Aircraft stall protection system

Patent metadata

Field	Value
Publication number	US-9703293-B2
Application number	US-201514840483-A
Country	US
Kind code	B2
Filing date	Aug 31, 2015
Priority date	Aug 31, 2015
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

An aircraft stall protection system and method include calculating a first angle of attack and a second angle of attack based on aircraft configuration and environmental conditions, the first angle of attack being greater than the second angle of attack. The system and method limit the actual aircraft angle of attack to the first angle of attack for a predetermined period of time and thereafter the system and method limit the actual aircraft angle of attack to the second angle of attack. The system and method allow the aircraft operator or pilot to extract maximum performance from the aircraft for any given set of flight conditions, without the risk of stalling or remaining in a high drag state for a prolonged period of time. This system and method are suitable for use in conjunction with a stall warning system.

First claim

What is claimed is:

1. A method of controlling an aircraft at high angles of attack, the method comprising:
measuring an actual angle of attack (α) for an aircraft;
calculating a short term alpha (α1);
calculating a long term alpha (α2);
calculating an activation alpha (α3);
determining if the actual angle of attack (α) is greater than α3;
limiting the actual angle of attack (α) to the short term alpha (α1) by activating at least one of an elevator, a stabilizer, a thrust lever, and a spoiler;
evaluating if a predetermined criteria has been met; and
limiting the actual angle of attack (α) to the long term alpha (α2), by activating at least one of an elevator, a stabilizer, a thrust lever, and a spoiler, if the predetermined criteria have been met.

2. The method of claim 1 , wherein the short term alpha (α1) is equal to or less than alpha stall.

3. The method of claim 1 , wherein the long term alpha (α2) is less than the short term alpha (α1).

4. The method of claim 3 , wherein the long term alpha (α2) may be coincident with the ceiling of the aircraft operational envelope or a predetermined angle of attack associated with optimum aerodynamic performance.

5. The method of claim 1 , wherein the activation alpha (α3) is less than the short term alpha (α1).

6. The method of claim 5 , wherein the activation alpha (α3) may be less than, equal to, or greater than the long term alpha (α2).

7. The method of claim 1 , wherein the predetermined criteria are dependent upon aircraft configuration, aircraft state, environmental flight condition, control input and time.

8. The method of claim 7 , wherein the aircraft configuration is dependent upon flap position, landing gear position, speedbrake position, gross weight, center of gravity, and system settings dependent upon environmental flight conditions.

9. The method of claim 7 , wherein the aircraft state is dependent upon the angle of attack, pitch angle, bank angle, airspeed, Mach, load factor, pitch rate, and angle of attack rate.

10. The method of claim 7 , wherein the environmental flight condition is dependent upon temperature and altitude.

11. The method of claim 7 , wherein the control input is dependent upon thrust, control inceptor position, and control inceptor force.

12. The method of claim 11 , wherein the control input is initiated at the activation alpha (α3).

13. The method of claim 11 , wherein the control input includes moving one or more aircraft longitudinal and lateral controls.

14. The method of claim 1 , wherein the short term alpha (α1) is determined based on aircraft configuration, aircraft state, and environmental flight condition.

15. The method of claim 1 , wherein the long term alpha (α2) is determined based on aircraft configuration, aircraft state, and environmental conditions.

16. The method of claim 1 , wherein the activation alpha (α3) is determined based on one of the short term alpha (α1), the long term alpha (α2), or other predefined calculations based on aircraft state.

17. A system for limiting the angle of attack of an aircraft approaching high angles of attack, the system comprising:
a stall protection processor operatively coupled to a memory;
at least one aircraft configuration sensor operatively coupled to the stall protection processor, the aircraft configuration sensor providing aircraft configuration data to the stall protection processor;
at least one altitude sensor operatively coupled to the stall protection processor, the at least one altitude sensor providing altitude data to the stall protection processor;
at least one temperature sensor operatively coupled to the stall protection processor, the at least one temperature sensor providing temperature data to the stall protection processor; and
a software program stored in the memory and executable on the processor, the software program including a first routine that calculates a short term alpha (α1), a long term alpha (α2) and an activation alpha (α3), the short term alpha (α1) being greater than the long term alpha (α2) and the activation alpha (α3) being less than, equal to, or greater than the long term alpha (α2),
wherein the stall protection processor instructs a flight control computer to limit the actual aircraft angle of attack to the short term alpha (α1), by activating at least one of an elevator, a stabilizer, a thrust lever, and a spoiler, for predetermined maximum period of time and the stall protection processor instructs the flight control computer to limit the actual aircraft angle of attack to the long term alpha (α2), by activating at least one of an elevator, a stabilizer, a thrust lever, and a spoiler, after the predetermined maximum period of time has expired or a separate predetermined criteria has been met.

18. The system of claim 17 , wherein the short term alpha (α1) is equal to or less than alpha stall.

19. The system of claim 17 , wherein the long term alpha (α2) is equal to the ceiling of the aircraft operational envelope or a predetermined angle of attack associated with optimum aerodynamic performance.

20. The system of claim 17 , wherein the activation alpha (α3) is less than the first maximum angle of attack (α1).

21. The system of claim 17 , wherein the short term alpha (α1), long term alpha (α2), and activation alpha (α3) are calculated based on aircraft configuration, aircraft state, and environmental flight condition.

22. The system of claim 17 , wherein the at least one aircraft configuration sensor comprises one or more of an angle of attack indicator, a flap position indicator, a slat position indicator, an airspeed indicator, an icing indicator, a thrust lever position indicator, a gear position indicator, a speed brake position indicator, a gross weight indicator, a load factor indicator, a center of gravity position indicator, a pitch rate indicator, a bank angle indicator, and an angle of attack rate indicator.

23. The system of claim 17 , wherein the altitude sensor comprises one or more of a barometric altitude sensor and a radio altimeter sensor.

24. The system of claim 17 , wherein the temperature sensor comprises one or more of a static air temperature sensor and a total air temperature sensor.

25. The system of claim 17 , further comprising a terrain collision avoidance system that is operatively connected to the stall protection processor, the terrain collision avoidance system providing terrain data to the stall protection processor.

26. An aircraft including an angle of attack limiting system, the aircraft comprising:
a flight control computer coupled to an elevator actuator, to a stabilizer actuator, to a thrust actuator, and to a spoiler actuator;
a stall protection processor operatively coupled to a memory and operatively coupled to the flight control computer;
at least one aircraft configuration sensor operatively coupled to the stall protection processor, the aircraft configuration sensor providing aircraft configuration data to the stall protection processor;
at least one altitude sensor operatively coupled to the stall protection processor, the at least one altitude sensor providing altitude data to the stall protection processor;
at least one temperature sensor operatively coupled to the stall protection processor, the at least one temperature sensor providing temperature data to the stall protection processor; and
a software program stored in the memory and executable on the process

Assignees

• Boeing Co

Inventors

• Leopold David Daniel
• Wilson Douglas Lee
• Mills Nikos Damian

Classifications

• B64D45/00 Primary

  Aircraft indicators or protectors not otherwise provided for · CPC title

• B64C9/00

  Adjustable control surfaces or members, e.g. rudders (trimming stabilising surfaces B64C5/10) · CPC title

• B64C13/16

  actuated automatically, e.g. responsive to gust detectors · CPC title

• B64C19/02

  Conjoint controls · CPC title

• G05D1/0816 Primary

  to ensure stability · CPC title