System and method for improving transition lift-fan performance

• US 10,427,784 B2
• Filed: 12/05/2011
• Issued: 10/01/2019
• Est. Priority Date: 12/05/2011
• Status: Active Grant

• Current Assignee: Aurora Flight Sciences Corporation (The Boeing Co.)
• Original Assignee: Aurora Flight Sciences Corporation (The Boeing Co.)
• Inventors: Parks, Robert
• Primary Examiner(s): Green, Richard R.
• Assistant Examiner(s): Fabula, Michael A.
• Application Number:
  US13/311,295
• Publication Number:
  US 20130140404A1
• Time in Patent Office: 2,857 Days
• Field of Search: 244 6, 244 7 R, 244 23 A, 244 122, 244 124
• CPC Class Codes: B64C 11/30 Blade pitch-changing mechanisms
• CPC Class Codes: B64C 29/0016 the lift during taking-off being created by free or ducted propellers or by blowers
• CPC Class Codes: B64C 29/0025 the propellers being fixed relative to the fuselage
• CPC Class Codes: B64C 29/0083 the lift during taking-off being created by several motors of different type
• CPC Class Codes: B64C 29/0091 Accessories not provided for elsewhere
• CPC Class Codes: B64D 27/24 using steam or spring force jet aircraft B64D27/16
• CPC Class Codes: G05D 1/102 specially adapted for vertical take-off of aircraft

Abstract

A system and method enabled to increase efficiency during a VTOL aircraft'"'"'s transition. A VTOL aircraft enabled to operate multiple lift fans arranged into separately controllable groups, wherein the VTOL aircraft initially has vertical flight but transitions to horizontal flight. A first group of lift fans may be kept at full throttle, a second group of lift fans may be throttled to balance thrust and/or weight, and a third group of lift fans may be shut off.

Claims

1. A vertical takeoff and landing (VTOL) aircraft having reduced peak power requirements during a transition flight between a hovering flight and a wingborne forward flight, the VTOL aircraft comprising:

a wing to provide lift during the wingborne forward flight and to provide an increasing amount of lift as airspeed increases during the transition flight;

a fuselage coupled with the wing, the fuselage being positioned to define a first wing portion on a first side of the fuselage and a second wing portion on a second side of the fuselage that is opposite that of the first side, wherein the first and second wing portions are substantially equal in length;

a forward thrust propulsion system coupled to said fuselage to produce a desired horizontal thrust during said wingborne forward flight and to accelerate the VTOL aircraft forward during said transition flight;

a first plurality of ducted lift fans positioned on the first wing portion to generate, in aggregate, a first desired total vertical thrust during said hovering flight, each of said first plurality of ducted lift fans having an axis of rotation that is fixed and substantially vertical, each of said first plurality of ducted lift fans being configured to be independently controlled between three throttle states, the three throttle states including a substantially full throttle state, an intermediate throttle state, and a substantially zero throttle state;

a second plurality of ducted lift fans positioned on the second wing portion to generate, in aggregate, a second desired total vertical thrust during said hovering flight, each of said second plurality of ducted lift fans having an axis of rotation that is fixed and substantially vertical, each of said second plurality of ducted lift fans being configured to be independently controlled between the three throttle states,

wherein, during said hovering flight and said transition flight, the VTOL aircraft is configured to independently control each of said first and second plurality of ducted lift fans,

wherein, during said transition flight from said hovering flight, the VTOL aircraft is configured to switch a throttle state of (1) at least one of said first plurality of ducted lift fans to generate a third desired total vertical thrust as a function of momentum drag upon the VTOL aircraft, and (2) at least one of said second plurality of ducted lift fans to generate a fourth desired total vertical thrust as a function of the momentum drag, and

wherein a number of ducted lift fans is maintained at the intermediate throttle state in each of said first and second plurality of ducted lift fans during said transition flight from said hovering flight is less than, or equal to, the sum of the ducted lift fans of each respective plurality of ducted lift fans operated in the substantially full throttle state and the substantially zero throttle state.

2. The VTOL aircraft of claim 1, wherein the first plurality of ducted lift fans includes a first ducted lift fan, a second ducted lift fan, and a third ducted lift fan and the second plurality of ducted lift fans includes a fourth ducted lift fan, a fifth ducted lift fan, and a sixth ducted lift fan.

3. The VTOL aircraft of claim 2, wherein, during the hovering flight, each of said first, second, third, fourth, fifth, and sixth ducted lift fans are in the intermediate throttle state.

4. The VTOL aircraft of claim 2, wherein, during the transition flight, said first and fourth ducted lift fans are in the substantially full throttle state, said second and fifth ducted lift fans are in the intermediate throttle state, and said third and sixth ducted lift fans are in the substantially zero throttle state.

5. The VTOL aircraft of claim 4, wherein said second, third, fifth, and sixth ducted lift fans are throttled during transitional flight by adjusting each ducted lift fan'"'"'s revolutions per minute (RPM).

6. The VTOL aircraft of claim 4, wherein said second, third, fifth, and sixth ducted lift fans are throttled during transitional flight by adjusting blade pitch.

7. The VTOL aircraft of claim 4, wherein said third and sixth ducted lift fans are covered to decrease aerodynamic drag on the VTOL aircraft.

8. The VTOL aircraft of claim 2, wherein at least one of said first, second, third, fourth, fifth, or sixth ducted lift fans includes one or more adjustable vanes to provide thrust and to reduce drag.

9. The VTOL aircraft of claim 1, wherein each ducted lift fan in the substantially zero throttle state is covered to decrease aerodynamic drag on the VTOL aircraft.

10. The VTOL aircraft of claim 1, wherein the VTOL aircraft uses a hybrid of turbine and electric thrusting.

11. The VTOL aircraft of claim 1, wherein said forward thrust propulsion system includes a turbine.

12. The VTOL aircraft of claim 1, wherein each of the first and second plurality of ducted lift fans employs electric thrusting.

13. A vertical takeoff and landing (VTOL) aircraft having reduced peak power requirements during a transition flight between a hovering flight and a wingborne forward flight, the VTOL aircraft comprising:

a wing to provide lift during the wingborne forward flight and to provide an increasing amount of lift as airspeed increases during the transition flight;

a fuselage coupled with the wing, the fuselage being positioned to define a first wing portion on a first side of the fuselage and a second wing portion on a second side of the fuselage that is opposite that of the first side, wherein the first and second wing portions are substantially equal in length;

a forward thrust propulsion system coupled to said fuselage to produce a desired horizontal thrust during said wingborne forward flight and to accelerate the VTOL aircraft forward during said transition flight;

first, second, and third ducted lift fans positioned on the first wing portion to generate, in aggregate, a first desired total vertical thrust during said hovering flight, each of said first, second, and third ducted lift fans having an axis of rotation that is fixed and substantially vertical, each of said first, second, and third ducted lift fans being configured to be independently controlled between three throttle states, the three throttle states including a substantially full throttle state, an intermediate throttle state, and a substantially zero throttle state;

fourth, fifth, and sixth ducted lift fans positioned on the second wing portion to generate, in aggregate, a second desired total vertical thrust during said hovering flight, each of said fourth, fifth, and sixth ducted lift fans having an axis of rotation that is fixed and substantially vertical, each of said fourth, fifth, and sixth ducted lift fans being configured to be independently controlled between the three throttle states,

wherein, during said hovering flight and said transition flight, the VTOL aircraft is configured to independently control each of said first, second, third, fourth, fifth, and sixth ducted lift fans, and

wherein, during said transition flight from said hovering flight, the VTOL aircraft is configured to;

(1) to control said first and fourth ducted lift fans remain in the substantially full throttle state as a function of momentum drag upon the VTOL aircraft, (2) throttle said second and fifth ducted lift fans to the intermediate throttle state as a function of the momentum drag, and (3) throttle said third and sixth ducted lift fans to the substantially zero throttle state as a function of the momentum drag.

14. The VTOL aircraft of claim 13, wherein, during the hovering flight, each of said first, second, third, fourth, fifth, and sixth ducted lift fans are in the intermediate throttle state.

15. The VTOL aircraft of claim 13, wherein said second, third, fifth, and sixth ducted lift fans are throttled during transitional flight by (1) adjusting each ducted lift fan'"'"'s revolutions per minute (RPM) or (2) adjusting blade pitch.

16. The VTOL aircraft of claim 13, wherein said third and sixth ducted lift fans are covered to decrease aerodynamic drag on the VTOL aircraft.

17. The VTOL aircraft of claim 13, wherein at least one of said first, second, third, fourth, fifth, or sixth ducted lift fans includes one or more adjustable vanes to provide thrust and to reduce drag.

18. The VTOL aircraft of claim 13, wherein said forward thrust propulsion system includes a turbine and each of the first and second plurality of ducted lift fans employs electric thrusting.

19. A vertical takeoff and landing (VTOL) aircraft having reduced peak power requirements during a transition flight between a hovering flight and a wingborne forward flight, the VTOL aircraft comprising:

a wing to provide lift during the wingborne forward flight and to provide an increasing amount of lift as airspeed increases during the transition flight;

a fuselage coupled with the wing, the fuselage defining a longitudinal axis;

a forward thrust propulsion system coupled to said fuselage to produce a desired horizontal thrust during said wingborne forward flight and to accelerate the VTOL aircraft forward during said transition flight;

a first plurality of ducted lift fans positioned on a port side of the longitudinal axis to generate, in aggregate, a first desired total vertical thrust during said hovering flight, each of said first plurality of ducted lift fans having an axis of rotation that is fixed and substantially vertical, each of said first plurality of ducted lift fans being configured to be independently controlled between three throttle states, the three throttle states including a substantially full throttle state, an intermediate throttle state, and a substantially zero throttle state;

a second plurality of ducted lift fans positioned on a starboard side of the longitudinal axis to generate, in aggregate, a second desired total vertical thrust during said hovering flight, each of said second plurality of ducted lift fans having an axis of rotation that is fixed and substantially vertical, each of said second plurality of ducted lift fans being configured to be independently controlled between the three throttle states,

wherein, during said hovering flight and said transition flight, the VTOL aircraft is configured to independently control each of said first and second plurality of ducted lift fans,

wherein, during said transition flight from said hovering flight, the VTOL aircraft is configured to switch a throttle state of (1) at least one of said first plurality of ducted lift fans to generate a third desired total vertical thrust as a function of momentum drag upon the VTOL aircraft, and (2) at least one of said second plurality of ducted lift fans to generate a fourth desired total vertical thrust as a function of the momentum drag, and

wherein a number of ducted lift fans is maintained at the intermediate throttle state in each of said first and second plurality of ducted lift fans during said transition flight from said hovering flight is less than, or equal to, the sum of the ducted lift fans of each respective plurality of ducted lift fans operated in the substantially full throttle state and the substantially zero throttle state.

20. The VTOL aircraft of claim 19, wherein the first plurality of ducted lift fans includes a first ducted lift fan, a second ducted lift fan, and a third ducted lift fan and the second plurality of ducted lift fans includes a fourth ducted lift fan, a fifth ducted lift fan, and a sixth ducted lift fan.

21. The VTOL aircraft of claim 19, wherein, during the hovering flight, each of said first, second, third, fourth, fifth, and sixth ducted lift fans are in the intermediate throttle state.

22. The VTOL aircraft of claim 21, wherein, during the transition flight, said first and fourth ducted lift fans remain in the substantially full throttle state, said second and fifth ducted lift fans are throttled to the intermediate throttle state, and said third and sixth ducted lift fans are throttled to the substantially zero throttle state.