Category: Aircraft Performance Objective Questions

250+ TOP MCQs on Aircraft Force Systems and Answers

Aircraft Performance Multiple Choice Questions on “Aircraft Force Systems”.

1. Inertial forces from the mass of the aircraft and its acceleration.
a) True
b) False
Answer: a
Clarification: Inertial forces from the mass of the aircraft and its acceleration. The inertial forces act in the velocity axis system. Inertial forces are a result of gravitational forces, aerodynamic forces and propulsive forces. Numerically it is given by Fa+Fg+Fp=Fi.

2. Gravitational force is the product of mass of the aircraft and its acceleration.
a) True
b) False
Answer: a
Clarification: Gravitational force is the product of mass of the aircraft and its acceleration. It is represented by Fg. It is described as the downward pulling force of the earth. It is also referred as W=mg. It can also be written as Fg=mg=W.

3. The aerodynamic forces arise from the relative motion between the aircraft and the air mass in which it is flying.
a) True
b) False
Answer: a
Clarification: The aerodynamic forces arise from the relative motion between the aircraft and the air mass in which it is flying. It is represented by Fa. The aerodynamic forces include lift, weight, drag and thrust.

4. In which of the following terms the forces of aircraft must be considered?
a) Aircraft weight, flight mach number, altitude
b) Aircraft weight, airspeed, altitude, temperature
c) Aircraft weight, flight mach number, temperature
d) Aircraft weight, airspeed, altitude
Answer: a
Clarification: An aircraft forces are described in terms of aircraft weight, flight mach number, altitude rather than in terms of aircraft weight, airspeed, altitude, temperature. In this the altitude becomes a basic variable of the aerodynamic forces.

5. Which of the following are the forces that are concerned with the performance of an aircraft?
a) Lift, drag, weight
b) Lift, drag, side force
c) Lift, drag
d) Lift, drag, weight, side force
Answer: b
Clarification: Lift, drag, side force are the forces that are concerned with the performance of an aircraft. The lift and drag forces play a crucial role in the performance of an aircraft.

6. Which of the following is the correct formula for reynolds number?
a) Re=(frac{rho Vl}{mu})
b) Re=(frac{PVl}{mu})
c) Re=(frac{rho mu l}{V})
d) Re=(frac{rho Vl}{P})
Answer: a
Clarification: The correct formula for reynolds number is given by Re=(frac{rho Vl}{mu}) where Re is Reynolds number, ρ is density of the fluid, V is the velocity of the fluid, l is the length of the fluid and μ is the dynamic viscosity of the fluid.

7. The range of Re in the typical flight is ___________
a) 106 to 109
b) 105 to 109
c) 106 to 108
d) 106 to 1010
Answer: a
Clarification: The range of Re in the typical flight is 106 to 109. The mathematical formula for reynolds number is given by Re=(frac{rho Vl}{mu}) where Re is Reynolds number, ρ is density of the fluid, V is the velocity of the fluid, l is the length of the fluid and μ is the dynamic viscosity of the fluid.

8. What is the range of mach number for a conventional aircraft?
a) 0 to 3.2
b) 0 to 2.2
c) 0 to 4.2
d) 0 to 1.2
Answer: b
Clarification: 0 to 2.2 the range of mach number for a conventional aircraft. The values of mach number can increase beyond 2.2 but arise a special case of problems. To avoid any kind of troubles an aircraft must always fly at a mach number below 2.2.

9. What is the critical mach number for most subsonic aircraft?
a) Around 0.8
b) Around 2
c) Around 1
d) Around 1.5
Answer: a
Clarification: For most subsonic aircraft the critical mach number occurs typically at mach number 0.8. At this mach number the local flow at points on the aircraft becomes supersonic and shock waves begin to form.

10. In transonic region the mach number affects the aerodynamic characteristics.
a) True
b) False
Answer: a
Clarification: In transonic region the mach number affects the aerodynamic characteristics. Transonic region is a region in which the mach number ranges from 0.8 to 1.2. It depends on the airspeed of the aircraft and temperature of surroundings.

11. Below the mach number 0.5 the flow is considered as incompressible flow.
a) True
b) False
Answer: a
Clarification: Below the mach number 0.5 the flow is considered as incompressible flow. In the region 0.5 < M < 0.8 the flow becomes compressible and significant but leads to small changes in the lift and drag characteristics.

250+ TOP MCQs on Effect of WAT on Cruise Performance and Answers

Aircraft Performance Multiple Choice Questions 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

Answer: a
Clarification: 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

Answer: a
Clarification: 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

Answer: d
Clarification: 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

Answer: a
Clarification: 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

Answer: a
Clarification: 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

Answer: a
Clarification: 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

Answer: a
Clarification: 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

Answer: b
Clarification: 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

Answer: b
Clarification: 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

Answer: a
Clarification: 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.

250+ TOP MCQs on Effect on the Take-off Distances of Flight Variables and Answers

Aircraft Performance Questions on “Effect on the Take-off Distances of Flight Variables”.

1. There are two atmospheric effects on the take-off distances.
a) True
b) False

Answer: a
Clarification: There are two atmospheric effects on the take-off distances. They are:

  • The take-off with reference to the indicated airspeed
  • The output of the power plant which is roughly proportional to relative density.

2. Which of the following is the correct formula of ground run distance with respect to aircraft weight?
a) SG=(frac{WV_{LOF}^2}{2g[F_N+D+mu (W-L)]_{0.7V_{LOF}^2}})
b) SG=(frac{WV_{LOF}^2}{2g[F_N-D+mu (W-L)]_{0.7V_{LOF}^2}})
c) SG=(frac{WV_{LOF}^2}{2g[F_N+D-mu (W-L)]_{0.7V_{LOF}^2}})
d) SG=(frac{WV_{LOF}^2}{2g[F_N-D-mu (W-L)]_{0.7V_{LOF}^2}})

Answer: d
Clarification: The formula for the ground run distance with respect to aircraft weight is given by SG=(frac{WV_{LOF}^2}{2g[F_N-D-mu (W-L)]_{0.7V_{LOF}^2}}) where W is weight, V is velocity, L is lift, D is drag, g is acceleration due to gravity and μ is runway coefficient of rolling friction.

3. Which of the following is the correct formula of airborne distance with respect to aircraft weight?
a) SA=(frac{W}{(F_N-D)_{av}}Big{frac{V_{2}^2+V_{LOF}^2}{2g}+35Big})
b) SA=(frac{W}{(F_N+D)_{av}}Big{frac{V_{2}^2+V_{LOF}^2}{2g}+35Big})
c) SA=(frac{W}{(F_N+D)_{av}}Big{frac{V_{2}^2-V_{LOF}^2}{2g}+35Big})
d) SA=(frac{W}{(F_N-D)_{av}}Big{frac{V_{2}^2-V_{LOF}^2}{2g}+35Big})

Answer: d
Clarification: The airborne distance is given by SA=(frac{W}{(F_N-D)_{av}}Big{frac{V_{2}^2-V_{LOF}^2}{2g}+35Big}) where

  • W is weight
  • D is drag
  • G is acceleration due to gravity
  • V is velocity
  • FN is normal force.

4. Which of the following statement is not correct?
a) The airborne distance is given by SA=(frac{W}{(F_N-D)_{av}}Big{frac{V_{2}^2-V_{LOF}^2}{2g}+35Big})
b) The ground run distance is given by SG=(frac{WV_{LOF}^2}{2g[F_N-D-mu (W-L)]_{0.7V_{LOF}^2}})
c) The ground run distance is directly proportional to aircraft weight
d) The ground run distance is directly proportional to aircraft drag

Answer: d
Clarification: The correct statements are as follows:

  • The airborne distance is given by SA=(frac{W}{(F_N-D)_{av}}Big{frac{V_{2}^2-V_{LOF}^2}{2g}+35Big})
  • The ground run distance is given by SG=(frac{WV_{LOF}^2}{2g[F_N-D-mu (W-L)]_{0.7V_{LOF}^2}})
  • The ground run distance is directly proportional to aircraft weight.

5. The increase in aircraft weight by 10% will result in increase in aircraft ground run distance by 20%.
a) True
b) False

Answer: a
Clarification: The increase in aircraft weight by 10% will result in increase in aircraft ground run distance by 20%. The ground run distance is given by SG=(frac{WV_{LOF}^2}{2g[F_N-D-mu (W-L)]_{0.7V_{LOF}^2}}). From the formula it is known that the ground run distance is directly proportional to aircraft weight.

6. What is the use of the headwind?
a) To change the datum height
b) To change the datum temperature
c) To change the fuel ratio
d) To change the pressure ratio

Answer: a
Clarification: The headwind is used to change the datum speed of the take-off. This headwind effects the ground run speed. For every 10% change in headwind, there is 20% decrease in the ground run distance.

7. The headwind only effects in the kinematic energy in the case of the airborne distance.
a) True
b) False

Answer: a
Clarification: The headwind only effects in the kinematic energy in the case of the airborne distance. The headwind is used to change the datum speed of the take-off. This headwind effects the ground run speed. For every 10% change in headwind, there is 20% decrease in the ground run distance.

8. There is no effect of runway conditions on the airborne distance.
a) True
b) False

Answer: a
Clarification: There is no effect of runway conditions on the airborne distance. The runway condition includes:

  • Slope of the runway
  • Friction of the runway.

9. Which of the following will not effect the ground run distance?
a) TAS
b) EAS
c) Weight
d) Thrust
Answer: d
Clarification: The ground run distance is not effected by thrust. The factors that affect ground run distance are:

10. The ground run distance is effected by the inverse of the density and directly proportional to square of the true airspeed.
a) True
b) False

Answer: a
Clarification: The ground run distance is effected by the inverse of the density and directly proportional to square of the true airspeed. The ground run distance is not effected by thrust. The ground run distance is not effected by thrust. The factors that affect ground run distance are: TAS, EAS and density.

11. The effect of TAS on airborne distance is half that of the ideal case.
a) True
b) False

Answer: a
Clarification: The effect of TAS on airborne distance is half that of the ideal case. The airborne distance is given by SA=(frac{W}{(F_N-D)_{av}}Big{frac{V_{2}^2-V_{LOF}^2}{2g}+35Big}) where W is weight

  • D is drag
  • G is acceleration due to gravity
  • V is velocity
  • FN is normal force.

250+ TOP MCQs on Fixed-Wing Aircraft – Mission Profile and Answers

Aircraft Performance Multiple Choice Questions on “Fixed-Wing Aircraft – Mission Profile ”.

1. Civilian aircraft mainly on _________
a) defense
b) maneuvering
c) climb of altitude
d) coverage of distance
Answer: d
Clarification: Civilian aircraft mainly on distance coverage. Civilian aircraft looks for making profit by managing fuel consumption. This is because it doesn’t need to perform any attacking maneuvers. A civilian aircraft is more preferred when it gives guaranteed safety for the passengers and also by offering luxury facilities.

2. There are two types of mission profiles.
a) True
b) False
Answer: a
Clarification: There are two types of mission profiles. They are civilian mission profile and military mission profile. A civilian mission profile on fuel consumption and distance covered whereas a military mission profile on endurance and speed.

3. Military aircraft is designed to be luxurious and entertaining.
a) True
b) False
Answer: b
Clarification: A military aircraft is not designed to be luxurious and entertaining. Military aircraft mainly on military maneuvers. A military aircraft is generally preferred to maintain high altitude and perform various military maneuvers at higher altitudes.

4. The surveillance aircraft on ________
a) maneuvering
b) attack
c) high altitude and cover long distance
d) speed
Answer: c
Clarification: The purpose of surveillance aircraft is to maintain high altitude and cover an estimated distance of flight in the given period of time. A surveillance aircraft doesn’t need to perform any kind of maneuvering or attack other aircrafts.

5. What is the full form of STOL?
a) Short take-off and landing
b) Straight take-off and landing
c) Smart take-off and landing
d) Supportive take-off and landing
Answer: a
Clarification: The full form of STOL is Short take-off and landing. STOL must also be able to stop within 1,500 feet after crossing a 50-foot obstacle on landing. This kind of landing is helpful in harsh landing.

6. What is the full form of VTOL?
a) Variety take-off and landing
b) Vertical take-off and landing
c) Various take-off and landing
d) Valuable take-off and landing
Answer: b
Clarification: The full form of VTOL is Vertical take-off and landing. This kind of aircraft can take-off, hover and land vertically. Helicopters come under this category.

7. What is the full form of STVOL?
a) Smart take-off and variety landing
b) Smart take-off and vertical landing
c) Short take-off and variety landing
d) Short take-off and vertical landing
Answer: d
Clarification: The full form of STVOL is Short take-off and vertical landing. Mostly fixed-wing aircrafts come under this category. STOVL performance of an aircraft is the ability of an aircraft to take off and clear a 50-foot obstruction in a distance of 1,500 feet from beginning the takeoff run and land vertically.

8. What is the full form of CTOL?
a) Commercial take-off and landing
b) Convenient take-off and landing
c) Convectional take-off and landing
d) Confidential take-off and landing
Answer: c
Clarification: The full form of CTOL is Convectional take-off and landing. These aircrafts take-off and land involving the use of runway. Passenger aircraft come under this category.

9. What effect does high density altitude have on aircraft performance?
a) Decrease in climb performance
b) Increase in climb performance
c) Increase in take-off performance
d) Increase in engine performance
Answer: a
Clarification: There will be a decrease in climb performance with increase in high density altitude. On increase of altitude there would be a decrease in density which results in decrease in power output of engine and airfoil efficiency, as a result there will be a decrease in climb increase performance.

10. What is meant by reserves?
a) Fuel used when the route is extended
b) Fuel used to take-off
c) Fuel used when in emergency
d) Fuel used while cruising
Answer: c
Clarification: The fuel used while the flight is in emergency is known as reserves. Minimum reserves are usually set by the regulatory authorities although the operator may increase them at his/her choice.

11. The stages of mission profile of a commercial aircraft are _______
a) Take-off → climb → cruise → descent → landing
b) Take-off → descent → climb → cruise → landing
c) Take-off → cruise → climb → descent → landing
d) Take-off → climb → descent → cruise → landing
Answer: a
Clarification: The stages of mission profile of a commercial aircraft are Take-off → climb → cruise → descent → landing. An aircraft firstly take-off from ground at the initial airport. At an altitude of 50 foot it starts climbing to higher altitudes, next it starts to cruise to some designated distance and later it starts descending to lower altitude. Finally at an altitude of 50 foot above the ground the aircraft starts landing in the destination airport.

250+ TOP MCQs on Lift Force and Answers

Aircraft Performance Multiple Choice Questions on “Lift Force”

1. Which of the following is the correct formula for lift of an aircraft?
a) L=(frac{1}{2})ρV2SCl
b) L=(frac{1}{2})V2SCl
c) L=(frac{1}{2})ρV2Cl
d) L=(frac{1}{2})PV2SCl
Answer: a
Clarification: The correct formula for lift of an aircraft is L=(frac{1}{2})ρV2SCl where L is lift, ρ is density, V stands for velocity of the aircraft, S is span and Cl is coefficient of lift. Lift is one of the fundamental aerodynamic force that is caused for the upward movement of the aircraft.

2. The zero-lift angle of attack is zero if the aerofoil is symmetric.
a) True
b) False
Answer: a
Clarification: The zero-lift angle of attack is zero if the aerofoil is symmetric. The zero-lift angle of attack is represented by α0. For symmetric airfoil the α0=0. For asymmetric airfoil the α0≠0. In the case of cambered airfoil the value of α0 is negative.

3. In the case of cambered airfoil the value of α0 is positive.
a) True
b) False
Answer: b
Clarification: In the case of cambered airfoil the value of α0 is negative. The zero-lift angle of attack is zero if the aerofoil is symmetric. The zero-lift angle of attack is represented by α0. For symmetric airfoil the α0=0, for asymmetric airfoil the α0≠0.

4. What is the theoretical value of lift curve slope of a flat airfoil?
a) 2π per radian
b) 4aπ per radian
c) 3π per radian
d) π per radian
Answer: a
Clarification: The theoretical value of lift curve slope of a flat airfoil is 2π per radian i.e. (frac{dC_l}{dalpha})=0 here (frac{dC_l}{dalpha}) is lift curve slope. This factor is depending on thickness of the airfoil and aspect ratio. The lift curve slope is directly proportional to thickness and inversely proportional to aspect ratio.

5. The lift curve slope is inversely proportional to thickness and directly proportional to aspect ratio.
a) True
b) False
Answer: b
Clarification: The lift curve slope is directly proportional to thickness and inversely proportional to aspect ratio. The lift slope curve is given by (frac{dC_l}{dalpha}). The theoretical value of lift curve slope of a flat airfoil is 2π per radian i.e. (frac{dC_l}{dalpha})=0.

6. What is meant by stalling angle of attack?
a) The angle at which we get maximum lift
b) The angle at which we get maximum drag
c) The angle at which we get minimum lift
d) The angle at which we get minimum drag
Answer: a
Clarification: Stalling angle of attack is the angle at which we get maximum lift. Stalling angle is the maximum angle at which the aircraft can be maintained in a steady state.

7. Which of the following is a correct condition when the angle of attack is beyond stalling angle?
a) Drag is greater than lift
b) Weight is less than lift
c) Drag is less than lift
d) Weight is less than thrust
Answer: a
Clarification: The drag is greater than lift in the condition where the angle of attack is beyond stalling angle. Stalling angle of attack is the angle at which we get maximum lift. Stalling angle is the maximum angle at which the aircraft can be maintained in a steady state.

8. What is the value of Cl of a symmetric airfoil if the angle of attack is 5°?
a) 0.548
b) 0.0548
c) 3.1416
d) 31.416
Answer: a
Clarification: The answer is 0.548. For a symmetrical aerofoil Cl= 2πα. Given α=5°,
Convert α into radians: α=5*(frac{pi}{180})
α=0.0873
Now substitute α in the above formula: Cl= 2π*0.0873
Cl=0.548.

9. What is stall buffet condition?
a) It is an aerodynamic vibration caused due to separation or turbulent airflow
b) it is a condition in which the separation is laminar
c) It is a condition in which the flow separation is not considered
d) It is a condition in which the turbulence is not considered
Answer: a
Clarification: Stall buffet condition is a condition in which the aerodynamic vibration caused due to separation or turbulent airflow. This starts at the back of the wing and moves forward as there is increase in angle of attack.

10. Leading edge flap deflection has the effect of increasing lift curve to a higher stalling angle of attack.
a) True
b) False
Answer: a
Clarification: Leading edge flap deflection has the effect of increasing lift curve to a higher stalling angle of attack. This helps in reducing the take-off and landing speeds of the aircraft.

11. Trailing edge deflection decreases the camber of the aerofoil section.
a) True
b) False
Answer: b
Clarification: Trailing edge deflection decreases the camber of the aerofoil section. This results in shifting the lift characteristics upwards when the zero angle of attack becomes more negative.

250+ TOP MCQs on Range and Endurance for Aircraft with Power Producing Engines and Answers

Aircraft Performance Multiple Choice Questions & Answers on “Range and Endurance for Aircraft with Power Producing Engines”.

1. Which of the following is the correct performance equation for power-producing engines?
a) ηV=PD
b) ηD=PV
c) ηP=VD
d) V=ηPD
Answer: c
Clarification: The correct equation for performance equation is ηP=VD where ŋ is propeller efficiency, P is drag power, D is drag and V is velocity. In a power-producing engine the shaft power is produced as well as propulsive thrust produced by the propeller which is converted into power.

2. What is the unit of specific fuel consumption?
a) kg/kW-sec
b) kg/W-hr
c) kg/hr
d) kg/kW-hr
Answer: d
Clarification: The unit of specific fuel consumption is given by kg/kW-hr. The formula for specific fuel consumption is C=(frac{Q_f}{P}) where Qf is fuel flow rate, P is power and C is specific fuel consumption.

3. Which of the following is the correct formula for specific fuel consumption?
a) Qf=(frac{P}{C})
b) Qf=(frac{C}{P})
c) C=(frac{P}{Q_f})
d) C=(frac{Q_f}{P})
Answer: d
Clarification: The unit of specific fuel consumption is given by kg/kW-hr. The formula for specific fuel consumption is C=(frac{Q_f}{P}) where Qf is fuel flow rate, P is power and C is specific fuel consumption.

4. What is the value of specific fuel consumption where the fuel heating is 42,800kJ/kg and power produced is 5760 kW-hr?
a) 0.135 kg/kW-hr
b) 7.43 kg/W-hr
c) 1.546 kg/kW-hr
d) 7.43 kg/kW-hr
Answer: d
Clarification: The answer is 7.43 kg/kW-hr. Given Qf=42,800 kJ/kg and P=5760 kW-hr. From the formula C=(frac{Q_f}{P}) we will find C. On substituting we get C=(frac{42800}{5760}).
On solving above equation we get the value of C=7.43 kg/kW-hr.

5. Specific air range is maximum when the aircraft is flying at minimum drag speed.
a) True
b) False
Answer: a
Clarification: Specific air range is maximum when the aircraft is flying at minimum drag speed and specific endurance is maximum when the aircraft is flying at minimum power speed. This is the same relation with thrust producing engines.

6. Specific endurance is maximum when the aircraft is flying at minimum drag speed.
a) True
b) False
Answer: a
Clarification: Specific air range is maximum when the aircraft is flying at minimum drag speed and specific endurance is maximum when the aircraft is flying at minimum power speed. This is the same relation with thrust producing engines.

7. What is the relation between specific air range and specific enurance?
a) SAR=V*SE
b) SAR=(frac{V}{SE})
c) SE=V*SAR
d) SE=(frac{V}{SAR})
Answer: a
Clarification: The formula for specific air range is given by: SAR=(frac{V}{CP}) where v is velocity, C is specific fuel consumption and P is power. The formula for specific endurance is given by: SE=(frac{1}{CP}) where C is specific fuel consumption and P is power.

8. Which of the following is the correct formula for specific air range?
a) SAR=(frac{eta}{C}frac{L}{D}frac{1}{W})
b) SAR=(frac{1}{PC})
c) SAR=(frac{eta W}{C}frac{L}{D})
d) SAR=(frac{1}{C}frac{L}{D}frac{1}{W})
Answer: a
Clarification: The correct formula for specific air range is given by SAR=(frac{eta}{C}frac{L}{D}frac{1}{W}) where η is propeller efficiency, C is specific fuel consumption, L is lift, D is drag, W is weight. SAR can also be written as SAR=(frac{V}{CP}) where v is velocity, C is specific fuel consumption and P is power.

9. Which of the following is the correct formula for specific endurance?
a) SE=(frac{V}{C}frac{L}{D}frac{1}{W})
b) SE=(frac{V}{PC})
c) SE=(frac{eta}{C}frac{L}{D}frac{1}{W})
d) SE=(frac{eta}{CV}frac{L}{D}frac{1}{W})
Answer: d
Clarification: The correct formula for specific endurance is given by SE=(frac{eta}{CV}frac{L}{D}frac{1}{W}) where η is propeller efficiency, C is specific fuel consumption, L is lift, D is drag, V is velocity, W is weight. SE can also be written as SE=(frac{1}{CP}) where C is specific fuel consumption and P is power.

10. What is the value of specific air range where the lift to drag ratio is 10, weight is 50000N, efficiency is 85% and specific fuel consumption is 7.43 kg/kW-hr?
a) 3000km
b) 4000 km
c) 1000km
d) 5000km
Answer: b
Clarification: The answer is 4000km. Given (frac{L}{D})=10, W=50,000kg, η=85%, C=4.25×10-5kg/kW-hr. From the equation SAR=(frac{eta}{C}frac{L}{D}frac{1}{W}). On substituting the values we get SAR= (frac{0.85}{4.25 times 10^{-8}})*10*(frac{1}{50000}).
On solving above equation we get SAR=4000 km.

11. What is the value of specific endurance where the lift to drag ratio is 10, weight is 50000N, efficiency is 85% , velocity is 250m/s and specific fuel consumption is 7.43 kg/kW-hr?
a) 30hr
b) 57.6hr
c) 10hr
d) 50hr
Answer: b
Clarification: The answer is . Given (frac{L}{D})=10, W=50,000kg, η=85%, C=4.25×10-5kg/kW-hr, V=69.44km/hr. From the equation SE=(frac{eta}{CV}frac{L}{D}frac{1}{W}). On substituting the values we get SE= (frac{0.85}{69.44 times 4.25 times 10^{-8}})*10*(frac{1}{50000}).
On solving above equation we get SE=57.6hr.