Tiltrotor Aircraft having Rotary and Non Rotary Flight Modes

• US 20170144746A1
• Filed: 02/09/2017
• Published: 05/25/2017
• Est. Priority Date: 12/02/2014
• Status: Active Grant

• Current Assignee: Bell Textron Inc.
• Original Assignee: Bell Helicopter Textron Incorporated (Textron Inc)
• Inventors: Schank, Troy Cyril, Fenny, Carlos Alexander, Maresh, Andrew, Tzeng, Chyau-Song
• Granted Patent: US 10,526,068 B2
• Time in Patent Office: Days
• CPC Class Codes: B64C 11/28 Collapsible or foldable blades
• CPC Class Codes: B64C 27/30 with provision for reducing drag of inoperative rotor
• CPC Class Codes: B64C 29/0033 the propellers being tiltable relative to the fuselage
• CPC Class Codes: B64D 27/20 within, or attached to, fuselages

Abstract

A mechanism for transitioning a tiltrotor aircraft between rotary and non rotary flight modes. The mechanism includes a gimbal lock positioned about a mast that is operable to selectively enable and disable a gimballing degree of freedom of a rotor assembly relative to the mast. A blade stop assembly, positioned about the mast, includes a plurality of arms having a radially contracted orientation and a radially extended orientation. A blade lock assembly is operably associated with each rotor blade assembly. Each blade lock assembly is operable to selectively enable and disable a folding degree of freedom and a pitching degree of freedom of the respective rotor blade assembly. A swash plate is operable to change the pitch of the rotor blade assemblies in the rotary flight mode and fold the rotor blade assemblies in the non rotary flight mode.

Claims

1. A mechanism for transitioning a tiltrotor aircraft between rotary and non rotary flight modes, the aircraft including a mast and a rotor assembly having a gimballing degree of freedom relative to the mast, the rotor assembly including a plurality of rotor blade assemblies each having a pitching degree of freedom and a folding degree of freedom, the mechanism comprising:

a gimbal lock positioned about the mast, the gimbal lock having a disengaged position relative to the rotor assembly, enabling the gimballing degree of freedom, in the rotary flight mode and an engaged position relative to the rotor assembly, disabling the gimballing degree of freedom, in the non rotary flight mode;

a blade stop assembly positioned about the mast, the blade stop assembly including a plurality of arms having a radially contracted orientation, in the rotary flight mode and a radially extended orientation, in the non rotary flight mode;

a blade lock assembly operably associated with each rotor blade assembly, each blade lock assembly having a first position, disabling the folding degree of freedom and enabling the pitching degree of freedom of the respective rotor blade assembly, in the rotary flight mode and a second position, enabling the folding degree of freedom and disabling the pitching degree of freedom of the respective rotor blade assembly, in the non rotary flight mode; and

a swash plate positioned about and operable to rise and fall relative to the mast, the swash plate operable to change the pitch of the rotor blade assemblies, in the rotary flight mode and operable to fold the rotor blade assemblies, in the non rotary flight mode.

2. The mechanism as recited in claim 1 wherein the gimbal lock further comprises a conical ring that engages the rotor assembly to disable the gimballing degree of freedom.

3. The mechanism as recited in claim 2 wherein the gimbal lock further comprises an actuator operably associated with the conical ring to raise and lower the conical ring relative to the mast to transition the gimbal lock between the engaged and disengaged positions.

4. The mechanism as recited in claim 3 wherein the actuator further comprises an actuation ring positioned about the mast, the actuation ring operable to raise and lower the conical ring relative to the mast.

5. The mechanism as recited in claim 1 wherein the blade stop assembly further comprises an actuator operably associated with the arms to transition the arms between the radially contracted orientation and the radially extended orientation.

6. The mechanism as recited in claim 5 wherein the actuator further comprises an actuation ring positioned about the mast, the actuation ring operable to transition the arms between the radially contracted orientation and the radially extended orientation.

7. The mechanism as recited in claim 1 further comprising an actuator that is common to the gimbal lock and the blade stop assembly such that the gimbal lock transitions between the disengaged and engaged positions as the arms of the blade stop assembly transition between the radial retracted and radially extended orientations.

8. The mechanism as recited in claim 1 wherein each rotor blade assembly includes a cuff and a rotor blade pivotably coupled to the cuff and wherein the swash plate is coupled to each cuff by a pitch link and a pitch horn such that rise and fall of the swash plate in the rotary flight mode changes the pitch of the rotor blade assemblies and such that rise and fall of the swash plate in the non rotary flight mode folds the rotor blades relative to the cuffs.

9. The mechanism as recited in claim 8 wherein each blade lock assembly further comprises:

a crank and a link coupled at a pivot joint, each link rotatably coupled to the respective rotor blade, each crank rotatably coupled to the respective cuff and operable to rotate relative to the respective cuff responsive to rise and fall of the swash plate in the non rotary flight mode; and

a blade lock having a fold lock position securing the pivot joint to the respective cuff and a pitch lock position securing the respective cuff to the respective arm of the blade stop assembly.

10. The mechanism as recited in claim 9 further comprising an actuator operably coupled to each blade lock, each actuator operable to shift the respective blade lock between the fold lock position and the pitch lock position.

11. The mechanism as recited in claim 10 wherein each blade lock further comprises a pitch lock and a fold lock, the pitch lock rotatably coupled to the respective cuff at an inboard location, the fold lock rotatably coupled to the respective cuff outboard of the pitch lock.

12. The mechanism as recited in claim 11 wherein each fold lock disables the folding degree of freedom of the respective rotor blade assembly in the rotary flight mode and enables the folding degree of freedom of the respective rotor blade assembly in the non rotary flight mode.

13. The mechanism as recited in claim 11 wherein each pitch lock disables the pitching degree of freedom of the respective rotor blade assembly in the non rotary flight mode and enables the pitching degree of freedom of the respective rotor blade assembly in the rotary flight mode.

14. The mechanism as recited in claim 1 wherein the aircraft is in the rotary flight mode when the gimbal lock is in the disengaged position, the arms of the blade stop assembly are in the radially contracted orientation and each of the blade lock assemblies is in the first position and wherein the aircraft is in the non rotary flight mode when the gimbal lock is in the engaged position, the arms of the blade stop assembly are in the radially extended orientation and each of the blade lock assemblies is in the second position.

15. A tiltrotor aircraft having rotary and non rotary flight modes, the aircraft comprising:

a mast;

a rotor assembly having a gimballing degree of freedom relative to the mast, the rotor assembly including a plurality of rotor blade assemblies each having a pitching degree of freedom and a folding degree of freedom;

a gimbal lock positioned about the mast, the gimbal lock having a disengaged position relative to the rotor assembly, enabling the gimballing degree of freedom, in the rotary flight mode and an engaged position relative to the rotor assembly, disabling the gimballing degree of freedom, in the non rotary flight mode;

a blade stop assembly positioned about the mast, the blade stop assembly including a plurality of arms having a radially contracted orientation, in the rotary flight mode and a radially extended orientation, in the non rotary flight mode;

a blade lock assembly operably associated with each rotor blade assembly, each blade lock assembly having a first position, disabling the folding degree of freedom and enabling the pitching degree of freedom of the respective rotor blade assembly, in the rotary flight mode and a second position, enabling the folding degree of freedom and disabling the pitching degree of freedom of the respective rotor blade assembly, in the non rotary flight mode; and

a swash plate positioned about and operable to rise and fall relative to the mast, the swash plate operable to change the pitch of the rotor blade assemblies, in the rotary flight mode and operable to fold the rotor blade assemblies, in the non rotary flight mode.

16. The aircraft as recited in claim 15 further comprising an engine having a turboshaft mode corresponding to the rotary flight mode of the aircraft and a turbofan mode corresponding to the non rotary flight mode of the aircraft, the engine providing torque and rotational energy to the mast in the turboshaft mode and providing no torque and rotational energy to the mast in the turbofan mode.

17. The aircraft as recited in claim 15 having a maximum forward airspeed in an airplane forward flight mode that exceeds a maximum forward airspeed limited by proprotor aeroelastic instability in a proprotor forward flight mode.

18. The aircraft as recited in claim 15 further comprising an actuator that is common to the gimbal lock and the blade stop assembly such that the gimbal lock transitions between the disengaged and engaged positions as the arms of the blade stop assembly transition between the radial retracted and radially extended orientations.

19. The aircraft as recited in claim 15 wherein each rotor blade assembly includes a cuff and a rotor blade pivotably coupled to the cuff and wherein the swash plate is coupled to each cuff by a pitch link and a pitch horn such that rise and fall of the swash plate in the rotary flight mode changes the pitch of the rotor blade assemblies and such that rise and fall of the swash plate in the non rotary flight mode folds the rotor blades relative to the cuffs.

20. The aircraft as recited in claim 15 wherein the aircraft is in the rotary flight mode when the gimbal lock is in the disengaged position, the arms of the blade stop assembly are in the radially contracted orientation and each of the blade lock assemblies is in the first position and wherein the aircraft is in the non rotary flight mode when the gimbal lock is in the engaged position, the arms of the blade stop assembly are in the radially extended orientation and each of the blade lock assemblies is in the second position.