# Aircraft Performance Questions and Answers – Effect of WAT on Cruise Performance

This set of Aircraft Performance Multiple Choice Questions & Answers (MCQs) focuses on “Effect of WAT on Cruise Performance”.

1. The range factor is proportional to the square root of the initial cruising weight.
a) True
b) False

Explanation: The range factor is proportional to the square root of the initial cruising weight. This way we know that the range of the aircraft will increase with its weight. This implies that increase in weight increases the fuel availability for the cruise.

2. Which of the following is a correct statement?
a) Increase in initial weight of aircraft implies increase in fuel available for cruise
b) Decrease in initial weight of aircraft implies increase in fuel available for cruise
c) Increase in initial weight of aircraft implies decrease in fuel available for cruise
d) Increase in initial weight of aircraft does not have any effect on the fuel available for cruise

Explanation: Increase in initial weight of aircraft implies increase in fuel available for cruise. The increase in initial weight increases the range of the aircraft which results in increasing the aircraft efficiency.

3. What happens if the final fuel weight increases in an aircraft?
a) Fuel ratio increases
b) Fuel ratio is not effected
c) Range of the aircraft is increased
d) Range of the aircraft is decreased

Explanation: The following cases happen if the final fuel weight increases in an aircraft:

• The fuel ratio decreases as fuel ratio is the ratio of the initial fuel weight to final fuel weight
• The range of the aircraft flying will be reduced.

4. What is the relation between air temperature and the aircraft range?
a) Air temperature increases with increase in the aircraft range
b) Air temperature decreases with increase in the aircraft range
c) Air temperature increases with decrease in the aircraft range
d) Air temperature is not effected by the aircraft range

Explanation: The air temperature increases with increase in the aircraft range. This is because the true airspeed (TAS) increases and the aircraft flies further in the given time during which it burns same quantity of the fuel.

5. What is the relation between altitude and the aircraft range?
a) Altitude increases with increase in the aircraft range
b) Altitude decreases with increase in the aircraft range
c) Altitude increases with decrease in the aircraft range
d) Altitude is not effected by the aircraft range

Explanation: Altitude increases with increase in the aircraft range. As the altitude increases the ambient relative pressure decreases and it is further decreased due to the decreasing effect of the temperature with altitude.

6. The minimum drag speed in terms of equivalent airspeed is unaffected by the altitude.
a) True
b) False

Explanation: The minimum drag speed in terms of equivalent airspeed is unaffected by the altitude. Also there will be an increase in the true airspeed, mach number and minimum drag speed with decrease in altitude.

7. The best range is obtained at 1.416 Vmd.
a) True
b) False

Explanation: The best range is obtained at 1.316 Vmd. The optimum altitude will be attained by the aircraft at the optimum cruise airspeed and critical mach number so that the best range is flown at the highest airspeed.

8. Which of the following factors are inversely proportional to the range of the aircraft?
a) Altitude
b) Ambient relative pressure
c) Temperature
d) Mach number

Explanation: The ambient relative pressure is inversely proportional to the range of the aircraft. Altitude increases with increase in the aircraft range. The air temperature increases with increase in the aircraft range. This is because the true airspeed (TAS) increases and the aircraft flies further in the given time during which it burns same quantity of the fuel.

9. The range of the aircraft is increased if the aircraft is flown at a higher than optimum altitude.
a) True
b) False

Explanation: The range of the aircraft is decreased if the aircraft is flown at a higher than optimum altitude. This is caused due to exceeded mach number and increase in drag. To avoid this condition an aircraft is always preferred to fly below optimum altitude.

10. Specific fuel consumption effects the range of an aircraft.
a) True
b) False

Explanation: Specific fuel consumption effects the range of an aircraft. In general fuel flow laws the specific fuel consumption is assumed to be constant but in reality it effects the range of an aircraft. The range is decreased further with decrease in temperature and considering specific fuel consumption.

Sanfoundry Global Education & Learning Series – Aircraft Performance.

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