the obviousness issue is ultimately one of law, certain basic factual inquiries must be made to set the context for the ultimate legal conclusion. Graham v. John Deere Co., 383 U.S. 1, 17 (1966).
a) The prior art
Douglas was not the first to propose the idea of directionally controlling the thrust of a jet engine either to brake or increase the lift of an airplane. As early as 1918, in British Patent No. 118,123 granted to Harris, a jet engine for propelling an airplane was disclosed. That patent specifically proposed that the tubes through which the propelling gases passed could be:
* * * angularly movable in a vertical direction on horizontal trunnions or pivots for enabling or assisting the aeroplane to rise or descend, and/or the tube may be movable laterally for enabling or assisting the aeroplane to turn. Normally of course the tube would occupy a position in which the aeroplane would be propelled horizontally in a straight path, and to change the movement of the aeroplane means may be provided to enable the pilot to readily alter the position of the tube as required. The tube may be moved to discharge the stream in the front of the aeroplane to produce a braking action and thus retard the speed of the aeroplane when landing. * * *
The prior patents to Anxionnaz (No. 2,396,911), Meyer (No. 2,420,323), and Lysholm (No. 2,280,835), and the text, GAS TURBINES AND JET PROPULSION FOR AIR-CRAFT by Smith, all disclose, broadly, the concept of vectoring directionally controlling) the hot combustion gases of a jet engine. Lysholm, like Harris, suggests that directional control of the gases may be employed either for increasing the lift or for braking the aircraft. Anxionnaz, Meyer, and Smith disclose deflection of the hot gases for increasing the lift or for maneuvering the aircraft. The Higby patent (No. 1,704,895), instead of vectoring hot gases, discloses the concept of vectoring cold air from a centrifugal fan for imparting lift and assisting in maneuvering the airplane.
These prior art patents disclose a variety of ways for deflecting or vectoring the thrust. Anxionnaz uses shutters or [103]*103flaps; Lysholm employs fixed conduits and flow control valves for channeling the thrust through the selected conduit; a swivelling nozzle is disclosed in the Smith text; in Harris, the jet tubes are pivotally mounted; and in Higby, pivoting conduits are used. Lysholm specifically discloses that deflection of the jet thrust will result in a fast running engine and a slow moving aircraft; that result is also inherent in both Harris and Meyer.
b) Differences between the prior art and claim 1
The functional concept expressed in claim 1 is that of diverting the combustion gases from a jet engine “to effect, in at least one position of the discharge conduit, a braking reaction on the aircraft.” This concept is expressly disclosed in the Harris patent. The differences between the Harris patent and claim 1 reside in the specific means for diverting the combustion gases. In particular, claim 1 specifies three elements: (a) means for diverting the gases from the jet tube, (b) a discharge conduit for receiving the diverted gases, and (c) means mounting the discharge conduit for pivoting movement. Harris does not disclose any means for diverting the gases from the jet tube; rather, Harris contemplates that the jet tube itself would be pivotally supported and would be used as the discharge conduit. Harris’ arrangement would necessarily have the outlet of the jet tube “movable about an axis in an arc of approximately 180°, in a plane substantially perpendicular to the plane of the wing” as called for in claim 1.
The Higby patent differs from the combination of claim 1 in two respects. By specifying “combustion gases,” it is implied in claim 1 that the propelling jet is a jet engine; Higby utilizes a cold air centrifugal fan. Higby also differs from claim 1 in that the range of movement of the pivotable conduits in Higby would not be sufficient to direct the thrust in a forward direction to achieve a braking reaction. However, Higby does disclose a means for diverting flow of a gas from a rearward direction, a discharge conduit for receiving the diverted gases, and means mounting the discharge conduit for pivoting movement for directional control of those gases.
[104]*104c) Level of skill in the art
The first flight of a jet-propelled airplane occurred in 1939. In 1941, as a result of development work commencing in the late 1920’s, the British flew their first jet airplane. The design of the powerplant used in that airplane subsequently was brought to the United States, and by late 1943 and early 1944, jet airplanes had been designed, built, and flown in this country. Thus, as of October, 1945, the field of jet propulsion, although in its infancy, had evolved into a working reality and had become a specialized part of the larger field of aircraft powerplants. In view of its obvious complexities, the level of skill of those working in that field must be considered to be relatively high, Westinghouse Electric Corp. v. Titanium Metals Corp. of America, 454 F. 2d 515 (9th Cir. 1971), cert. denied, 407 U.S. 911 (1972), although less well developed than when the accused structures were produced. At the least, the level of skill in 1945 had progressed beyond that represented by the disclosures of the prior art references discussed herein.
d) The obviousness determination
At the outset, it is necessary to address a matter not heretofore mentioned but which appears to be the major argument advanced by plaintiff for nonobviousness. Plaintiff contends the Douglas patent discloses that the resultant force of the deflected jet thrust must pass “near to or through the center of gravity of the aircraft.” This feature, plaintiff asserts, is “the patentee’s vital contribution to the art” and is “essential” to the success of a V/STOL airplane.
There are two difficulties with this argument. The first is that the Douglas patent nowhere discloses that the resultant force must pass through or near to the center of gravity either of the engine or of the aircraft. Indeed, during the prosecution of the patent, Douglas attempted to amend his disclosure to include this “teaching” but the Patent Office required its cancellation on the basis that it was not disclosed in the application as originally filed. Obedient to this requirement, and without argument, Douglas canceled the amenda-tory material.
Figure 6 of the patent does pictorially illustrate an arrangement in which the resultant force would act through the [105]*105center of gravity. However, that showing does not aid plaintiff in his argument. Neither the elected species of Fig. 1, nor the embodiment of Fig. 3, disclose such a relationship. Since two of the three embodiments disclosed do not illus* trate that relationship, it can hardly be said that the patent teaches that the resultant must act through a certain point.2
Thus, it is attributing too much to Douglas to assess the obviousness of his contribution, as defined by claim 1, in the contest of an airplane in which the proper relationship between the vectored thrust and the center of gravity is maintained. The facts are that Douglas only proposed a solution to the problem of how, mechanically, to directionally vary the thrust, not how to vary the thrust while maintaining controllability of the aircraft. From the standpoint of adequacy, the specification will permit no broader interpretation. The pictorial illustration of Fig. 6, from which it may be inferred that the thrust acts at or near to the center of gravity, is unpractical.
The second difiiculty with plaintiff’s argument is that this vital feature is not covered by claim 1. The arrangement of Fig. 6 falls outside the language of the claim, which requires the jet tube to be parallel to the line of flight. Moreover, the only claim that specifically defines the point through which the resultant acts is dependent claim 8 wherein the resultant is described as passing through “a point between the leading and trailing edges of the wing.” However, even that limitation does not describe the resultant as passing through the center of gravity of the aircraft since, in conventional aircraft, the center of gravity is located at the quarter chord of the wing.
The claims are the measure of the invention and resolution of the obviousness question must be based on what is claimed. Kemode Manufacturing Co. v. United States, 171 Ct. Cl. 698, 347 F. 2d 315 (1965). Since Douglas only discloses, and claims, a mechanism for varying the thrust of a jet engine to achieve certain results, but has left it to those in the art [106]*106to determine how to accomplish that without adversely affecting the controllability of the airplane, it is in that context that obviousness must be determined. Turning then to claim 1, it is apparent from the foregoing analysis of the prior art that the Harris patent discloses the basic concept of vectoring the jet thrust to provide either lift or braking. This basic concept being known, the remaining aspects of the claim relate only to the mechanics by which the thrust is directionally controlled.
The prior art discloses a variety of ways for directionally controlling the propelling thrust in an airplane. Harris discloses pivoting the jet tubes for that purpose. While Harris is ambiguous in that it is unclear whether the entire engine would be pivoted with the tubes or the jet tubes would pivot independently of the engine, this does not alter the pertinence of that reference. Even if it is assumed that Harris intended the engine to pivot as a unit with the tubes, Higby discloses a mechanism for maintaining the engine stationary while directionally controlling the thrust. In view of Higby, the conclusion is inescapable that one skilled in the art who wanted to accomplish the objectives of Harris, but without pivoting the engine, would find it obvious to use the independently pivotable conduits disclosed by Higby. No new and unobvious function would result from such a modification of Harris.
Given the relatively high level of skill in this particular art, given the suggestion in Harris for pivotally supporting the jet tube, and given the disclosure of the Higby patent in which pivotally mounted conduits are plainly disclosed, it must be concluded that it would have been obvious in 1946 that the claimed arrangement of conduits could be used to control the direction of the thrust.
In reaching this conclusion, due regard has been given to the presumptively correct decision of nonobviousness implicit in the patent examiner’s allowance of this patent. However, neither Harris nor Higby was cited by the examiner. Where, as here, the most pertinent prior art references were not cited by the examiner, the presumptions to which the [107]*107patentee is entitled are greatly weakened, if not entirely overcome. Nossen v. United States, 189 Ct. Cl. 1, 416 F. 2d 1362 (1969), rehearing denied, 191 Ct. Cl. 198, 422 F. 2d 1340 (1970), cert. denied, 400 U.S. 823 (1970).
As a means of guarding against “slipping into use of hindsight,” Monroe Auto Equipment Co. v. Heckethorn Manufacturing & Supply Co., 332 F. 2d 406, 412 (6th Cir. 964), cert. denied, 379 U.S. 888 (1964), the secondary considerations urged by plaintiff in support of nonobviousness have also been carefully reviewed. In large part, these are based on the undisputed success of the Kestrels and Harriers which were the first usable aircraft with V/STOL capabilities and which are the only operational aircraft with that capability even today. However, to be of any value on the issue of obviousness, success must be attributable to the claimed invention and not to other factors. Palmer v. United States, 182 Ct. Cl. 896, 904 (1968). Here, the evidence shows that other factors are highly significant to the success of those airplanes.3
As noted previously, a major consideration in V/STOL airplanes is the pilot’s ability to control the airplane during vectoring of the thrust. Controllability was achieved in the accused planes in two ways. The first was the use of four nozzles so arranged that the resultant force of the vectored jets acted at or near to the center of gravity of the airplane. The other was the use of a system of puffer jets to provide an auxiliary control. Neither of these is disclosed nor claimed in the Douglas patent.
In summary, Douglas proposed a specific mechanism for accomplishing the objectives earlier suggested by Harris. The mechanism itself was an obvious variation of that previously suggested by Higby. Unobviousness, if any, lay not in the mechanism but in the manner in which the mechanism was used in an airplane to vary the thrust direction while maintaining controllability of the airplane. The builders of the [108]*108accused Pegasus, by expending some $70 million in tbe development of that engine, solved that problem, not Douglas. Having contributed nothing to the development of the critical relationship, Douglas cannot rely on the subsequent success of the accused airplanes to sustain the validity of his patent.
Claim 1 is invalid under 35 U.S.C. § 103. The patent being invalid, the petition must be dismissed.
BINDINGS 03? 3?ACT
1. U.S. Patent No. 2,601,104, entitled “Jet Propulsion and Control Means Therefor,” issued June 17,1952, on an application filed September 10,1946. The patent claims the priority date of British Patent No. 643,989, filed in Great Britain on October 15,1945.
2. Aubrey E. Douglas, an individual, is a British subject residing at Saltford Farm, Somerset, England. Plaintiff Douglas’ ownership of the patent has not been contested in this suit. Plaintiff did not appear at the trial, defendant having waived its right to require his presence.
Disclosure of the patent
3. The problem of controlling a jet aircraft is particularly critical at slow speeds when the effect of the airfoil surfaces is less due to the reduced velocity of the air passing over them. Thus the control of all fixed-wing aircraft is said to be “sluggish” as the aircraft approaches the stall speed. This problem is compounded in jet-propelled fixed-wing aircraft by the fact that jet engines do not accelerate rapidly. Thus, if the pilot desires a sudden burst of power from the engine, as in a balked landing situation, a jet engine is poorly equipped to provide it. As a result, jet aircraft have been required to land at high speed, to the detriment of certain other safety factors, and with the requirement of long landing fields.
4. The patent in suit discloses apparatus for the control of jet-propelled aircraft during takeoff, landing, and while airborne. In particular, Douglas’ idea was to divert the efflux of the jet away from the normal rearward direction, to various other directions including downward and rearward, di[109]*109rectly downward, downward and forward, and/or directly forward so as to provide lift and/or braking components of reaction, wliile still maintaining the operation of the engine at full power and available for redirection to provide normal forward thrust, if desired. A slow moving aircraft and fast running engine are thus made possible by the deflection of the jet stream.
5. (a) Three embodiments for controlling the direction of the output combustion gases from a jet engine are disclosed and illustrated. The embodiment shown in Figs. 1 and 2 employs a baffle D for diverting at least a portion of the combustion gases from the normal rearward direction of flow in jet tube C into conduit E, and thence into pivotably mounted conduit H. Conduit H may be pivoted through a range of about 40° in order to vector combustion gases either forwardly (for braking) or downwardly (for additional lift).
(b) In the second embodiment (Figs. 3 — 5), the jet tube terminates in an elbow joint formed from a number of arcuate members constructed to nest together in order to form a curved conduit. This elbow joint deflects the combustion gases downwardly from their normal “straight through” rearward flow, to any point on an arc of 180°.
(c) The third embodiment (Figs. 6,7) shows a jet engine A mounted in the wing of an aircraft. The longitudinal axis of engine A is transverse to the long axis or horizontal center line of the aircraft. The engine is provided with a conduit or tube C. In forward flight, the normal position of the jet tube C is directly rearward. By pivoting the tube C through any chosen degree in an arc of 0° to 110°, the direction in which the combustion gases are discharged may be varied.
(d) The first two embodiments utilize essentially three components:
(i) a jet tube through which the gases normally discharge for propulsion of the aircraft;
(ii) means for diverting the gases from their normal rearward direction; and
[110]*110(iii) a movable conduit that receives the diverted gases and directs them to the desired direction.
In the embodiment of Fig. 6, all three components are combined into a single element, the pivotably mounted L-shaped conduit C.
6. The Douglas patent discloses a vectored thrust principle in which direction other than the normal rearward direction may be imparted to the thrust generated by the hot combustion gases from a jet engine.
7. In any airplane, it is important that the resultant of the jet thrust forces pass through or near to the center of gravity (c.g.) of the airplane. If, by vectoring the jet thrust, the resultant force passes to the rear of the c.g. of the airplane, a nosedown attitude will be imparted to the aircraft which, if not corrected, will cause the aircraft to nosedive. The need for the resultant forces to pass through the c.g. is particularly critical when a plane is operated in the VTOL mode because there is no airflow over the ailerons and rudder which would enable the pilot to use those controls to maintain the correct attitude of the airplane. This is less critical during STOL operation where there is airflow over the control surfaces.
8. The Douglas specification contains no mention of the relationship between the resultant of the vectored thrust and the center of gravity. During prosecution of the patent, Douglas attempted to amend his specification to include the statement that “the reactionary effect generated by the diversion of the jet should pass through the proximity of the center of gravity of the aircraft.” The examiner required cancellation of this statement, holding that it was new matter, and Douglas did not contest that requirement. The examiner did permit Douglas to insert a claim (claim 8) that calls for the reaction of the vectored jet to pass “through a point between the leading and trailing edges of the wing.” However, that point is not necessarily coincident with the center of gravity which, in conventional aircraft, is normally located at the quarter chord of the wing.
[111]*1119. The embodiments of Figs. 1 and 3 of the Douglas patent do not show the resultant force as passing through the center of gravity of the aircraft. The embodiment of Fig. 6 does illustrate an arrangement in which the resultant force acts near the center of gravity. Figs. 1 and 3 employ a double 90° bend for the gases; Fig. 6 has a single 90° bend.
10. Each of the disclosed embodiments could, with appropriate balancing of forces and suitable controls, be used both in the VTOL and STOL modes.
Sufficiency and operatvomess of the disclosure
11. The patent in suit discloses a workable arrangement for directionally controlling the jet thrust and one that would be understood by those ordinarily skilled in the art. Those in the art would understand that, to achieve a controllable aircraft, it would be necessary, in addition, to minimize pitching moments about the center of gravity of the aircraft created by varying the direction of the jet.
12. Douglas submitted his ideas to Vickers-Armstrong Ltd. in 1948. That company designed an airplane based on Douglas’ idea. Although the airplane was never built, there is no evidence that the company had any difficulty in understanding the idea. None of the other companies or organizations to which Douglas disclosed his idea expressed any lack of understanding as to its operativeness or utility.
The scope and meaning of the claim
13. Claim 1, the only claim now asserted by plaintiff, provides as follows:
Apparatus for controlling the reaction of a propelling jet in a rigid wing aircraft, comprising a jet tube mounted approximately parallel to the line of flight, means for diverting the flow of at least part of the combustion gases from the jet tube to cause them to move in a direction other than normal, a discharge conduit associated with the jet tube adapted for receiving the diverted gases, the discharge outlet of said discharge conduit being selectively movable about an axis in an arc of approximately 180°, in a plane substantially perpendicular to the plane of the wing for directionally controlling the discharge of gases from the conduit to effect, in at least one position [112]*112of the discharge conduit, a braking reaction on the aircraft.
14. (a) During prosecution of the patent, Douglas was required to make an election of species. Douglas elected the species of Figs. 1 and 2 wherein the discharge conduit is rotatable through a range of approximately 45°. Simultaneous with this election of species, Douglas presented claims which included the limitation that the discharge conduit be movable “in an arc of approximately 180°.” Although the Examiner initially interpreted this limitation as calling for the jet tube to be movable in an arc, and rejected the claims as being misdescriptive, that rejection was withdrawn.
(b) Thereafter, Douglas continued to present claims containing the limitation “in an arc of approximately 180°” and continued to assert that that limitation was applicable to an arrangement such as shown in Figs. 1 and 2. Nowhere in the file wrapper history is there any indication that the Examiner either failed to understand the broad interpretation that Douglas placed on this limitation or disagreed with that interpretation.
(c) The species of Figs. 1 and 2 remained the elected species throughout the prosecution of the Douglas patent. The file wrapper history shows that the phrase “in an arc of approximately 180°” was intended to cover the species of Figs. 1 and 2 wherein the range of movement was no more than 45°.
(d) The meaning to be attributed to the phrase “in an arc of approximately 180°” is that the discharge outlet is movable within an arc of no greater than 180° to accomplish the claimed function. Any discharge outlet that is movable through an arc of up to 180° comes within the scope of this limitation.
(e) The limitation that the discharge outlet is movable “in a plane substantially perpendicular to the plane of the wing” was inserted in the claim to distinguish it from the arrangement shown in Gazda Patent No. 2,486,272 wherein a reaction jet was movable in a plane parallel to a helicopter blade.
(f) The “normal direction” referred to in claim 1 refers to the direction in which the gases issuing from a jet tube would [113]*113normally flow in propelling an airplane, i.e., in a direction opposite to the forward line of flight.
The scope and content of the prior art
15. The first flight of a jet-propelled aircraft occurred in 1939. However, the use of gas turbines as a jet engine for propelling aircraft was suggested long prior to that time. One such early suggestion is contained in British Patent No. 118,123, issued in 1918. The British patent to Whittle (No. 34Y,206), issued in 1930, marks the practical beginning of the efforts to produce an operational jet airplane.
16. Almost from the very inception of jet propulsion as a means for propelling an airplane, it was realized that the jet thrust also could be used for braking, lift, or control of an airplane. The British patent to Harris (No. 118,123) and the patents to Anxionnaz (No. 2,396,911),Meyer (No. 2,420,323), and Lysholm (No. 2,280,835), all disclose, broadly, the concept of vectoring, or directionally controlling, the hot gases of a jet engine. The patents to Harris and Lysholm specifically disclose the use of a vectored jet thrust either to impart lift or to provide a braking reaction on the aircraft. The Higby patent (No. 1,704,895) discloses the concept of vectoring cold air from a centrifugal fan for imparting lift to an airplane. The patents to Anxionnaz and Meyer, as well as the text GAS TURBINES AND JET PROPULSION FOR AIRCRAFT by Smith, disclose the concept of deflecting the jet to assist in maneuvering the aircraft. Vectoring of the gases in both Higby and Lysholm, as well as in the early patent to Valdez (No. 1,'629,767), was accomplished by passing the gases through two bends.
17. Various techniques for deflecting or vectoring the jet thrust were known prior to the Douglas patent. One technique was the use of shutters or flaps (Anxionnaz); another was the use of fixed conduits and flow control valves (Ly-sholm) ; still another was the use of a swivelling nozzle (Smith text, Plaintiff’s Exhibit 24A); a further technique was pivotably mounting the jet tubes (Harris); another was the use of pivotally mounted L-shaped conduits (Higby; Valdez).
[114]*11418. The patents to Anxionnaz, Lysholm, Meyer, and Valdez were cited by the Patent Office during prosecution of the Douglas patent. The Harris and Higby patents were not cited.
19. The manner in which the jet tubes in the Harris patent would be pivoted is ambiguous. Although suggesting the use of trunnions as pivots for the jet tubes, it is unclear whether the tubes would pivot independently of the remainder of the engine or the engine would pivot with the tubes.
20. The use of pivotably mounted conduits for directionally controlling the discharge of gases, with the conduits being selectively movable about an axis in a plane substantially perpendicular to the plane of the wing, is disclosed in both the Harris and Higby patents.
21. By late 1943 and early 1944, jet airplanes had been designed, built, and flown in this country. By October, 1945, the field of jet propulsion had become a specialized part of the larger field of aircraft powerplants. The level of skill of those working in that specialized field as of that date was relatively high.
Differences between prior art and claim 1
22. (a) Claim 1 does not require that the jet engine remain stationary. The claimed concept of diverting combustion gases in an arc to effect, in at least one position, a braking reaction on the aircraft is disclosed in the Harris patent. The combination of claim 1 differs from Harris only in the specific mechanical means employed to divert the combustion gases through the desired arc. In particular, Harris does not disclose any means for diverting the gases from the jet tube; rather, Harris would direct the gases by pivoting the jet tube itself, a concept similar to Fig. 6 of the Douglas patent. In fact, to the extent claim 1 is readable on Fig. '6, it is also readable on the Harris patent.
(b) The combination of claim 1 differs from Higby only in the type of propelling jet employed and the degree of rotation of the discharge conduit. Higby contemplates the use of cold air instead of hot combustion gases; nor does Higby [115]*115contemplate pivoting the discharge conduits to a forward position to impart a braking reaction. Higby discloses the same essential combination of elements for directionally controlling the propelling jet as that employed in the Douglas patent and the accused aircraft, i.e., (i) a means for diverting the flow, (ii) a discharge conduit for receiving the diverted gases, and (iii) means mounting the discharge conduit for pivoting movement about an axis in a plane substantially perpendicular to the plane of the wing. As in Douglas, the gases in Higby would pass through two 90° bends.
Other considerations tearing on validity
23. (a) Based on Douglas’ ideas, Vickers-Armstrong proposed an airplane in which the jet thrust could be deflected up to 60°. In order to obtain the proper balance of forces and avoid the introduction of pitching moments about the c.g. when the jet was deflected, very substantial modifications in the airplane were proposed. Even then, the airplane would have had no VTOL capability. This proposal did not progress beyond the preliminary design stage.
(b) It was not until the advent of the light weight gas turbine engines having a high thrust-to-weight ratio that it became apparent that rigid-wing aircraft with V/STOL capability could be built. Starting in about 1952, essentially four approaches were taken by the industry: tilt thrust (the wings and/or the engines are tilted to direct the thrust in the desired direction); augmented thrust (lift fans are driven by the engines to generate the lift); dual propulsion (separate engines for lift and for propulsion are used); and vectored thrust (represented by the accused airplanes).
(c) Development in the United States was concentrated in areas other than vectored thrust. By 1969, some 12-15 development programs, at a cost of millions of dollars, had been undertaken in the United States in an attempt to produce a satisfactory V/STOL airplane. None of those programs was successful in terms of producing a usable aircraft.
(d) A fundamental problem in vectoring the thrust of a propelling jet is in maintaining the controllability of the [116]*116airplane as the direction of the thrust is varied. Those in the art recognized that directional control of the thrust could be achieved without adversely affecting the trim so long as the resultant force always passed through or near to the center of gravity; however, as indicated by the substantial modifications proposed by Vickers-Armstrong in the hope of accomplishing this goal, this was difficult to achieve. Douglas’ only suggestion for achieving this critical relationship is contained in Fig. 6 where the engine is located transversely of the airplane, approximately in line with the c.g. of the aircraft; however, the transverse mounting of the engine is impractical.
(e) The British-made Kestrel and Harrier aircraft, using the vectored thrust principle, are the only usable V/STOL aircraft that have been developed and built to date. Approximately 2.5 million technical man hours, at a cost of approximately $70 million, were expended in developing the Pegasus engine used in the Kestrel aircraft. Although Douglas did disclose his ideas to the builder of the Pegasus engine, there is no evidence that any use was made of that disclosure.
ULTIMATE FINDINGS AND CONCLUSIONS
1. The specification of the Douglas patent contains a written description of the invention in sufficiently full, clear, concise, and exact terms as to enable any person skilled in the art to make and use the same.
2. The invention described in the Douglas patent is operative and possesses utility.
3. The differences between the subject matter of claim 1 and the prior art are such that the subject matter as a whole would have been obvious in October, 1945 to a person having ordinary skill in the art.
CONCLUSION OF LAW
Upon the foregoing findings of fact and opinion, which are made a part of the judgment herein, the court concludes as a matter of law that plaintiff is not entitled to recover, and plaintiff’s petition is dismissed.
[117]*117Appendix
Patented June 17, 1952
2,601,104
UNITED STATES PATENT OFFICE
JET PROPULSION AND CONTROL MEAN'S THEREFOR
Aubrey Douglas, Saltford, England
Application September 10,1946, Serial No. 696,839 In Great Britain October 15,1945
8 Claims. td. 244 — 12)
i
This invention relates to jet propulsion for aircraft and Is particularly concerned with a method of and means for controlling the propulsive effort created by the efflux or jet whereby a reverse action Is obtainable.
According to the Invention, a method of controlling the reaction jet of a jet propelled or partially jet propelled aircraft consists in baffling or reducing the effective area of the Jet nozzle and/or diverting partially or otherwise the combustion gases m a direction other than the normal direction of flow.
It Is to be understood the aforesaid method is additional to the normal means of controlling the efflux.
The invention also comprises means for baffling the efflux from a jet nozzle or for reducing the effective area of said nozzle and diverting the combustion gases, by means, for example, of ducts or conduits, in a direction other than that of their normal flow whereby the reaction created may be utilized for braking purposes, for assisting take off or landing or other control purposes.
In order that the invention may be clearly understood and readily carried into effect, reference is directed to the accompanying drawings, wherein:
Fig. 1 illustrates diagrammatically In plan view partly in section, a part of an aircraft wing embodying the invention.
Fig. 2 is a section on the lines 2 — 2, Fig. 1, looking in the direction of the arrows.
Figs. 3, 4, 5 illustrate a side elevation, a longitudinal section and a. cross-section along the line 11 — 11 of Fig. 4 respectively of a modified form of a diversion means according to the inven-
Fig. 6 is a plan view of a wing and part of a fuselage of a Jet propelled aircraft showing an application of the invention thereto and embodying a modified form of the Invention.
Fig. 7 is a section on the line 13 — 13, Fig. 6.
The drawings are essentially diagrammmatlc and the same reference characters are used throughout the figures for the same or equivalent
The form of the invention illustrated in Figs. 1 and 2 of the drawings is applied to an aircraft in which a jet propulsion unit A is mounted in a wing B and consists Is disposing in the main jet tube C, a -baffle or diaphragm D associated with means (not shown on drawings) whereby it may be gradually introduced into the gas stream or closed thereon to divert its force, the cross-section of the Jet tube being suitably shaped, to re-celve the baffle. The combustion gases so diverted are lead by one or more ducts or conduits E, each having an outlet F to the inlet G of a discharge conduit H, the outlet J for the said conduit H 5 pointing in any required direction, for example, forward and/or downward for the purpose of checking the speed of the aircraft or increasing its lift..
The outlet J of the conduit H is directionally 10 controlled so that the resultant force thereof will act In the plane or in planes parallel to the plane of symmetry of the aircraft, so that the diverted gases may be directed towards the ground and forward or backward as required for increasing 15 the lift at braking or taking off respectively as Illustrated in Fig. 2. For this purpose, the conduit H is mounted In bearings K, L, a trunnion M integral with the conduit H resting in the bearing K and the Inner end of the conduit H 20 being mounted in the bearing L. In order to rotate the conduit H along its path of movement, a pinion N is secured to the inner end of the conduit H, a suitable means being furnished to actuate the said pinion to effect the required dls-25 position of the conduit H.
The conduit E may be lead straight into the conduit H or as an optional feature as shown in Fig. 1 of the drawings, the inner end G of the conduit H may be splayed to receive the outlet 30 end F of the conduit E, thus introducing an ejector drawing air, for example, from a boundary layer into the chamber O and from there into the conduit H. The conduit H is normally housed within the wing structure, the lower face of 35 which Is fitted with doors P which are dropped when it is desired to bring the conduit into position for operative purposes. The outlet J of the conduit may be furnished with a closure Q.
The invention is applicable to all forms of jet 40 propulsion units whether mounted in the aircraft wings or in the fuselage of an aircraft, the ducts or conduits being disposed in the most suitable position in relation to the propulsion unit subject to the inlets being arranged in the dis-45 charge conduit and the outlet in such a position as to create a rectionary effort, whether directed in axial opposition to the normal jet flow or at an angle thereto, the resultant force being utilized as a means of control.
fiO Figs. 3, 4, 5 show a modification of the invention in which the Jet nozzle C has an elbow Joint Q formed of a number of members which are capable of nesting together to form a through conduit (see Fig. 4) or being diverted by concerted 65 or independent operation as shown in Fig. 3 to [118]*118give a discharge in the reverse direction or in a direction determined by a path o( 180° in a plane or In planes parallel to the plane of symmetry of the aircraft through which the nozzle can be turned,
The elbow Joint Q comprises four members O', Q2, Q3, Q\ of which Ql and Q* are fixed to the jet nozzle elements H and C, respectively, permitting the intermediate members Q2 and Q"1 to be independently operated to an open position to io enable quick recovery of the normal jet flow to a comparatively straight line course. Further, all or one of the members Q1, Q3 and Q3 may be slotted to permit partial flow of the gases to reduce the initial pressure at the outlet of the nozzle and obtain a smooth braking effect when the nozzle is brought into use. In effect the elbow constitutes a valve controlling the gas flow. The jet nozzle conduit may also be reduced to provide a Venturi portion as at Q5 to which inlets 20 Q6 are made from any suitable surface of the aircraft. 15
Figure 5 indicates diagrammatically a method of operating the several parts of the elbow. In this figure Ql is fixed to the conduit H and op- 25 erable therewith, Q2 is secured to a sleeve Q7, and Q3 to a shaft Q9, the member Q< being free of the shaft and secured to the jet nozzle.
Figs. 6 and 7 illustrate an arrangement in which the jet propulsion unit A is mounted in a wing B transversely to the thrust and drag line, the nozzle C having an elbow part C2 wnlch is mounted in a pivotal bearing M such as described with reference to Fig. 1, the inlet end of the discharge nozzle being mounted for rotation in a gland R. The normal position of the discharge nozzle is as indicated in dotted lines in the Figs. 12 and 13, whereas the braking position of the discharge nozzle is Indicated in full lines in these two figures. The outlet of the dischaige nozzle <jo is fitted with a diffusion cone C3, this cone may be adjustable, for example, axially slidable or can be rectangular and provided with adjustable 30 louvres.
Broadly speaking, the invention improves the 45 controllability of jet propelled or partially Jet propelled aircraft by two methods, one is to decrease the speed at which the machine is airborne, the other is to increase the lift whereby the machine becomes and remains airborne by 50 diverting the 'normal jet flow to produce two thrust components, one reacting horizontally forward to induce a rearward braking reaction in the machine, the other acting vertically downwards and thereby generating an increased lift- 55 ing force.
The invention may comprise any number or arrangement of ducts of any suitable cross-section or of variable cross-sectional area, whereby the velocity of the effluent in the conduits may $0 be accelerated or retarded as desired.
Boundary layer tapping is particularly effect__ tlve when the propulsion unit is running at full speed and is most required when the aircraft is travelling at a comparatively slow speed, for §5 example, at landing; a slow running aircraft and a fast running engine is thus made possible by the deflection of the jet stream.
What I claim and desire to secure by Letters Patent is;
1. Apparatus for controlling the reaction of a propelling jet in a rigid wing aircraft, comprising a jet tube mounted approximately parallel to the line of flight, means for diverting the flow of at least part of the combustion gases from the Jet tube to cause them to move in a direction other than normal, a discharge conduit associated with the Jet tube adapted for receiving the diverted gases, the discharge outlet of said discharge conduit being selectively movable about an axis in an aic of approximately 180°, in a plane substantially perpendicular to the plane of the wing for directionally controlling the discharge of gases from the conduit to effect, In at least one posltion of the discharge conduit, a braking reaction on the aircraft.
2. Apparatus according to claim I, wherein In at least another position of the discharge conduit, a braking and lifting reaction on the air-ciaft is effected.
3. Apparatus according to claim 1, wherein "the discharge end of the discharge conduit is movable in a plane parallel to the plane of symmetry of the aircraft.
4. Apparatus according to claim 1, wherein the means for diverting the flow of at least part of the gases, is a valve.
5. Apparatus according to claim 1, wherein the discharge conduit is mounted for pivotal movement.
6. Apparatus according to claim I, wherein the discharge conduit is mounted for pivotal movement and comprises an elbow Joint formed of a number of members capable of nesting together.
7. Apparatus according to claim l, wherein the discharge conduit is mounted within an aircraft wing structure and the outlet of- said conduit, in controlled operative position, is at the under side of the wing structure.
8. Apparatus according to claim 1. wherein the reaction generated by the diversion of the Jet passes through a point between the leading and trailing edges of the wing.
AUBREY DOUGLAS.
REFERENCES CITED
The following references are of record In the file of this patent:
UNITED STATES PATENTS
Number Name Date
Re. 23,198 Anxlonnaz_Feb. 21, 1950
141,039 Dow -.July 22, 1873
141,340 Evans.. July 29, 1873
614,527 Wauters ..Feb. 13, ¡894
'1,382,535 Offcn_June 21, 1921
1,629,767 Valdés.May 24, 1927
1.642.752 Landon_Sept. 20, 1927
1,714,917 Martin_May 28, 1929
1,813,189 Moore__July 7, 1231
_ 2,024,274 Camplnl.Dec. 17, 1935
2,280,835 Lysholm_Apr. 28, 1942
2,420,323 Meyer_May 13, 1947
2,483.272 Gazda.Oct. 25» 1949
FOREIGN PATENTS
Number Country Date
432,727 France .. Oct. 11, 1911
[119]*119June 17, 1952 a. Douglas 2,601,104
JET PROPULSION AND CONTROL MEANS THEREFOR
Filed Sept. 10, 1946 3 Sheets-Sheet 1
[120]*120June 17, 1952 a. douglas 2,601,104
JET PROPULSION AND- CONTROL MEANS THEREFOR
Filed Sept. 10, 1946 3 Sheets-Sheet 2
[121]*121June 17, 1952 a. douglas 2,601,104
Filed Sept. 10, 1946 3 Sheets-Sheet 3
This opinion incorporates the greater pait of the opinion prepares by Trial Judge Hal H. Cooper, with modifications and additions by the Judges. The Trial Judge considered the issue of the invalidity of the patent and held that it was invalid. He then went on to consider whether, in the event the patent was held to be valid, there was an infringement. Since this court holds that the patent was invalid, we do not decide the second issue.