Aerospace Engineering Gate Yearwise 


Aerospace Engineering Gate 2021 Questions with Answer

Ques 14 GATE 2021

A two-cell wing box is shown in the figure. The cell walls are 1.5 mm thick and the shear modulus G = 27 GPa. If the structure is subjected to a torque of 12 kNm, then the wall AD will experience a shear stress of magnitude _______ MPa. (round off to one decimal place)


(2.1 to 2.5) is the correct answer.

Ques 15 GATE 2021

u(x, y) is governed by the following equation:
∂2u/∂x2 - 4(∂2u/∂x∂y) + 6(∂2u/∂y2) = x + 2y.
The nature of this equation is: _______.

A

linear

B

elliptic

C

hyperbolic

D

parabolic


(b) is the correct answer.

Ques 16 GATE 2021

An airplane weighing 5500 kg is in a steady level flight with a speed of 225 m/s. The pilot initiates a steady pull-up maneuver with a radius of curvature of 775 m. The location of the center of gravity (CG), center of pressure on the wing (CP), and point of action (T) of tail force are marked in the figure. Use g = 9.81 m/s2. Neglect drag on the tail and assume that tail force is vertical. Assuming the engine thrust and drag to be equal, opposite and collinear, the tail force is _______ kN. (round off to one decimal place)


(14.8 to 15.2) is the correct answer.

Ques 17 GATE 2021

Consider a jet transport airplane with the following specifications: Lift curve slope for wing-body ∂Cwb/∂αwb = 0.1/deg, Lift curve slope for tail ∂CLt/∂αt = 0.068/deg, Tail area St = 80 m2, Wing area S = 350 m2, Distance between mean aerodynamic centers of tail and wing-body lt = 28 m, Mean aerodynamic chord c̄ = 9 m, Downwash ε = 0.4α, Axial location of the wing-body mean aerodynamic center xac/c̄ = 0.25, Axial location of the center of gravity xcg/c̄ = 0.3. All axial locations are with respect to the leading edge of the root chord and along the body x-axis. Ignore propulsive effects. The pitching-moment-coefficient curve slope (Cmα) is _______ /deg. (round off to three decimal places)


(-0.025 to -0.023) is the correct answer.

Ques 18 GATE 2021

A jet aircraft has the following specifications: wing loading = 1800 N/m2, wing area = 30 m2, drag polar CD = 0.02 + 0.04CL2 and CL,max = 1.6.
Take the density of air at sea level as 1.225 kg/m3. The speed at which the aircraft achieves maximum endurance in a steady and level flight at sea level is _______ m/s. (round off to two decimal places)


(64.30 to 64.60) is the correct answer.

Ques 19 GATE 2021

An aircraft with twin jet engines has the following specifications:
Thrust produced (per engine) = 8000 N,
Spanwise distance between the two engines = 10 m, Wing area = 50 m2,
Wing span = 10 m, Rudder effectiveness, Cnδr = -0.002/deg,
Density of air at sea level = 1.225 kg/m3.
The rudder deflection, in degrees, required to maintain zero sideslip at 100 m/s in steady and level flight at sea level with a non-functional right engine is _______. (round off to two decimal places)


(6.50 to 6.60) is the correct answer.

Ques 20 GATE 2021

For a conventional fixed-wing aircraft in a 360° inverted vertical loop maneuver, what is the load factor (n) at the topmost point of the loop? Assume the flight to be steady at the topmost point.

A

n = 1

B

n < 1

C

n = -1

D

n > -1


(d) is the correct answer.

Ques 21 GATE 2021

For a conventional fixed-wing aircraft, which of the following statements are true?

A

Making Cmα more negative leads to an increase in the frequency of its short-period mode.

B

Making Cmq more negative leads to a decreased damping of the short-period mode.

C

The primary contribution towards Clp is from the aircraft wing.

D

Increasing the size of the vertical fin leads to a higher yaw damping.


(a,c,d) is the correct answer.

Ques 22 GATE 2021

Which of the following statement(s) is/are true?

A

Service ceiling is higher than absolute ceiling for a piston-propeller aircraft.

B

For a given aircraft, the stall speed increases with an increase in altitude.

C

Everything else remaining the same, a tailwind increases the range of an aircraft.

D

For a jet aircraft constrained to fly at constant altitude, there exists an altitude where its range is maximum.


(b,c,d) is the correct answer.

Ques 23 GATE 2021

A conventional fixed-wing aircraft, with a horizontal tail and vertical fin, in steady and level flight is subjected to small perturbations. Which of the following statement(s) is/are true?

A

Vertical fin has a stabilizing effect on the lateral stability of the aircraft.

B

Vertical fin has a destabilizing effect on the directional stability of the aircraft.

C

Presence of wing anhedral increases the lateral stability of the aircraft.

D

Horizontal tail has a stabilizing effect on the longitudinal static stability of the aircraft.


(a,d) is the correct answer.

Ques 24 GATE 2021

Consider the velocity field V⃗ = (2x + 3y)î + (3x + 2y)ĵ. The field is _______.

A

divergence-free and curl-free

B

curl-free but not divergence-free

C

divergence-free but not curl-free

D

neither divergence-free nor curl-free


(b) is the correct answer.

Ques 25 GATE 2021

The figure shows schematics of wave patterns at the exit of nozzles A and B operating at different pressure ratios.

Nozzles A and B, respectively, are said to be operating in: _______.

A

over-expanded mode and under-expanded mode

B

under-expanded mode and perfectly expanded mode

C

perfectly expanded mode and under-expanded mode

D

under-expanded mode and over-expanded mode


(a) is the correct answer.

Ques 26 GATE 2021

The shape of a supersonic diffuser that slows down a supersonic flow to subsonic flow is _______.

A

converging

B

diverging

C

diverging-converging

D

converging-diverging


(d) is the correct answer.

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