GB2080231A - Controlling helicopters - Google Patents

Abstract

A rotary wing aircraft includes a fuselage 10, a gas turbine engine operated air compressor 16 within the fuselage, and a jet nozzle driven rotor assembly 12 situated over the fuselage and having a rotor axis about which the assembly rotates. A rotor support means, including a generally hollow mast 46 defining an air conduit to the rotor assembly, supports the assembly for rotation about the rotor axis. A movable support member 48 is operatively connected to the fuselage and the mast for laterally shifting the latter and to thereby shift the rotor axis and the entire rotor assembly laterally relative to the fuselage to shift the aerodynamic centre of the aircraft relative to its centre of gravity. Between the hollow rotor mast and the air compressor, a flexible air conduit 70 is provided within the fuselage to accommodate the lateral shifting movement of the rotor assembly relative to the fuselage. <IMAGE>

Description

SPECIFICATION Jet nozzle rotary wing aircraft The present invention relates to rotary wing aircraft, and in particular to a jet nozzle driven rotary wing aircraft which has means for laterally shifting the rotor assembly thereof relative to the aircraft fuselage.

In rotary wing aircraft, it is critical to maintain an aerodynamically balanced center of gravity. This is true of all aircraft but is particularly critical in rotary wing aircraft such as helicopters. Helicopters are characterized by a rotor assembly which includes a mast for support thereof. This mast defines the axis of rotation of the rotor assembly and preferably should be directly above the balanced weight of the helicopter. In loading a helicopter, it has been importans to pay special attention to the weight distribution of the load.

If there is an excessive shift or displacement of the center of gravity of a rotary wing aircraft such as a helicopter, loss of control can result, particularly under less than ideal flight conditions, since control response in rough air or extreme turbulence can be ineffectual in cases where there is an improper distribution of the load. Consequently, it would be highly desirable to provide means for shifting the actual axis of rotation of the rotor assembly, for instance as defined by the rotor mast, before or during flight in order to accommodate changes in flight conditions orto simply accommodate inaccurate initial distribution of the load.

The development of high performance lightweight gas turbines has made it increasingly feasible to power the rotor assembly of a helicopter by ducting compressed air and/or the tu rbine gases directly to jet nozzles located atthe rotor blade tips. This technique of rotor drive obviously eliminates the need for heavy torque transmitting members from the engine to the rotor blades. Accordingly, a new and improved means for shifting the axis of rotation of the rotor assembly before or during flight to relocate the position of the assembly relative to the fuselage is possible and is described by the present invention.

It would, therefore, be desirable to provide in a rotary wing aircraft, a new and improved means for laterally shifting the axis of rotation of the rotor assembly relative to the fuselage of the aircraft, to thereby shift the aerodynamic center of gravity of the aircraft.

Thus, the present invention provides a rotary wing aircraft which includes a fuselage, air compressor means associated with said fuselage, a jet nozzle driven rotor assembly situated over said fuselage and having a rotor axis about which said assembly rotates, rotor support means supporting said rotor assembly for rotation about said rotor axis and including a generally hollow rotor mast defining an air conduit to said rotor assembly, mounting means operatively connected between said fuselage and said rotor support means for lateral shifting said rotor support means to thereby shift said rotor axis and said rotor assembly laterally relative to said fuselage to change the aerodynamic center of gravity of the aircraft, and flexible air conduit means between said hollow rotor mast and said air compressor means to accommodate said lateral shifting of said rotor assembly and said rotor axis relative to said fuselage.

The mounting means for the rotor support means of the rotor assembly includes a movable support plate. The support plate cooperates with the rotor mast to move the rotor assembly. Guiding means is provided for the support plate and includes a pair of generally parallel worm gears. The support plate has a plurality of nuts threaded onto the worm gears to accommodate movement. In a preferred embodiment, a servomotor is provided for rotating the worm gears by means of a common drive chain and a pair of sprocket gears fixed to the pair of worm gears to rotate the latter. Although other means such as a hand crank or hydraulic drive operable by the pilot within the cabin or cockpit are also contemplated.

Another feature of the invention is the provision of seal means between the rotor support means and the fuselage. More particularly, the fuselage has an opening through which the hollow rotor mast extends to the jet nozzle driven rotor assembly. The seal means comprises a sealing plate surrounding the hollow rotor mast which is sufficiently large to coverthe opening through the fuselage in a fashion accommodating lateral shifting movement of the rotor mast.

Other advantages and features of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings, in which: FIGURE 1 is a side elevational view of a jet nozzle driven rotary wing aircraft embodying the concepts of the present invention, partially broken away and in section to better illustrate the operative components of the invention; and FIGURE 2 is a perspective view, on an enlarged scale, of the mounting means for laterally shifting the rotor support means of the rotor assembly of the aircraft.

Referring to the drawings in greater detail, and first to Figure 1, a rotary wing aircraft in the form of a helicopter is shown which includes a fuselage, generally designated 10, and a jet nozzle driven rotor assembly, generally designated 12. A light-weight gas turbine engine 14 is appropriately mounted within the fuselage 10 and is effective to operate an air compressor 16. An exhaust tunnel 18 extends rearwardly of engine 14 so as to direct exhaust gases rearwardly toward a vertical rear control surface 20 which is provided for yaw control.

The aircraft also includes a plexiglas cockpit area, generally designated 22. Within the cockpit 22 includes conventional equipment such as an operator's seat 24, a control panel 26, a collective pitch stick 28, and a conventional cyclic pitch stick 30 which has a thumb switch 32 on the top thereof. The aircraft further includes landing skids 34 mounted on the underside of the fuselage 10 by appropriate brackets 36 or the like.

The rotor assembly 12 is of the jet nozzle driven type which includes a plurality of hollow rotor blades 28 with jet nozzles 40 at the distal ends thereof. The jet nozzles extend generally tangentially to the rotor blades at the blade tips and are effective to discharge the compressed air, resulting in rotor rotation. The rotor assembly 12 also includes a central vertical cylindrical hub assembly 42 which has flexible duct work extending outwardly therefrom in the form of individual flexible air conduits 44 for each rotor blade 38.

Rotor support means is provided for supporting the rotor assembly 12 for rotation about a central vertical axis defined by the hub assembly 42. More particularly, the rotor support means includes a generally hollow rotor mast 46. Rotor mast 46 defines an air conduitto the rotor assembly 12 and particularly to the air conduits 44 in communication with the rotor blades 38.

It should be noted at this point that appropriate means, not shown in order to avoid cluttering the drawings, is provided between the hub assembly 42 and the rotor mast 46 to hold the rotor assembly 12 onto the rotor mast, yet permit relative rotation therebetween, with various such conventional means being known and contemplated.

Mounting means is provided operatively connected between the fuselage and the rotor support means for laterally shifting the latter to thereby shift the rotor axis and the entire rotor assembly laterally relative to the fuselage to change the aerodynamic center of gravity of the aircraft. More particularly, referring to Figure 2, the mounting means includes a movable support member 48 in the form of a plate which has a central aperture 50 therethrough. The hollow rotor mast46 extends through the aperture 50 in support plate 48 and is laterally shiftable or movable thereby. Additionally, and still referring to Figure 2, means is provided for guiding and shifting support plate 48 in the form of a pair of generally parallel guide member 52 in the form of worm gears.

A plurality of follower nuts 54 are threaded onto the worm gears 52 and fixed to support plate 48 for laterally shifting the support plate in response to rotation of the worm gears.

Singular servomotor means is provided for rotating the worm gears 52. More particularly, a reversible motor 56 is appropriately mounted within the fuselage and has a drive shaft 58 which has a single sprocket gear 60 on the distal end thereof. A sprocket gear 62 is fixed to one end of each of the worm gears 52, and a common drive chain 64 is operatively meshed with the sprocket gears 62 on the worm gears 52 and the sprocket gear 60 fixed to the motor drive shaft 58. Additionally, the ends of the worm gears 52 opposite the sprocket gears 62 are rotatably mounted within a support bracket 66 appropriately mounted within the fuselage 10 of the aircraft. Referring to Figure 1, a second support plate 68 rotatably mounts and properly spaces the worm gears 52 at the ends thereof adjacent the drive chain 64, but support bracket 68 is not shown in Figure 2 to further the illustration.

Referring back to Figure 1, in order to accommodate the lateral shifting movement of the rotor assembly 12, i.e. rotor mast 46, relative to the fuselage of the aircraft, flexible air conduit means 70 is provided between the rotor mast and the air com pressormeans 16.

Still referring to Figure 1, seal means is provided between the rotor support means and the fuselage in order to pressurize the interior of the latter, yet accommodate the lateral shifting of the rotor assembly. More particularly, an enlarged opening 72 is provided at the top of the aircraft fuselage, the opening being sufficiently enlarged to accommodate maximum lateral shifting of the rotor assembly. The rotor mast 46 extends upwardly through this opening and is stabilized below the opening by the support plate 48. Additionally, the seal means includes a sealing plate or gasket 74 which surrounds the rotor mast 46 and is tightly sealed thereto.The sealing gasket bears against the underside of the fuselage and surrounds the opening 72 a sufficient distance outwardly therefrom to accommodate maximum lateral shifting of the rotor mast In operation, control over the critical aerodynamic center of gravity of the aircraft is extremely simple.

As previously stated, the rotor mast preferably should be directly above the balanced weight of the aircraft. With the above described invention, an operator of the aircraft can easily shift the rotor mast 46 laterally to the fuselage 10 from within the cockpit area 22, simply by actuating the reversible motor 46 in one direction or the other. For instance, the thumb switch 32 on the pitch stick 30 could be employed. It will be appreciated of course, that other control means may also be employed. For instance, a hand crank or hydraulic drive operable by the pilot within the cabin or cockpit are contemplated.With the above described embodiment, however, the movable support plate 48 can be shifted laterally along the worm gears 52 by actuating the reversible motor 56, with the direction of the motor determining the direction of rotation of the worm gears through the common drive chain 64 and the sprocket gears 60, 62 to thereby determine the direction of movement of the support plate and, thus, the direction of lateral shifting of the rotor mast 46. As previously stated, shifting of the rotor mast, in turn, shifts the axis of rotation of the rotor assembly 12 and thereby shifts the aerodynamically critical center of gravity of the aircraft. This simple operative invention effectively provides a controlled response of the aircraft in rough air or extreme turbulence where the weight of the aircraft might be improperly distributed which is unique in jet nozzle driven rotary wing aircraft.

It will be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The' present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive. The invention is not to be limited to the details given herein but may be modified within the scope of the appended claims.

Claims (22)

1. A rotary wing aircraft which includes a fuselage, air compressor means associated with said fuselage, a jet nozzle driven rotor assembly situated over said fuselage and having a rotor axis about which said assembly rotates, rotor support means supporting said rotor assembly for rotation about said rotor axis and including a generally hollow rotor mast defining an air conduit to said rotor assembly, mounting means operatively connected between said fuselage and said rotor support means for laterally shifting said rotor support means to thereby shift said rotor axis and said rotor assembly laterally relative to said fuselage to change the aerodynamic center of gravity of the aircraft, and flexible air conduit means between said hollow rotor mast and said air compressor means to accommodate said lateral shifting of said rotor assembly and said rotor axis relative to said fuselage.

2. An aircraft according to claim 1 wherein said mounting means includes a movable support member and means for laterally guiding the movement of said support member.

3. An aircraft according to claim 2 wherein said support member comprises a support plate cooperating with said rotor mast to thereby move said rotor support means and said rotor assembly.

4. An aircraft according to claim 2 wherein said guiding means for said support member includes a pair of generally parallel guide members.

5. An aircraft according to claim 4 wherein said guide members comprise a pair of worm gears and said support member includes follower means engageable with said worm gears for moving said support member along said worm gears in response to rotation thereof.

6. An aircraft according to claim 5 wherein servomotor means are included for rotating said worm gears.

7. An aircraft according to claim 6 wherein said worm gears each have a gear member thereon and a common drive means coupled thereto and to said servomotor means.

8. An aircraft according to claim 7 wherein said drive means comprises a drive chain and said gear members comprise sprocket gears.

9. An aircraft according to claim 7 wherein said follower means comprise a plurality of nuts threaded onto said worm gears.

10. An aircraft according to claim 5 wherein said support member comprises a support plate cooperating with said rotor mast to thereby move said rotor support means and said rotor assembly.

11. An aircraft according to claim 2 wherein said guiding means for said support member includes at least one worm gear, and said support member includes a follower member engageable with said worm gear for moving said support member along said worm gear in response to rotation thereof.

12. An aircraft according to claim 11 wherein said follower means comprises a nut threaded onto said worm gear.

13. An aircraft according to claim 12 wherein servomotor means are included for rotating said worm gear.

14. An aircraft according to claim 11 wherein said support member comprises a support plate cooperating with said rotor mast to thereby move said rotor support means and said rotor assembly.

15. Arotarywing aircraftwhich includesafuselage, air compressor means on said fuselage, a jet nozzle driven rotor assembly situated over said fuselage and having a rotor axis about which said assembly rotates, rotor support means supporting said rotor assembly for rotation about said axis, and mounting means operatively connected between said fuselage and said rotor support means for laterally shifting said rotor support means to thereby shift said rotor axis and said rotor assembly laterally relative to said fuselage to change the aerodynamic center of gravity of the aircraft.

16. An aircraft according to claim 15 wherein said mounting means includes a movable support member and means for laterally guiding the movement of said support member.

17. An aircraft according to claim 16 wherein said guiding means for said support member includes at least one worm gear, and said support member includes a follower member engageable with said worm gear for moving said support member along said worm gear in response to rotation thereof.

18. An aircraft according to claim 17 wherein said follower means comprises a nut threaded onto said worm gear.

19. An aircraft according to claim 17 wherein servomotor means are included for rotating said worm gear.

20. An aircraft according to claim 17 wherein said support member comprises a support plate cooperating with said rotor support means to thereby move said rotor support means and said rotor assembly.

21. An aircraft according to claim 15 wherein said fuselage includes a yawing through which said rotor support means extends, and seal means associated with said rotor support means, said seal means being laterally shiftable with said rotor support means.

22. A rotary wing aircraft substantially as hereinbefore described with reference to the accompanying Figures 1-2.