# Aircraft Performance Questions and Answers – Climb and Descent Performance with Mixed Power Plants

This set of Aircraft Performance Multiple Choice Questions & Answers (MCQs) focuses on “Climb and Descent Performance with Mixed Power Plants”.

1. Which of the following is the correct performance equation for mixed power-plants?
a) Emaxsinγ2=$$\Big[\frac{\lambda}{u}+\tau \Big]-\frac{1}{2}[u^2+u^{-2}]$$
b) Emaxsinγ2=$$\Big[\frac{\lambda}{u}-\tau \Big]-\frac{1}{2}[u^2-u^{-2}]$$
c) Emaxsinγ2=$$\Big[\frac{\lambda}{u}+\tau \Big]-\frac{1}{2}[u^2-u^{-2}]$$
d) Emaxsinγ2=$$\Big[\frac{\lambda}{u}-\tau \Big]-\frac{1}{2}[u^2+u^{-2}]$$

Explanation: The correct performance equation for mixed power-plants is given by the formula Emaxsinγ2=$$\Big[\frac{\lambda}{u}+\tau \Big]-\frac{1}{2}[u^2+u^{-2}]$$ where u is airspeed, γ is the angle at which the force is acting on the aircraft and τ is dimensionless thrust and Emax is endurance.

2. The best gradient of climb is attained at _____________
a) airspeed below maximum drag speed
b) airspeed below maximum power speed
c) airspeed below minimum power speed
d) airspeed below minimum drag speed

Explanation: The best gradient of climb is attained at airspeed below minimum drag speed. The best rate of climb is attained at airspeed above minimum drag speed. The actual airspeeds will be a function of excess propulsive thrust.

3. The best rate of climb is attained at _____________
a) airspeed above maximum drag speed
b) airspeed above maximum power speed
c) airspeed above minimum power speed
d) airspeed above minimum drag speed

Explanation: The best gradient of climb is attained at airspeed below minimum drag speed. The best rate of climb is attained at airspeed above minimum drag speed. The actual airspeeds will be a function of excess propulsive thrust.

4. At which speed the maximum rate of climb occurs?
a) u=0.76
b) u=0.98
c) u=1
d) u=2

Explanation: The maximum rate of climb occurs at the airspeed u=0.76 m/sec. The best gradient of climb is attained at airspeed below minimum drag speed. The best rate of climb is attained at airspeed above minimum drag speed. The actual airspeeds will be a function of excess propulsive thrust.

5. The rate of climb of an aircraft is measured by _______
a) variometer
b) altimeter
c) pitot-static prob
d) gyroscope

Explanation: The rate of climb of an aircraft is measured by variometer. The best gradient of climb is attained at airspeed below minimum drag speed. The best rate of climb is attained at airspeed above minimum drag speed.
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6. The advanced ratio is given by _______________
a) J=$$\frac{D}{nV}$$
b) J=$$\frac{nV}{D}$$
c) J=$$\frac{V}{nD}$$
d) J=$$\frac{n}{VD}$$

Explanation: The advanced ratio is given by J=$$\frac{V}{nD}$$ where J is advance ratio, V is velocity and D is propeller diameter and n is rotational speed. Propeller efficiency is depended on advanced ratio.

7. What is the use of partial climbs?
a) It is used for calculating climb rate
b) It is used for calculating gradient of climb
c) It is used for calculating speed
d) It is used for calculating velocity

Explanation: The use of partial climbs is to calculate rate of climb. The other method for calculating climb rate is level accelerated method. Level accelerated is best suitable for thrust producing engines. Partial climb is best suitable for power-producing engines.

8. The partial climb is best suitable for power-producing engines.
a) True
b) False

Explanation: The use of partial climbs is to calculate rate of climb. The other method for calculating climb rate is level accelerated method. Level accelerated is best suitable for thrust producing engines. Partial climb is best suitable for power-producing engines.

9. Level accelerated is best suitable for thrust producing engines.
a) True
b) False

Explanation: The use of partial climbs is to calculate rate of climb. The other method for calculating climb rate is level accelerated method. Level accelerated is best suitable for thrust producing engines. Partial climb is best suitable for power-producing engines.

10. There is an alternative method to calculate climb rate and gradient.
a) True
b) False

Explanation: The alternative method is to measure the maximum excess thrust and power by level flight accelerations. The other method for calculating climb rate is level accelerated method.

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