ANNA university previous question papers BE – Aircraft stability an control -VI Sem



B.E. Aeronautical Engineering, VI SEMESTER

                                               PART A   (10 X 2 = 20 Marks)




1.         Define static stability and dynamic stability.

2.         What do you mean by degree of freedom.

3.         What is meant by aileron reversal?

4.         What is snaking. Sketch the snaking motion of an aircraft.

5.         Difference between stick fixed and stick free.

6.         What is meant by `Weather Cock Stability’.

7.         What are the condition for longitudinal static stability.

8.         How is dihedral useful for lateral stability.

9.         What is porpoising mode?

10.       What is meant by phugoid oscillation? Explain.


                                         PART B   (5 X 16 = 80 Marks)



11 (a) Explain the significance of Routh’s discriminant.


(b) Drive an expression for the tail contribution to the pitching moment of an aircraft

if i? is the wing setting angle and it is the tail setting angle.


12 (a)   A wing body model is tested in a subsonic wind tunnel.

?L=0 = -1.50, at ? = 50, CL is 0.52. At ? = 10 and 7.880 CMcg are -0.01 and 0.05

respectively. The c.g location is 0.35c. iw = 0 and tail volume ratio is 0.34. The

tail  setting    is 2.70 and the tail lift curve slope is 0.1 per degree. ?0 = 0 and

d?/d? =  0.35. At ? = 80, calculated CMcg for the aircraft.

( OR )


(b)  i. Discuss in detail the power effects on longitudinal static stability.

ii For the problem in 12, find the neutral point location and also static margin.


13(a) Write short notes on

i. Variable incidence tail plane

ii. Adverse Yaw

( OR )


(b)    i.What is the coupling between rolling and yawing moments, explain with suitable


ii.What is the effect of running propeller on directional stability


14 (a)   Explain the following Phenomenon

i.Dutch Roll

ii.Spiral instability



( OR )


(b)   Write short notes on

i.Stability derivatives in longitudinal dynamic stability

ii.Stability quartic

iii.Spoils in lateral control


15 (a)   An airplane W/s = 3000 N/m2, V = 450 kmph flying at 6 km attitude  has the  characteristic equation in longitudinal mode of the form  (?2 + ? + 6) (3?2 + ? + 1) = 0. Find the period and time to dump and comment whether oscillation can be ignored.

( OR )

      (b)  Write short notes on

i.Tail volume ratio

ii.Controls of aircraft

iii.Rudder requirement in directional control



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