Aircraft Design Questions and Answers Part-3

1. The subsequent step after the requirements in conceptual design phase is _____
a) design take-off gross weight
b) control
c) stability
d) lofting

Answer: a
Explanation: The Conceptual design often begins with the mission requirements of the aircraft. Once the requirements are set, next step is to estimate the design take-off gross weight. This is done due to the fact that weight will directly affect the vital performance parameters.

2. The “Design take-off gross weight” and “maximum take-off weight” are always interchangeable.
a) True
b) False

Answer: b
Explanation: During the conceptual design process design take-off gross weight is calculated based on requirements. Based on the mission profile we can use terms interchangeably in general. However, it is not the case for each and every mission.

3. Design take-off gross weight includes ______
a) only fuel weight
b) only crew weight
c) only payload weight
d) crew, payload and fuel weights

Answer: d
Explanation: Design take-off gross weight is total weight of the aircraft to be designed. It is the combination of all possible weights of an aircraft. Hence, from the given options, it is easy to say that it includes every type of weight

4. Avionics systems are an example of ____ weight.
a) empty
b) crew
c) passenger
d) payload

Answer: a
Explanation: Crew weight is the weight of all crew members. Passenger weight includes the weight of the passenger. Empty weight will include avionics, subsystems, power plant etc…

5. Take-off gross weight of an aircraft is summation of _____
a) empty and payload weight
b) fuel, payload, crew, empty and miscellaneous weight
c) fuel and crew weight
d) only passenger and crew weight

Answer: a
Explanation: Typically, take-off gross weight is the maximum possible weight of aircraft during take-off. It includes weight of crew, passenger, fuel, empty and some miscellaneous weight.

6. In general, the fuel weight is represented by a fraction of total take-off weight.
a) True
b) False

Answer: a
Explanation: For given Aircraft, we know the typical values for crew and payload. However, we do not know fuel weight as well as empty weight. Hence, they are represented in terms of the fraction of total take-off weight. This can simplify the calculation.

7. A general aviation aircraft is flying with crew load of 115lb, payload of 220lb and fuel weight of 100lb. Find out the design take-off gross weight of the aircraft, given 95lb empty weight.
a) 530lb
b) 241lb
c) 435lb
d) 500lb

Answer: a
Explanation: Given,
Crew load = 115lb
Payload weight = 220lb
Fuel weight = 100lb
Empty weight = 95lb
Now, the design take – off gross weight is given by,
W0 = Wcrew + Wpayload + Wfuel + Wempty
W0 = 115+220+100+95
So, W0 = 530lb.

8. A jet airliner aircraft is flying with crew load of 150kg, payload of 520lb and fuel weight of 500lb. Find out the empty weight if design take-off gross weight of the aircraft is given 1525lb.
a) 79kg
b) 79lb
c) 170lb
d) 355lb

Answer: a
Explanation: Given,
Design take-off gross weight, W0 = 1525lb
Crew load = 150kg = 150*2.205lb = 330.693lb
Payload weight = 520lb, fuel weight = 500lb
Now the design take – off gross weight is given by,
W0 = Wcrew + Wpayload + Wfuel + Wempty
1525 = 330.693 + 520 + 500 + Wempty
So, Wempty = 174.307lb = 79 kg.

9. Cessna 172R has total gross weight of the 1110.98kg with fuel capacity of 210 kg and weight of crew and passenger is 125kg. Find out empty weight fraction.
a) 775.98kg
b) 69.84kg
c) 0.6984
d) 0.6984lb

Answer: c
Explanation: Given,
Design take-off gross weight, W0 = 1110.98kg
Crew and payload weight = 125kg
Fuel weight = 210kg.
Here, first we need to find the empty weight and then we can find empty weight fraction.
Now the design take – off gross weight is given by,
W0 = Wcrew + Wpayload + Wfuel + Wempty
1110.98 = 125 + 210 + Wempty
So, Wempty = 775.98kg
Hence, empty weight fraction = (Wempty / W0) = 775.98/1110.98 = 0.6984.

10. A Jet transport aircraft is flying with crew load of 175kg, payload of 1400kg and fuel weight of 500kg. Find out Fuel to empty weight fraction, if design take-off gross weight of the aircraft is 5600lb.
a) 1.076
b) 0.1831
c) 0.196
d) 0.1418

Answer: a
Explanation: Given,
Design take-off gross weight, W0 = 5600lb = 2539.6825kg
Crew load = 175kg
Payload weight = 1400kg, fuel weight = 500kg
Now the design take – off gross weight is given by,
W0 = Wcrew + Wpayload + Wfuel + Wempty
2539.682 = 175+ 1400 + 500 + Wempty
So, Wempty = 464.682kg
Fuel weight fraction = Wfuel / W0
Empty weight fraction = Wempty / W0
Now fuel to empty weight fraction = Wfuel / Wempty = 500/464.682 = 1.076.