Propulsion system for a V/STOL airplane

• US 4,505,443 A
• Filed: 08/27/1981
• Issued: 03/19/1985
• Est. Priority Date: 12/29/1978
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: General Dynamics Corporation
• Inventors: Cragin, Glynn P. Jr., Bradfield, Ganey W.
• Primary Examiner(s): Blix, Trygve M.
• Assistant Examiner(s): Corl, Rodney
• Application Number:
  US06/296,710
• Time in Patent Office: 1,300 Days
• Field of Search: 244/12.1, 244/12.4, 244/12.5, 244/13, 244/15, 244/23 D, 244/52, 244/55, 244/207, 244/211, 244/212, 244/216, 239/265.27, 239/265.41, 60/228, 60/229, 60/230
• US Class Current: 244/12.5
• CPC Class Codes: B64C 29/0066 with horizontal jet and jet deflector

Abstract

A propulsion system for an airplane to permit it to achieve vertical and/or short take-offs and landings. The propulsion system is integrated into a wing/nacelle unit and includes a thrust vectoring system. A separate flow turbofan engine is mounted in each wing/nacelle unit. A system of three flaps is located at the rear of each wing/nacelle unit for deflecting the turbofan engine exhaust downward, rearward, or any angle in between. These three flaps are arranged to provide a main thrust nozzle in the horizontal flight position without any additional flaps between them. One flap is located at the wing/nacelle upper surface trailing edge. Two slots are provided at the leading edge of this flap. The upper forward most slot is provided as an exit nozzle for the engine turbine exhaust, which is shrouded from the fan exhaust. The second of these two slots removes a portion of the high energy fan exhaust from the fan discharge duct and ejects it over the flap upper surface. The other two flaps are positioned such that, in the horizontal position they are both aligned with the wing/nacelle lower surface and in the vertical position, one is aligned with the wing/nacelle lower surface and the other is aligned with the wing/nacelle upper surface. When the flaps are in the vertical position, the aft most slot in the upper flap and a slot formed between the upper flap and the lower aft flap provide a means of improving the turning efficiency of the fan exhaust stream.

Claims

1. In a vertical and/or short takeoff and landing (V/STOL) airplane, a propulsion system providing enhanced thrust and airplane handling qualities through more efficient turning of its exhaust between horizontal and upward directed flight modes which comprises:

propulsion means for generating a higher than ambient static pressure flow of thrust producing exhaust gas, said propulsion means being a high by-pass ratio turbofan engine having an engine core exhaust;

exhaust nozzle means for directing at least a portion of said exhaust gas flow from the propulsion means to the airplane exterior, and to turn the flow between substantially horizontal and downwardly directed flow positions;

said exhaust nozzle means comprising;

primary thrust nozzle means for the exit of a major portion of said exhaust gas flow, and

secondary thrust nozzle means for bleeding off a minor portion of the exhaust gas flow;

said secondary thrust nozzle means positioned to effect the bleed-off from said major portion of the exhaust gas flow downstream of the commencement of the turn therein so as substantially to prevent formation of dynamic pressure-induced contra-rotating vortices in the outside of the turn thereby substantially preventing thrust reducing contra-rotating vortex formation in the gas flow therein; and

said secondary thrust nozzle means being directionally movable so as to direct the bleed-off to flow closely parallel to the major portion of the exhaust flow at all positions thereof whereby the bleed-off is turned together with the major portion of the exhaust flow, effectively to provide a coherent unitary-like exhaust stream passing from said airplane at all angles of flow from horizontal to downward flow;

thereby maximizing both the thrust from said major portion of the flow and the recovery of thrust from said bleed-off flow and improving the handling qualities of the airplane at all positions of turning of the exhaust gas flow

at least one of said primary thrust nozzle means and said secondary thrust nozzle means being in the form of elongated slot means that are formed by a tandemly arranged series of movable flap means providing lifting surfaces for said airplane and in which said bleed-off exhaust flow is directable over at least some of said lifting surfaces substantially tangent thereto to retard boundary layer separation during horizontal and transitional flight positions and to enhance the turning of said bleed-off flow together with said major portion of the exhaust gas flow;

the engine core exhaust being caused to exit from said airplane upstream of the exit of the exhaust from the engine fan.

2. The propulsion system of claim 1 in which said bleed-off issues from the fan exhaust of the turbofan engine and is directed over said at least some of said lifting surfaces between said surfaces and said core exhaust.

3. The propulsion system of claim 1 in which said nozzle means for exit of the core and fan exhaust are positioned closely adjacent one another to facilitate combining the flows so as to exit from the airplane as a coherent, unitary-like exhaust gas stream.

4. A propulsion system for vertical and short take-off and landing airplane, comprising:

a nacelle having an upper surface and a lower surface, forming an upper surface and a lower surface of an airfoil, respectively;

a fan mounted in said nacelle;

a turbine engine mounted in the nacelle behind the fan and connected to the fan for driving the fan;

a fan nozzle and exhaust turning means located downstream of the fan for discharging fan exhaust at a predetermined angle between a generally horizontal direction for forward thrust and generally downward direction for vertical thrust, the latter forming a bend;

fan exhaust bleed-off means for bleeding off through a nozzle a portion of the fan exhaust stream from an outer portion of the turning means downstream of the leading edge thereof to reduce vortex formation in the turned exhaust stream;

an engine nozzle and exhaust turning means located downstream of the engine for discharging engine exhaust downstream of a shroud means at a predetermined desired angle between a generally downward direction for vertical thrust, forming a bend; and

shroud means extending from the rear of the engine to the engine nozzle for separating the engine exhaust from the fan exhaust until the engine exhaust passes through the engine nozzle and the fan exhaust passes through the fan nozzle;

the fan nozzle and exhaust turning means, the fan exhaust bleed-off means, and the engine nozzle being positioned closely adjacent each other and oriented in the same direction in all flight modes to direct the exhaust streams in a unitary flow in the direction of the thrust vectors so as to recover the thrust potential of all streams in all flight modes and so that the fan exhaust and engine exhuast combine immediately downstream of the fan nozzle and the engine nozzle in all flight positions.

5. The propulsion system according to claim 4 wherein the fan nozzle and exhaust turning means comprises a plurality of flaps mounted to the nacelle, with one of the flaps being an upper flap positioned at the nacelle upper surface to form a part of the airfoil upper surface, the upper flap having fan exhaust slot means for discharging a portion of the fan exhaust over the upper flap in the horizontal and the vertical flight positions and all positions in between to increase induced circulation over the airfoil upper surface.

6. The propulsion system according to claim 5 wherein two of the flaps are positioned apart from each other in the horizontal and vertical flight positions to define a main thrust nozzle, free of additional flaps, for discharging the majority of the exhaust from the fan.

7. The propulsion system according to claim 5 wherein the engine nozzle and exhaust turning means comprises engine exhaust slot means adjacent the fan exhaust slot means for discharging the engine exhaust over the upper flap in the horizontal and the vertical flight positions and all positions in between to increase induced circulation over the airfoil upper surface.

8. The propulsion system according to claim 4 wherein the fan and engine nozzles are located at the trailing edge of the nacelle in all flight positions to minimize suckdown forces on the airfoil lower surface.

9. A propulsion system for a vertical and/or short takeoff and landing airplane, comprising:

a duct having an upper surface and a lower surface respectively forming an upper surface and a lower surface of an airfoil;

means for forcing a flow of higher than ambient static pressure propulsion gas through said duct;

an upper flap located near the trailing edge of the duct upper surface and forming a part of the airfoil upper surface, the upper flap being pivotal from a horizontal flight position in which it is generally aligned with the duct upper surface to an upward flight position in which the upper flap points generally downward;

a lower flap adjacent the trailing edge of the duct lower surface and forming a part of the airfoil lower surface, the lower flap being pivotal from a horizontal flight position generally aligned with the duct lower surface to an upward flight position in which the lower flap points generally downward; and

an intermediate flap operative with the duct and pivotal between a horizontal flight position in which the intermediate flap is rearward of the lower flap, generally aligned with the duct lower surface and forming a part of the airfoil lower surface and an upward, or vertical, flight position in which the leading edge of the intermediate flap is adjacent the trailing edge of the upper flap and in which the intermediate flap points generally downward, becoming the trailing edge of the airfoil upper surface;

in the horizontal flight position, the space between the upper flap and the intermediate flap defining a horizontal flight main thrust nozzle; and

in the upward, or vertical, flight position, the space between the lower flap and intermediate flap defining an upward, or vertical, flight main thrust nozzle.

10. A propulsion system for a vertical and short takeoff and landing airplane, comprising:

a nacelle having an upper surface and a lower surface, forming an upper surface and a lower surface of an airfoil, respectively;

a turbo-fan engine mounted in the nacelle for providing an exhaust gas stream of higher than ambient static pressure;

fan exhaust nozzle means downstream of the engine for discharging fan exhaust;

turbine exhaust nozzle means located downstream of the engine for discharging turbine exhaust;

shroud means extending from the rear of the turbine to the turbine exhaust nozzle means for separating the turbine exhaust from the fan exhaust until the turbine exhaust passes through the turbine exhaust nozzle means and the fan exhaust passes through the fan exhaust nozzle means for preventing undesired internal interaction between the two flows of exhaust gas;

said shroud means and turbine exhaust nozzle means positioned to discharge said turbine engine exhaust to the exterior upstream of the discharge to the exterior of the exhaust from the fan; and

said fan and turbine exhaust nozzle means each being directionally movable and adapted to effect turning of the exhaust from said nozzle means together as a coherent, unitary-like stream exiting from said airplane.

11. The propulsion system according to claim 10 wherein the fan and engine nozzle means are located at the trailing edge of the nacelle in all flight positions to reduce suckdown forces on the airfoil lower surface.

12. In a V/STOL airplane, a propulsion system for efficiently turning its exhaust between horizontal and upward flight, the system comprising:

a nacelle;

a turbofan engine located in the nacelle;

said turbo fan engine being capable of providing sustained super atmospheric pressure for propulsion;

a shroud in the nacelle to contain the engine exhaust and separate it from the fan exhaust;

plural flaps located in series in a rearward portion of the nacelle to form a thrust nozzle for the exhaust of the turbofan engine and being movable between horizontal and upward flight positions;

said plural flaps being capable of forming a thrust nozzle capable of sustaining said super atmospheric pressure upstream of its exit in all positions;

slot means formed in series adjacent leading edges of the flaps to receive the engine exhaust from the shroud and bleed-off a portion of the fan exhaust over the upper surfaces of selected ones of the flaps to induce super circulation and prevent boundary layer separation during horizontal and transitional flight;

said slot means during transitional and upward flight, due to the bleed-off, minimizing the formation of counter rotating vortices in the turning exhaust thus increasing the thrust efficiency of the vectored exhaust;

said slot means and flaps forming a series of movable and directional thrust nozzles to vector the bleed-off exhaust along the upper surfaces of the selected flaps and turn the exhaust progressively downward for upward flight.

13. In a V/STOL airplane in which a higher than ambient static pressure flow of exhaust gas comprising fan exhaust and engine exhaust from a power means is turned to effect the change between flight modes respectively having greater horizontal and greater vertical thrust vectors, the method of improving airplane flight characteristics which comprises:

directing at least a portion of said exhaust gas flow through a closed conduit means ot exit through a thrust-producing nozzle downstream of the power means;

turning the exhaust gas flow through an angle from a condition in which the exhaust flow is directed predominately horizontally to a condition in which the exhaust flow is directed predominately downwardly, thereby forming a bed;

bleeding-off a portion of the exhaust flow from an outer portion of the bend downstream of the bend leading edge to reduce vortex formation in said conduit means, and directing the vortex bleed-off portion over a portion of an airfoil upper surface substantially tangent thereto at all positions of bending of the flow for thrust recovery and to improve lift by supercirculation thereover, and reduce boundary layer separation;

maintaining the engine exhaust and the fan exhaust separate from each other until immediately after discharge from the nozzle;

recovering the thrust potential of the engine exhaust stream and the bleed-off exhaust stream in the direction of the thrust vectors of the primary exhaust in all flight modes; and

maintaining all streams closely adjacent each other and oriented in the same direction in all flight modes so they coact to effect maximum thrust.

14. In a V/STOL airplane in which the fan exhaust and the engine exhaust are turned to effect the change between flight modes respectively having greater horizontal and greater vertical thrust vectors, the method of controlling the fan exhaust and engine exhaust in all flight modes, comprising:

directing the fan exhaust and the engine exhaust through separate thrust producing nozzles;

separating the fan exhaust from the engine exhaust until passing through their respective nozzles;

bleeding off through a nozzle a portion of the fan exhaust flow from an outer portion of the turn downstream of the leading edge thereof to reduce vortex formation in the turned exhaust stream, and

positioning the respective nozzles of the engine exhaust, bleed-off exhaust, and the fan exhaust in all flight modes closely adjacent each other and oriented in the same direction in all flight modes to direct the exhaust streams in a unitary flow in the direction of the thrust vectors so as to recover the thrust potential of all streams in all flight modes.