1. Copyright 2008-Purdue University
AAE 556 Aeroelasticity
Control effectiveness-part 2
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring

2. Copyright 2008-Purdue University
Summary
Control surfaces generate less lift because the control deflection creates a nose-down pitching moment as it generates lift.
At a special dynamic pressure (a combination of airspeed and altitude) the deflection of an aileron creates more downward lift due to nose-down deflection than upward lift
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring

3. Two different ways to compute the pressure distribution resultants
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring

4. Copyright 2008-Purdue University
Force equivalence definition producing the same effect with different models
Solve for the distance d from the AC = Ld d e
A lift force at d produces the same result as a lift force and moment at the AC
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring

5. Resultant lift position
mid-chord
small
flap
Distance aft of 1/4 chord
big flap AC
Flap to chord ratio
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring

6. Reversal in terms of divergence parameters
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring

7. Copyright 2008-Purdue University
lift effectiveness expression when divergence dynamic pressure is less than reversal
<1
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring

8. Plots of aileron effectiveness as functions of reversal q when R<1
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring

9. Aileron effectiveness when R>1
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring

10. Summary aileron deflection creates ...
(a shift in zero lift line due to "camber" created by control surface deflection)
twisting downward if lift vector due control deflection is behind section shear center
downward
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring

11. Torsional divergence a classical model
Idealizations
11/23/2018
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AAE556 – Spring

12. Copyright 2008-Purdue University
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring

13. Copyright 2008-Purdue University
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring

14. Copyright 2008-Purdue University
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring

15. Copyright 2008-Purdue University
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring

16. Copyright 2008-Purdue University
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring

17. Copyright 2008-Purdue University
Divergence
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring

18. Copyright 2008-Purdue University
11/23/2018
Copyright 2008-Purdue University
AAE556 – Spring