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Correct answer is (a) piston prop

Best explanation: 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.

Correct OPTION is (a) Length L = Lactual*(SF) ^0.4

Easy explanation: If our CHOSEN existing ENGINE has length of Length of Lactual then, the length of RUBBER engine is given by, Length L = Lactual*(SF)^0.4. SF stands for scale factor.

The CORRECT choice is (a) 0.8

Easiest EXPLANATION: GIVEN, BPR = 2.1.

Now, SFC at CRUISE is given by,

SFC = 0.88*e ^(-0.05*BPR) = 0.88 * e ^(-0.05*2.1) = 0.7922 = 0.8.

The correct option is (a) 4.9

To ELABORATE: GIVEN, MACH number M = 1.8, thrust T = 10000 unit, BPR = 0.71.

Now, Ratio of length to diameter is given by,

L/D = 10.625*T^-0.1*M^0.2*e ^0.04*BPR = 10.625*10000^-0.1*1.8^0.2*e ^0.04*0.71

Hence, L/D = 10.625*0.3981*1.1247*1.028 = 4.9.

Right choice is (a) 2D RAMP inlet

The best I can explain: 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.

The correct ANSWER is (a) CHIN inlet

For explanation I would SAY: 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.

Correct answer is (a) wing root inlet

The best EXPLANATION: 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.

Correct option is (a) updraft cooling

Easy explanation: 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.

Correct choice is (a) Loss of AVAILABLE fuel volume

The best I can explain: 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.

Right CHOICE is (a) combustion chamber, turbine and compressor

The best I can explain: A turbine engine is widely used engine in AVIATION sector. A typical turbine engine consists of FOLLOWING fundamental parts: Compressor, combustion chamber and turbine. Apart from this, most FIGHTER AIRCRAFTS consist of afterburning section.

Correct choice is (a) TAIL podded engine

The best EXPLANATION: 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.

Right ANSWER is (a) 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.

Correct ANSWER is (a) \(\sqrt{Vtip^2+ V^2}\)

Explanation: The helical tip speed is given by, (Vtip) helical = \(\sqrt{Vtip^2+ V^2}\). The tip of propeller is FOLLOWING a helical PATH through air. At sea level helical tip speed of wooden propeller should be below 850 fps TYPICALLY.

The correct answer is (a) 8.4 UNIT

The explanation: GIVEN, scale factor SF = 0.85, actual DIAMETER D = 8.56 unit

Now, scaled ENGINE diameter d = D*SF^0.12 = 8.56* 0.85^0.12 = 8.4 unit.

The CORRECT OPTION is (a) 1.045

The EXPLANATION is: 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.

The CORRECT option is (a) Boundary layer bypass DUCT

To explain: 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.

The correct answer is (a) VARIABLE pitch propeller is used to improve thrust characteristics

For explanation: Variable pitch propeller is used to improve thrust characteristics across broad speed range. Variable pitch can be used to ALTER accelerating force. However, variable pitch has some drawbacks as well. Hence, it should be used as per MISSION requirements.

The correct ANSWER is (a) True

The best I can explain: Bladder tanks are one of the EXAMPLE of typical fuel tank arrangement. Bladder tank is made by using THICK rubber bag. They can be made self-sealing. The self-sealing property of the bladder tank is one of the important parameters and advantages of this type. This plays a major ROLE during the selection of bladder fuel tank.

Correct answer is (a) 2001.5 UNIT

To explain: Given, Thrust T1 = 8000N, BPR = 1.2

Now, thrust at cruise T = 0.60 * T^10.9 * E ^(0.02*BPR) = 0.60 * (8000)^0.9 * e ^(0.02*1.2) = 0.60*3256.724*1.024 = 2001.49 = 2001.5 unit.

Correct option is (a) turbofan

To ELABORATE: 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.

The correct answer is (a) NACA FLUSH INLET

To EXPLAIN: 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.

Correct option is (a) MIXED isentropic compression inlet

Easy EXPLANATION: 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.

The correct answer is (a) True

Explanation: Convergent SECTION alone can be used to increase flow velocity if flow is in subsonic speed. However at SUPERSONIC speeds only convergent section of the nozzle cannot provide required velocity. At supersonic speeds, convergent section works as the diffuser.

Correct answer is (a) inboard section of the wing

For 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.

The correct option is (a) Bladder tanks can be manufactured self-sealing

For explanation I would say: Bladder tanks can be made self-sealing. Bladder TANK is WIDELY used due to this property. Bladder tank is not only available FUEL tank. There are another fuel tanks as integral fuel tanks, DISCRETE fuel tank ETC. Lift is not always same as weight.

Correct choice is (a) Slow down the incoming AIR

Best 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.

Correct option is (a) fixed CONVERGENT nozzle

For explanation I would say: 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.

Correct option is (a) 81 UNIT

Explanation: Given, THRUST = 9600unit, MACH number M = 0.7

Length L = 2.22*T^0.4*M^0.2 = 2.22*9600^0.4*0.7^0.2 = 2.22*39.165*0.9311 = 80.95 ∼ 81 unit.

Right option is (a) To increase pressure and temperature

The best EXPLANATION: Compressor is USED to compress the flow. Compressor Increases pressure and temperature of the flow FLOWING through it. Due to increase in pressure, velocity of the flow reduces. Flow EXPANSION can be achieved through NOZZLE.

Correct choice is (a) Side inlet location of BURIED engine

The 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.

Right option is (a) 0.1 UNIT to 0.3 unit

The explanation: Given, LENGTH l = 10 unit.

Typical boundary layer diverter THICKNESS = 1% to 3% of length

= 1% of (10) to 3% of (10)

= 0.1 unit to 0.3 unit.

Right choice is (a) Keep it as long as possible

The 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.

The correct ANSWER is (a) 1570.8 UNIT

For explanation: GIVEN, DIAMETER d = 25 unit, n = 1200rpm.

Now, static tip speed V = ᴨ*n*d/60 = ᴨ*1200*25/60 = 1570.8 unit.

Right choice is (a) 9.167

Easiest 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.

Right option is (a) 3123 UNIT

Explanation: GIVEN, THRUST T = 15000N, BPR = 1.2

Now, weight is given by, W = 0.084 * (T^1.1)* e (-0.045*BPR).

W = 0.084 * (15000^1.1) * e ^(-0.045*1.2) = 0.084*39237.4147*0.9474 = 3123 unit.

The CORRECT choice is (a) 36.87 unit

Easy EXPLANATION: GIVEN, Thrust = 8000unit, BPR = 1.2

Diameter d is given by, d = 0.393 * (T^0.5) * e ^(0.04 * BPR) = 0.393 * (8000)^0.5 * e ^(0.04 * 1.2)

= 0.393*89.442*1.049 = 36.87 unit.

Right CHOICE is (a) 0.556

The best I can EXPLAIN: Given, BPR =1.5

Maximum thrust SFC = 0.67*E^(-0.12*BPR) = 0.67* e^(-0.12*1.5) = 0.556.

Right CHOICE is (a) total pressure deliver to the engine divided by freestream total pressure

The best 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.

Correct OPTION is (a) increases

Easy 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.