Question 1
A jet transport aircraft has fuel storage of 1200kg. It has completed taxi phase and preparing for take-off. At the end of the taxing, it has fuel fraction of 0.98. Determine how much fuel is available after taxing. Given take-off gross weight is 9000kg.
A. 1020kg
B. 180kg
C. 1800kg
D. 2240lb
View Answer
Answer: Option A
Explanation:
Given,Aircraft take-off gross weight W0 = 9000kg, Fuel storage = 1200kgFuel weight fraction after taxi = Wtaxi/W0 = 0.98Here, there is no provision of reserved fuel is mentioned so, we are neglecting reserve fuel fraction.Now, from fuel fraction method,Used fuel weight fraction is Wf / W0 = 1 – (Wtaxi/W0)= 1 – 0.98 = 0.02Hence, fuel used during taxing mission = Wf = W0 * 0.02 = 180kg.Now, remaining fuel weight = fuel storage – fuel used during taxi= 1200 – 180 = 1020kg.
Question 2
A prop-driven aircraft having fuel weight of 650kg. Now, aircraft is taxing on runway, after which it has fuel fraction of 0.975. Determine fuel used during taxing of aircraft, if W0 = 5000kg.
A. 225kg
B. 125kg
C. 221kg
D. 125.65lb
View Answer
Answer: Option B
Explanation:
Given,Aircraft take-off gross weight W0 = 5000kg,Fuel weight fraction after taxi = Wtaxi/W0 = 0.975Here, there is no provision of reserved fuel is mentioned. So, we are neglecting reserve fuel fraction.Now, from fuel fraction method,Used fuel weight fraction is Wf /W0 = 1 – (Wtaxi/W0)= 1 – 0.975 = 0.025Hence, fuel used during taxing mission = Wf = W0 * 0.025 = 125kg.
Question 3
A prop-driven aircraft is cruising with 90% propeller efficiency. If, range of aircraft is 7*106 ft, C=1.38*10-7 s-1 and L/D = 14 then what will be the fuel weight fraction for the cruise?
A. 0.9216
B. 0.9261
C. 0.9289
D. 0.9365
View Answer
Question 4
According to FAA, general aviation aircraft requires reserved fuel in terms of _____
A. additional cruise fuel of half hour
B. additional climb fuel
C. no provision is mentioned in FAA
D. additional taxi-way fuel of three hours
View Answer
Answer: Option A
Explanation:
For a typical aircraft, it is mandatory to carry reserved fuel. This reserved fuel can be utilized at the time of emergency. According to FAA regulation, for general aviation category we need to provide additional cruise fuel so that it can be used to improve endurance by half hour.
Question 5
An airliner with take-off gross weight of 2100kg is cruising with fuel weight fraction of 0.280. Then, what will be the weight of fuel (Wf)?
A. 588kg
B. 588lb
C. 90kg
D. 28lb
View Answer
Answer: Option A
Explanation:
Given,Aircraft take-off gross weight W0 = 2100kg,Fuel weight fraction = Wf/W0 = 0.28Hence, fuel weight Wf = (Wf/W0) * W0 = 0.28*2100 = 588kg.
Question 6
Aircraft fuel weight does not include reserved fuel fraction.
A. True
B. False
View Answer
Answer: Option B
Explanation:
The total fuel carried by aircraft consists of usable fuel and reserved fuel. Useable fuel is provided for completing a particular mission. Reserved fuel is for an emergency.
Question 7
Choose appropriate option for cruise mission leg weight fraction.
A. Breguet endurance formula
B. Breguet range formula
C. Cruise invert method
D. Breguet approximation
View Answer
Answer: Option B
Explanation:
Breguet endurance formula is used to determine the endurance of aircraft. Range formula is used to calculate range for respective mission. In simple sizing method we consider that the cruise is ending with descent. Also, we assume that cruise range has accounted for descent as well. Hence, we use range formula to determine fuel fraction.
Question 8
Choose the correct statement based on fuel weight.
A. Fuel required is solely based on mission profile
B. Fuel weight is independent of SFC of engine
C. The required amount of the fuel for mission depends on aerodynamics, SFC, mission itself etc
D. Fuel requirement is not affected by any factors
View Answer
Answer: Option C
Explanation:
Total aircraft fuel requirement does not solely depend on mission profile. Fuel weight for mission depends on number of factors such as mission profile, aerodynamics, SFC of engine etc.
Question 9
For given mission leg ‘n’, mission leg weight fraction is _____
A. Wn / Wn-1
B. Wn / Wn-2
C. Wn-1 / Wn+1
D. Wn / Wn+1
View Answer
Answer: Option A
Explanation:
For any mission leg or mission phase, mission fuel fraction is ratio of fuel weight at the end and at beginning of each phase. Hence, if it is mission phase n then, (n-1) will be the phase before nth phase. Hence, correct answer is Wn / Wn-1.
Question 10
Fuel consumption during cruise is affected by wetted area.
A. True
B. False
View Answer
Answer: Option A
Explanation:
Fuel conception or fuel fraction during cruise segment will be affected by the overall aerodynamic efficiency. The aerodynamic efficiency is ratio of lift and drag. Lift is directly affected by the wetted area, which affects L/D. As a result, it will affect fuel fraction during cruise mission phase.
Question 11
How will you determine climb mission weight fraction?
A. Climb Endurance
B. Loiter
C. Always constant
D. Cruise Speed
View Answer
Answer: Option A
Explanation:
Climb phase usually measured by rate of climb. Climb endurance formula is used to determine the endurance of aircraft at climb phase. Typically we can find climb weight fraction from historic time line however in some cases we can also use climb endurance formula to determine fuel fraction.
Question 12
If all the other factors remain unchanged and only aerodynamic efficiency of the aircraft is doubled then, what will be the cruise segment fuel weight fraction?
A. Will increase
B. Will decrease
C. Will remain same
D. Will be independent of aerodynamic efficiency
View Answer
Question 13
In A/C, we provide reserve fuel for _____
A. loiter maneuver
B. weight reduction
C. to increase weight
D. there is no provision for it
View Answer
Answer: Option A
Explanation:
Every aircraft has a particular mission profile to follow. Fuel requirement are based on it. In some cases, aircraft need to loiter for more time. If some additional fuel is nor provided then, in such cases aircraft will not be able to perform any additional loiter. Hence, for such cases and also for emergencies we provide reserved fuel.
Question 14
Mission leg fuel fraction is defined by _____
A. weight at end of the phase to that of at the begin
B. weight at end of the phase to that of at the begin
C. weight of phase at the begin
D. weight at end of the phase
View Answer
Answer: Option A
Explanation:
Mission leg is nothing but the individual mission segment or phase. Mission leg fuel fraction is weight of the fuel at end of the phase to that of at beginning of that mission leg.
Question 15
The typical method for determining fuel weight used is called as _____
A. fuel-fraction method
B. fuel-invert method
C. fuel interpolation
D. fuel fraction mining
View Answer
Answer: Option A
Explanation:
Fuel- fraction method is a simple method for estimating fuel fraction of the aircraft. It is the most commonly used method due to the simplicity of calculations.
Question 16
Total fuel weight of aircraft is ______
A. mission fuel only
B. sum of mission fuel, reserve fuel and trapped fuel
C. sum of trapped and mission fuel
D. reserved fuel only
View Answer
Answer: Option B
Explanation:
The fuel weight of aircraft is sum of useable mission fuel, reserved fuel and trapped fuel. Mission fuel is the actual useable fuel for the respective mission. Trapped fuel is unusable fuel which has been trapped in supply lines or which cannot be used.
Question 17
What is the working principle of ‘fuel-fraction’ method?
A. Division of mission profile into number of phases and finding individual phase fuel fraction
B. Division of mission profile into 3 phases only
C. Calculating fuel fraction for each stage
D. Assuming any value for fuel fraction
View Answer
Answer: Option A
Explanation:
The fuel fraction method is mostly used method for fuel weight fraction. This is very simple method in which we divide whole mission profile into number of mission phases. After that we calculate individual mission segment weight fraction. And based on which we determine approximated fuel weight.
Question 18
What will be the total fuel weight fraction for x-number of mission phases?
A. Wf / W0 = 1 – (Wx / W0)
B. Wf / W0 = 1 + (Wx / W0)
C. Wf / W0 = 1 / (Wx / W0)
D. Wf / W0 = 1 + (Wx / W0)
View Answer
Answer: Option A
Explanation:
The fuel-fraction method is used to determine total fuel weight fraction.According to which if there are x – number of mission phases in mission profile then the total fuel weight fraction is given by,Wf / W0 = 1 – (Wx / W0)Since, reserved fuel is not mentioned we can neglect it.
Question 19
What will be the weight fraction of the aircraft at final mission segment w.r.t. W0?
A. Multiplication of individual weight fraction
B. Division of individual weight fraction
C. Addition of individual weight fraction
D. Subtraction of individual weight fraction
View Answer
Answer: Option A
Explanation:
We can divide whole mission profile of aircraft into number of mission phases or legs. Fuel fraction at each mission segment will be fuel weight at end of phase to that of beginning. Hence, if there are z – number of mission phase then, final mission phase fraction will be multiplication of individual weight fraction which will give weight fraction w.r.t. take-off gross weight W0
Question 20
Which of the following is part of the fuel-fraction method?
A. Developing lofting
B. Empty weight fraction
C. Calculating individual mission segment weight fraction
D. Finding volume ratio
View Answer
Answer: Option C
Explanation:
Lofting is a vital part of preliminary design phase. The fuel fraction method is very simple and basic approximation method. Here, mission profile is divided and then for every individual phase we calculate mission segment weight fraction.