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Airplane Performance(18)Static Stability(5)Atmosphere and Basics(4)Atmosphere and Aircraft Basics(4)Dynamic Stability(2)

Airplane Performance

18 Questions

GATE→2026→Flight Mechanics→Airplane Performance

Q1

NAT[1 Mark]

An aircraft starts gliding in power-off condition at an altitude of 4 km. Given that the maximum lift to drag ratio of the aircraft is 15, the maximum glide range that the aircraft can cover, measured along the ground, is ________ km (rounded off to the nearest integer).

Explanation

GATE→2026→Flight Mechanics→Airplane Performance

Q2

NAT[2 Marks]

𝑊𝐴 and 𝑊𝐵 are the respective maximum take-off weights of an aircraft for two ambient air conditions given below. Condition A: 𝑝 = 1 bar, 𝑇 = 50 o C; Condition B: 𝑝 = 0.66 bar, 𝑇 = −30 o C If all other parameters relevant for take-off are kept the same in these two conditions, the ratio 𝑊𝐵 /𝑊𝐴 is ________ (rounded off to 3 decimal places).

Explanation

GATE→2025→Flight Mechanics→Airplane Performance

Q3

MSQ[2 Marks]

A general aviation airplane is gliding with a speed 𝑉𝑔 at minimum glide angle. Which of the following statements is/are true?

(A)

𝑉𝑔 is equal to the speed corresponding to the maximum lift to drag ratio of the airplane.

(B)

𝑉𝑔 increases with decreasing wing loading when all other parameters remain constant.

(C)

𝑉𝑔 increases with decreasing altitude when all other parameters remain constant.

(D)

𝑉𝑔 increases with increasing altitude when all other parameters remain constant.

Explanation

GATE→2025→Flight Mechanics→Airplane Performance

Q4

NAT[2 Marks]

A jet-powered airplane is steadily climbing at a rate of 10 m/s. The air density is 0.8 kg/m3, and the thrust force is aligned with the flight path. Using the information provided in the table below, the airplane’s thrust to weight ratio is ______ (rounded off to one decimal place). Airplane speed 80 m/s Lift coefficient, 𝐶𝐿 0.8 Aspect ratio 6 Oswald efficiency factor 0.8 Zero-lift drag coefficient 0.02

Explanation

GATE→2025→Flight Mechanics→Airplane Performance

Q5

NAT[2 Marks]

While taking off, the net external force acting on an airplane during the ground roll segment can be assumed to be constant. The airplane starts from rest. 𝑆𝐿𝑂 and 𝑉𝐿𝑂 are the ground roll distance and the lift-off speed, respectively. 𝛼𝑉𝐿𝑂 (𝛼> 0) denotes the airplane speed at 0.5 𝑆𝐿𝑂. Neglecting changes in the airplane mass during the ground roll segment, the value of 𝛼 is _____ (rounded off to two decimal places).

Explanation

GATE→2024→Flight Mechanics→Airplane Performance

Q6

MCQ[1 Mark]

The acceleration of a body travelling in a straight line is given by 𝑎= −𝐶1 −𝐶2𝑣2 where 𝑣 is the velocity, and 𝐶1, 𝐶2 are positive constants. Starting with an initial positive velocity 𝑣𝑜, the distance travelled by the body before coming to rest for the first time is:

(A)

1 2𝐶2 ln (1 + 𝐶2 𝐶1 𝑣𝑜 2)

(B)

1 2𝐶2 ln (1 −𝐶2 𝐶1 𝑣𝑜 2)

(C)

1 2𝐶2 ln(𝐶1 + 𝐶2𝑣𝑜 2)

(D)

1 2𝐶2 ln(1 + 𝐶2𝑣𝑜 2)

Explanation

GATE→2024→Flight Mechanics→Airplane Performance

Q7

NAT[1 Mark]

A particle acted upon by a constant force 4𝑖̂ + 𝑗̂ −3𝑘̂ N is displaced from point A with position vector 𝑖̂ + 2𝑗̂ + 3𝑘̂ m to point B with position vector 5𝑖̂ + 4𝑗̂ + 𝑘̂ m. The work done by this force is _______ J (answer in integer).

Explanation

GATE→2024→Flight Mechanics→Airplane Performance

Q8

NAT[2 Marks]

In the figure shown below, the magnitude of internal force in member BC is ___________ N (rounded off to 1 decimal place).

Explanation

GATE→2023→Flight Mechanics→Airplane Performance

Q9

MCQ[1 Mark]

An ideal glider has drag characteristics given by C = C + C , where D D 0 Di 2 C = KC is the induced drag coefficient, C is the lift coefficient, and K is a D L L i constant. For maximum range of the glider, the ratio C C is D 0 Di

(A)

1

(B)

1 3

(C)

3

(D)

3 2 Aerospace Engineering (AE)

Explanation

GATE→2023→Flight Mechanics→Airplane Performance

Q10

NAT[1 Mark]

An airplane weighing 40 kN is landing on a horizontal runway during which it is retarded by an arresting cable mechanism. The tension in the arresting cable at a given instant, as shown in the figure, is 100 kN. Assuming that the thrust from the engine continues to balance airplane drag, the magnitude of horizontal load factor is ________. (round off to one decimal place)

Explanation

GATE→2023→Flight Mechanics→Airplane Performance

Q11

NAT[1 Mark]

Airplane A and Airplane B are cruising at altitudes of 2 km and 4 km, respectively. The free stream density and static pressure at altitude 2 km are 1.01 kg/m3 and 79.50 kPa, respectively, and at altitude 4 km, they are 0.82 kg/m3 and 61.70 kPa, respectively. The differential pressure reading from the pitot-static tubes is 3 kPa for both the airplanes. Assuming incompressible flow, the ratio of cruise speeds of Airplane A to Airplane B is ______. (round off to two decimal places) Aerospace Engineering (AE)

Explanation

GATE→2023→Flight Mechanics→Airplane Performance

Q12

MCQ[2 Marks]

Consider a general aviation airplane with weight 10 kN and a wing planform area of 15 m2. The drag coefficient of the airplane is given as CD = CD0 + KCL2 with C = 0.025 and K = 0.05 . For level flight at an altitude where the density is D0 0.60 kg/m3 and thrust 1 kN, the maximum cruise speed is (rounded off to the nearest integer)

(A)

87 m/s

(B)

30 m/s

(C)

36 m/s

(D)

101 m/s Aerospace Engineering (AE)

Explanation

GATE→2023→Flight Mechanics→Airplane Performance

Q13

NAT[2 Marks]

An airplane with wing planform area of 20 m2 and weight 8 kN is flying straight and level with a speed of 100 m/s. The total drag coefficient is 0.026 and the air density is 0.7 kg/m3. The total thrust required to introduce a steady climb angle of 0.1 radians is ____ N. (round off to the nearest integer)

Explanation

GATE→2023→Flight Mechanics→Airplane Performance

Q14

NAT[2 Marks]

The maximum permissible load factor and the maximum lift force coefficient for an airplane is 7 and 2, respectively. For a wing loading of 6500 N/m2 and air density 1.23 kg/m3, the speed yielding the highest possible turn rate in the vertical plane is ___________ m/s. (round off to the nearest integer)

Explanation

GATE→2022→Flight Mechanics→Airplane Performance

Q15

MCQ[1 Mark]

The service ceiling of an airplane is the altitude

(A)

at which maximum rate of climb is 100 m/min

(B)

beyond which theoretically the airplane cannot sustain level flight

(C)

at which maximum power is required for flight

(D)

at which maximum rate of climb is 100 ft/min

Explanation

GATE→2022→Flight Mechanics→Airplane Performance

Q16

NAT[1 Mark]

An unpowered glider is flying at a glide angle of 10 degrees. Its lift-to-drag ratio is ______ (round off to two decimal places).

Explanation

GATE→2022→Flight Mechanics→Airplane Performance

Q17

MCQ[2 Marks]

Consider a conventional subsonic fixed-wing airplane. $e$ is the Oswald efficiency factor and $AR$ is the aspect ratio. Corresponding to the minimum $\frac{C_D}{C_L^{3/2}}$, which of the following relations is true?

(A)

C_D / C_L^2 = 1 / (pi e AR)

(B)

C_D / C_L^2 = 4 / (3 pi e AR)

(C)

C_D / C_L = 1 / (pi e AR)

(D)

C_D / sqrt(C_L) = 1 / sqrt(pi e AR)

Explanation

GATE→2022→Flight Mechanics→Airplane Performance

Q18

NAT[2 Marks]

A conventional airplane of mass $5000\text{ kg}$ is doing a level turn of radius $1000\text{ m}$ at a constant speed of $100\text{ m/s}$ at sea level ($g = 10\text{ m/s}^2$). The bank angle of the airplane is ______ degrees.

Explanation

Static Stability

5 Questions

GATE→2025→Flight Mechanics→Static Stability

Q19

MCQ[1 Mark]

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?

(A)

Left aileron: down; Right aileron: up; Rudder: left

(B)

Left aileron: down; Right aileron: up; Rudder: right

(C)

Left aileron: up; Right aileron: down; Rudder: left

(D)

Left aileron: up; Right aileron: down; Rudder: right

Explanation

GATE→2025→Flight Mechanics→Static Stability

Q20

MCQ[1 Mark]

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

(A)

Wing with a positive dihedral angle

(B)

Fuselage with a high wing

(C)

Fuselage with a low wing

(D)

Swept back wing

Explanation

GATE→2025→Flight Mechanics→Static Stability

Q21

MCQ[1 Mark]

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

(A)

The center of gravity of the airplane should be aft of the neutral point.

(B)

The center of gravity of the airplane should be forward of the neutral point.

(C)

The stability coefficient 𝜕𝐶𝑚 𝜕𝛼 (𝐶𝑚 is the airplane pitching moment coefficient and 𝛼 is the angle of attack) is positive.

(D)

The static margin is negative.

Explanation

GATE→2023→Flight Mechanics→Static Stability

Q22

MCQ[1 Mark]

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 and absolute angle of attack α?a mcg (Note: nose-up moment is positive.)

(A)

[Visual option A — diagram not captured in source JSON]

(B)

[Visual option B — diagram not captured in source JSON]

(C)

[Visual option C — diagram not captured in source JSON]

(D)

[Visual option D — diagram not captured in source JSON]

Explanation

GATE→2022→Flight Mechanics→Static Stability

Q23

MCQ[1 Mark]

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

(A)

It contributes to C_m_alpha < 0

(B)

It makes C_m_alpha = 0

(C)

It contributes to C_m_alpha > 0

(D)

It makes C_m0 > 0 and C_m_alpha > 0

Explanation

Atmosphere and Basics

4 Questions

GATE→2025→Flight Mechanics→Atmosphere and Basics

Q28

MCQ[1 Mark]

A general aviation airplane is flying at an altitude of 5000 m. The indicated airspeed is 250 km/h. Assume that there are no instrument errors and position errors. Neglecting compressibility effects, which one of the following options is FALSE?

(A)

The true airspeed is greater than 250 km/h.

(B)

The calibrated airspeed is 250 km/h.

(C)

The true airspeed is 250 km/h.

(D)

The equivalent airspeed is 250 km/h.

Explanation

GATE→2023→Flight Mechanics→Atmosphere and Basics

Q29

MSQ[2 Marks]

Consider the International Standard Atmosphere (ISA) with h being the dT geopotential altitude (in km) and being the temperature gradient (in K/m). dh  dT  Which of the following combination(s) of  h,  is/are as per ISA?  dh 

(A)

7, − 6.5  10−3 ( )

(B)

9, 4  10−3 ( )

(C)

(15, 0 )

(D)

35, 3  10−3 ( )

Explanation

GATE→2022→Flight Mechanics→Atmosphere and Basics

Q30

MSQ[1 Mark]

For International Standard Atmosphere (ISA) up to 11 km, which of the following statement(s) is/are true?

(A)

The hydrostatic/aerostatic equation is used

(B)

The temperature lapse rate is taken as -10^-2 K/m

(C)

The sea level conditions are taken as: pressure 1.01325 x 10^5 Pa; temperature 300 K; density 1.225 kg/m^3

(D)

Air is treated as a perfect gas

Explanation

GATE→2022→Flight Mechanics→Atmosphere and Basics

Q31

MSQ[2 Marks]

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

(A)

φ=0, θ=2, psi=0, α=2, β=0

(B)

φ=5, θ=0, psi=0, α=2, β=0

(C)

φ=0, θ=3, psi=0, α=3, β=5

(D)

φ=0, θ=5, psi=0, α=2, β=5

Explanation

Atmosphere and Aircraft Basics

4 Questions

GATE→2025→Flight Mechanics→Atmosphere and Aircraft Basics

Q28

MCQ[1 Mark]

A general aviation airplane is flying at an altitude of 5000 m. The indicated airspeed is 250 km/h. Assume that there are no instrument errors and position errors. Neglecting compressibility effects, which one of the following options is FALSE?

(A)

The true airspeed is greater than 250 km/h.

(B)

The calibrated airspeed is 250 km/h.

(C)

The true airspeed is 250 km/h.

(D)

The equivalent airspeed is 250 km/h.

Explanation

GATE→2023→Flight Mechanics→Atmosphere and Aircraft Basics

Q29

MSQ[2 Marks]

Consider the International Standard Atmosphere (ISA) with h being the dT geopotential altitude (in km) and being the temperature gradient (in K/m). dh  dT  Which of the following combination(s) of  h,  is/are as per ISA?  dh 

(A)

7, − 6.5  10−3 ( )

(B)

9, 4  10−3 ( )

(C)

(15, 0 )

(D)

35, 3  10−3 ( )

Explanation

GATE→2022→Flight Mechanics→Atmosphere and Aircraft Basics

Q30

MSQ[1 Mark]

For International Standard Atmosphere (ISA) up to 11 km, which of the following statement(s) is/are true?

(A)

The hydrostatic/aerostatic equation is used

(B)

The temperature lapse rate is taken as -10^-2 K/m

(C)

The sea level conditions are taken as: pressure 1.01325 x 10^5 Pa; temperature 300 K; density 1.225 kg/m^3

(D)

Air is treated as a perfect gas

Explanation

GATE→2022→Flight Mechanics→Atmosphere and Aircraft Basics

Q31

MSQ[2 Marks]

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

(A)

φ=0, θ=2, psi=0, α=2, β=0

(B)

φ=5, θ=0, psi=0, α=2, β=0

(C)

φ=0, θ=3, psi=0, α=3, β=5

(D)

φ=0, θ=5, psi=0, α=2, β=5

Explanation

Dynamic Stability

2 Questions

GATE→2026→Flight Mechanics→Dynamic Stability

Q32

MSQ[1 Mark]

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

(A)

Static stability of an aircraft is sufficient to guarantee its dynamic stability

(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

GATE→2025→Flight Mechanics→Dynamic Stability

Q33

MSQ[2 Marks]

A general aviation airplane is initially in steady and level flight. The stability coefficient 𝜕𝐶𝑚 𝜕𝑞 (𝐶𝑚 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?

(A)

The angle of attack of the horizontal tail increases.

(B)

The contribution of the horizontal tail to the airplane’s pitching moment about the center of gravity is more stabilizing.

(C)

The lift generated by the horizontal tail increases.

(D)

The contribution of the horizontal tail to the airplane’s pitching moment about the center of gravity is less stabilizing.

Explanation