Document
United States Patent [191 [ii] Patent Number: 4,767,083
Koenig et al. [45] Date of Patent: Aug. 30, 1988
4,442,986 4/1984 Rousseau ........................... 24412.1
[54] HIGH PERFORMANCE FORWARD SWEPT
4,478,378 10/1984 Capuani ............................. 244A2.5
WING A I R C R A m FOREIGN. PATENT DOCUMENTS [75] Inventors: David G. Koenig, Sunnyvale; Kiyoshi Aoyagi, Mountain View; Michael R.
681193 1/1965 Italy ................................... 24412.3
Dudley, Los Altos, all of Calif.; Susan
1328210 8/1973 United Kingdom ................ 244/207
B. Schmidt, Pensacola, Fla.
OTHER PUBLICATIONS [73] Assignee: The United States of America as Moore et al, “X29 Forward Swept Wing Aerodynamic represented by the Administrator of Overview”, AIAA-83-1834, 7-1983.
the National Aeronautics and Space Jane’s, All the World Aircraft, 1982-1983, p. 808.
Administration, Washington, D.C.
Primaly Examiner-Galen Barefoot [21] Appl. No.: 933,963 Attorney, Agent. or Firm-Darrell G. Brekke; John R.
[22] Filed: Nov. 24,1986 Manning; Charles E. B. Glenn
[51] I n t . (3.4 ....................... B64C 21/04; BUD 29/02
r 5 7 1 ABSTRACT U.S. C l . .................................. 244/12.3; 244/12.4; [52] A high performance aircraft capable of subsonic, tran- 24/20? 24/45 A; 24/55 sonic and supersonic speeds employs a forward swept [58] Field of Search ....................... 24/15, 12.1, 1 2 . 3 , wing planform and at least one first-and-second-solu- 244A2.4, 1 2 . 5 , 207, 208, 45 R, 45 A, 53 B, 55, tion ejector located on the inboard section of the wing.
73, 36 A high degree of flow control on the inboard sections of
W I References Cited
the wing is achieved along with improved maneuver- ability and control of pitch, roll and yaw. Lift loss is U.S. PATENT DOCUMENTS delayed to higher angles of attack than in conventional
3,017,140 1/1962 Barnard ................................. 244/15
aircraft. In one embodiment the ejectors may be advan-
3,397,854 8/1968 Reyle .................................... 244/55
tageously positioned spanwise on the wing while the 3,576,300
4/1971 Palfreyman ........................... 244/36
ductwork is kept to a minimum.
3,677,501 7/1972 Denning ............................. 244A2.5
3,785,593 1/1974 Von Ohain et al. ................ 244/208
4,326,686 4/1982 Runge ................................. 244/207
9 Claims, 6 Drawing Sheets
U.S. Patent Aug. 30,1988 Sheet 1 of 6 4,767,083
1 2 ’ 1 3 /’ IO 23-‘ 43 ’. 1 4 ’ 44
FIG-2
U.S. Patent Aug. 30,19ss Sheet 2 of 6 4,767,083
250 32 43 4 7 300 24b
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i [
I I I
30b 20b
29~1 25b 31 15b 33
17, 1 9 1 9 ,/ 1 7 1 3 22 IO 22 1 3
FIG-4
U.S. Patent Aug. 30,1988 Sheet 3 of 6 4,767,083
4,767,083
Sheet 4 of 6
US. Patent Aug. 30,1988
STA ENGINE POWER -50 c FLIGHT SPEED
COMPUTER * SERVOS
EJECTOR MODE 42 J.
_---e- i
f l G - 6
3 1
“‘7
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US. Patent Aug. 30,1988 Sheet 5 of 6
FIG-8
FIG-9
US. Patent Aug. 30,1988 Sheet 6 of 6 4,767,083
FIG-IO
73, 91\ / “ 5 \ 52/92 A 7 1
\
4.767,083
sessment of Forward Swept Wing Technology,” March 1980.
HIGH PERFORMANCE FORWARD SWEPT WING Notwithstanding the above-mentioned attributes, AIRCRAFT because the FSW aircraft tends to stall first on the in- 5 board wing sections rather than on the outboard sec- ORIGIN OF THE INVENTION tions, the inventors have found a need for additional The invention described herein was made by employ- flow or stall control in FSW aircraft when operating in ees of the United States Government and may be manu: low speed flight experienced during takeoff and landing factured and used by or for the Government for govern- as well as at high angles of attack. Further, there is a mental purposes without the payment of any royalties 10 need for an improved FSW that can operate at high thereon or therefor.
subsonic and moderate supersonic speeds (M, 1.5-3.0) and exhibit either or both good maneuverability and TECHNICAL FIELD efficient sustained cruise flight characteristics.
The invention relates to an improved high perfor- SUMMARY OF THE INVENTION mance forward swept wing aircraft with an ejector for augmenting thrust and improving flow and stall control Accordingly, it is an object of the invention to pro- throughout the aircraft’s speed regime.
vide a forward swept wing aircraft with improved flight characteristics that may be economically con- BACKGROUND OF THE INVENTION structed.
Present day efforts in the aircraft industry are di- It is another object of the invention to provide an 20 rected to developing aircraft that can operate at very aircraft with an improved cruise flight efficiency (de- high or supersonic speeds. Such supersonic aircraft, fined by the amount of fuel used to travel a given dis- particularly when used as combat fighter planes, should tance at specified airspeeds and altitudes).
be highly maneuverable to allow rapid turns, rolls, It is still another objective of the invention to provide dives-md ascents without danger of stalling or loss of 25 an aircraft with a higher degree of inflight maneuver- control. Some aircraft may need to cruise long distances ability, measured by low and high speed vertical and at supersonic speeds requiring the most efficient inte- lateral turn capability and fore/aft control of propulsive gration of the engine-propulsion system and the exter- force.
rial airframe aerodynamics. Also, it is desirable that the It is still another object of the invention to provide an aircraft should be capable of performing ladings and 30 aircraft which may utilize reduced runway lengths for takeoffs at low subsonic speeds, using a minimum length takeoff and landing.
runway or, for some missions, landing or taking off It is still a further object of the invention to provide these goals for high speed aircraft, an aircraft wherein there is reduced structural plus T~ necessary to have optimum control of powered lift propulsion weight for a given aerodynamic lift without it is 35 penalizing cruise efficiency.
and air flow.
Recent investigations of aircraft configurations in& It is yet another object of the invention to provide an that a significant number of benefits may be aircraft capable of delaying lift loss to higher angles of
swept wing (Fsw) attack and controlling the aircraft when it starts to
achieved by utilizing a occur more than possible in conventional aircraft.
with a When an FSW is used in The attainment of the foregoing and related objects 40 canard at transonic and low supersonic maneuvering may be achieved through the use of an aircraft compris- flight, favorable interference is provided over the in- ing a wing which is swept forward, a fuselage, a canard, board portion Of the wing where the shock is strongest’ a vertical tail, one or ejectors which are designed This leads to higher aerodynamic efficiency than with to perfom well throughout the full flight envelope of the use Of aft swept wings’ In an aft-swept wing ‘Onfig- 45 the aircraft, lifting jets, and at least one power plant for uration the spanwise flow normally thickens the bound- providing pressurized hot or cold gas to the ejectors as ary layer at the tips. The flow on an FSW tends to well as the propulsive jets.
separate first at the inboard section while good flow In accordance with this invention, a high perfor- conditions can be maintained at the tip because of low mance aircraft capable of subsonic, transonic and super- induced angles of attack of the outer wing sections and 50 sonic speeds employs a forward swept wing planform because the a i r tends to flow toward the root rather and at least one ejector located on the fuselage or in- than to the tip as it does on a sweptback wing. These board section of the forward swept wings. Each ejector flow conditions result in stall characteristics which device includes a variable-area inlet, primary nozzles allow the ailerons to remain effective at high angles of for releasing engine gas and an aft-located variable-area attack, even after most of the wing has stalled. Thus the 5 5 exhaust. The inlet serves as a suction source and acts to FSW aircraft is more controllable at higher lift coeffici- control air flowing about the aircraft, particularly along ents. Another benefit is a geometric advantage when the root or mid-section of the wings. The ejector is the FSW is utilized in an STOVL aircraft. A conflict in capable of operating in first (subsonic) or second solu- the positioning of wing box and the portion of the tion (supersonic) modes. Each ejector inlet and exhaust power system providing vertical thrust can produce 60 includes actuated hinged walls or flaps for changing the problems with the fineness ratio, overall length, and flow area and modulating the pressure and velocity of area ruling. On a sweptback wing most of the root air flow through the ejector. The controlled air flow chord must be positioned at the center of gravity which may be advantageously used for stall prevention and to conflicts with the positioning of the vertical thruster in enhance circulating lift. The thrust of each ejector can any STOVL configuration. For the FSW, the root of 65 be individually controlled to provide desired aircraft the wing (containing the wing box) is located behind the maneuvers. By virtue of the combination of the FSW center of gravity. FSW aircraft are described, for exam- configuration and the ejector apparatus, a high degree ple, in DARPA Report 8709-80-TR-73, “Second As- of flow control on the inboard sections of the wing,
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improved maneuverability and control of pitch, roll and DETAILED DESCRIPTION OF THE yaw are made possible as well as efficient use of the INVENTION available thrust.
This invention is directed to an aircraft which incor- Turning now to the drawings, and more particularly porates the FSW configuration and a thrust augmenting 5 to FIG. 1 , there is shown a supersonic aircraft, having a ejector, that is, an ejector that is designed for maximum substantially symmetrical configuration about center- thrust output as measured by the ratio of its momentum line CL, with a fuselage 10 which has a conical type increment to that of its reference (primary) jet. The nose section 12 and a tapered tail section 14. Swept- 16a ejector is located in a general inboard location on the back canard horizontal trim and control surfaces wing upper suface where stall control is most needed on 10 and 166 are located between cockpit 18 and forward the FSW due to its tendency to stall from inboard to swept wings 20a and 206. The forward swept wings are outboard. The ejector is not as sensitive to inlet distor- located towards the rear of the aircraft mainly behind tion as a gas turbine engine and therefore may ingest the aircraft center of gravity. Gloves or strakes 22a and any nonuniform and turbulent flow which may develop 22b span between the fuselage and the wing leading on top of the wing. Thus, if any stall does start in the 15 edge and serve as fairings. The leading edge of each form of flow separation near the leading edge, the inlet forward swept wing is preferably within the angle of the ejector will ingest the resulting turbulent flow range of 20" to 50' (wing tip forward relative to perpen- and help to prevent lift loss. In the embodiment of the dicular to the longitudinal centerline CL). The leading invention for an aircraft capable of supersonic speed a edge of each forward swept wing is preferably provided single power plant is used with either one ejector or one 20 with leading edge flaps or slats (not shown) which may main ejector and two supplemental ejectors all located be dropped for stall control during high angle of attack on the upper, inboard section of the wing. In another and/or high lift condition modes. The trailing edges of aspect of the invention, a subsonic aircraft is provided the wings are provided with conventional flaps (not with two power plants situated in nacelles located illustrated). The leading and trailing edge devices are below the forward swept wings. A thrust augmenting 25 well within the purview of the art, the details thereof ejector is positioned on top of the wing above each form no part of the claimed invention, and the design power plant. A valved crossover duct interconnects the thereof may vary as desired. The trailing edges of wings port and starboard ejectors. Thus, if one engine fails, gas 2Oa and 20b have a greater angle relaive to the center- can still be routed to both eiectors. Other variations of line than the leading edges so that the wings taper from all embodiments such as the addition of additional en- 30 a wide inboard area to a narrower area at their outboard gines will not alter the function and advantages of the ends. Typical wing thicknesses for high performance invention. aircraft, particularly those flying at transonic and super- The attainment of the foregoing and related objects, sonic speeds, are well below 8% of the local chord advantages and features of the invention should be more measured in a cross section of wing which is parallel to readily apparent to those skilled in the art after review 35 the aircraft plane symmetry. For transonic and super- of the following more detailed description of the inven- sonic aircraft, this value is usually below 4% to mini- tion taken together with the drawings.
mize total wave drag of the aircraft. For single engine fighter aircraft such as the X-29 this means that the root BRIEF DESCRIPTION O F THE DRAWINGS chord thickness is less than seven inches. With a tip-to- FIG. 1 is a top plan view of a supersonic forward 40 root chord ratio of 0.3, the tip chord maximum thick- swept wing aircraft made in accordance with this inven- ness is about two inches. Because of the necessity of the tion.
thickness to be less at the leading and trailing edges, the FIG. 2 is a side view of the FSW aircraft of FIG. 1 .
total wing volume of a high performance aircraft is The wings, canards, and ejector are not illustrated to minimal and most of the volume is occupied by the main make it easier to see other features of the aircraft. 45 wing spar, skin and supporting structure as well as mis- FIG. 3 is a forward-looking schematic cross sectional sion electronic gear and control system actuators. Verti- view of the ejector employed in the aircraft of FIG. 1 . cal tail fins 240 and 24b are provided at the aircraft tail FIG. 4 is a forward-looking schematic cross sectional section to enable directional stability and steering con- view taken through the fuselage (of the aircraft of FIG.
trol. Downward pointing lifting jets 11 in the area of 1 ) where the forward lifting jet doors are located.
50 door 1 3 (FIG. 4) are situated in the fuselage near the FIG. 5 is a perspective view of the ductwork coupled skin and beneath the aft end of the cockpit. One array of to the output of the engine for the aircraft of FIG. 1 . lifting jets 11 is positioned below the port canard and a FIG. 6 is a left side schematic cross sectional view second array is located below the starboard canard. A solely of the ejector plus a schematic of the circuit for door 13, flush with the fuselage, is just below each array actuating the pivotal inlet and exhaust flaps.
55 of lifting jets. See FIGS. 2 , 4 and 5 . A smaller door 17 FIG. 7 is a left side schematic cross sectional view of is situated flush in the fuselage above each door 13. A the rear portion of the ejector when the flaps are in a vertical passageway 19 interconnects each door 17 with hover-like configuration.
its respective door 13 (see FIG. 4) The doors 13 and 17 FIG. 8 is a top plan view of a second embodiment of are closed when the lifting jets are not in use and the the invention. It depicts an aircraft having two more 60 doors are opened when the jets are used so that air may ejectors than the aircraft in FIG. 1 .
flow through each passageway 19. A turbojet or turbo- FIG. 9 is a left side schematic cross sectional view fan engine 26 with an air inlet 21 provides the principal solely of the ejector for the aircraft of FIG. 8 .
source of power for the aircraft. Gas flow from engine FIG. 10 is a top plan view of still another embodi- 26 is carried to the lifting jets by means of ducts 22 ment of the invention, a subsonic aircraft. 65 (FIGS. 2 , 5 ) when diverter valves 23 are opened. The FIG. 11 is a left side view of an engine and a sche- lifting jets are utilized during landing, takeoff and high matic cross sectional view of the wing and ejector speed maneuvering modes to provide a thrust to en- above the engine for the aircraft of FIG. 10.
hance control and to provide lift during vertical flight.
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Turning now especially to FIGS. 1, 2 and 6, a thrust choose to channel a large quantity or all of the engine augmenting ejector 27 is positioned over the forward gas into the ejector.
swept wing structure spanning the inboard portion of The ejector thrusting system functions in the follow- the wing between tail fins 24a, 246. The ejector is a ing manner. When the primary energized fluid from multi-wall structure that encircles a major gas duct and 5 engine 26 is mixed with the secondary freestream fluid a plurality of gas-emitting nozzles 31, 32 and is capable ingested in the inlet the mixed fluids achieve a momen- tum which is larger than the momentum of the primary of channeling ingested air from an inlet 28 past the nozzles and out an exhaust 29. A gas duct 43 divides the fluid alone when exhausted ambient pressure. The interior of the ejector into two passageways of equal thrust augmenting ejector operates at an overall static streamwise cross sectional areas. The left passageway 1 0 pressure ratio which is slightly less than one, that is, the has opposed walls 15a, 156 and facing walls 25a. 256 ratio of the pressure ambient air approaching the inlet at whereas the right passageway has opposite walls 30u, station 0 (FIG. 6) to the static pressure of the exhaust at 306 and facing walls 354 356. Downstream from the station 8 is about one. For any flight condition, the inlet 28 are opposed linear arrays of nozzles. Nozzles 31 ejector inlet entrains air coming over the wing and are in the first array and the bases of these nozzles are 15 strakes and acts as a source of suction or a sink at the upper root of wings 20a and 206. The ejector inlet ac- substantially level with the upper surface of the wing, celerates or decelerates the ingested mass flow by and nozzles 32 are in the second array directly above.
amounts depending on flight conditions, engine power The nozzles 31,32 are supported and fed gas by mani- folds 46, 47 respectively (FIG. 5). Each nozzle 31, 32 setting, and whether or not the ejector is set to operate has one or more downstream pointing orifice 33 for 20 in the first or second solution mode. When the mixed releasing gas derived from engine 26. The orifices can fluids reaching station 6 are subsonic the ejector is oper- be circularly shaped, slot-shaped, etc. Each nozzle may ating in the first solution. When the mixed flow at that have, for example, a single orifice 33 (FIGS. 3, 6) that station is sonic or supersonic, the ejector is operating in occupies most of the downstream face. The ejector is of the second solution.
In operation, streamwise variations in total internal constant section spanwise and injects freestream air 25 through the inlet where the air is mixed with engine gas cross section area for the inlet and exhaust of the ejector expelled from nozzles 31, 32. The vertical dimension are varied so as to produce maximum thrust augmenta- (the dimension or axis normal to the wing panel) of the tion for a desired aircraft flight mode. This augmenta- inlet and exhaust areas are variable along the longitudi- tion, in either solution of operation, may exceed a ratio nal axis. Both the inlet and exhaust of the ejector have 30 of two. More specifically, when the aircraft is hovering, pivotable interconnected hinged flaps or wall segments. taking off or landing, the inlet is normally converging The hinge or pivot axes 45 for the flaps extend along the (flaps 36,37 slope downward from station 1-3) and the span of the ejector. As the flaps are moved, different exhaust is diverging and acting as a diffuser. In this nozzle configurations (diverging/converging) are cre- instance the mixed primary and secondary fluids are ated at the inlet and exhaust, and the areas of the inlet 35 subsonic and the ejector operates in the first solution and exhaust are varied. FIG. 6 includes a schematic mode. If the first solution mode was maintained with cross sectional view of the augmentor depicting the increasing airspeed; however, the net thrust of the ejec- pivotable flaps 36,37 of the inlet 28 and pivotable flaps tor would deteriorate.
38-41 of exhaust 29. The flaps 36-41 are actuated by As high subsonic flight speeds are attained and tran- servos 42 which are controlled bv a comuuter 50 that 40 sonic flight is approached the inlet flaps are moved to responds to signals that are repr&entati;e of ejector provide a slightly diverging configuration (flaps 36, 37 mode, engine power, flight speed, angle of attack and slope upward from station 1-3). Then when sufficient altitude. Additional signals representative of other real stagnation pressures are developed, a converging- time aircraft conditions may be inputted to the com- diverging configuration and second solution ejector puter for ejector control purposes. The computer con- 45 flow is initiated to maintain desired net ejector thrust.
trols the servos and pivots the inlet and exhaust flaps to When the second solution is introduced the exhaust insure that maximum ejector net thrust is obtained at all nozzle configuration is converted from diverging to flight and engine conditions. The ingested air flow is converging-diverging as needed to produce sonic flow considered the secondary flow in the ejector whereas therethrough. When the aircraft is desired to operate at the gas from the engine emitted from nozzle 31, 32 is 50 supersonic speeds the ejector is still maintained in the considered the primary flow (or energizing gas flow).
second solution mode with the inlet and exhaust each After the ingested air is mixed with the primary flow having a converging-diverging configuration. (That is, from nozzles 31,32 the mixed stream is released from the the upstream end of flap 36 is pivoted above the down- ejector via the exhaust. The purpose of the exhaust is to stream end so that the inlet air is first converged. The return the internal static pressure to that of ambient at 55 upstream end of flap 37 is pivoted downward with or slightly downstream of the ejector and maximize the respect to the downstream end so that the air passing by total net thrust for given combinations of aircraft flight is diverged. At the ejector exhaust, flaps 38, 40 are condition and engine power setting. 39, pivoted in a converging manner and opposed flaps FIG. 5 is a perspective view of the ductwork coupled 41 are swung in a diverging configuration.) The second to the exhaust of engine 26. The gas ejected from engine 60 solution operation enables thrust augmentation and 26 is directed into large cylindrical duct 43 with an supersonic flow in the ejector at station 7 up to at least exhaust orifice 4 4 . Opposed manifolds 46, 47 support Mach number 2.
nozzles 31, 32 and supply them with gas derived from The theory of first and second solution ejector opera- duct 43. Ducts 22 also derive gas from duct 43. When tion is elaborated on in the articles, “Thrust Augment- diverter valves 23 are opened, gas flows from duct 43 to 65 ing Ejectors,” Part I, AIM Journal, Vol. 21, No. 2, lifting jets 11 via ducts 22. A restrictor (not shown) in October 1983, and “Thrust Augmenting Ejectors,” Part the aft end of duct 43 permits the gas flow from orifice 11, AIAA Journal, Vol. 21, No. 12, December 1983, by 44 to be varied. At takeoff and other times the pilot may Morton Alperin and Jiunn-Jeng Wu.
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FIG. 7 is a schematic cross sectional view of the rear cept for a reduction in components. The geometry and mode of operation for the secondary ejectors is the portion of the ejector and it depicts how the flaps of the ejector exhaust may be moved fn a downward position same as for the principal ejector. The wing upper sur- so as to change the direction of thrust normal to the face serves as the lower internal floor or wall of the longitudinal axis of the aircraft. This configuration of 5 eiector and thus changes in eiector internal cross sec-
-
tion needed in the various flight operations must come theejector exhaust is particularly useful for powered lift during takeoff and landing, hovering, and control dur- from the upper wall structure of the ejector. Ejectors 51,52 have pivotable flaps 36-39 as in ejector 27; how- ing high speed flight to enhance turning during tactical ever, they do not have any flaps 40,41. See FIG. 9. The maneuvering.
In whichever mode the subject ejector is operated 10 flaps are also actuated by computer-controlled servos.
(first or second solution) it can increase thrust at all Further, the secondary ejectors only have one array of nozzles, a lower array of nozzles 31 that are supplied flight speeds over that which could be produced by the gas from the engine 26 by means of ducts 54 connected engine alone. As a consequence, for a given total thrust to manifold 46. Alternatively, the ducts 54, supporting needed to propel the aircraft the engine size can be reduced and a corresponding fuel economy can be real- 15 and feeding nozzles 31, may be supplied by ducts 53 ized. This is particularly true for high subsonic, tran- coupled to central duct 43. The maximum duct size is sonic and supersonic flight speeds where second solu- limited by available space in the wing and the minimum tion ejector operation brings higher overall propulsion size is dictated by a need to keep gas flow Mach num- efficiencies. bers in the duct below 0.25-0.4. Optionally, to simplify 20 mechanical design of the secondary ejectors, the num- The hot engine gas is cooled considerably when it is ber of inlet and outlet pivotable flaps could be reduced mixed in the ejector with the ingested air. Thus, the fluids ejected from the ejector present a lesser infrared from two to one. The single flap would be the same size signature than the engine gas. The net result is that the as the replaced double flaps and the design of the single subject aircraft is more difficult to detect with an IR door would be optimized for the cruise flight condi- detector than conventional aircraft. 25 tions. Because of the secondary ejectors small size, the The ejector is very useful as a flow control device to overall propulsion efficiency of the aircraft would not control stall on the wing surfaces. This feature is most be penalized materially when the ejectors were oper- helpful at high flight angles of attack where the strake ated "off design" at low flight speed.
and wing exhibit leading edge flow separation. If this 10 depicts still another embodiment of the in- FIG.
30 vention, a subsonic transport aircraft which is particu- flow separation were allowed to progress, the portion of the wing involved would lose lift. Placement of the larly suited for transport usage. Fuselage 66 houses a injector inlet on the upper wing surface in the region cockpit 67 and space for passengers and cargo. A verti- extending from the leading edge back to midchord al- cal stabilizer and rudder 76 is located at the aft. For- lows the inlet to ingest the turbulent flow of relatively ward swept wings 71, 72 with strakes 77, 78 are at- low momentum (resulting from separation) and delay 35 tached to the rear of the fuselage mainly behind the wing stall and its resulting lift loss. The flow on an FSW aircraft center of gravity. The wings are tapered from tends to separate first at the root. Thus, it is more effi- inboard to outboard. The forward sweep of the wings is cient to locate the ejector at the wing root for flow preferably in the range of 20" to SO" perpendicular to control purposes as well as for structural and power the longitudinal axis of the aircraft. Canards 68 and 69 transfer reasons. 40 are situated aft of the cockpit and forward of strakes 77, In the past, ejectors operating only in the first solu- 78. The strakes and wings are provided with leading tion were utilized on subsonic aircraft to enhance thrust edge stall control devices such as leading edge slats.
at low airspeeds. These ejectors were retracted and FIG. 11 shows the slats in their extended position 73 stowed within the contours of the wings to avoid drag (providing maximum retardation of separation) and as the aircraft accelerated to high cruise flight. This 45 their retracted position 74 (position of non-use). Ejec- approach is completely impractical for modern high tors 86, 87 are positioned above the inboard portion of performance aircraft, such as fighters, which are built the forward swept wing panels. Nacelle-encased en- with relatively small wing thicknesses and small overall gines 88, 89, such as turbofan engines, are suspended aircraft cross-sections that are a necessity in order to below the FSW by pylons 83. Engines 88, 89 are posi- limit transonic and supersonic drag. These ejectors, at 50 tioned beneath ejectors 86, 87, respectively. A duct 79 best, only perform over the lower portion of the flight channels gas from each engine up to a manifold 81 that envelope.
supports and feeds gas to a linear array of ejector noz- A second embodiment of the FSW aircraft incorpo- zles 82. The ducts 79 are routed through the pylons 83, rating the subject invention is depicted in FIG. 8. In this respectively, and each duct 79 has a diverter valve 84 embodiment two additional secondary ejectors 51, 52 5 5 therein to control the amount of gas flow from the are located adjacent to the primary ejector 27 and sym- engine to the ejector. This arrangement of components, metrical to the longitudinal axis of the aircraft. Other- that is, the positioning of the engines beneath the ejec- wise the aircraft is identical to the one depicted in FIG.
tors, allows ducts 79 to be advantageously short. As 1. These secondary ejectors are smaller than the pri- with the secondary ejectors in the second embodiment, mary ejector and are located at positions on the upper 60 the upper wing surface is used as the lower wall of surface of the swept forward wings to allow the inlets to ejectors 86, 87. Ejectors 86, 87 are very similar to sec- serve as additional flow control for the wing leading ondary ejectors 51, 52 except that they have a single edges. These ejectors are also useful to provide auxil- pivotable inlet flap 91 and a single hinged exhaust flap iary lateral and directional control. As the exhausts of 92. As in the previous embodiments the flaps are con- ejectors 51, 52 eject gas over the trailing edge wing 65 trolled by a computer 50 and servos 42. Although ejec- flaps they also augment flap lift during takeoff, landing, tors 86,87 have no requirement to operate at supersonic and high speed maneuvering. Ejectors 51, 52 are basi- speeds, the pivotable inlet/exhaust flaps 91,92 still have cally scaled down versions of principal ejector 27 ex- to be programmed to provide maximum ejector thrust
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at low and high subsonic and transonic flight speeds tions. The angle of the streamlines may be derived by employing either first or second solutions as appropri- computational methods or by wind tunnel tests.
In the third embodiment of the invention the ejector ate. The ejectors are positioned mostly on the inboard can stay on top of the wing but near the engine for portion of the FSW at a point where the wing tends to 5 maximum stall protection and minimal duct length stall first with increasing angle of attack. As stated pre- while still allowing placement of the engine-ejector viously, this allows the inlet of each ejector to ingest the combination at the spanwise position where the best low momentum flow over the wing leading edge and effective stall control can be accomplished. The place- delay spreading the stall to either the wing panels hav- ment does not interfere with the wing root structure ing sweptback leading edges (near the fuselage) or the 10 near the fuselage (which takes fuselage and landing gear inboard part of the swept forward panel.
loads) or is it at a location which is too far out on the For the sake of simplification of the power system of wing structure for adequate structural support (due to this embodiment only two engines have been disclosed the thinness of the wing). The embodiment of FIG. 10 is in the drawings. It is to be understood that the subsonic particularly suited for larger and heavier aircraft than aircraft may be powered by three or more engines (one 15 those depicted in FIGS. 1 and 8 . In those situations engine in the center plus two wing-mounted engines) or where the larger aircraft do not require vertical takeoff two or more engines mounted on each side of the fuse- and landing capability the ratio of total available pro- lage. When engines 88, 89 are both operating, gas is pulsion thrust (direct engine thrust plus ejector thrust) channeled to the ejector primary nozzles 82 via duct 79 to actual flying weight of the aircraft will be less than and manifold 81. To help maintain equal amounts of 20 one. The ratio will preferably be larger for the aircraft thrust on each side of the aircraft when an engine fails of FIGS. 1 and 8 . Therefore, the size of engine and or is shut down, a crossover duct 93 with valves 94,95 ejector combination will be less in proportion to aircraft therein interconnects the two manifolds 81. Valves 94, size for the subsonic aircraft of FIG. 10 than the super- 95 are preferably valves that permit unidirectional flow sonic aircraft of FIGS. 1 and 8 . Also, in order to cruise such as globe valves. When both engines are running, 25 efficiently at subsonic speeds, the aspect ratio (ratio of the valves are closed to isolate the crossover duct 93 wingspan to chord) of the wing of the FIG. 10 aircraft from the gas network. If an engine is shut down or will be higher than the ratio employed on the super- becomes inoperative, the proper valves are activated in sonic aircraft.
such a manner as to permit gas to flow to the ejector Several significant advantages are intrinsic in the over the non-working engine. When an engine becomes 30 third-embodiment aircraft. The ejectors delay the lift inoperative the exhaust pressure/mass-flow schedule of loss due to wind stall to higher angles of attack and, in the operating engine must be quickly trimmed (by the some cases, increase the maximum lift that can be ob- valving system and other controls) to produce thrust tained by the aircraft. Very importantly, as the ejectors symmetry within the lateral and directional control operate in the second solution for the higher flight power of the aircraft. It is essential that the valve con- 35 speeds, the ejectors remain outside the aircraft contour trol system be very responsive in order to maintain without causing drag penalties. This permits the aircraft normal aircraft flight orientation during an engine fail- to have more storage volume for cargo, fuel, or avion- ure.
ics. The placement of the ejectors over the engines The trailing edge flap system for all embodiments minimizes the amount of ductwork needed and signifi- preferably minimally comprises an inboard flap set and 40 cant hardware economies are realized. Still further, the an outboard flap set which is either blown (equipped ejectors enable lower safe landing and takeoff speeds by with boundary layer control), plain or slotted. Gas for interacting with the trailing edge flap system to increase the blowing may be derived from the ejector nozzle lift through both circulation lift induced by blowing manifolds. When these flaps are deflected the same on over the top of the flap and by the vectoring of the both sides the lift coefficient is increased to facilitate 45 direct thrust of the ejector.
takeoff and landing. The flaps can also be used for pitch It should be understood that the invention is not lim- control by deflecting the inboard and outboard flaps by ited to the specific embodiments described above, and different amounts. Roll control is obtained by lateral that other variations in configuration may be made differential deflection, particularly with the outer-most within the scope of the invention. For example, direc- flaps serving as ailerons. The flaps behind the ejectors 50 tional control and stability of the aircraft may be (second and third embodiments) work in conjunction achieved by the use of either one or two vertical stabi- with the pivotable flaps on the ejector exhausts to de- lizers. In some instances the spanwise area of the injec- flect the ejector flow downward or upward. This re- tor may be varied for aerodynamic and/or installation sults in beneficial power-induced lift of varying considerations. Varying the number of engines will not amounts.
55 alter the advantages of the invention. The need for the It will be noted in the plan views that the inlet and canard is dependent to a certain extent on the amount of exhaust edges of ejectors 51,52,86 and 87 are truncated.
forward sweep in the wings. In some situations pitch The rear end angle (from plan view) of these ejectors control could be derived by other means. For example, has been slanted to increase the flap area covered by the the canard could be eliminated where trim and control flow ejected from the ejectors. Stated another way, the 60 in pitch is provided by symmetrically adjusting the angling prevents the rear end of the ejector from over- spanwise variation in wing lift by differentially control- hanging the trailing edge flap.
ling the front (outboard) and rear (inboard) wing flaps.
Although the longitudinal axes of ejectors 86,87 are What is claimed is: shown to be substantially parallel to the fuselage longi- 1 . A high performance aircraft comprising: tudinal axis, it is to be understood that for optimum 65 a fuselage; ejector performance the actual 16yaw”angle of the ejec- forward swept wings connected to said fuselage; tors should coincide with the flow angle on the upper at least one engine having an inlet for generating a surface of the wing under up and away flight condi- pressurized gas;
4,767,083
hinged flaps for changing the flow area and modulating thrust augmenting ejector means having an inlet lo- flow Pressure and velocity.
cated apart from said at least one engine inlet and 6 . An aircraft as in claim 5 wherein said variable-area responsive to said pressurized gas, said ejector inlet and said variable-area outlet each at least have two inlet located above and on an inboard par- connected hinged flaps.
tion of said wings for augmenting thrust, enhancing 7 . An aircraft as in claim 6 wherein the flaps of said circulating lift, and stall control, and said ejector outlet are moved in a downward position so as to means including a number of nozzles arranged change the direction of ejector means thrust normal to dong the span of the wings, a variable-area inlet the longitudinal axis of the aircraft.
and a variable-area outlet.
10 8. A high performance aircraft comprising: 2. An aircraft as in claim 1 wherein said nozzles are fuselage; arranged in first and second opposed linear arrays.
forward swept wings connected to said fuselage; 3. An aircraft as in claim 2 wherein said ejector means at least one engine having an inlet for generating a includes opposed first and second manifolds that supply pressurized gas; and thrust augmenting ejector means having an inlet lo- gas to said first and second nozzle arrays, respectively. 15 4. A high performance aircraft comprising: cated apart from said at least one engine inlet and responsive to said pressurized gas, said ejector a fuselage; forward swept wings connected to said fuselage; means inlet located above and on an inboard por- at least one engine having an inlet for generating a tion of said wings for augmenting thrust, enhancing pressurized gas; and 20 circulating lift, and stall control; and having an inlet lo- two ejectors operable in both first and second solu- thrust augmenting ejector tion modes, said ejectors being located above said cated apart from said at least one engine inlet and wings adjacent to said ejector means and forward responsive to said pressurized gas, said ejector of said ejector means, said ejectors being positioned "let located above and On an inboard symmetrical to the longitudinal axis of said aircraft, 25 tion of said wings for augmenting thrust, enhancing and said ejectors each having a single linear array circulating lift, and stall control, and vertical tail of nozzles, a variable-area inlet, and a variable-area fins for providing directional stability and steering outlet.
control, said vertical tail fins for providing direc- inlets 9. aircraft as in claim 8 wherein said tional stability and steering control, said Vertical 30 and outlets include servo-actuated hinged flaps for t a i l fins being mounted on said ejector means. changing flow area and modulating the flow pressure 5. An aircraft as in claim 1 wherein said inlets and and velocity.
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outlets of said ejector means include servo-actuated