Aircraft Design - Propulsion and Fuel System Integration Quiz(MCQ)

1 .

Which of the following is not an aircraft propulsion system?

A)

High lift device

B)

Piston engine

C)

Rocket engine

D)

Reciprocating engine

Correct Answer : High lift device

Explanation : High lift devices are not part of aircraft propulsion system. High lift device is used to increase lift produced. Flaps are an example of high lift device which are used at takeoff and landing.

2 .

Which of the following is not the type of an aircraft propulsion?

A)

Rocket engine

B)

Longerons

C)

Air breathing propulsion

D)

Non air breathing propulsion

Correct Answer : Longerons

Explanation : Longerons are structural elements of an aircraft. Longerons are heavy structural members that run straight and used to prevent bending.

3 .

Which of the following is an advantage of the piston prop engine?

A)

Highest speed

B)

Limited performance

C)

Supersonic speed always

D)

Cheap and low fuel consumption

Correct Answer : Cheap and low fuel consumption

Explanation : Piston prop engine are widely used during early era. Piston prop engine provides cheap and low fuel consumption. Piston prop engine suffers from speed limits.

4 .

Which of the following is a type of compressor?

A)

Flap

B)

Rudder compressor

C)

Centrifugal compressor

D)

Incline compressor

Correct Answer : Centrifugal compressor

Explanation : Centrifugal Compressor is type of compressor. Centrifugal compressor uses centrifugal force to fling the air. Flow does not coincide with axis of rotation. Flap is secondary control surface of an aircraft.

5 .

What is the use of Turbine?

A)

To compress the flow

B)

To increase pressure

C)

Generate work to drive shaft

D)

To increase temperature

Correct Answer : Generate work to drive shaft

Explanation : Turbine is an essential component of gas turbine engine. Turbine is used to decrease temperature and pressure of the gas. Combustion products pressure is reduced by turbine. Turbine generates work to drive the shaft.

6 .

Following diagram represents _____

A)

rocket

B)

piston prop

C)

turbojet

D)

turboprop

Correct Answer : piston prop

Explaination : Piston prop engine is shown in above diagram. A typical piston prop engine relies piston and propeller blades to generate useful work and thrust. They are heavy and produces more noise.

7 .

Following diagram represents ______

A)

piston engine

B)

turboprop design

C)

piston prop aircraft

D)

turbojet engine with centrifugal compressor

Correct Answer : turbojet engine with centrifugal compressor

Explaination : A typical Turbojet with centrifugal compressor is shown in above schematic diagram. Centrifugal force is used as working principle to drive this type of compressor. As shown in figure, it consists of combustion chamber and turbine stage as well.

8 .

Following diagram represents ______

A)

typical turbo jet

B)

turbofan

C)

turboprop

D)

reciprocating

Correct Answer : typical turbo jet

Explaination : As shown in figure, a typical Turbojet engine is shown. Here, turbojet engine is operated by axial flow Compressor as shown in the above schematic diagram. As air passes through Compressor, pressure will increase and then it will be directed to combustion and preceding stages.

9 .

Following diagram represents _________

A)

rocket

B)

ramjet

C)

scramjet

D)

turboprop

Correct Answer : turboprop

Explaination : A turboprop is different from traditional piston prop engine. Here, propeller is connected to turbine engine via gear box. Rocket is type of aircraft and spacecraft propulsion system.

10 .

Following diagram represents _______

A)

turbofan

B)

turbojet

C)

piston engine

D)

to and fro engine

Correct Answer : turbofan

Explaination : A typical turbofan engine is shown in the above diagram. Turbofan operates with same principle as other has turbine engine. However, it has a fan mounted at inlet as shown. Fuel Efficiency of such engine is more than typical Turbojet.

11 .

What do you mean by scale factor in terms of rubber engine?

A)

Lift to drag ratio

B)

Thrust required to thrust available

C)

Thrust coefficient to drag coefficient

D)

ratio of thrust required by rubber engine to the actual thrust from selected existing engine

Correct Answer : ratio of thrust required by rubber engine to the actual thrust from selected existing engine

Explanation : For a typical rubber engine, scale factor is defined as ratio of thrust required by rubber engine to the actual thrust from selected existing engine. Scale factor can vary based on our requirements. Lift to drag ratio is primarily concern of aerodynamics of aircraft.

12 .

A Turbofan engine is to be scale in order to have our desired engine characteristics. If length of the existing engine selected is 2.5 unit and required scale factor is 0.8 then, evaluate approximate length of our engine.

A)

2.28 unit

B)

5.6 unit

C)

10 unit

D)

15 unit

Correct Answer : 2.28 unit

Explaination : Given, actual length L_actual = 2.5unit, S.F. = 0.8
Approximate length is given by,
Length L = L_actual*(SF) ^0.4
Length L = 2.5*(0.8) ^0.4 = 2.28 unit.

13 .

Diameter of rubber engine is 94 inch and required scale factor is 0.7 then, what will be the actual diameter of selected engine?

A)

50 in

B)

112.35 in

C)

150 in

D)

200 in

Correct Answer : 112.35 in

Explanation : Given, diameter d = 94 inch, S.F. = 0.7
Now, actual diameter is given by,
Actual diameter D = d / (SF)^0.5 = 94 / (2.7)^0.5 = 112.35in.

14 .

Which of the following is an advantage of nose inlet?

A)

Clean airflow

B)

Unclean airflow

C)

Swirled flow always

D)

Very long internal duct

Correct Answer : Clean airflow

Explanation : The nose inlet offers clean air flow. It was used in some fighters such as Mig 21. This type of inlet requires long internal duct which is one of the disadvantages of nose inlet. They are typically located at the nose section of an aircraft.

15 .

Chin inlet sufferers from __________

A)

shorter duct length

B)

foreign object ingestion problem

C)

typically good at high AOA

D)

duct length is shorter than the nose inlet

Correct Answer : foreign object ingestion problem

Explanation : Chin inlet is good at operating higher AOA. They offers advantages similar to nose but required duct length is shorter. One of the disadvantage of this type is foreign object ingestion. This good affect the performance of engine as well.

16 .

Large cowl lip radius will produce _______

A)

expansion fan

B)

shock attached flow

C)

shock separated flow outside of the inlet

D)

high lifting tendency always

Correct Answer : shock separated flow outside of the inlet

Explanation : Engine performance is influenced by cowl lip radius. A large cowl lip radius will produce shock separated flow on the outside of an inlet. Large cowl lip will reduce distortions. This is very helpful at higher AOA.

17 .

Following diagram represents _________

A)

inlet applicability

B)

empennage

C)

exhaust section

D)

outlet geometry

Correct Answer : inlet applicability

Explaination : Typical inlet application limits based on Mach number is shown in the diagram. Above diagram is illustrating the selection criteria. This criteria is presented for different types of inlets based upon designed Mach values.

18 .

If bypass ratio of subsonic non afterburning engine is 1.5 then, what will be the value of maximum thrust specific fuel consumption.

A)

0.0789

B)

0.092

C)

0.12

D)

0.556

Correct Answer : 0.556

Explanation : Given, BPR =1.5
Maximum thrust SFC = 0.67*e^(-0.12*BPR) = 0.67* e^(-0.12*1.5) = 0.556.

19 .

Evaluate required scale factor if ratio of weight of the rubber engine and the actual selected engine is 0.8.

A)

0.012

B)

0.8164

C)

1

D)

6.2

Correct Answer : 0.8164

Explanation : Given, ratio of rubber engine weight (w) and actual engine weight (W) = 0.8
Now, weight of the rubber engine is given by, w = W * SF^1.1
Hence, SF^1.1 = w/W = 0.8
1.1*ln (SF) = ln0.8 = -0.223
Hence, ln (SF) = -0.223/1.1 = -0.2028
Hence, SF = e^-0.2028 = 0.8164.

20 .

What is the use of inlet section?

A)

Slow down the incoming air

B)

Increase lift by wing

C)

Increase lift curve slope of tail

D)

Increase the mach number of incoming air

Correct Answer : Slow down the incoming air

Explanation : One of the primary function of emulate is to reduce velocity of incoming air. Lift produced by wings can be increased with the help of high lift device such as flaps. Lift curve slope can be altered by using different angle of attacks.

21 .

Inlet pressure recovery is defined as ______

A)

lift to drag ratio

B)

total dynamic pressure

C)

incoming velocity by incoming Mach number

D)

total pressure deliver to the engine divided by freestream total pressure

Correct Answer : total pressure deliver to the engine divided by freestream total pressure

Explanation : Inlet pressure recovery is nothing but the total pressure which is deliver to the engine divided by the free stream total pressure. Dynamic pressure is exerted due to velocity of the fluid. Lift drag ratio is more important for the aerodynamics of the aircraft.

22 .

Which of the following is a type of inlet?

A)

Slat

B)

Flap

C)

NACA flush inlet

D)

Fuselage

Correct Answer : NACA flush inlet

Explanation : Inlet has primary function to reduce flow velocity of the incoming air. NACA flush inlet is one of the example of typical inlet profile. Flap and slat are secondary control surfaces. Gisele is main body of an aircraft.

23 .

Following diagram represents _____

A)

Flash inlet

B)

NACA flush inlet

C)

Helical inlet

D)

Pitot tube cavity

Correct Answer : NACA flush inlet

Explaination : A typical NACA flush inlet is shown in the above diagram. NACA flush inlet was used by several early jets but in modern days it is rarely used. NACA flush inlet can be used to reduce wetted area.

24 .

Following diagram represents _____

A)

Pitot inlet

B)

Bell inlet

C)

Flush inlet

D)

NACA flush inlet

Correct Answer : Pitot inlet

Explaination : The typical schematic diagram of pitot inlet is shown in above figure. A Pitot inlet is nothing but a simple forward facing hole. This inlet works well at typical low supersonic speed regimes.

25 .

Following diagram represents ______

A)

Pitot inlet

B)

Conical inlet

C)

Flush inlet

D)

2D ramp inlet

Correct Answer : 2D ramp inlet

Explaination : A typical schematic diagram of 2d ramp is shown in above figure. 2d ramp inlet is used for supersonic speed regimes. It uses flow over wedge concept. Conical Inlet is also termed as round inlet. NACA flush inlet was used by early jets.

26 .

Following diagram represents ___

A)

Isothermal expansion

B)

Isotropic compression

C)

Mixed isentropic compression inlet

D)

Mixed Isotropic expansion

Correct Answer : Mixed isentropic compression inlet

Explaination : As shown in figure a mixed isentropic compression inlet is shown. As shown in the diagram, it uses both internal and external compressions. This can lead to higher efficiency. Expansion is the reverse or opposite process of compression.

27 .

At which diameter we should design a supersonic after burning engine for a fighter which will have thrust at takeoff 150000 Unit and bypass ratio of 0.7.

A)

114.67 unit

B)

160.78 unit

C)

235.78 unit

D)

350.39 unit

Correct Answer : 114.67 unit

Explanation : Given, Thrust T = 150000 unit, BPR = 0.7.
Now, Diameter D is given by, D = 0.288*T^0.5*e ^0.04*BPR = 0.288*150000^0.5*e^0.04*0.7
Hence, D = 0.288*387.3*1.028 = 114.67 unit.

28 .

Which of the following is not an inlet location?

A)

Lofting

B)

Tail root location

C)

Chin buried engine

D)

Side inlet location of buried engine

Correct Answer : Side inlet location of buried engine

Explanation : Here, typical side inlet location of buried engine is shown. Tail root engine is located at root section of the tail. Lofting is mathematical modelling of aircraft components. It is an important step in aircraft design. Chin buried is similar to that of the nose inlet section. Chin inlet suffers from various drawbacks such as ingestion of foreign objects etc.

29 .

Which of the following will use suction to divert the boundary layer?

A)

Step diverter

B)

Thrust loading

C)

Boundary layer suction

D)

Power loading curve

Correct Answer : Boundary layer suction

Explanation : Boundary layer suction is one of the type of the boundary layer diverter. Here, the boundary layer air is removed with the help of suction. It doesn’t benefit from the ram impact. Power loading is related to propulsion system performance.

30 .

Which of the following is an example of boundary layer diverter?

A)

Thrust loading

B)

Boundary layer bypass duct

C)

Power loading curve

D)

Fuselage fineness ratio

Correct Answer : Boundary layer bypass duct

Explanation : A boundary layer bypass duct or simply a separate inlet duct is one of example of boundary layer diverter. Fuselage fineness ratio is defined as ratio of fuselage length to the maximum diameter. Thrust loading is ratio of Thrust to weight. Power loading ratio of weight and power.

31 .

Which of the following is an incorrect example for BL diverter?

A)

Flap

B)

Step diverter

C)

Boundary layer suction

D)

Boundary layer bypass duct

Correct Answer : Step diverter

Explanation : Boundary layer diverter is used to divert the boundary layer formed typically on the body. Step diverter, BL bypass duct and BL suction are some of the techniques used for this purpose. Flap is an example of high lift device.

32 .

Find the diameter ratio of an engine which has mach number of 0.7. Consider isentropic flow.

A)

1.045

B)

2.045

C)

3.45

D)

5.64

Correct Answer : 1.045

Explanation : Given, Mach number M = 0.7
Now, for Mach number 0.7 area ratio is 1.094.
Now, diameter ratio is given by,
Diameter ratio = (area ratio)^0.5 = 1.094^0.5 = 1.045.

33 .

Following diagram represents __________

A)

chin inlet

B)

armpit inlet

C)

tail tip inlet

D)

wing tip inlet

Correct Answer : chin inlet

Explaination : A typical chin inlet arrangement is shown in the diagram. When inlet is located at tip of the wing then, it is termed as wing tip inlet. Chin inlet are similar to that of the nose inlets.

34 .

Following diagram represents _______

A)

lift curve

B)

armpit inlet

C)

tail section

D)

wingtip inlet

Correct Answer : armpit inlet

Explaination : The above diagram is representing the typical armpit inlet location. This type of inlet is risky. This can be used to have short internal duct. Lift curve is curve representing lift variations.

35 .

Following diagram represents ________

A)

chin inlet

B)

nose inlet

C)

wing root inlet

D)

armpit inlet

Correct Answer : wing root inlet

Explaination : A typical wing root inlet can be seen in the above diagram. Nose inlet is located at nose section of the aircraft which can offer clearer airflow. Chin is similar to nose inlet with some fundamental modification. Armpit inlet location is considered to be risky.

36 .

Following diagram represents __________

A)

buried engine

B)

nose buried engine location

C)

side buried engine location

D)

typical Podded engine

Correct Answer : typical Podded engine

Explaination : A typical Podded engine configuration is shown in the above diagram. Buried engines are located inside aircraft body itself. Nose buried engine and side buried engine are typical example of buried engine arrangements.

37 .

Following diagram represents _______

A)

tail podded engine

B)

wing root buried engine

C)

wingtip buried engine

D)

wingtip podded engine

Correct Answer : tail podded engine

Explaination : As shown in figure, typical tail podded engine is shown. As the name suggests this engine is located at empennage section of the aircraft. Wingtip is located at the tips of wing.

38 .

What is the function of a typical nozzle?

A)

To generate lift to fly

B)

To increase pressure

C)

To reduce flow velocity

D)

To expand exhaust flow

Correct Answer : To expand exhaust flow

Explanation : Function of nozzle is to expand flow. Nozzle is used to increase flow velocity by decreasing pressure and temperature of the flow. Lift is generated by wings primarily. Pressure can be increased by using compressor.

39 .

Following diagram represents _________

A)

cd nozzle

B)

rocket engine

C)

fixed convergent nozzle

D)

fixed divergent nozzle

Correct Answer : fixed convergent nozzle

Explaination : A typical convergent nozzle is shown in the above figure. The illustrated fixed convergent nozzle Increases velocity of the flow for subsonic condition. For supersonic expansion divergent section is required.

40 .

Consider a flow with 0.5M. Now, as area decreases, velocity of the flow inside convergent section _______

A)

increases

B)

decreases

C)

reduces by half always

D)

velocity is independent of area

Correct Answer : increases

Explanation : Given, Mach number = 0.5. The flow is in subsonic speed region.
For subsonic speed, as area decreases the flow velocity will increase for convergent nozzle.

41 .

Following diagram represents _____

A)

lift curve

B)

drag polar

C)

preliminary sizing of capture area

D)

drag coefficient curve

Correct Answer : preliminary sizing of capture area

Explaination : Preliminary sizing of capture area is shown in the above diagram. It provides typical guidelines and values to get preliminary sizing of capture area. Drag polar is used to provide relationship between lift and drag.

42 .

If area ratio is 1.110 then, at which mach number flow is flowing?

A)

0.21

B)

0.68

C)

1.89

D)

2.4

Correct Answer : 0.68

Explanation : Given, area ratio A/A* = 1.110
Now, as we know, A/A* = (1/M)*(1+0.2M2)3*0.5787
For given problem, we will substitute different values of Mach number from the options.
Let’s consider M = 0.68
Hence, for assumed value of Mach number,
A/A* = (1/0.68)*(1+0.2*0.68²)³*0.5787
A/A* = 0.8510*1.09248³ = 1.110.
The evaluated area ratio is equal to the given area ratio.
Hence, correct value of Mach number is 0.68.

43 .

___________ is the most common type of boundary layer diverter used for supersonic applications.

A)

Aileron

B)

Elevator

C)

Empennage

D)

Channel diverter

Correct Answer : Channel diverter

Explanation : Channel diverter is considered as most common type of boundary layer diverter used for supersonic applications. It offers high performance among the other types. Empennage is tail section of the aircraft.

44 .

At exhaust of nozzle temperature is 200k and density of the flow is 1.01 kg/m³. If back pressure is 1 bar then, nozzle is _______

A)

over expanded

B)

design condition

C)

under expansion

D)

nozzle can be under or over expanded

Correct Answer : over expanded

Explaination : Given, temperature t 200k, density d 1.01 kg/m³
Now, exit pressure p = d*R*T = 200*287*1.01 = 57974 = 0.57 bar < 1 bar
Since exit pressure p < back pressure, the nozzle is over expanded.

45 .

What is the old thumb rule to design a propeller?

A)

Keep it as long as possible

B)

Keep it as short as possible

C)

Keep it as half of diameter always

D)

Keep it as short and wide as possible

Correct Answer : Keep it as long as possible

Explanation : ‘Keep it as long as possible’ is old thumb rule for propeller. However, the length of the propeller is limited by the tip speed. Propeller tip speed should be below sonic speed.

46 .

Propeller has diameter of 25 unit. What will be the static tip speed of the propeller? (Given n = 1200rpm.)

A)

1570.8 unit

B)

2345.67 unit

C)

3004.5

D)

7643.23

Correct Answer : 1570.8 unit

Explanation : Given, diameter d = 25 unit, n = 1200rpm.
Now, static tip speed V = ?*n*d/60 = ?*1200*25/60 = 1570.8 unit.

47 .

If propeller has static tip speed of 600 ft. per second then, find diameter of propeller. Given n = 1250rpm.

A)

3.2876

B)

9.167

C)

19.8976

D)

23.96

Correct Answer : 9.167

Explanation : Given, Static tip speed V = 600 ft. per second, n = 1250rpm.
Now, diameter d = V*60/π*n = 600*60/π*1250 = 9.167 ft.

48 .

Following diagram represents ____

A)

updraft cooling

B)

updraft lifting

C)

downdraft lifting

D)

downdraft cooling

Correct Answer : updraft cooling

Explaination : Downdraft and updraft cooling are typical cooling system used in aircraft. Above diagram is representing typical updraft cooling system. Here, in this method cooling air flows in upward direction. It creates more efficient cooling flow than the downdraft cooling.

49 .

Find the ratio of weight to length of the turboprop engine which has bhp of 3000.

A)

60.1206

B)

60.012

C)

60.12

D)

12.60

Correct Answer : 12.60

Explanation : Given, bhp = 3000.
Now, ratio of weight to length is given by,
W/L = 0.403*(bhp)^0.43 = 0.403*3000^0.43 = 12.60.

50 .

A turboprop engine is designed to generate bhp of 2500. Estimate the appropriate weight of the engine based on statistical models.

A)

21kg

B)

321 slug

C)

893.84 lb.

D)

4555lb

Correct Answer : 893.84 lb.

Explanation : Given, bhp = 2500
Now, approximate value of weight is given by, W = 1.67*bhp^0.803 = 1.67*2500^0.803 = 893.84 lb.

51 .

Which of the following is an example of a cooling system?

A)

Downdraft cooling

B)

Sideway lofting

C)

Downdraft lofting

D)

Sideway circulation

Correct Answer : Downdraft cooling

Explanation : Downdraft cooling is a typical example of a cooling system which can be used in aircraft. Air flows in downward direction in the downdraft cooling configuration. Lofting is mathematical modelling of skin and aircraft. Circulation is related to vorticity in the flow.

52 .

If a propeller is designed to have 200 Hp then find the appropriate diameter for the propeller. Consider 2 blades.

A)

82.73 unit

B)

34.56

C)

180

D)

210

Correct Answer : 82.73 unit

Explanation : Given, power = 200Hp, number of blades = 2
Now, diameter d = 22*(Hp)^0.25 = 22*(200)^0.25 = 82.73 unit.

53 .

Fuel system includes _________

A)

rudder

B)

elevator

C)

high lift device

D)

fuel tanks, fuel lines, fuel pump, etc

Correct Answer : fuel tanks, fuel lines, fuel pump, etc

Explanation : Fuel system includes fuel tanks, fuel lines, supply lines, pump, etc. Elevator and rudder are known as primary control surface. Elevator is used for pitch up and pitch down. Rudder provides yaw motion. High lift device is used to increase the amount of lift.

54 .

Which of the following is not the type of fuel tank?

A)

Bladder

B)

Flap

C)

Integral

D)

Discrete

Correct Answer : Flap

Explanation : There are mainly 3 types of fuel tank: discrete, bladder and integral. Flap is not type of fuel tank. Flap is a high lift device. Flap is used to increase lift produced by wings during takeoff and landing.

55 .

Following diagram represents _____

A)

tail fuel tank

B)

tip tank at tail

C)

rip tank location

D)

typical central fuel tank location

Correct Answer : typical central fuel tank location

Explaination : Typical fuel tank is shown in the diagram. As shown in the diagram Fuel tank is located at the centre and hence it is a typical central fuel tank. Tip tank will be located at the tip of wing typically.

56 .

What is the disadvantage of bladder fuel tank?

A)

Self sealing

B)

Thrust loading

C)

Loss of available fuel volume

D)

No loss in fuel volume

Correct Answer : Loss of available fuel volume

Explanation : A typical bladder tank is formed by stuffing a shaped rubber bag into a cavity in the aircraft structure. However, the thick rubber bag results in the kids of available fuel volume. Self-sealing property is one of the advantages of the bladder tank. Thrust loading is the ratio of thrust to weight.

57 .

Integral tanks are _________

A)

cavities within the aircraft�s airframe itself

B)

there is no such type of fuel tank

C)

external tanks needs to be fabricated

D)

external tanks required to put in the airframe

Correct Answer : cavities within the aircraft�s airframe itself

Explanation : As name suggests a typical integral tank is an integral part of the aircraft itself. Integral tanks are cavities within the structure of airframe. These cavities are then sealed in order to form a fuel tank. Integral tanks are not external tanks

58 .

Typically, main fuel tank is located near to the ____

A)

at cockpit

B)

at passenger cabin

C)

inboard section of the wing

D)

at tip of the wing

Correct Answer : inboard section of the wing

Explanation : Typically, main fuel tank is located near to the inboard section of the wing. At tip, tip tanks are placed. Due to safety parameters, one soul avoid placing fuel tanks at the passenger cabin or at the cockpit.