Tilting landing gear systems and methods

Patent metadata

Field	Value
Publication number	US-11958592-B2
Application number	US-202217873865-A
Country	US
Kind code	B2
Filing date	Jul 26, 2022
Priority date	Dec 31, 2018
Publication date	Apr 16, 2024
Grant date	Apr 16, 2024

Abstract

Systems and methods for mechanically rotating an aircraft about its center-of-gravity (CG) are disclosed. The system can enable the rear, or main, landing gear to squat, while the nose landing gear raises to generate a positive pitch angle for the aircraft for takeoff or landing. The system can also enable the nose gear and main gear to return to a relatively level fuselage attitude for ground operations. The system can include one or more hydraulically linked hydraulic cylinders to control the overall height of the nose gear and the main gear. Because the hydraulic cylinders are linked, a change on the length of the nose cylinder generates a proportional, and opposite, change in the length of the main cylinder, and vice-versa. A method and control system for monitoring and controlling the relative positions of the nose gear and main gear is also disclosed.

First claim

What is claimed is:

1. A landing gear system for an aircraft comprising:
a nose gear disposed proximate a front of the aircraft, the nose gear comprising:
a main strut/gear link;
a rotatable aft/retract link rotatably attached to the main strut/gear link;
a pivot-piston rotatably attached to the aft/retract link;

the nose gear controllably movable between a first position, in which the nose gear is extended, and a second position, in which the nose gear is retracted; and
a main gear, coupled to the nose gear, the main gear disposed proximate a rear of the aircraft, the main gear controllably movable between a third position, in which the main gear is extended, and a fourth position, in which the main gear is retracted;
wherein, in a ground position, the nose gear is in the second position and the main gear is in the third position and a fuselage of the aircraft is substantially level with the ground; and
wherein, in a pitch angle position, the nose gear is in the first position, and the main gear is in the fourth position and the fuselage of the aircraft is rotated to a positive pitch angle with respect to the ground;

a valve coupled to a main cylinder and the pivot-piston, the valve comprising a closed position and an open position;
wherein, in the closed position, the valve prevents a flow of a fluid between the pivot-piston and the main cylinder;
wherein, in the open position, the valve enables the flow of the fluid between the pivot-piston and the main cylinder.

2. The landing gear system of claim 1 , wherein:
the pitch angle position comprises a takeoff pitch angle position; and
the landing gear system rotates the fuselage of the aircraft to a predetermined takeoff pitch angle (α TO ).

3. The landing gear system of claim 1 , wherein:
the pitch angle position comprises a landing pitch angle position; and
the landing gear system rotates the fuselage of the aircraft to a predetermined landing pitch angle (α L ).

4. The landing gear system of claim 1 , further comprising:
a main cylinder coupled to the main gear;
a nose cylinder coupled to the nose gear; and
wherein a flow of fluid between the nose cylinder and the main cylinder causes the pivot-piston to extend and the main cylinder to retract or vice-versa.

5. The landing gear system of claim 4 , wherein:
the valve comprises a hydraulic valve; and
the fluid comprises hydraulic fluid.

6. The landing gear system of claim 4 , wherein:
the valve comprises a pneumatic valve; and
the fluid comprises one of air or nitrogen.

7. A rotating landing gear system for an aircraft, comprising:
a nose gear disposed proximate a front of the aircraft, the nose gear comprising:
a main strut/gear link;
a rotatable aft/retract link rotatably attached to the main strut/gear link;
a pivot-piston rotatably attached to the aft/retract link; and

two or more main gears disposed proximate a rear of the aircraft;
two or more main cylinders, each mechanically coupled to the two or more main gears to move the main gears between a third position, in which the main gears are extended, and a fourth position, in which the main gears are retracted; and

a hydraulic valve hydraulically coupling an upper master link, the pivot-piston, and the main cylinders to enable fluid to flow between a nose cylinder and the main cylinders to change a pitch angle of the aircraft with respect to the ground.

8. The rotating landing gear system of claim 7 , wherein the nose cylinder and the two or more main cylinders are sized and shaped such that, when the hydraulic valve is opened with the aircraft on the ground, the nose cylinder and the two or more main cylinders maintain their relative positions.

9. The rotating landing gear system of claim 8 , wherein a total piston surface area of the two or more main cylinders is greater than a total piston surface area of the nose cylinder; and
wherein a distance between the nose gear and a center-of-gravity (C G ) of the aircraft is greater than a distance between the two or more main gears and the C G .

10. The rotating landing gear system of claim 7 , wherein the nose cylinder and the two or more main cylinders are sized and shaped such that, when the hydraulic valve is opened with the aircraft in the air, the nose cylinder retracts and the two or more main cylinders extend.

11. The rotating landing gear system of claim 10 , wherein a total weight of the two or more main gears is greater than a total weight of the nose gear.

12. The rotating landing gear system of claim 7 , further comprising:
a first set of two or more levers, each disposed between the two or more main gears and the two or more main cylinders; and
a second lever disposed between the nose gear and the nose cylinder;
wherein the first set of levers and the second lever are sized and shaped such that a first movement of the two or more mains gears causes a proportionately greater second movement of the nose gear.

13. The rotating landing gear system of claim 12 , wherein the second movement is three times greater than the first movement.

14. A method for mechanically rotating an aircraft to a desired pitch angle during a procedure, the method comprising:
determining that the aircraft has reached a predetermined speed;
opening a hydraulic valve hydraulically coupled to a nose gear cylinder and a main gear cylinder to enable fluid to flow from the nose gear cylinder to the main gear cylinder, or vice-versa, to achieve the desired pitch angle, the nose gear disposed proximate a front of the aircraft, the nose gear comprising:
a main strut/gear link;
a rotatable aft/retract link rotatably attached to the main strut/gear link; and
a pivot-piston rotatably attached to the aft/retract link; and

determining that the nose gear has moved to a third position and a main gear have moved to a first position in which the aircraft is positioned at the desired pitch angle; and
closing the hydraulic valve to hydraulically lock a position of the nose gear relative to the main gear.

15. The method of claim 14 , wherein:
the procedure comprises a takeoff; and
the predetermined speed comprises a rotation speed (V 1 ) for the aircraft.

16. The method of claim 14 , wherein:
the procedure comprises a landing; and
the predetermined speed comprises a reference landing speed (V REF ) for the aircraft.

17. The method of claim 14 , further comprising determining that a predetermined force has been applied to a control stick of the aircraft that is greater than or equal to a minimum stick force prior to opening the hydraulic valve.

18. The method of claim 14 , wherein:
a second position of the nose gear and the first position of the main gear comprises a ground position in which the nose gear and the main gear place the aircraft at substantially zero pitch angle; and
wherein the predetermined speed comprises a taxiing speed.

19. The method of claim 14 further comprising activating a hydraulic pump to cause the fluid to flow from the nose gear cylinder to the main gear cylinder, or vice-versa, to achieve the desired pitch angle.

20. The method of claim 14 , further comprising:
determining that a force on at least one of the nose gear or the main gear is greater than or equal to a minimum force indicating that the aircraft is on the ground;
opening the hydraulic valve to enable fluid to flow from the nose gear cylinder to the main gear cylinder;
determining that the nose gear and the main gear have moved to a ground position in which a fuselage of the ai

Assignees

• Jetzero Inc

Inventors

• Whitlock Jennifer
• Long Joshua B
• Donastorg Cristina
• Kennelly Brendan
• Page Mark A

Classifications

• B64C25/001 Primary

  Devices not provided for in the groups B64C25/02 - B64C25/68 · CPC title

• B64C25/22

  fluid · CPC title

• B64C2025/008

  Comprising means for modifying their length, e.g. for kneeling, for jumping, or for leveling the aircraft · CPC title

• B64C25/04 Primary

  Arrangement or disposition on aircraft · CPC title

• B64C25/26

  Control or locking systems therefor · CPC title