Correct Answer : design take-off gross weight
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.
Correct Answer : crew, payload and fuel weights
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.
Correct Answer : 1.076
Explaination :
Correct Answer : 79kg
Correct Answer : empty
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…
Correct Answer : empty and payload weight
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.
Correct Answer : 0.3-0.7
Explanation : Empty weight fraction has typical range from 0.3-0.7 according to historical guidelines. Higher empty weight fraction indicates more weight. The range given is based on typical guideline and hence in some cases it can go beyond 0.7 as well.
Correct Answer : Flying boat-0.77, Jet trainer-0.65
Explanation : Here, we need to think logically. The flying boat has more empty weight than the typical jet trainer aircraft. A flying boat needs to carry additional load of boat hull compare to a typical jet trainer aircraft.
Correct Answer : lowest possible empty weight fraction
Explanation : One of the most important and crucial requirements of military aircraft is minimum possible weight. The lower the weight lesser the drag and lesser the thrust requirement. Hence, a military aircraft should as lightest as possible.
Correct Answer : [A] is false but [R] is true
Explaination : Military aircraft has to be lighter in weight is true. Flying boats are heavier than that of the typical military aircraft. The reason behind it is that flying boat has to carry extra weight of hull. Hence, [A] and [R] both correct but [R] is not the correct reason for given assertion.
Correct Answer : W0 = Wcrew + Wpayload + Wfuel + Wempty
Explaination : The design take-off gross weight is the total weight of the aircraft. It consists of every possible segments either it is payload or fuel. Hence, it can be seen as the addition of the all possible weight in an aircraft.
Correct Answer : False
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.
Correct Answer : sum of mission fuel, reserve fuel and trapped fuel
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.
Correct Answer : The required amount of the fuel for mission depends on aerodynamics, SFC, mission itself etc
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.
Correct Answer : weight at end of the phase to that of at the begin
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.
Correct Answer : Both [A] and [R] are true and [R] is the correct reason for [A]
Explaination : The low-level strike mission has to fly at just few km off the ground. During such flight the L/D ratio – aerodynamic efficiency is reduced in drastic manner. Since flight needs to be at higher velocity more thrust will be required. This will increase fuel consumption as compare to high altitude flight. Hence, both [A] and [R] are true and [R] is the correct reason for [A].
Correct Answer : 1020kg
Explaination : 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.
Correct Answer : fuel-fraction method
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.
Correct Answer : Division of mission profile into number of phases and finding individual phase fuel fraction
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.
Correct Answer : loiter maneuver
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.
Correct Answer : additional cruise fuel of half hour
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.
Correct Answer : 0.9261
Correct Answer : Will increase
Correct Answer : Climb Endurance
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.
Correct Answer : Simple cruise mission profile
Explaination : The diagram is representing altitude vs time relation. It is also called ‘mission profile’ of an aircraft. This mission profile consist only basic phases of flight. Hence, it can be termed as simple cruise mission profile.
Correct Answer : Calculating individual mission segment weight fraction
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.
Correct Answer : Breguet range formula
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.
Correct Answer : 150lb
Explaination : Aircraft gross weight W0 = 10000lbFuel weight fraction at the end of mission = Wx/W0 = 0.985Here, 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 – (Wx / W0)= 1 – 0.985 = 0.015Hence, fuel consumed during this mission = Wf = W0 * 0.015 = 10000 * 0.015 = 150lb.
Correct Answer : Wf / W0 = 1 – (Wx / W0)
Explaination : 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.
Correct Answer : Initial guess of take-off gross weight based on mission specifications
Explanation : Lofting is definition of skin. Drafting is related to drawing. Based mission specification, crew and payload weight is determined. After which next step is to make an initial guess of take-off gross weight.
Correct Answer : To find crew and payload weight so initial W0 can be guess
Explanation : Take-off gross weight is determined in stepwise manner. It is an iterative process in which we first find weight of crew, passenger, payloads etc. After which next step is to guess gross weight based on crew and payload weight.
Correct Answer : Gross weight will increase
Correct Answer : 2157lb
Explanation : Given crew and payload = 180kg,Empty weight fraction We / W0 = 0.48Fuel weight is 0.7 times empty weight.Hence, Wf = 0.7*WeHence, Wf / W0 = 0.7*We / W0 = 0.7*0.48 = 0.336Gross weight of aircraft is,W0 = Wcrew + Wpayload + Wfuel + WemptyBy re-arranging,W0 = Wcrew + Wpayload / [1 – (Wf/ W0) – (We / W0)] = 180 / [1-0.336-0.48] = 978.26kg = 2157.06lb.
Correct Answer : fuel, crew, payload and empty weight
Explanation : Total take-off gross weight is nothing but the sum of all the possible aspects of an aircraft. Hence, it will depend on fuel weight, crew and payload weight and also on empty weight.
Correct Answer : 4430kg
Explaination : Given crew weight = 150kg, payload weight = 600kgFuel weight fraction Wf / W0 = 1.06[1 – Wx/W0],Now from fuel fraction method,Wx / W0 = multiplication of each phase fraction= 0.975*0.98*0.96*0.8*0.96*0.97= 0.6833Now,Wf / W0 = 1.06 * [1 – (Wx / W0)] = 0.3357Empty weight fraction We / W0 = 0.481Gross weight of aircraft is,W0 = Wcrew + Wpayload + Wfuel + WemptyBy re-arranging,W0 = Wcrew + Wpayload / [1 – (Wf/ W0) – (We / W0)] = 150 + 600 / [1-0.3357-0.495] = 4430kg
