Jones v. United States, (1951)

Full title: JONES v. UNITED STATES

Court: United States Court of Federal Claims

Date published: Oct 2, 1951

100 F. Supp. 628 (Fed. Cl. 1951)

Opinion

No. 46969.

October 2, 1951.

Floyd H. Crews, New York City (Thurman Arnold, Washington, D.C., Russell G. Pelton and Darby Darby, all of New York City, on the briefs), for plaintiff.

H.L. Godfrey, Washington, D.C., and Newell A. Clapp, Acting Asst. Atty. Gen., for defendant.

Before JONES, Chief Judge, and LITTLETON, WHITAKER, MADDEN and HOWELL, Judges.

The court, having considered the evidence, the report of Commissioner Hayner H. Gordon, and the briefs and argument of counsel, makes the following Special Finding of Fact:

1. This is a patent suit alleging infringement of United States letters patent No. 2,078,854 issued April 27, 1937, to Clifford C. Jones, the plaintiff, on an application filed in the Patent Office June 20, 1936.

The patent relates to aviation and its title is "Boundary Layer Air Control." The plaintiff owns the entire right, title and interest to the patent in suit.

A copy of the patent in suit, plaintiff's exhibit 1, and a copy of the Patent Office file wrapper and contents thereof which materialized into the patent in suit, defendant's exhibit 43, are made a part of this finding by reference.

Sustentation of Airplanes

2. An airplane is maintained in flight by its forward motion through the air in such manner as to produce a lifting effect upon the wings.

When the Wright brothers made test flights the wings were very thin. It has been subsequently found, however, that a thick wing is more efficient, and at the time of the filing of the application which materialized into the patent in suit several more or less standardized wing forms had been developed. These wing sections, known as airfoils in aviation parlance, in general possess a blunt leading edge followed by a relatively thick midsection, then tapering to a narrow or sharp rear or trailing edge. One representative form airfoil is known as the "Clark Y Airfoil."

Fig. 1, reproduced herewith, illustrates the streamlined air flow occurring about a Clark airfoil as it moves from right to left through the air. The blunt leading edge of the airfoil or wing displaces the air as shown, some being slightly compressed

underneath the wing. In the streamlined pattern shown, other portions of the air are moved upwardly and follow a more or less curved streamlined path over the upper surface of the wing. Normally, still air at sea level exerts a pressure of 14.7 pounds per square inch. On the undersurface of the wing where the air has been forced down as the airfoil moves forward, the pressure of the air is increased. On the upper surface of the wing the air has a longer path than across the bottom of the wing, so that its relative velocity with respect to the wing is increased and consequently its density and its pressure on the top of the wing are less. The pressure below the wing is thus greater than 14.7 pounds per square inch while the pressure on the top of the wing is less than this amount. This difference in pressure produces "lift".

3. Fig. 2, reproduced herewith, is illustrative of the pressures exerted on a wing typified by the Clark airfoil, the relative length and direction of the arrows in this figure showing the various pressure effects present on the wing. This figure illustrates, with the wing flying in the attitude relative to the air shown in Fig. 1, that the lift, because of the reduced pressure on the top of the wing, is much greater than the lift contributed to the lower surface of the wing. Fig. 2 also illustrates the increased pressure exerted by the air against the front edge of the wing because of its forward movement. The oval-shaped zone adjacent the leading edge of the wing, Fig. 2, does not mean that a blob of air is pushed ahead of the wing as it progresses through the air. This oval-shaped space merely indicates what the relative length of other pressure lines would be if drawn within its confines.

Immediately adjacent the leading edge and where pressure exists against the forward movement as indicated in Fig. 2, there is a slight increase in the normal density of air which will vary in accordance with the length of the pressure lines in this forwardly projecting zone. The direction of pressure in the forwardly projecting zone is opposed to that in the forward portion of the upwardly projecting zone, and in the vicinity of the leading edge where these two zones meet, normal atmospheric pressure will exist.

In the two figures just described, which are based on defendant's exhibit 14, the fore and aft axis of the wing is shown at zero angle of attack with respect to the air through which it is moving. If the leading edge of the wing should be tilted upwardly so that the angle of attack becomes 4 or 5 degrees, both the streamlined pattern shown in Fig. 1 and the pressure pattern in Fig. 2 will change. If such increased angle of attack is used, the air will be still further compressed underneath the wing, and the streamlines of the upper surface will be more sharply deflected upwardly. Such action will increase the lift of the wing on both of its surfaces. With the forward edge of the wing thus raised to cause such increased lift, more effort will be required to force the wing through the air at the same speed as before. Resistance to the forward movement of the wing, including the frictional effects present in the boundary layer, is termed "drag," and it is the power of the engines applied through the propellers that is necessary to overcome the drag.

For any given set of conditions a wing of larger area will give more lift but its drag will be similarly increased. The efficiency

of an airplane wing is expressed aerodynamically as the lift-drag ratio, and the objective sought by aeronautical engineers is a ratio of maximum lift to minimum drag. This means minimum engine power relative to the speed and load-carrying capacity of an airplane.

Boundary layer

4. Friction exists in all fluids¹ when the individual particles of the fluid move relative to each other. Such fluid friction is called "viscosity". The viscosity effect in water is readily observable from the deck of a moving ship. The layer or film of water in immediate contact with the hull of the ship travels at the speed of the ship but each succeeding outward film or layer has less forward motion imparted to it from the inner layers until an outer layer is reached that does not partake of any of the forward motion of the ship.

1 The word "fluid" as used in physics includes both liquids and gases.

This same viscosity or frictional effect is present whenever there is relative movement between a surface and air in contact therewith. Whenever an airplane wing moves through the air at a conventional speed, the microscopically thin layer of air immediately adjacent the surface moves with it at the same speed. If the air is contemplated as being made up of a series of very thin laminar layers each layer has some motion imparted to it by friction from the preceding layer until an outer layer is reached in which this viscosity or frictional effect has entirely disappeared.

Fig. 3 illustrates with greater detail the effect just mentioned. In this figure the airflow is shown as moving from left to right across the surface of a stationary flat plate. At the left-hand end of the plate and at the surface of the plate itself the air is stationary with respect thereto. At the top surface of this portion of airflow the air is moving with full stream velocity. In between these limits the layers or lamini of air are shearing over each other in much the same manner that sheets of paper would slide over each other if the bottom of a stack of paper were held stationary and the other sheets moved parallel with the surface of the paper. This portion of the airflow adjacent the plate is termed "laminar flow." At a certain point, depending upon numerous variables, transition of the laminar flow takes place and the airflow adjacent the plate becomes turbulent. In this portion of the airflow there is an eddying motion superimposed upon a general flow in which a random turbulent motion takes place. Fig. 3 is nondimensional in character, and the thickness of the laminar and turbulent layers is greatly enlarged for the purposes of illustration. In actual practice the laminar airflow on an airplane wing varies only from a few thousandths to a few hundredths of an inch in thickness, and the turbulent portion is only a few inches in thickness. This layer of air, including both the laminar and turbulent portions, is known to those skilled in the art as the boundary layer. In report No. 474 entitled "Nomenclature for Aeronautics" by the National Advisory Committee for Aeronautics originally published March 1934, boundary layer is defined as "A layer of fluid, close to the surface of a body placed in a moving stream, in which the impact pressure is reduced as a result of the viscosity of the fluid."

5. Instruments have been devised for measuring the thickness and other characteristics of the boundary layer air on an airplane wing, and various mathematical expressions for calculating same have been derived.

Fig. 4, which is taken from defendant's exhibit 17, shows (as well as can be shown in a small drawing) the boundary air layer existing about a wing section of a B-17 airplane flying at a speed of 250 MPH at an altitude of 20,000 feet, at an angle of attack of approximately four and one-half degrees. The chord (distance from leading edge to trailing edge) of the B-17 wing section shown in Fig. 4 is approximately 162 inches or 13.5 feet.

The laminar flow on both the upper and lower parts of the wing which exists back to the points marked "transition" varies from a few thousandths of an inch to a few hundredths of an inch in thickness and therefore cannot be shown on the drawing. The transition point on the upper wing surface is approximately 9 inches aft of the leading edge, and on the lower wing surface is about 48 inches aft of the leading edge. From the transition points to the trailing edge of the wing, the turbulent boundary layers increase from a small portion of an inch to a maximum of about 6 inches on the upper surface and 2.5 inches on the lower surface.

The extent and thickness of the laminar and turbulent portions of the boundary layer air are affected by numerous variables, such as altitude, speed, angle of attack, character of wing surface, etc. It is a complex phenomenon.

Separation

6. There is no frictional effect outside the boundary layer. Inside the boundary layer, and particularly in the turbulent portion thereof, friction is present. Under certain conditions an increased pressure will tend to build up over the rearward portion of airfoils, especially with certain angles of attack. If this takes place, the increased pressure and the presence of friction will tend to slow down the boundary layer flow at the rear to such an extent that the boundary layer air begins to accumulate and the flow at a certain point separates from the surface thereof. Such separation causes vortices to form and distorts the streamline flow over the wing and causes a reduction in lift.

Friction in the boundary layer and separation are deleterious to efficient lift-drag ratio, and one of the primary objects of aerodynamical research is to minimize turbulence and separation. Ordinarily this is done by carefully designing the contour of the wing surfaces.

The Patent in Suit

7. The Jones patent in suit is directed to minimizing the effects of turbulence and separation by the removal of boundary air layer or a portion thereof from airfoil surfaces. The patent in suit relates both to a method and apparatus for accomplishing the method which, broadly speaking, consists in removing quantities of air adjacent the airfoil surfaces through spanwise slots arranged in the surface of the airfoils, compressing this air within the airfoil or wing section by means of a power-operated compressor, and then discharging the air into a different pressure zone through other spanwise slots.

Other objects of the invention deal with the use of spanwise slots located in various portions of the airfoil or wing surface which are made effective or ineffective by automatic mechanism at various speeds. This is illustrated in Figs. 1-4 of the Jones patent, reproduced herewith.

Fig. 1 shows an airfoil operating at what the patentee terms "very slow speed." In this type of operation this figure teaches the drawing in of air from a slot in the lower side of the wing as shown at a, drawing in of air from a slot c at the trailing edge of the wing, compressing and ejecting the air from the midportion of the upper surface of the wing through the slot b.

In Fig. 2, reproduced here, the Jones patent teaches the reverse operation of this structure, the control valves in this case being set for what the patent terms "slow speed." Here boundary air layer is drawn in from the upper surface of the wing at its midpoint through the slot b, compressed and ejected from the lower surface of the wing through the slot a, and also at the trailing edge of the slot c.

Fig. 3, which relates to "cruising speed," draws in boundary air layer through a slot in the upper surface of the wing and ejects it all at the trailing edge.

Fig. 4 shows the drawing in of air at the nose or leading edge of the airfoil (apparently in front of the laminar portion of the conventional boundary layer) and ejecting the same through a slot in the trailing edge.

8. The valves that control the opening and closing of these various slots and which cause certain slots to operate at certain speeds and not otherwise, are

shown in detail in Figs. 5 and 6 of the Jones patent reproduced herewith. As shown in these figures, a vane 41 projects downwardly from the wing. With no air pressure against the vane, this is held in a forward position by the spring 48. As the speed of the airplane increases, wind pressure against the vane moves it rearwardly, causing the three cylindrical valves 29, 30, and 31, all of which are located within the wing and connected by rods to the vane 41, to open and close in the proper manner to control the ingress and egress of the air through the slots in the manner indicated in Figs. 1-4, inclusive, reproduced in the previous finding.

The blower 10, which is power-operated from the engine of the airplane, is conventional in character and is known to those skilled in the art as a Roots blower. It consists of a pair of coacting impellers mounted on parallel horizontal shafts and operating in an elliptical casing. The patent states that the blower casing serves as the main spar of the wing, thus indicating that the blower is coextensive with the major length of the wing.

9. As shown in Fig. 7 of the patent, reproduced herewith, the patentee discloses means which is responsive to an increase in the speed of the airplane for increasing the speed of the blower relative to the airplane speed. As disclosed, this consists of a selective gearshift mechanism of conventional automobile design and wherein sliding gears on parallel shafts may be selectively meshed with each other to drive the blower at different speed. These gears instead of being controlled by a manually operated gearshift lever, as in an automobile, are controlled by a gearshift lever extending downwardly and carrying at its lower end a vane 23 located outside the airfoil or wing.

When the airplane is moving at "very slow speed" the vane is in its forward position, and the speed of the blower is at its lowest value relative to the engine speed. As the speed of the airplane increases, the wind pressure against the vane 23 also increases, moving the vane in such manner as to increase the speed of the blower relative to the engine. With a further increase in the speed of the airplane the vane is moved to the extreme rearward position shown in Fig. 7 of the patent, and the blower is then driven at its maximum speed relative to the engine speed.

The airflow represented in Fig. 1 of the patent in suit (with air blown out of the upper slot) is obtained by reversing the blower. The patentee does not state what speed shall constitute "very slow speed," "slow speed," "cruising speed," or "high speed."

The principal object of the invention set forth in the patent relates to a method of controlling the boundary layer volume and intensity flow conditions on the total surface of an airfoil. This indicates that the various spanwise slots shown in the patent extend over the entire span of the airfoil.

10. The patentee recognizes the definition of boundary air layer known to those skilled in the art as the layer of air adjacent the airfoil surface in which viscosity and frictional effect are present (see Findings 4-6). The patent states with respect to this concept of boundary air layer, as follows: "To date, the subject of boundary layer has been best expressed as the radical difference between the behavior of an ideal fluid and that of a viscous fluid when flowing around a mass and, while this identifies without a doubt that there exists on the surfaces of a body a volume of air known

as boundary layer, it is more of a fictional definition of what boundary layer does rather than what it really is, and all efforts thus far have been toward controlling and removing boundary layer from the upper surface of an airfoil.

The patentee, however, in explanation of the operation of the structures and the method disclosed in his patent, employs a different concept or theory of boundary layer air. The patentee's concept of boundary air layer, as expressed in the patent, is that it is the quantity or mass of air which an airfoil displaces equal in volume to that of the airfoil, and as the airfoil progresses through the air a similar volume of air is displaced for each chord length that the airfoil advances. Thus, the faster the airplane flies the greater the total volume of air which is displaced per unit of time. Under the Jones definition of boundary air layer volume, the thicker the airfoil the greater the boundary layer air volume becomes.

The Jones concept of boundary layer involves a considerably greater volume of air than that conventionally referred to as boundary layer. Such concept is understandable to those skilled in the art. It is herein referred to because it has a bearing upon the interpretation of the claims of the patent in suit here in issue. Whether such concept of boundary air layer is correct or erroneous is immaterial as long as the patentee has defined it.

In connection with one of the objects set forth in the patent and with reference to the blower, it is stated that it is "capable of constantly performing the required exhausting and accelerating of the mass to act uniformly on the complete boundary layer flow volume over the entire airfoil surfaces."

The boundary air layer volume here referred to is that defined by the patentee.

11. The patentee's theory of airflow over the surfaces of an airfoil and the various pressures produced on the airfoil, as exemplified by Fig. 8 of the patent and the descriptive matter relating thereto, varies from the conventional theories of airflow and pressure zones as illustrated in Figs. 1 and 2 of Findings 2 and 3. This also is immaterial. The Jones disclosure is similar to the conventional theory of airflow and pressure insofar as it indicates an impact sector at the leading edge of the airfoil, a normal atmospheric pressure in the vicinity of the leading edge, a subatmospheric zone existing above the wing, a superatmospheric zone existing below the wing, and a zone of higher pressure than normal atmosphere at the trailing edge of the wing.

The patentee uses the phrase "aerodynamic section" as referring to airfoil section. This, as well as other terms used in the phraseology of the claims, such as "normal atmospheric pressure," "subatmospheric zone," "superatmospheric zone," "trailing edge of a wing," and "leading edge," is a term that is self-explanatory and understood by those skilled in the art.

12. The claims in suit are as follows:

"1. The method of modifying the absolute coefficients of the lift and drag of an aerodynamic section while in motion, said section possessing in the vicinity of its leading edge a normal atmospheric pressure zone, above its upper cambered surface a subatmospheric pressure zone, below its lower cambered surface a superatmospheric pressure zone at a higher pressure than the subatmospheric pressure zone and adjacent its trailing edge a resultant atmospheric pressure zone created by the convergence of the airflows passing from the section and of a higher pressure than the normal pressure zone, the steps of removing the boundary layer volume substantially over the entire span of said section, from and at a point adjacent a lower pressure zone, compressing said removed boundary layer volume within said section, and discharging said compressed boundary layer volume at a point adjacent a higher pressure zone, thereby utilizing said compressed and discharged boundary layer volume to remove boundary layer volume from the higher pressure zone.

"3. In the method set forth in claim 1, the additional step of uniformly varying the rate of removal and discharge of the boundary layer volume in proportion to the speed of the aerodynamic section.

"7. The method of modifying the absolute coefficients of lift and drag of an aerodynamic section while in motion, said section possessing in the vicinity of its leading edge a normal atmospheric pressure zone, above its upper cambered surface a subatmospheric pressure zone, below its lower cambered surface a superatmospheric pressure zone at a higher pressure than the subatmospheric zone and adjacent its trailing edge a resultant atmospheric pressure zone created by the convergence of the airflows passing from the section and of a higher pressure than the normal pressure zone, the steps of removing the boundary layer volume of air substantially over the entire span of said section from and at a point adjacent the normal atmospheric pressure zone, compressing said boundary layer volume of air and discharging said volume at a point adjacent the resultant atmospheric pressure zone in rear of trailing edge of the said aerodynamical section.

"9. The method of improving the lift and drag coefficients of an aerodynamic section while in motion which comprises selectively removing portions of boundary layer air volume from adjacent either the upper airfoil surface or the leading edge thereof, increasing the density of the removed portion, and discharging said portion into the zone adjacent the trailing edge of said airfoil.

"10. In an aircraft provided with an airfoil section, a blower, means for inducing a portion of the boundary layer air volume from a point adjacent an exterior surface of said section and feeding said portion to the blower, means for discharging said portion at increased pressure at a remote point adjacent the exterior surface of said section, means for driving the blower and means responsive to increase in speed of the aircraft for increasing the speed of the blower and the rate of discharge of the boundary layer air volume.

"11. In an aircraft in combination with an airfoil and a device as set forth in claim 10, means forming a spanwise slot adjacent the leading edge of the airfoil section for the intake of air and means forming another spanwise slot adjacent the trailing edge of the airfoil section for the discharge of air.

"15. In an aircraft provided with an airfoil section, a device as set forth in claim 10, a motor, selective gear transmission means connecting the motor to the blower, and means responsive to changes in air speed for controlling said transmission means for varying the volumetric intake and discharge of the boundary layer air volume.

"16. In an aircraft provided with an airfoil section, a blower, transverse slots located substantially over the entire span of said section at separated points in the surface of said section, a conduit connecting each slot to said blower, a valve in each conduit and means for simultaneously operating said valves, said conduits and blower being arranged to draw in boundary air through one slot and discharge said air through a remote slot.

"18. In an aircraft, an airfoil section, means forming a slot adjacent the leading edge and extending along substantially the entire span of the said airfoil section for the intake of the boundary layer air, means forming another slot adjacent the trailing edge and extending along substantially the entire span of the airfoil section for discharge of the boundary layer air, and a blower connected to each of the slots and substantially coextensive in span therewith, to uniformly induce air through the forward slot and discharge air through the rearward slot."

13. There is no evidence of conception or reduction to practice of the alleged invention set forth in the claims in suit prior to June 20, 1936, the filing date of the patent in suit.

There is also no evidence of the issuance of any license or the construction by plaintiff, other than models, of an airplane embodying the disclosure of the patent in suit.

The Alleged Infringing Structures

14. The charge of infringement in this case is predicated upon the construction or use by the Government and without the consent of the plaintiff, of three types of airplanes. These are listed as follows:

The Boeing B-17

15. The Boeing B-17 airplane alleged by plaintiff to constitute an infringement is illustrated in a large scale drawing, plaintiff's exhibit 18. This is a large airplane, the span from wing tip to wing tip being about 103 feet. The fuselage is approximately nine feet in diameter so that the span of each individual wing is approximately 47 feet. The power plants consist of four engines mounted in engine nacelles, two being located in a forwardly projecting position on each wing. For convenience, a reduced scale drawing showing a portion of the fuselage and one wing with two engines, is reproduced herewith.

Three rectangular openings, indicated on the drawing reproduced herewith by reference numerals 7, 15, and 22, are located adjacent each engine and in the leading edge of the wing and slightly below the median line thereof. These openings, which are relatively small in area and length as compared to the span of the wing, are located in the high pressure zone or high pressure area against the wing as it moves forward in normal flight. (See Fig. 2 in Finding 3.) These openings which are termed ram air openings, a term which aptly describes their function, are located to receive therein as much air as possible from the impact pressure existing at this point in the leading edge of the wing.

The ram air opening 15 is connected by a duct within the wing which extends to a rotary compressor, which, in turn, is directly driven by a turbine operated by the exhaust gases from the engine. This combination device, called a turbosupercharger,

receives the ram air, compresses it, and delivers the same to the inlet manifold of the engine. The exhaust gases from the engine pass through a duct to the turbine portion of the turbosupercharger and also to an alternate exhaust opening underneath the wing. This opening is provided with a valve termed a waste gate.

The degree of opening of the waste gate varies the amount of exhaust gases fed to the turbine of the turbosupercharger and thus varies the extent to which the ram air is compressed prior to entering the inlet manifold. The extent of the waste gate opening is automatically controlled in such manner as to increase the speed of the turbosupercharger as the altitude increases. The fundamental purpose of the turbosupercharger is to supply air to the engine at pressures comparable with sea level pressure when the airplane is operating at higher altitudes. The speed of the turbosupercharger is responsive to variations in altitude and is not responsive to the speed of the airplane. The exhaust gases from the engine passing out of the turbosupercharger and the waste gate are discharged under the wing. These gases do not in any way reduce the effect of boundary air layer but instead tend to increase turbulence.

What has been stated about the operation of a B-17 engine and what is subsequently stated is equally applicable to all four engines and their associated ram air openings as their operation and equipment are all substantially identical. The power plants of the B-17 airplane have always used constant speed propellers in which the pitch of the propeller blades is adjustable so that with a given throttle setting the speed of the engines and the propellers always remains constant for all intended airplane operation, including climb and dive.

16. The wings on the B-17 airplane are provided with open lattice like ribs so that there is an open interior space extending throughout the entire span of the wing. These ribs do not form any air passages or ducts. Air is admitted to the interior of the wings be means of the other openings 7 and 22 in the manner and for the purpose described in subsequent findings 17, 18.

In the event the ram air opening 15 described in the previous finding, and which supplies air for the engine charge, becomes clogged, as by hitting a bird in flight, an emergency relief valve located in the ram air duct is so connected as to open and permit the passage of the air from the interior of the wing to the turbosupercharger. In addition to this emergency valve, there is a second valve located adjacent the intercooler and manually controllable. By means of this valve the pilot may admit air from the interior of the wing to the turbosupercharger when he so desires.

17. When air is compressed by the turbosupercharger it becomes heated. Such heat will decrease the density of the air. In order to overcome this heating effect, the air on its way from the turbosupercharger to the engine inlet manifold passes through a device called an intercooler. Constructionally, this is roughly analogous to an automobile radiator with the exception that air is cooled instead of water. The air for cooling the intercooler enters by way of the second ram air inlet shown on the drawing at 22. This air, after passing over the intercooler, is merely "dumped" into the interior of the wing. This air passes through the intercooler and into the wing solely under the impact pressure at the leading edge thereof, and no power device such as a blower or fan, is utilized in connection with the passage of this air through the intercooler.

18. The third ram air opening indicated by the reference numeral 7, supplies air by virtue of the impact pressure to an oil cooler which cools the circulating engine oil. This air, after passing through the oil cooler, is also dumped into the interior of the wing, and, similarly to the intercooler air, impact pressure alone is used to force the air through the oil cooler and no power device is utilized.

Four slots indicated by the numeral 24, are located in the upper portion of the wing immediately to the rear of each engine nacelle. These slots are to permit the escape of the waste air which has come into the wing through the intercooler and oil cooler. There is no blower or similar mechanism to force this waste air out through these slots, and it escapes from them through its own natural remaining pressure. The ratio of velocity of the air in these openings to the stream velocity of the air flowing over the wing is less than unity. Some of the impact pressure existing in the air as it enters the ram air openings 7 and 22 having been lost in forcing through the intercooler or oil cooler, the air as it passes over the openings 24 is low energy air and its velocity is less than the free-stream velocity outside the wing. This low energy air escaping out of the openings 24 is not capable of reducing the boundary air layer by adding energy to it, but, if anything, increases boundary layer air effect.

The Republic P-47

19. The second type of airplane alleged to constitute an infringement is the Republic P-47 which is illustrated in an enlarged scale drawing in evidence as plaintiff's exhibit 19. This drawing shows a top plan view, a side elevational view partly broken away, and a front end elevational view, partly broken away. For convenience, the side elevational view and the end elevational view, Figs. 2 and 3, are reproduced herewith.

In general, this airplane consists of an elongated fuselage of conventional design with a single engine mounted in the nose thereof and a pair of wings extending on each side from the lower portion of the fuselage. These wings are also of conventional design and do not contain any slots, ducts, or blowers. With the exception of the inner ends of the wings at their point of attachment to the fuselage, as shown in Fig. 3, the wings are not otherwise illustrated in the accompanying drawing. The pilot's compartment is shown at the top of the fuselage, and all P-47 airplanes were built with a single cockpit adapted to receive one person only, except that subsequent to the spring of 1944 two P-47 airplanes were converted from single seaters to double seaters by the construction of a second cockpit in each airplane.

20. The single engine or power plant of the P-47 is fundamentally the same in structure and operation as the power plants used in the B-17 airplane and described in the previous findings. As shown in the accompanying drawing, a ram air inlet 6 of inverted V-shape located within and at the front end of the engine cowling, at the bottom thereof, receives air from the impact pressure zone of the fuselage. This ram air flows rearwardly through a duct located in the bottom of the fuselage and to the rear thereof. A portion of this air enters the compressor of a supercharger 15 where it is compressed. This air then flows through an intercooler 19 and through two ducts (one on each side of the fuselage) to the inlet manifold of the engine. The remaining portion of this air, by virtue of the impact pressure, passes through the intercooler 19 to cool the air from the supercharger and is discharged by its natural remaining pressure through two discharge ports 21 located on either side and near the rear of the fuselage.

21. The turbine of the supercharger is driven by the exhaust gases of the engine which pass through two ducts 14 (one on each side of the fuselage) from the exhaust manifold to the turbine. The exhaust port of the turbine is located at 16 underneath and near the rear of the fuselage. Waste gates are provided in each of these ducts just behind the engine for controlling the speed of the turbosupercharger, and the extent of the waste gate opening is automatically controlled to compensate for variations in the altitude, so that the turbosupercharger will supply air to the engine at pressures comparable with sea level pressure when the airplane is operating at high altitude. The speed of the turbosupercharger is responsive to variations in altitude and not responsive to the speed of the airplane.

The engine on the P-47 airplane uses a constant speed propeller so that with a given throttle setting the speed of the engine and the propeller remains constant for all intended airplane operation including climb and dive.

Ram air for an oil cooler is supplied through two cylindrical ram air openings 5 located on either side of the ram air opening 6. (See Fig. 3 of the Republic P-47 drawing.) This ram air, after passing through the oil cooler, is discharged just aft the engine through two openings, one on each side of the fuselage, under its own natural remaining pressure.

22. In the power plant system described in the previous findings in connection with the P-47 airplane the only air that is compressed is that air which is compressed by the turbosupercharger, all of which is fed into the inlet manifold of the engine and thus becomes a part of the fuel charge.

The exhaust gases from the engine that pass out from the fuselage to atmosphere, either through the waste gates or the exhaust from the turbine of the turbosupercharger, will tend to increase turbulence and do not in any way reduce the effect of boundary layer upon the fuselage.

The remaining air that passes out of the openings in the fuselage is the air from the intercooler and the air from the oil cooler. In each instance this air enters the appropriate ram air openings in the front of the fuselage because of the impact pressure due to the movement of the airplane while in flight, and some of this pressure having been lost in forcing the air through the intercooler and oil cooler and associated ducts, its velocity upon release through the fuselage openings is less than the free-stream velocity outside the fuselage. This low energy air escaping out of the openings in the fuselage is not capable of reducing the boundary air layer by adding energy or velocity to it, but, if anything, increases the boundary air layer effect.

The Lockheed P-80

23. The third type of airplane alleged to infringe is the Lockheed P-80 which is illustrated in an enlarged scale drawing in evidence as plaintiff's exhibit 20. This drawing shows a top plan view, a side elevational view partly broken away, and a front elevational view partly broken away. The Lockheed P-80 is an airplane of the jet-propulsion type. It consists of a somewhat elongated oval-shaped fuselage with a pair of wings or airfoils attached to the fuselage at its approximate mid-section and a conventional jet-propulsion power plant housed within the fuselage. The wings are conventional in character and are not provided with any slots, ducts, or blowers.

24. For convenience, the side elevational and front elevational views of plaintiff's exhibit 20 are reproduced herewith. As shown in the side elevational view, the power plant is located to the rear of the pilot's cockpit. Air for the engine charge is obtained by means of two ram air scoops 4 positioned respectively on opposite sides of the fuselage a substantial distance forwardly of the leading edges of the airfoils (approximately one-third the distance between the leading edges and the elongated pointed front end of the fuselage). These ram air scoops protrude from the sides of the fuselage and resemble in appearance a pair of ears as shown in the front elevational view. The scoops protrude outwardly a sufficient distance from the sides of the fuselage to receive ram air forced in by the forward motion of the airplane.

The ram air entering the scoops is carried by ducts back to the power plant located behind the pilot's compartment where the ram air enters a compressor 14 in which the pressure of this air is increased. The high-pressure air is then delivered to a combustion chamber 8 where it is mixed with fuel and burned. The exhaust gases from this combustion chamber pass through the turbine 13 and out into an exhaust cone or pipe 9, which terminates in a circular opening at the rear end of the fuselage. The exhaust gases as they leave the circular opening in the rear end of the fuselage form the engine jet blast 10, which drives the airplane forward.

25. The compressor 14 and the turbine 13 are mounted on the same shaft and turn as one unit. There is no selective gear transmission between them. The speed of the turbine, and therefore the compressor, is controlled by the amount of fuel fed to the combustion chamber and this, in turn, is controlled by the throttle which is manipulated by the pilot. The P-80 does not have means responsive to an increase in the speed of the airplane for increasing the speed of the compressor. As the airplane moves forward through the air a boundary air layer is formed on the surface of the fuselage ahead of the ram air scoops 4. As this boundary air layer is subjected to friction and therefore does not possess the impact energy of the free air, it is not desirable to have the boundary air layer enter the ram air scoops. In order to prevent this, a series of inlet openings 11 are located at the side of the openings 4 immediately adjacent the surface of the fuselage, so that the boundary layer air enters these inlets rather than the scoop openings leading to the power plant. The inlets 11 are provided with what are termed "bleed-off" passages having outlets 12 on the exterior of the fuselage which are located a short distance to the rear of the openings 11 at a point of lower pressure. The boundary air layer, therefore, is led off through the bleed-off passages to outlets at the rear of the ram air scoops. This arrangement does not involve any compression of the boundary air layer and merely acts to prevent it from entering the ram air scoops that lead to the compressor.

Prior Art

26. The following prior art was available to those skilled in the art more than two years prior to the filing date (June 20, 1936) of the Jones application maturing into the patent in suit, or prior to said filing date.

Patents Accepted

---------------------------------------------------------------------------- Country | Patentee | Number | Date of issue | Defendant's | | | | exhibit -----------------|--------------|-----------|-----------------|------------- Germany ........ | Betz et al. | 539,614 | Nov. 28, 1931 | 21-21a United States .. | Upson ...... | 1,848,809 | Mar. 8, 1932 | 22 Do .......... | Stout ...... | 1,980,233 | Nov. 13, 1934 | 23 Do .......... | Price ...... | 1,957,413 | May 1, 1934 | 24 Germany ........ | Oplatek .... | 589,059 | Oct. 31, 1935 | 25-25a United States .. | Stalker .... | 2,041,792 | May 26, 1936 | 26 Do .......... | Stalker .... | 1,843,993 | Feb. 9, 1932 | 27 Do .......... | Jones ...... | 1,980,140 | Nov. 6, 1934 | 28 Do .......... | Hallowell .. | 1,725,914 | Aug. 27, 1929 | 29 Germany ........ | Drexler .... | 359,421 | Sept. 21, 1922 | 30-30a United States .. | Lyons ...... | 1,741,578 | Dec. 31, 1929 | 31 Do .......... | Stalker .... | 1,913,644 | June 13, 1933 | 32 Do .......... | Trey et al. | 1,979,298 | Nov. 6, 1934 | 33 Do .......... | Craddock ... | 1,585,281 | May 18, 1926 | 34 France ......... | Dupre ...... | 547,589 | Sept. 27, 1922 | 35-35a United States .. | Ward ....... | 1,833,600 | Nov. 24, 1931 | 36 Do .......... | Kauffman ... | 1,703,396 | Feb. 26, 1929 | 37 Do .......... | Martin ..... | 1,847,093 | Mar. 1, 1932 | 38 Do .......... | Diehl ...... | 1,779,160 | Oct. 21, 1930 | 39 Do .......... | Verville ... | 1,427,872 | Sept. 5, 1922 | 40 | | | | Great Britain .. | Wood ....... | 413,948 | July 26, 1934 | 41 Do .......... | Campini .... | 406,713 | Feb. 28, 1934 | 42 ----------------------------------------------------------------------------

Printed publication

National Advisory Committee for Aeronautics Technical Memorandum No. 452, entitled "Motion of Fluids with Very Little Viscosity," by L. Prandtl, accession date in Library of Congress March 3, 1928 (defendant's exhibit 5).

Of the patents listed above, the following represent prior art considered by the Patent Office during the prosecution of the Jones application which materialized into the patent in suit:

Upson, No. 1,848,809 (defendant's exhibit 22); Stout, No. 1,980,233 (defendant's exhibit 23); Stalker, No. 1,843,993 (defendant's exhibit 27); Jones, No. 1,980,140 (defendant's exhibit 28); Drexler, No. 359,421 (defendant's exhibits 30-30a).

The patents and printed publication herein set forth are made a part of this finding by reference.

27. The Prandtl article entitled "Motion of Fluids with Very Little Viscosity" (defendant's exhibit 5) is a theoretical and mathematical treatise in which the effects of boundary layer flow over surfaces are discussed. The article makes reference to certain experiments that were conducted in which the flow of a fluid over surfaces was tested. These experiments utilized the flow of water in a glass tank, the water containing small reflecting particles so that photographs of its flow and distribution over bodies could be made.

Included in the photographs are several showing the flow lines around a cylindrical body in which the boundary layer flow results in separation and turbulence. Further photographs show such a cylinder provided with a slot in its surface leading into the hollow interior of the cylinder and from which water is withdrawn. These particular photographs show, and are described in the text as showing, the elimination of separation when the transition layer can be intercepted.

28. German patent to Betz et al. (defendant's exhibit 21; translation, 21-a) is entitled "Arrangement for Influencing the Boundary Layer of Bodies Exposed to a Flow." This patent indicates that it is old in the art to improve the flow conditions about a body "by suctioning off or removing the boundary layer of the medium moving along the body" and that "This removal of the boundary layer is used to increase the transverse thrust in the case of surfaces exposed to a flow such as airplane wings, propeller blades and the like or for the purpose of diminishing the resistance in the case of such bodies or in vehicles." The stated object of the invention set forth in this patent is as follows: "* * * the boundary layer of the medium flowing relatively to the body in question along its surface retarded by friction is suctioned away at one or more points of the body surface and the medium suctioned away fed back to one or more points of the surface with increased speed and there used for the removal of the boundary layer and thus to avoid disturbing eddy action."

The single figure of the patent, which is reproduced herewith, shows an airplane wing 11 having a leading edge, a trailing edge, and upper and lower cambered surfaces. The wing is provided at one or more points with suction slots 12. As here shown, these slots are located along the upper surface of the wing toward the leading edge and are thus positioned in a subatmospheric pressure zone. A blower 14 operated by a motor 13 is located in the wing so as to apply suction to the boundary layer through the slots 12.

Toward the trailing edge where the subatmospheric pressure is less, and therefore in a higher pressure zone, the upper airfoil surface is provided with "one or more blast openings 15" through which the compressed boundary layer air is discharged.

Claim 1 of this patent read as follows: "1. Arrangement for influencing the boundary layer of bodies exposed to the flow of a medium, such as transverse thrust bodies (for example airplane wings, propeller blades) vehicles, etc. in which the boundary layer gliding directly along the surface, retarded by friction, of the medium flowing relatively to the body is suctioned away at one or more points of the body, characterized thereby, that the suctioned off medium at one or more points of the surface suited for the removal of the boundary layer is fed back with increased energy."

The Betz patent discloses a structure and method "of removing the boundary layer from and at a point adjacent a lower pressure area or zone, compressing the removed boundary layer within the wing, and discharging said compressed boundary layer at a point adjacent a higher pressure area or zone, thereby utilizing the compressed and discharged boundary layer to remove boundary layer from the higher pressure area or zone."

29. United States patent to Upson (defendant's exhibit 22) is a patent cited by the Patent Office during the prosecution of the Jones application. Two of the objects stated in this patent are as follows:

"Another object is to provide automatically operated means for drawing air from the upper surface of an airplane wing during those phases of flight in which air eddies are present or liable to become present above such wings, such means being relatively inoperative during normal horizontal flight.

"Another object is to provide an airplane having wings slotted or otherwise perforated lengthwise thereof along their upper surfaces, automatically actuated means being provided for drawing air through such slots and discharging it at a point where it will not improperly affect the flight of the airplane."

The specification of the patent discusses the efforts to eliminate the presence of eddies on the wing, and states with reference thereto that "It has also been shown by laboratory tests that the same purpose may be served by sucking in air from the so-called boundary layer adjacent the upper surface of the wing, the suction being applied thru the medium of a power driven suction blower."

Fig. 6 of the patent, reproduced herewith, shows in cross-section an airfoil having a leading edge, a trailing edge and upper and lower cambered surfaces. In the upper surface and toward the leading edge the airfoil is provided with a slot 46 which extends the full span of the wing. This spanwise slot opens into an interior spanwise passageway 47 which is "split up lengthwise of the wing into one or more passages," and each of these passages is provided with a blower 70. Toward the trailing edge of the airfoil, the upper surface is provided with spanwise slots 75' which extend in front of the ailerons at each end of the wing. The blower 70 is operated through beveled gears 72 by a propeller 74.

The blades of the propeller 74 are disposed so that the rotation thereof is a minimum for horizontal flight. But when the angle of attack of the airfoil approaches the stalling angle, irrespective of the forward speed of the airfoil, the propeller 74 becomes effective to operate the blower 70 to exert its maximum suction and compression effect. As a result, "boundary layer air adjacent the upper surface of the wing" is drawn by "suction" into the wing or airfoil through the spanwise slot 46, then compressed within the airfoil, and next discharged through the spanwise slots 75' to remove boundary layer air in this part of the wing.

This patent discloses a structure and method for removing the boundary layer air substantially over the entire span of the wing from and at a point adjacent a lower pressure zone, compressing the removed air within the airfoil and discharging the compressed boundary layer air at a point adjacent a higher pressure zone.

30. United States patent to Stout (defendant's exhibit 23) was also cited by the Patent Office during the prosecution of the Jones application. One of the objects of this patent is stated as follows: "Another object is to provide means for drawing air from the upper surface of an airplane wing for increasing the lift of the wing during those phases of flight in which air eddies occur and for maintaining the lift of the wing when eddies are liable to occur above the wing."

The structure disclosed herein is an airplane provided with a fuselage and airfoils or wings which extend outwardly from the sides of the fuselage. As shown in Fig. 2, reproduced herewith, each wing is provided with two elongated slots 11 in its upper surface in a forward position, and two elongated discharge slots 12 located in its trailing edge. The specification states that the inlet slots "may extend throughout the length of the wings or any desired portions thereof."

Within each wing is mounted an engine 13 which drives the rearwardly positioned propeller 26, and also a blower 14, forward of the engine. The suction side of the blower is connected to the upper slot "for increasing the lift of the wing during those phases of flight in which air eddies occur." The compression side of the blower is connected by conduits 16 to the engine for cooling the engine cylinders. The heated and compressed air is then discharged from the wing through the trailing edge slot 12. The operation of this structure is summarized in the patent as follows: "In the operation of the cooling devices each blower 14 withdraws the boundary layer of air from the upper surface at a point adjacent the top of the wing 10 and directs the air through the conduit 15, and then forces this air through the individual conduits 16, to each cylinder 17, and thence to the exhaust ports 12."

31. German patent to Oplatek (defendant's exhibit 25; translation, 25-a) discloses an airplane consisting of a fuselage with airfoils or wings extending from each side thereof and a power plant consisting of an engine in the nose of the fuselage driving a propeller. While in flight this airplane would have the conventional zones of various pressures surrounding its airfoils.

A series of elongated openings in four rows extend over the entire span of each upper airfoil surface and constitute, in effect, four spanwise slots in this surface. The lower surface of each airfoil is similarly provided with four rows of elongated openings. An airtight wall or partition extends fore and aft through the midpoint of each airfoil, separating the upper airfoil surface from the lower airfoil surface. Three blowers are mounted in this partition and are driven by beveled gearing from the engine shaft. These blowers function to draw in air from the slots in the upper surface of the airfoil and to discharge it under pressure through the slots in the lower surface. The object of the construction herein disclosed is referred to "as means for producing buoyancy in airplanes by air conduction." The specification states in part as follows:

For the buoyancy it is necessary that the air above the wing will remain after being conveyed underneath the wing and will not be set in circulation again whereby the buoyant effect would be canceled.

The patentee teaches by this quotation that the air be compressed under the wing and thus give additional buoyancy. No reference is made in this patent to boundary layer air control.

32. United States patent to Stalker (defendant's exhibit 32) is entitled "Means of Energizing the Boundary Layer on Aircraft Parts." The principal object stated in the patent relates to "provision of means for removing the boundary layer * * *."

As disclosed in a portion of Fig. 1 of the patent, reproduced herewith, the structure consists of an airfoil or airplane wing provided with a partition extending through its midsection in which a blower 12 is mounted. This blower is for the purpose of drawing in boundary layer air through spanwise slots 19 and 24, positioned in the upper surface of the airfoil and somewhat to the rear thereof. This air, after being compressed by the blower, is discharged by the airfoil through a spanwise slot positioned in the upper surface of the airfoil and near the leading edge thereof. The slot 20 is located in a pressure zone in which the pressure is lower than the pressure in the zones containing the suction openings. The stream of air issuing from the opening 20 is directed tangentially and rearwardly of the wing so as to add energy to the boundary layer on the wing surface.

The blower 12 is geared to the propeller of the airplane, and the propeller in turn is driven by the engine of the airplane so that normally the blower is driven by the engine. There is, however, an overrunning clutch mechanism provided between the engine and the propeller so that when the airplane is in a glide or dive the forward motion of the plane will rotate or drive the propeller even though the engine at that time be "idling." During this specific mode of operation (gliding or diving, with engine idling) the speed of the blower is directly responsive to the speed of the propeller, and this in turn is at that particular time directly responsive to the speed of the airplane.

The patent states that "The removal of the boundary layer of air on an airfoil surface improves the lift and reduces the resistance. When the boundary layer is removed the result is an energization of the boundary layer to replace its energy lost by friction with the aircraft surface. This treatment of the boundary layer is an energization or acceleration of it."

33. French patent to Dupré (defendant's exhibit 35; translation, 35-a) discloses an airplane comprising a wing, a fuselage, and a power plant in the fuselage provided with a conventional propeller located at the front end of the fuselage.

The specification states as an object "* * * an aviation apparatus with thick wings the peculiar feature of which consists in that passages of suitable form are provided in the wings and in the fuselage, rotors being provided in these passages for the purpose of suctioning the streamlines on the external surface of the wing and on the periphery of the fuselage so as to diminish the effects of the friction and vortices and in order to utilize the passive resistances of the streamlines and convert them, as far as possible, into active reactions facilitating the propulsion of the apparatus."

The interior of the wing is provided with a plurality of spaced air passages that extend fore and aft the wing from the leading edge to the trailing edge. Each air passage has a flared inlet opening in the leading edge of the wing and a flattened opening at the trailing edge of the wing. The flared openings in the leading edge join each other so as to form in effect a more or less continuous leading edge opening. The adjacent flattened openings at the trailing edge of the wing also form in effect a more or less continuous trailing edge slot. The fore and aft passageways are provided with a series of blowers driven from a central power plant, these blowers operating to compress the air which enters the openings in the leading edge of the wing and discharge the same under pressure at the trailing edge of the wing. A part of the air thus compressed is discharged from rearwardly inclined openings in the bottom surface of the wing a short distance forwardly of the trailing edge. The specification states that these openings permit the escape of compressed streamlines "which envelop and carry along by their own speed the streamlines from underneath the wing and facilitate their flow and consequently cause a fresh diminution in friction."

34. United States patent to Martin (defendant's exhibit 38) states that one of the objects of the invention "is to provide an alteration of pressure distribution in flight so that the aeroplane drag is lessened and so that the lift of the aeroplane is increased."

Figs. 1 and 2 of this patent illustrate an airplane in which a wing is attached to the upper portion of the fuselage which has a power plant located in the front end thereof and which drives a conventional propeller. The forward end of the fuselage is provided with a series of circular slots located in the impact pressure zone and adjacent the propeller blades and an opening in the propeller blade itself which receive air under the impact pressure. This air, after passing through a blower to increase its pressure, circulates around the engine to cool the same.

This compressed air is then discharged through two slots located respectively in the upper and lower portions of the fuselage and, in addition, through two slots in the upper surface of the wing. The air is discharged from these slots in a rearward direction and at a velocity greater than the normal rate of flow due to the flight of the airplane (at a velocity higher than the free-stream velocity). There is a valve in each of the discharge slots whereby the pilot can selectively open or close them at will.

Figs. 5 and 6 of the Martin patent show a modification in which the features of this patent are applied to an airplane wing which contains within itself the power plant for operating the propeller. As shown in these figures, two spanwise slots are provided in the leading edge of the wing, one just above the leading edge and the other just below. These slots are connected to a blower chamber from which air under pressure passes through a passage around the motor and is then discharged in a series of three spanwise slots located in the upper surface of the wing.

Valves are provided to control the three slotted discharge openings in the top of the wing and, in addition, the two entrance air slots have similar control means which permit the pilot to open and close them selectively at will. Both the inlet and outlet openings are therefore provided with means for selectively opening and closing the same.

35. British patent to Campini (defendant's exhibit 42) discloses an airplane of the jet-propulsion type comprising an airplane wing, an elongated fuselage which is secured at its midsection to the wing, and a jet-propulsion power plant which is housed in the fuselage.

As shown in Fig. 4 of this patent, reproduced herewith, an annular air inlet 1 is located just to the rear of the pilot's compartment and which the specification states "is of narrow elongated form so that the fluid drawn in is the layer of air immediately adjacent said skin surface." This air then passes through a duct 3 leading to a pair of centrifugal compressors 4 and 4'. The high pressure air leaving the compressors is then delivered to a combustion chamber 5 which is supplied with fuel. The exhaust gases from this combustion chamber pass into an exhaust cone 24 in the rear end of the fuselage and issue therefrom in the form of a blast jet which provides propulsive force for the airplane. The compressors are driven by an engine 0.

The structure here disclosed permits entrance of boundary air layer through the annular opening in the forward part of the fuselage. This structure is similar to the defendant's airplane, the Lockheed P-80, alleged to infringe, with the exception that the latter is provided with structure (boundary layer "bleed-offs") for preventing the boundary layer air from entering the compressors.

A modification of this structure is shown in another figure of this patent in which a circular opening is provided in the nose of the fuselage for the entrance of the air instead of the annular opening 1 as shown in the figure reproduced in connection with this finding.

Validity and Infringement

36. The prior art discloses two methods of treating boundary air layer. The first is by removing it from the surface of an airfoil by drawing or sucking it in through a slot or opening in the airfoil surface. The second method is to use a slot in the airfoil surface through which air is forcibly ejected at a velocity greater than the velocity of the boundary layer air (usually tangentially to the airfoil surface). This latter method tends to prevent the formation of turbulence by adding energy to the sheet of boundary layer air as it flows over the airfoil, thus overcoming its decreased velocity due to friction.

The claims in suit of the Jones patent relate to both methods, and the basic elements upon which the claims in suit are predicated include an inlet slot, a power-driven blower, and an outlet slot.

The Jones specification states that "* * * the invention broadly consists of mechanically controlling and removing the laminar air layers or boundary layer volume from the sustaining surfaces of an airfoil. This is accomplished by providing a plurality of intake and exhaust ports at definitely located portions of the airfoil whereby the boundary layer volume may be selectively removed from certain of these portions, supercharged or compressed and accelerated through the medium of an impeller or blower, and discharged through certain other of the ports to additionally remove a further accumulation of boundary layer mass."

37. In interpreting the claims in suit it is necessary for those skilled in the art to take into consideration the following:

Jones, instead of using the conventional concept of boundary air as that layer of air adjacent the airfoil surface in which viscosity effects are present and which varies in thickness from a few thousandths of an inch to several inches, gives in the patent specification his definition of boundary layer air volume as the total volume of aid displaced by the airfoil each time it moves forward its chord length.

The claims in suit fall into two categories. Claims such as 1, 3, and 7 specify "removing boundary layer volume," whereas claims 9 and 10 relate to the removal of a portion of the boundary layer air volume. Those claims which specify, broadly, removal of the boundary layer volume rather than a portion thereof, must be interpreted as a removal of the boundary layer volume as defined by Jones, rather than the conventional and relatively thin boundary air layer. (See Finding 10.)

Claims 1 to 4 and other claims of the Jones application as originally filed were rejected by the Patent Office in the first action, in view of the prior art. Claim 3 read as follows: "The method of improving the lift and drag coefficients of an aerodynamic section while in motion which comprises removing a portion of the relatively rarefied subatmospheric boundary layer air volume from one point adjacent the exterior surface of said section, increasing the density of said portion, and discharging said portion at a remote point adjacent the exterior surface of said section."

Jones acquiesced in this rejection and canceled the claim, substituting claims of more limited character. In this amendment substitute claim 24 was filed. This claim, which ultimately became claim 1 of the patent, is paraphrased in the next finding. Jones at the time of filing this amendment stated in connection therewith "Claims 1 to 4 have been replaced by claims 24 and 25 which clearly avoid the references of record, both as to structure and result. No reference of record discloses the idea of removing boundary layer air volume substantially over the entire span of an airfoil from and at a point adjacent a normal or subatmospheric pressure zone, compressing this volume, and discharging same at high velocity into a superatmospheric pressure zone to remove stagnated boundary layer air from the latter zone."

The requirement as to removal of the boundary layer substantially over the entire span of the airfoil and which has been italicized in the subsequent paraphrasing of claim 1, constitutes an express limitation of this claim.

38. The plaintiff alleges infringement of claims 1, 3, 7, 9, 10, 11, and 18 by all three types of defendant's airplanes (Boeing B-17, The Republic P-47 and The Lockheed P-80). In all three Government structures the only purpose of receiving air into openings in the forward portion of a wing or fuselage and compressing it by means of a power-actuated blower is to supply an appropriate amount of oxygen for the fuel charge of the engines.

For convenience, claim 1 is paraphrased as follows:

Claim 1

(a) The method of modifying the absolute coefficients of the lift and drag of an aerodynamic section while in motion, said section possessing in the vicinity of its leading edge a normal atmospheric pressure zone, above its upper cambered surface a subatmospheric pressure zone, below its lower cambered surface a superatmospheric pressure zone at a higher pressure than the subatmospheric pressure zone and adjacent its trailing edge a resultant atmospheric pressure zone created by the convergence of the airflows passing from the section and of a higher pressure than the normal pressure zone,

(b) the steps of removing the boundary layer volume substantially over the entire span of said section, from and at a point adjacent a lower pressure zone,

(c) compressing said removed boundary layer volume within said section, and

(d) discharging said compressed boundary layer volume at a point adjacent a higher pressure zone,

(e) thereby utilizing said compressed and discharged boundary layer volume to remove boundary layer volume from the higher pressure zone. [Italics supplied.]

The Boeing B-17

39. Referring first to the Boeing B-17 (Findings 15 to 18, inclusive), the three rectangular openings 15, 22, and 7 associated with each power plant are located in the lower portion of the leading edge and in the impact pressure zone of the wing. The ram air at these openings is at a higher pressure than at any other point on the wing.

As to paragraph (b) of the above claim, the air received by these openings is not at a point adjacent a lower pressure zone but instead is in a high pressure zone. The total span of all six openings in a wing is only approximately 10 percent of the entire span of the wing.² Even if these openings were for the sole purpose of removing boundary layer volume their total width would be insufficient to remove the boundary layer air "substantially over the entire span of the wing."

2 By measurement of the large scale drawing of this airplane, plaintiff's exhibit 18, the entire span of the wing approximates 305 mm., whereas the total width of the six openings approximates 30 mm.

40. Referring to paragraphs (c), (d), and (e) of the above claim, the only compression of the ram air received by the openings in the leading edge of the B-17 is that received by the two openings 15, and this is utilized not to remove boundary layer volume but to form a fuel charge for the engines. The hot exhaust gases from the engine which are discharged either from the turbine or an alternate exhaust opening underneath the wing do not in any way reduce the effect of boundary air layer but instead tend to increase turbulence.

The ram air which is forced in the other openings 22 and 7 in the leading edge of the wing is for cooling the intercooler and the oil cooler. After circulating through these devices this air is "dumped" into the interior of the wing and flows out through the discharge slots 24 located in the top of the wing and toward the rear thereof. This air exists under its own natural remaining pressure after circulation through the coolers. It has not been compressed and is not discharged under pressure to remove boundary layer volume. This low energy air, the velocity of which is less than the relative velocity of the free air over the wing, is not capable of reducing boundary air layer by adding energy to it.

Claim 1 is not infringed by the Boeing B-17.

41. Claim 3 is paraphrased as follows:

Claim 3

In the method set forth in claim 1, the additional step of uniformly varying the rate of removal and discharge of the boundary layer volume in proportion to the speed of the aerodynamic section.

This claim adds to the phraseology of claim 1 the additional feature of the Jones patent which, as disclosed therein, consists of selective gearshift mechanism located between his engine and his compressor and which is automatically controlled by the speed of the airplane. No such feature is present in the Boeing B-17. The only speed variation of the compressor of the B-17 and which is used to compress air for the fuel charge, is an altitude control in which the compressor automatically speeds up as the altitude increases so as to supply additional air for the fuel charge.

Claim 3 is not infringed by the Boeing B-17.

42. Claim 7 is paraphrased below:

Claim 7

(a) The method of modifying the absolute coefficients of lift and drag of an aerodynamic section while in motion, said section possessing in the vicinity of its leading edge a normal atmospheric pressure zone, above its upper cambered surface a subatmospheric pressure zone, below its lower cambered surface a superatmospheric pressure zone at a higher pressure than the subatmospheric pressure zone and adjacent its trailing edge a resultant atmospheric pressure zone created by the convergence of the airflows passing from the section and of a higher pressure than the normal pressure zone.

(b) the steps of removing the boundary layer volume of air substantially over the entire span of said section from and at a point adjacent the normal atmospheric pressure zone,

(c) compressing said boundary layer volume of air, and

(d) discharging said volume at a point adjacent the resultant atmospheric pressure zone in rear of trailing edge of the said aerodynamical section.

The method of removing boundary layer air as expressed by this claim is substantially similar to the method expressed by claim 1, the only distinction being that paragraph (b) calls for the removal of boundary layer air at a point "adjacent the normal atmospheric pressure zone" instead of, as set forth in claim 1, "at a point adjacent a lower pressure zone," and paragraph (d) specifies the discharging of the boundary layer air in the rear of the trailing edge instead of, as stated in claim 1, "at a point adjacent a higher pressure zone."

As previously stated in consideration of claim 1, no boundary layer air is introduced in any of the ram air openings in the leading edge of the B-17 airplane, and there is no compression of boundary air layer and its discharge in the rear of the trailing edge of the wings of the B-17 airplane. For the reasons stated in connection with claim 1 and those here stated, claim 7 is not infringed by the Boeing B-17 airplane.

43. Claim 9 is paraphrased as follows:

Claim 9

(a) The method of improving the lift and drag coefficients of an aerodynamic section while in motion which comprises —

(b) selectively removing portions of boundary layer air volume from adjacent either the upper airfoil surface or the leading edge thereof,

(c) increasing the density of the removed portion, and

(d) discharging said portion into the zone adjacent the trailing edge of said airfoil.

Item (b) of this claim is the pertinent portion thereof. As filed in the Patent Office this claim (then original claim 5) was rejected over the prior art and the Patent Office also called attention that the claim was alternative in form since it called for drawing air in from either one of two places.

The applicant, Jones, then argued on the first amendment and defined the meaning of the claim as follows: "Claim 5 definitely covers selectively removing boundary layer air from either the upper surface or leading edge. In this operation, a series of acts may be performed in a desired sequence. As a first step, valve 36 may be closed and valve 39 open to draw air through slot b; and, as a second step, valve 36 may be opened and valve 39 closed to draw air in at slot a. Slot sequence should not be held to be alternative. The references alone or together do not disclose such steps or sequence nor the idea of discharging the compressed air from the trailing edge into the high pressure zone."

This claim, including the method of selectively removing boundary air layer from two different locations, inferentially includes ducts and valves for this purpose. The openings in the leading edge of the B-17 wing are for the purpose of receiving ram air and not boundary layer air, and there is no alternative opening in the upper airfoil surface of the B-17 wing, as required by claim 9, which may be selectively used for receiving boundary layer air.

For these reasons and those already stated as to the purpose of the compression of the ram air introduced through the ram air openings of the B-17 airplane, claim 9 is not infringed.

44. Claim 10 is directed to structure rather than to a method. This claim is paraphrased as follows:

Claim 10

(a) In an aircraft provided with an airfoil section,

(b) a blower,

(c) means for inducing a portion of the boundary layer air volume from a point adjacent an exterior surface of said section and feeding said portion to the blower,

(d) means for discharging said portion at increased pressure at a remote point adjacent the exterior surface of said section,

(e) means for driving the blower and

(f) means responsive to increase in speed of the aircraft for increasing the speed of the blower and the rate of discharge of the boundary layer air volume.

The nonapplication of the terminology of paragraphs (a), (b), (c), (d), and (e) of this claim, which relate in substance to inducing a portion of the boundary layer air volume by means of a power-driven blower and discharging it from the airfoil section at a remote location, has already been dealt with in connection with previously considered claims.

Paragraph (f) of the claim relates to the selective gear mechanism of the Jones patent which is automatically controlled by the speed of the airplane. This is shown in Fig. 7 of the Jones patent reproduced in Finding 9. As has been previously stated, the blower or supercharger of the B-17 airplane automatically controls to compensate for variations in altitude and is not responsive to the speed of the airplane.

Claim 10 is not infringed by the B-17 airplane.

45. Claim 11 adds to claim 10 the following phraseology:

Claim 11

means forming a spanwise slot adjacent the leading edge of the airfoil section for the intake of air and

means forming another spanwise slot adjacent the trailing edge of the airfoil section for the discharge of air.

Claim 11 thus defines in a somewhat more specific manner paragraphs (c) and (d) of claim 10.

For the reasons stated in connection with claim 10, claim 11 is not infringed by the B-17 airplane.

46. Claim 18 is paraphrased as follows, with italicization added:

Claim 18

(a) In an aircraft,

(b) an airfoil section,

(c) means forming a slot adjacent the leading edge and extending along substantially the entire span of the said airfoil section for the intake of the boundary layer air,

(d) means forming another slot adjacent the trailing edge and extending along substantially the entire span of the airfoil section for discharge of the boundary layer air, and

(e) a blower connected to each of the slots and substantially coextensive in span therewith, to uniformly induce air through the forward slot and discharge air through the rearward slot.

This claim is specifically directed to the Jones construction in which the blower and its casing serve as the main spar of the wing and are coextensive with the major length of the wing. As already indicated, the B-17 airplane has no slots extending substantially the entire span of the airfoil section. In addition, the turbosupercharger located at the rear of each engine is not coextensive in span with the wings.

This claim is not infringed by the B-17 airplane.

The Republic P-47

47. The second type of Government airplane alleged to infringe the group of claims just considered is the Republic P-47 (Findings 19-22, inclusive). This airplane comprises a conventional elongated fuselage and a pair of wings also conventional in character and having no slots or openings. The airplane contains a single power plant, the structure and operation of which are fundamentally the same as the power plants in the B-17 airplane. As in the case of the B-17 airplane, the only air that is compressed by a power-driven blower is that utilized for the fuel charge of the engine. The speed of the blower or supercharger, as in the case of the B-17, is responsive to variations in altitude and not responsive to the speed of the airplane. The ram air inlet for this air is located in the impact or high pressure zone at the most forward portion of the fuselage and consists of an inverted V-shaped opening, as shown in Fig. 3 of the drawings of the P-47 reproduced in Finding 20. The fuselage is oval in character and tapers to the rear where the rudders are attached. Such fuselage does not have a leading edge or a trailing edge or spanwise slots or openings extending over the entire span for receiving boundary air layer.

48. Two cylindrical ram air openings are located in the nose of the fuselage, and also in the impact pressure zone, which receive air for cooling the oil. This air is not compressed by a blower mechanism. After passage through the oil cooler this air is discharged just aft of the engine through two openings, one on each side of the fuselage, under its own natural remaining pressure. At the discharge openings this air is low energy air and of relatively low velocity as compared with the free streamline flow of air over the surface of the fuselage. This air has not been compressed and does not add energy to any boundary air layer existing on the surface of the fuselage.

The exhaust gases of the engine, after passing through the turbosupercharger, pass out through an exhaust opening at the rear and in the bottom of the fuselage. These exhaust gases will contribute to turbulence rather than prevent it.

It is unnecessary to reiterate in greater detail the facts set forth in the previous findings, 36 to 46, relative to the B-17 airplane and the phraseology of claims 1, 3, 7, 9, 10, 11, and 18.

This group of claims is not infringed by the P-47 airplane.

49. In addition to the group of claims just considered plaintiff alleges that claim 16 of the patent in suit is infringed by the P-47. This claim is paraphrased as follows:

Claim 16

(a) in an aircraft provided with an airfoil section,

(b) a blower,

(c) transverse slots located substantially over the entire span of said section at separated points in the surface of said section,

(d) a conduit connecting each slot to said blower,

(e) a valve in each conduit and

(f) means for simultaneously operating said valves, said conduits and blower being arranged to draw in boundary air through one slot and discharge said air through a remote slot. [Italics supplied.]

This claim specifies a structure for the treatment of boundary air layer having transverse slots located substantially over the entire span at separated points in the airfoil, inlet and outlet conduits connecting the slots to a blower with a valve in each conduit, and means for simultaneously operating the valves. There are no transverse slots located over the entire span present in the P-47 airplane, and there are no valves present in either the inlet or outlet ducts to the compressor side of the turbosupercharger. There are no valves present in the inlet and outlet conduits of the compressor with means for simultaneously operating them. This claim is not infringed by the P-47 airplane.

The Lockheed P-80

50. The plaintiff alleges infringement by the Lockheed P-80 of all the claims considered in the previous findings and, in addition, claim 15. This plane is described in detail in Findings 23-25, inclusive, and is illustrated in connection with Finding 24. It is an airplane of the jet-propulsion type, having an elongated fuselage which contains the power plant in the rear thereof. Ram air is collected by means of two air scoops located on each side of the fuselage, the location being to the rear of the front end thereof. This air is fed to a compressor unit mounted directly on the shaft of the turbine. This air, after being compressed, passes into a combustion chamber where fuel is added, and the resulting mixture is burned. After passing through the turbine the exhaust gases pass out through a circular opening in the rear of the fuselage and form the jet blast which drives the airplane forward.

The most important distinction between the P-80 plane and the structure and methods called for by the claims in suit is the fact that the air scoops are not located directly adjacent the fuselage, where they would receive boundary layer air, but instead are spaced therefrom by means of a series of multiple openings termed "boundary layer air bleed-offs." The function and purpose of these bleed-offs is to entrap the boundary layer air with its reduced velocity due to friction from the surface of the fuselage, and to prevent it from entering the ducts leading to the compressor. The boundary air layer thus entrapped is led off through the bleed-off passages to outlets at the rear of the air scoops, and the structure does not involve any compression of the boundary air layer.

None of the claims previously considered are infringed by the Lockheed P-80.

51. Claim 15, which plaintiff alleges to be infringed by the P-80 airplane, adds to previously considered claim 10 the following elements:

Claim 15

a motor,

selective gear transmission means connecting the motor to the blower, and means responsive to changes in air speed for controlling said transmission means for varying the volumetric intake and discharge of the boundary layer air volume.

The P-80 airplane has no selective gear transmission means connecting the motor to the blower and no means for controlling such a transmission means. This claim is not infringed by the Lockheed P-80 airplane.

52. Prior art patent to Campini (see Finding 35) discloses an airplane of the jet-propulsion type similar in all respects to the P-80 airplane with the exception that the intake air openings or slots adjacent the fuselage are not provided with means for entrapping the boundary air layer and preventing the same from reaching the compressor. If the phraseology of any of the claims in suit were applicable to the P-80 airplane such phraseology would be more readily applicable to the Campini structure and would be invalid.

53. The Betz patent (Finding 28), the Upson patent (Finding 29), the Stout patent (Finding 30) and the Martin patent (Finding 34) all disclose structures and methods for dealing with boundary air layer control closely similar to the disclosure of the patent in suit and to the phraseology of the claims in suit.

The Betz patent discloses a structure the purpose of which is to remove boundary layer air from the airfoil at a point adjacent a lower pressure zone, compressing this removed boundary layer air within the airfoil and discharging the same at a point adjacent a higher pressure zone in order to use it at the latter point for removal of the boundary layer air and to avoid turbulence. This is the basic concept of the Jones patent.

The Betz disclosure fails to specify the length of the entrance and exist slots.

The Upson patent and the Stout patent, however, both teach the use of entrance slots for the removal of boundary air layer which extend over the entire span of the wing. Unless the term "boundary layer volume" as used in claims 1, 3, and 7 is limited to the definition of this term, as defined in the Jones patent, these claims would be invalid in view of the prior art patents referred to, all of which deal with the removal of boundary air layer as this term is used in the conventional sense.

54. Claim 9 in suit is directed in substance to selectively removing portions of boundary layer air volume from adjacent either the upper airfoil surface or the leading edge thereof. Figs. 5 and 6 of the Martin patent disclose two spanwise slots in the leading edge of the wing, one just above the leading edge and the other just below. These slots are connected to a blower chamber from which air is subsequently discharged into a series of three discharge openings located in the top of the wing, the rearmost slot being near the trailing edge of the airfoil. Both inlet openings are provided with valves by means of which the pilot can selectively open and close them.

Claim 9 is invalid in view of the Martin disclosure.

55. None of the claims in suit are infringed by any of the Government structures and claim 9 is invalid.

HOWELL, Judge.

This is a suit to recover for the alleged infringement of United States letters patent No. 2,078,854, issued to plaintiff on April 27, 1937, on an application filed in the Patent Office June 20, 1936. Plaintiff is the owner of the entire right, title, and interest to the patent which is entitled "Boundary Layer Air Control."

The defendant contends that insofar as the claims here in issue are involved, the patent is not infringed, and that certain of the claims are invalid in view of the prior art.

The essential facts established by the record in this case are fully set forth in the findings, and except for certain controverted issues hereinafter discussed, it is unnecessary to refer to them in detail.

The patent in suit, which will be more fully described below, relates both to a method and a mechanism for removing the boundary air layer adjacent to the airfoil surfaces of an airplane wing.

Friction is present in the air when the individual particles thereof either move relative to each other or relative to a surface. When an airplane wing moves through the air the thin layers of air immediately adjacent thereto tend to move with it at substantially the same speed because of this frictional effect. If the air is contemplated as being in a number of thin layers, each outward layer has less forward motion imparted to it from the inner layer until an outer layer is reached which does not partake of any of the forward motion of the wing. This outer layer of air contains no turbulence as a result of the forward motion of the airplane wing. The air thus affected is known to those skilled in the aeronautic art as the boundary layer and is technically defined as "a layer of fluid, close to the surface of a body placed in a moving stream, in which the impact pressure is reduced as a result of the viscosity of the fluid."

Characteristics of the boundary air layer are well known and are capable of both measurement and computation. The thickness of the boundary air layer is, of course, dependent upon such factors as speed through the air of the airfoil or wing, the shape of the airfoil, the altitude and the angle of the wing relative to the air. In an example given in finding 5, the thickness of the boundary air layer on a B-17 wing section (one of the alleged infringing Government airplanes), flying at a speed of 250 miles per hour, at an altitude of 20,000 feet, varies from a few thousandths of an inch in the front edge of the wing to a maximum of about 6 inches at the rear thereof. We have referred somewhat in detail to the conventional boundary air layer because in the patent in suit the patentee expresses a different concept of boundary air layer.

The Jones patent in suit relates both to a method and mechanism for removing the boundary air layer adjacent the airfoil surfaces by sucking it in through spanwise slots, compressing it by means of a power-operated compressor driven by the engine, and then ejecting the compressed air into a different pressure zone through other spanwise slots. The engine-operated blower has its speed controlled by means of a gear shift or selective speed mechanism similar to that employed on automobiles except that the gears are shifted or selected by a mechanism responsive to the relative speed of travel of the airplane through the air. The Jones patent also has a speed responsive device actuated by the relative speed of the airplane through the air which simultaneously actuates the valves that open and close entrance and exist spanwise slots located at various points on the surface of the airplane wing.

Findings 7 to 11, inclusive, describe the Jones patent disclosure in detail, and it is unnecessary to further discuss them other than to call attention to the Jones theory of boundary air layer which appears to be inconsistent with this phenomena as it is recognized and treated by those skilled in aeronautical art. The Jones theory is that as the airfoil or wing moves through the air it displaces a mass of air equal in volume to that of the wing, and that as the wing progresses through the air, a similar volume of air is displaced each time the wing moves forward chord length (a distance equal from the front to the rear of the wing). According to the Jones theory the boundary air layer is much larger for a thick wing than a thin wing, and is a quantity not dependent upon air friction or altitude. Even to one unskilled in aeronautical art, it is apparent that under the Jones theory the compressor in the wings and the entrance and discharge slots would all have to be of such a large capacity that the airplane would literally suck its way through the air. Whether such concept of boundary air layer is correct or not is immaterial as long as the patentee has defined it in such a manner that it is understandable.

See White v. E.L. Bruce Co., 3 Cir., 162 F.2d 304, 307: "We are not holding the patentee to the correctness of his scientific explanation of the result achieved. He is not bound by his theory."

In the present situation, however, certain of the claims in suit, i.e., claims 1, 3, and 7, call for the removal of the boundary air layer, and obviously the monopoly expressed by such claims would require the removal of the boundary air layer, as Jones has defined it, rather than the removal of the conventional and relatively thin boundary air layer. Other claims in suit specify removal of portions only of the boundary air layer volume.

The defendant's structures alleged to infringe comprise three different types of airplanes — the Boeing B-17, the Republic P-47, and the Lockheed P-80. The structure and operation of these three airplanes are described in findings 15 to 25, inclusive, and it is therefore only necessary to refer to them briefly in this opinion. In all three instances these airplanes have openings either in the forward edge of the wing or near the front end of the fuselage, the purpose of these openings being either to receive air and compress it by means of a power actuated blower to supply oxygen for the fuel charge of the engines, or to supply air under its natural pressure for cooling purposes.

Referring to the B-17, this airplane is equipped with four engines, two being mounted on each wing. Adjacent each engine are three rectangular openings in the front edge of the wing. The first of these openings supplies air for the fuel charge to a rotary compressor driven by a turbine operated by the exhaust gases from the engine. This compresses the air and delivers it to the engine. The speed of the compressor is controlled not by the speed of the airplane or the engine but by an automatic device which responds to the altitude of the plane and causes air to be compressed in accordance with the altitude, supplying more air at the higher altitudes because of the thinner oxygen content of the air.

The second opening provides a natural flow of air through an intercooler, the function of which is to cool the air on its way from the compressor to the engine. After passing through the intercooler this cooling air is dumped into the interior of the wing and escapes through a number of slots in the rear thereof. The third opening merely supplies air under natural pressure to an oil cooler, this air also being dumped into the interior of the wing and escaping through the slots in the rear thereof. No blower is utilized to force the waste air in the interior of the wing out through these slots, and this air will cause turbulence rather than eliminate it.

The Republic P-47, is a single-engined plane with the engine located in the front end of the fuselage. There are no slots in the wings of this plane, but the power plant is similar in function and operation to the power plants utilized in the B-17. The air for the fuel charge and for cooling the compressed air and the oil is received through openings at the front end of the fuselage just behind the propeller. The air passing through the intercooler and the oil cooler escapes under its natural remaining pressure through openings in the sides of the fuselage.

The plaintiff contends that a "compensating valve" is present to discharge high pressure air out of the air supply system extending between the supercharger or compressor and the engine in the B-17 and the P-47 airplanes. The weight of evidence in this case fails to establish the presence of such a valve.

The Lockheed P-80, is an airplane of the jet propulsion type, the power plant consisting of a rotary air compressor directly driven by a gas turbine mounted on the same shaft. Air is received by two air scoops located on each side of the fuselage and fed to the compressor. Fuel is then injected into the air in a combustion chamber and the products of combustion fed to the turbine, after which they escape through a tail pipe at the rear end of the fuselage at high velocity and form the jet blast which drives the airplane forward. In this construction there is present a device to prevent boundary air layer from entering the air scoops, for between the fuselage and the air scoops are located a series of small ducts to catch the boundary air layer and lead it elsewhere under its own pressure. (See finding 25.) Thus, the air scoops are located sufficiently far out from the fuselage to purposely prevent them from receiving boundary air layer which is not wanted because its velocity has been slowed down due to friction.

A comparison of the accused structures with the claims in suit is next in order. The record discloses only a constructive reduction to practice by the plaintiff when he filed his patent application which materialized into the patent in suit, and there is no evidence of the existence of any license or the construction by plaintiff, other than some models, of any airplane embodying the disclosure of the patent in suit.

The prior art cited by the Government and referred to in detail in findings 26 to 35, inclusive, shows numerous prior attempts to treat boundary air layer by drawing it in through slots in an airfoil surface and forcibly ejecting the air through other slots at a velocity greater than the velocity of the boundary air layer. We are here dealing with a paper patent in a crowded field and the claims must be rather narrowly construed in the light of the specification. See Yates v. Jones, 4 Cir., 176 F.2d 794.

Claims 1, 3, 7, 9, 10, 11 and 18 in suit are alleged to be infringed by all three types of defendant's airplanes. In addition, claim 15 is alleged to be infringed by the Lockheed P-80 and claim 16 by the Republic P-47.

When the Jones application was pending before the Patent Office, certain of his originally filed claims were rejected in view of prior art. Jones acquiesced in this rejection and substituted claims of a more limited character, among which was the claim which ultimately became claim 1 of the patent. At the time of filing this amendment, Jones stated in connection therewith: "Claims 1 to 4 have been replaced by claims 24 and 25 which clearly avoid the references of record, both as to the structure and result. No reference of record discloses the idea of removing boundary layer air volume substantially over the entire span of an airfoil from and at a point adjacent a normal or subatmospheric pressure zone, compressing this volume, and discharging same at high velocity into a superatmospheric pressure zone to remove stagnated boundary layer air from the latter zone."

The phraseology of claim 1 is limited to removal of the boundary layer volume over substantially the entire span of an airfoil. This same limitation also appears in claims 3, 7 and 18. See Smith v. Magic City Club, 282 U.S. 784, 51 S.Ct. 291, 293, 75 L.Ed. 701, in which Chief Justice Hughes stated as follows: "The case, in our opinion, thus calls for the application of the principle that where an applicant for a patent to cover a new combination is compelled by the rejection of his application by the Patent Office to narrow his claim by the introduction of a new element, he cannot after the issue of the patent broaden his claim by dropping the element which he was compelled to include in order to secure his patent."

Referring to the B-17, the total span of all six openings in the wing for the admission of air approximates only 10 percent of the entire span of the wing. Even if these openings were for the function of removing and treating the boundary air layer, and we have already indicated that this is not their purpose, claims 1, 3, 7 and 18 are not infringed because of the limitation just referred to. Noninfringement based upon this limitation makes unnecessary any extended discussion of whether these small openings would remove the large volume of air displaced by the entire wing as contemplated by the Jones theory. We are of the opinion they could not.

We next refer to the P-47 in connection with this group of claims. This is the single-engined airplane with the engine and power plant located in the nose of the fuselage. A fuselage is known to those in the aeronautical art as an elongated and more or less cylindrical body housing the power plant, its accessories, and the pilots and passengers. Its front end is somewhat rounded and it tapers more or less to a point at the rear end, having a streamlined contour to reduce its resistance. It has neither a leading edge nor a trailing edge, nor does it possess a span in the sense that this term is used in aeronautics as applied to a wing. The only opening at the front of the fuselage in the P-47 through which air is received and compressed is an inverted "V" shaped opening located at the bottom of the front end of the fuselage, and the air here received is for the sole purpose of forming the fuel charge for the engine.

This group of claims (1, 3, 7 and 18) are not infringed because of the limitations just referred to.

What we have said with respect to the P-47 also applies with respect to the noninfringement of these claims by the P-80 in which air for forming the fuel charge is received by two scoops located on the forward end of the fuselage and extending outwardly therefrom like a pair of protrudent ears.

Referring next to claim 9, this claim carries the following limitation: "selectively removing portions of boundary layer air volume from adjacent either the upper airfoil surface or the leading edge thereof."

This phrase, interpreted in the light of the Jones specification, has reference to a series of ducts and valves by which slots located in one portion of the airfoil may be closed, and slots located in another portion may be opened. None of the accused structures have such devices, and this claim is not infringed.

Claim 10 includes the following limitation: "means responsive to increase in speed of the aircraft for increasing the speed of the blower and the rate of discharge of the boundary layer air volume."

By reference to the Jones specification, this structure is the mechanism which changes the speed ratio between the blower and engine in accordance with variations in the speed of the airplane as it moves through the air. As we have already stated, with respect to the B-17 and the P-47, the speed of the supercharger is controlled by the altitude of the plane and not its speed.

In the case of the P-80 airplane, the compressor for the air for the fuel charge is directly driven and is on the same shaft as the rotor of the gas turbine. The speed of the compressor is not responsive to the speed of the airplane but is controlled by the amount of fuel fed to the combustion chamber, which in turn is controlled by the pilot through the throttle setting. This distinction may be emphasized by indicating that the airplane when climbing under full throttle would have a much relatively lower air speed than when diving with the throttle set toward the closed position.

This claim further calls for an airfoil section, a blower, and means for inducing a portion of the boundary layer air volume from a point adjacent an exterior surface of the airfoil section. We have already pointed out that the P-80 is structurally designed to eliminate the boundary air layer. This claim is not infringed.

Claim 11 is based upon claim 10 and merely adds thereto by way of limitation certain spanwise slots. For the reasons stated in connection with claim 10, this claim is not infringed by any of the Government airplanes.

Claim 15, which the plaintiff alleges to be infringed by the P-80 airplane, also adds certain limitations to claim 10 by specifying a selective gear transmission means connecting the motor to the blower and means responsive to changes in air speed for controlling the transmission means. No such structure is present, and for the reasons already stated, the P-80 structure does not infringe this claim.

Plaintiff alleges that claim 16 is infringed by the P-47. This claim is limited in scope and specifies such elements as transfer slots located substantially over the entire span of the airfoil section, with a conduit connecting each slot to the blower, a valve in each conduit, and means for simultaneously operating said valves. There is no such structure present in the P-47 and this claim is not infringed.

Various other limitations occur in the claims in issue which point to noninfringement. These distinctions are set out in detail in findings 36 to 51, inclusive, in which the claims are paraphrased, and, except to state that these findings are supported by the record, it is unnecessary to reiterate them in detail here.

Referring again to claim 9 in suit, this claim is directed to selectively removing portions of boundary air layer volume, either adjacent the upper airfoil surface or the leading edge thereof. We refer to the prior art Martin patent (finding 38) which shows two spanwise slots in the leading edge of the wing connected to a blower chamber. Both inlet openings are provided with valves by means of which the pilot can selectively open and close them. This claim is invalid. (See finding 54.)

In the over-all picture presented by this case, there comes to mind the analogy of the automobile which is provided with a grille at the front for admitting air under the hood. The function and purpose of the air thus admitted is to provide air for the carburetor, which forms the engine fuel charge, and for cooling purposes, and not for reducing air friction on the body of the car as it travels along the highway. Formation of the fuel charge and cooling of the mechanism are similarly the sole functions for the air inlets in the three Government structures.

For these reasons we are of the opinion that the claims here in issue are not infringed, and claim 9 is invalid. The petition is accordingly dismissed.

It is so ordered.

JONES, Chief Judge, and MADDEN, WHITAKER, and LITTLETON, Judges, concur.