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Which of these statements about flutter are correct or incorrect?

I. If flutter occurs, IAS should be reduced.
II. Resistance to flutter increases with increasing wing stiffness.

  • A
    I is correct, II is incorrect.
  • B
    I is correct, II is correct.
  • C
    I is incorrect, II is correct.
  • D
    I is incorrect, II is incorrect.

Flutter of control surfaces is a divergent oscillatory motion of a control surface caused by its natural frequency, the interaction of aerodynamic forces, inertia forces and the stiffness of the structure.

To prevent flutter, stiffness should be increased and/or the CG of the control surface should be moved forward of the control hinge (in front of the torsion axis). A low stiffness would make a control surface more susceptible to flutter because a flexible structure will keep vibrating longer after a disruption than a stiff structure.

Aerodynamic forces increase with increasing speed. Consequently, the chances of flutter increase. Therefore, if flutter occurs, airspeed should be reduced.

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