This document discusses reconfigurable flight control design for a combat flying wing aircraft with multiple control surfaces. It describes the aircraft and its control surfaces. It analyzes how failures of ailerons, elevators, or rudders can be addressed through control surface redundancy and reconfiguration techniques like control allocation. Simulation results show that with control reconfiguration, the aircraft can still maintain safe flight and perform missions despite surface failures.

1. Reconfigurable Flight Control Design for combat
flying wing with multiple control surface
Akhil S
S7 ME
Roll no 10
GECBH

2. Contents
• Introduction
• Aircraft description
• Analysis
• Principle and implementation
• Simulation
• Conclusion

3. Introduction
Aircraft control surface failures – 3 types
Lock-in-place (LIP)
Loss-of-effectiveness (LOE)
Float
When these failures occurs, they will affect
• Control capability of the Aircraft
• Endanger flight safety

4. Aircraft Description
Inboard elevons (IEs) and Outboard elevons (OEs)
Position limit : -300 to 300
Split drag rudders (SDRs) and Spoiler slot deflectors
(SSDs)
Position limit : 00 to 600
Flight attitude control system

5. Elevons and drag rudders
Elevons
Elevons are aircraft control surfaces that combine the functions of
the elevator (used for pitch control) and the aileron (used for roll control)
Drag Rudders
A rudder is a device used to steer. On an aircraft the rudder is used
primarily to counter adverse yaw and p-factor and is not the
primary control used to turn the airplane

6. Adverse yaw and p-factor
• Adverse yaw : Natural and undesirable tendency for
an aircraft to yaw in the opposite direction of a roll.
P-factor(asymmetric blade effect) : It is an aerodynamic phenomenon
experienced by a moving propeller, that is responsible for asymmetrical
relocation of the propeller's center of thrust when aircraft is at a high angle
of attack

7. Elevator Control System (Primary)
• Drive or climb
• Rotate around lateral axis
• Forward and aft. Action
• Push / pull rod or cable

8. Aileron control system
• Prevent side slip, skid
• Bangking / rolling
• Differential mechanism
• Greater up than down

9. Rudder control system
A rudder is a device used to steer.
On an aircraft the rudder is used
primarily to counter adverse
yaw and p-factor and is not the
primary control used to turn the
airplane

10. Analysis of Flight Control Reconfiguration
Characteristics and Capability
• In conventional configuration
Roll control Aileron
Pitch control Elevator
Yaw control Rudder
What happens when any of these fails ?

11. Need for Reconfiguration(Redundancy design)
1. When Aileron fails ?
Differential deflection of elevator achieves reconfiguration
2. When elevator fails ?
Symmetric deflection of aileron can provide pitching thereby
control capability
3. When rudder fails ?
Fulfill yaw control only rolling

12. How combat flying differs from other
conventional Aircrafts

13. Contrast of attainable moment subsets (right
SSD in failure)

14. Principle and Implementation of Flight
Control Reconfiguration
• Flight control reconfiguration approaches
• Implement of flight control reconfiguration based on control
allocation
• Principle of control allocation
• Adjust strategies of control reconfiguration

15. Flight control reconfiguration approaches
multiple mode switch
pseudo inverse Eigen structure
assignment
adaptive control
sliding mode control
control allocation

16. Implementation of flight control
reconfiguration based on control allocation

17. Principle of control allocation
Based certain optimization calculations to allocate 3-axis control
So when no failures condition is considered, it will be as

18. Adjust strategies of control reconfiguration
It was made on an assumption – Control surface failure detection system can work well
When the kth control surface has a
1. LIP failure

19. Strategies cont…
2. LOE failure
3. Float failure

20. Allocation results after the right SDR is
subjected to three typical failures

21. Stimulation and Analysis
• Taking LIP failure for example to stimulate flight control reconfiguration
• Due to LIP failure makes 3-axis control capabilities decrease more
Numerical Stimulation
• Six degree of freedom non linear dynamic model
• Initial flight condition is a horizontal flight at 4000m
• Speed is taken as 204 m/s
• Roll angle = 250
• Pitch angle = 300
• Yaw angle = -300
• Stimulation step time = 0.02s

22. Time histories of attitude angles

23. Time histories of normal control surfaces

24. Conclusion
1) Having different reconfiguration characteristics as compared with the
conventional aircraft, the combat flying wing is fitted with multiple control
surfaces, and has redundant control surfaces in three axes. Therefore, it has
basic conditions to reconfigure.
2) The flight control reconfiguration approach based on control allocation does
not need to modify the dynamic inversion flight control law of the aircraft, just
via appropriately modifying the control allocation block, and then it can
comparatively effectively realize the reconfigurable design during control
surface failures. So it is suitable for the modular design of the complicate flight
control system for the flying wing.
3) Despite the presence of control surface failures, the combat flying wing using
this flight control reconfiguration approach can still guarantee its flight safety,
and can comparatively better perform some flight missions with certain
amplitude

25. Questions ???

26. References
• Reconfigurable Flight Control Design for Combat Flying Wing
withMultiple Control Surfaces by WANG Lei, WANG Lixin
• Wikipedia

27. THANK YOU