GATE AE Static Stability & Control: Previous Year Questions

GATE AE 2026, Question 23 (1 mark, MSQ)

Flight Mechanics & Space Dynamics - Static Stability & Control

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

Official answer: B, C, D

GATE AE 2025, Question 22 (1 mark, MCQ)

Flight Mechanics & Space Dynamics - Static Stability & Control

A general aviation airplane is in steady and level flight. The airplane is prone to adverse yaw. Which one of the following options best describes the deflections of aileron and rudder to achieve a coordinated right turn?

1. Left aileron: down; Right aileron: up; Rudder: left
2. Left aileron: down; Right aileron: up; Rudder: right
3. Left aileron: up; Right aileron: down; Rudder: left
4. Left aileron: up; Right aileron: down; Rudder: right

Official answer: B

GATE AE 2025, Question 23 (1 mark, MCQ)

Flight Mechanics & Space Dynamics - Static Stability & Control

For a general aviation airplane, which one of the following has a destabilizing effect on its static roll stability?

1. Wing with a positive dihedral angle
2. Fuselage with a high wing
3. Fuselage with a low wing
4. Swept back wing

Official answer: C

GATE AE 2025, Question 25 (1 mark, MCQ)

Flight Mechanics & Space Dynamics - Static Stability & Control

To achieve longitudinal static stability of a general aviation airplane, which one of the following conditions should be satisfied?

1. The center of gravity of the airplane should be aft of the neutral point.
2. The center of gravity of the airplane should be forward of the neutral point.
3. The stability coefficient $\dfrac{\partial C_m}{\partial \alpha}$ ($C_m$ is the airplane pitching moment coefficient and $\alpha$ is the angle of attack) is positive.
4. The static margin is negative.

Official answer: B

GATE AE 2024, Question 27 (1 mark, MSQ)

Flight Mechanics & Space Dynamics - Static Stability & Control

In a conventional configuration airplane, the rudder can be used:

1. to overcome adverse yaw during a turning maneuver
2. to overcome yawing moment due to failure of one engine in a multi engine airplane
3. for landing the airplane in crosswind conditions
4. for enhancing longitudinal stability

Official answer: A, B, C

GATE AE 2024, Question 48 (2 marks, MSQ)

Flight Mechanics & Space Dynamics - Static Stability & Control

For an airplane having directional / weathercock static stability, which of the following options is/are correct?

1. The airplane when disturbed in yaw, from an equilibrium state, will experience a restoring moment
2. The variation of yawing moment coefficient ($C_n$) with sideslip angle ($\beta$) for the airplane will look like a straight line of positive slope through the origin in the $C_n$–$\beta$ plane (see figure)
3. The airplane will always tend to point into the relative wind
4. The airplane when disturbed in yaw will return to equilibrium state in a finite amount of time after removing the disturbance

Official answer: A, B, C

GATE AE 2023, Question 19 (1 mark, MCQ)

Flight Mechanics & Space Dynamics - Static Stability & Control

For a longitudinally statically stable aircraft, which one of the following represents the relationship between the coefficient of pitching moment about the center of gravity $C_{m_{cg}}$ and absolute angle of attack $\alpha_a$? (Note: nose-up moment is positive.)

Official answer: D

GATE AE 2022, Question 19 (1 mark, MCQ)

Flight Mechanics & Space Dynamics - Static Stability & Control

Regarding the horizontal tail of a conventional airplane, which one of the following statements is true?

1. It contributes to $C_{m_\alpha} < 0$
2. It makes $C_{m_\alpha} = 0$
3. It makes $C_{m_\alpha} > 0$
4. It makes $C_{m0} > 0$ and $C_{m_\alpha} > 0$

Official answer: A

GATE AE 2018, Question 15 (1 mark, MCQ)

Flight Mechanics & Space Dynamics - Static Stability & Control

The pilot of a conventional airplane that is flying steady and level at some altitude, deflects the port side aileron up and the starboard aileron down. The aircraft will then

1. pitch, nose up.
2. roll with the starboard wing up.
3. pitch, nose down.
4. roll with the port wing up.

Official answer: B

GATE AE 2018, Question 51 (2 marks, NAT)

Flight Mechanics & Space Dynamics - Static Stability & Control

A statically-stable aircraft has a $C_{L_\alpha} = 5$ (where the angle of attack, $\alpha$, is measured in radians). The coefficient of moment of the aircraft about the center of gravity is given as $C_{M,c.g} = 0.05 - 4\alpha$. The mean aerodynamic chord of the aircraft wing is 1 m. The location (positive towards the nose) of the neutral point of the aircraft from the center of gravity is ______ (in m, accurate to two decimal places).

Official answer: -0.81 to -0.79

GATE AE 2016, Question 59 (2 marks, NAT)

Flight Mechanics & Space Dynamics - Static Stability & Control

An aircraft is flying level in the North direction at a velocity of 55 m/s under cross wind from East to West of 5 m/s. For the given aircraft $C_{n\beta} = 0.012$/deg and $C_{n\delta r} = -0.0072$/deg, where $\delta r$ is the rudder deflection and $\beta$ is the side slip angle. The rudder deflection exerted by pilot is __________ degrees.

Official answer: 8.6 to 8.7

GATE AE 2014, Question 31 (1 mark, NAT)

Flight Mechanics & Space Dynamics - Static Stability & Control

The moment coefficient measured about the centre of gravity and about aerodynamic centre of a given wing-body combination are 0.0065 and -0.0235 respectively. The aerodynamic centre lies 0.06 chord lengths ahead of the centre of gravity. The lift coefficient for this wing-body is _____.

Official answer: 0.45 to 0.55

GATE AE 2014, Question 64 (2 marks, MCQ)

Flight Mechanics & Space Dynamics - Static Stability & Control

Consider the following four statements regarding aircraft longitudinal stability: P. $C_{M,cg}$ at zero lift must be positive. Q. $\partial C_{M,cg}/\partial\alpha_a$ must be negative ($\alpha_a$ is absolute angle of attack). R. $C_{M,cg}$ at zero lift must be negative. S. Slope of $C_L$ versus $\alpha_a$ must be negative. Which of the following combination is the necessary criterion for stick fixed longitudinal balance and static stability?

1. Q and R only
2. Q, R, and S only
3. P and Q only
4. Q and S only

Official answer: C