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GATE 2026 AE – Question 23

Flight Mechanics & Space Dynamics · Static stability: stability and control derivatives, longitudinal, directional and lateral stability, hinge moments and stick forces · 1 mark · Multiple select

Which of the following statements is/are TRUE about the stability of an aircraft?

  1. Static stability of an aircraft is sufficient to guarantee its dynamic stability
  2. Static stability of an aircraft is related only to its initial tendency to return towards the equilibrium position from which it is disturbed
  3. An aircraft may be dynamically unstable even if it is statically stable
  4. Dynamic stability is related to the time history of aircraft motion after being disturbed from its equilibrium position

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Show answer and explanation

Correct answer: (B) Static stability of an aircraft is related only to its initial tendency to return towards the equilibrium position from which it is disturbed; (C) An aircraft may be dynamically unstable even if it is statically stable; (D) Dynamic stability is related to the time history of aircraft motion after being disturbed from its equilibrium position

Explanation

Static stability is only the initial tendency to return to equilibrium. Dynamic stability concerns the time history of the motion afterwards. An aircraft can be statically stable and still be dynamically unstable (for example with a growing oscillation), so static stability is not sufficient.