GATE AE Flight Dynamics: Previous Year Questions

GATE AE 2025, Question 38 (2 marks, MSQ)

Flight Mechanics & Space Dynamics - Flight Dynamics

A general aviation airplane is initially in steady and level flight. The stability coefficient $\dfrac{\partial C_m}{\partial q}$ ($C_m$ is the airplane pitching moment coefficient and $q$ is the pitch rate) is negative. The airplane is perturbed with a small nose-up constant pitch rate. Assume that the horizontal tail does not stall during the perturbation, and unsteady effects are neglected. When compared to steady and level flight condition, which of the following statements is/are true during the perturbed motion?

1. The angle of attack of the horizontal tail increases.
2. The contribution of the horizontal tail to the airplane's pitching moment about the center of gravity is more stabilizing.
3. The lift generated by the horizontal tail increases.
4. The contribution of the horizontal tail to the airplane's pitching moment about the center of gravity is less stabilizing.

Official answer: A, B, C

GATE AE 2024, Question 62 (2 marks, NAT)

Flight Mechanics & Space Dynamics - Flight Dynamics

For a general aviation airplane, one of the complex conjugate pair of eigenvalues for longitudinal dynamics is given by $-0.039 \pm 0.0567\,i$ (in SI units). If the system is disturbed to excite only this mode, the time taken for the amplitude of response to become half in magnitude is _______ s (rounded off to 1 decimal place).

Official answer: 17.7 to 17.9

GATE AE 2022, Question 45 (2 marks, MSQ)

Flight Mechanics & Space Dynamics - Flight Dynamics

For a conventional airplane in straight, level, constant velocity flight condition, which of the following condition(s) is/are possible on Euler angles $(\phi, \theta, \psi)$, angle of attack ($\alpha$) and the sideslip angle ($\beta$)?

1. $\phi = 0^o, \theta = 2^o, \psi = 0^o, \alpha = 2^o, \beta = 0^o$
2. $\phi = 5^o, \theta = 0^o, \psi = 0^o, \alpha = 2^o, \beta = 0^o$
3. $\phi = 0^o, \theta = 3^o, \psi = 0^o, \alpha = 3^o, \beta = 5^o$
4. $\phi = 0^o, \theta = 5^o, \psi = 0^o, \alpha = 2^o, \beta = 5^o$

Official answer: A

GATE AE 2018, Question 65 (2 marks, NAT)

Flight Mechanics & Space Dynamics - Flight Dynamics

An aircraft wind tunnel model, having a pitch axis mass moment of inertia ($I_{yy}$) of 0.014 kg-m$^2$, is mounted in such a manner that it has pure pitching motion about its centre of gravity, where it is supported through a frictionless hinge. If the pitching moment ($M$) derivative with respect to angle of attack ($\alpha$), denoted by $M_\alpha$, is $-0.504$ N-m/rad and the pitching moment ($M$) derivative with respect to pitch rate ($q$), denoted by $M_q$, is $-0.0336$ N-m/(rad/s), the damping ratio of the resulting motion due to an initial disturbance in pitch angle is approximately _________ (accurate to three decimal places).

Official answer: 0.195 to 0.205

GATE AE 2016, Question 31 (1 mark, MCQ)

Flight Mechanics & Space Dynamics - Flight Dynamics

The damping ratio in phugoid motion for gliders is usually less compared to powered aircraft because

1. gliders are unpowered.
2. gliders are light.
3. lift to drag ratio is higher for gliders.
4. gliders fly at low speed.

Official answer: C

GATE AE 2016, Question 61 (2 marks, MCQ)

Flight Mechanics & Space Dynamics - Flight Dynamics

The aircraft velocity (m/s) components in body axes are given as $[u, v, w] = [100, 10, 10]$. The air velocity (m/s), angle of attack (deg) and sideslip angle (deg) in that order are

1. [120, 0.1, 0.1]
2. [100, 0.1, 0.1]
3. [100.995, 0.1, 5.73]
4. [100.995, 5.71, 5.68]

Official answer: D

GATE AE 2016, Question 62 (2 marks, MCQ)

Flight Mechanics & Space Dynamics - Flight Dynamics

The Dutch roll motion of the aircraft is described by following relationship $$\begin{bmatrix}\Delta\dot{\beta}\\ \Delta\dot{r}\end{bmatrix} = \begin{bmatrix} -0.26 & -1 \\ 4.49 & -0.76 \end{bmatrix}\begin{bmatrix}\Delta\beta\\ \Delta r\end{bmatrix}$$ The undamped natural frequency (rad/s) and damping ratio for the Dutch roll motion in that order are:

1. 4.68, 1.02
2. 4.49, 1.02
3. 2.165, 0.235
4. 2.165, 1.02

Official answer: C

GATE AE 2014, Question 34 (1 mark, MCQ)

Flight Mechanics & Space Dynamics - Flight Dynamics

In most airplanes, the Dutch roll mode can be excited by applying

1. a step input to the elevators
2. a step input to the rudder
3. a sinusoidal input to the aileron
4. an impulse input to the elevators

Official answer: B