Aircraft Propulsion Systems 1) The output of a diesel engine can be increased without increasing the engine revolution or size in following way (a) feeding more fuel (b) increasing fly heel size (c) heating incoming air (d) scavenging (e) supercharging 2) Compression loss in I.C engines occurs due to (a) leaking piston rings (b) use of thick head gasket (c) clogged air-inlet slots (d) increase in clearance volume caused by bearing-bushing wear (e) all of the above 3) It the temperature of intake air in I.C engines is lowered, then its efficiency will (a) increase (b) decrease (c) remain same (d) increase up to certain limit and then decrease (e) decrease up to certain limit and then increase 4) For the same compression ratio (a) Otto cycle is more efficient than the Diesel (b) Diesel cycle is more efficient than Otto (c) both Otto and Diesel cycles are, equally efficient (d) compression ratio has nothing to with efficiency (e) Which is more efficient would depend on engine capacity 5) As a result of detonation in an I.C engine, following parameter attains very high value (a) peak pressure (b) rate of rise of pressure (c) rate of rise of temperature (d) peak temperature (e) rate of rise of horse-power 6) Most high speed compression engines operate on (a) Diesel cycle (b) Otto cycle (c) Dual combustion cycle (d) Special type of air cycle 1/9 Dr Tran Tien Anh@ HCMUT (e) Carnot cycle 7) Which of the following medium is compressed in a Diesel engine cylinder? (a) air alone (b) air and fuel (c) air and lub oil (d) fuel alone (e) air, fuel and lub oil 8) The air-fuel ratio of the petrol engine is controlled by (a) fuel pump (b) governor (c) injector (d) carburettor (e) scavenging 9) Diesel fuel, compared to petrol is (a) less difficult to ignite (b) just about the same difficult to ignite (c) more difficult to ignite (d) highly ignitable (e) none of the above 10) In diesel engine the diesel fuel injected into cylinder would burn instantly at about compressed air temperature of (a) 250oC (b) 500oC (c) 1000oC (d) 1500oC (e) 2000oC 11) A 75 cc engine has following parameter as 75 cc (a) fuel tank capacity (b) lub oil capacity (c) swept volume (d) cylinder volume (e) clearance volume 12) In diesel engine, the compression ratio in comparison to expansion ratio is (a) same (b) less (c) more 2/9 Dr Tran Tien Anh@ HCMUT (d) variable (e) more/less depending on engine capacity 13) The cam shaft of a four stroke I.C engine running at 1500 rpm will run at (a) 1500 rpm (b) 750 rpm (c) 3000 rpm (d) any value independent of engine speed (e) none of the above 14) Engine’s pistons are usually made of aluminium alloy because it (a) is lighter (b) wears less (c) absorbs shocks (d) is stronger (e) does not react with fuel and lub oil 15) The specific fuel consumption of a petrol engine compared to diesel engine of same H.P is (a) same (b) more (c) less (d) less or more depending on operating conditions (e) unpredictable 16) A diesel engine as compared to petrol engine (both running at rated load) is (a) more efficient (b) less efficient (c) equally efficient (d) unperdictable (e) other factors will decide it 17) Which of the following is false statement: Excess quantities of sulphur in diesel fuel are objectionable because it may cause the following (a) piston ring and cylinder wear (b) formation of hard coating on piston skirts (c) oil sludge in the engine crank case (d) detonation (e) forms corrosive acids 18) Pick up the wrong statement about supercharging (a) supercharging reduces knocking in diesel engines (b) there can be limited supercharging in petrol engines because of detonation 3/9 Dr Tran Tien Anh@ HCMUT (c) supercharging at high altitudes is essential (d) supercharging results in fuel economy (e) supercharging is essential in aircraft engines 19) The actual volume of fresh charge admitted in 4-stroke petrol engine is (a) equal to stroke volume (b) equal to stroke volume and clearance volume (c) less than stroke volume (d) more than stroke volume (e) more than cylinder volume 20) The reason for supercharging in any engine is to (a) increase efficiency (b) increase power (c) reduce weight and bulk for a given out-put (d) effect fuel economy (e) none of the above 4/9 Dr Tran Tien Anh@ HCMUT 21) The operation of forcing additional air under pressure in the engine cylinder is known as (a) scavenging (b) turbulence (c) supercharging (d) pre-ignition (e) dissociation and carburretion of fuel 22) Supercharging is essential in (a) diesel engines (b) gas turbines (c) petrol engines (d) aircraft engines (e) marine engines 23) The mean effective pressure obtained from engine indicator indicates the (a) maximum pressure developed (b) minimum pressure (c) instantaneous pressure at any instant (d) exhaust pressure (e) average pressure 24) For the same power developed in I.C engines, the cheaper system is (a) naturally aspirated (b) supercharged (c) centrifugal pump (d) turbocharger (e) none of the above 25) A diesel engine has (a) valve (b) valves (c) valves (d) valves (e) no valve 26) The blade angle of a propeller is the angle between: a) The root chord and the tip chord of the propeller b) The chord and the airflow relative to the propeller c) The chord of the propeller and the longitudinal axis of the aircraft d) The propeller chord and the plane of rotation of the propeller 5/9 Dr Tran Tien Anh@ HCMUT 27) The blade angle: a) Is constant along the propeller blade b) Decreases from root to tip c) Increases from root to tip d) Varies with changes in engine rpm 28) The Geometric Pitch of a propeller is: a) The distance it would move forward in one revolution at the blade angle b) The angle the propeller chord makes to the plane of rotation c) The distance the propeller actually moves forward in one revolution d) The angle the propeller chord makes to the relative airflow 29) A right hand propeller: a) Rotates in a clockwise direction when viewed from the rear b) Is a propeller fitted to the right hand engine c) Rotates in an anti-clockwise direction when viewed from the rear d) Is a propeller mounted in front of the engine 30) The angle of attack of a fixed pitch propeller: a) Depends on forward speed only b) Depends on forward speed and engine rotational speed c) Depends on engine rotational speed only d) Is constant for a fixed pitch propeller 31) During the takeoff run a fixed pitch propeller is: a) At too coarse an angle for maximum efficiency b) At too fine an angle for maximum efficiency c) At the optimum angle for efficiency d) At the optimum angle initially but becomes too coarse as speed increases 32) For an aircraft with a fixed pitch propeller, an increase in rev/min during the take off run at full throttle is due to: a) An increase in propeller blade slip b) The engine overspeeding c) A more efficient propeller blade angle of attack d) The propeller angle of attack increasing 6/9 Dr Tran Tien Anh@ HCMUT 33) An aircraft with a fixed pitch propeller goes into a climb with reduced IAS and increased rev/min The propeller: a) Angle of attack will decrease b) Pitch will decrease c) Angle of attack will increase d) Angle of attack will remain the same 34) For an aircraft with a fixed pitch propeller, propeller efficiency will be: a) Low at low speed, high at high speed b) High at low speed, low at high speed c) Constant at all speeds d) Low at both low and high speed, and highest at cruising speed 35) The blade angle of a fixed pitch propeller would be set to give the optimum angle: a) During takeoff b) During the cruise c) At the maximum level flight speed d) For landing 36) Propeller torque results from the forces on the propeller: a) Caused by the airflow, giving a moment around the propeller's longitudinal axis b) Caused by centrifugal effect, giving a moment around the propellers' longitudinal axis c) Caused by the airflow, giving a moment around the aircraft's longitudinal axis d) Caused by centrifugal effect, giving a moment around the aircraft's longitudinal axis 37) The thrust force of a propeller producing forward thrust: a) Tends to bend the propeller tips forward b) Tends to bend the propeller tips backward c) Tends to bend the propeller in its plane of rotation d) Causes a tension load in the propeller 38) A propeller which a) Rotates the engine b) Rotates the engine c) Rotates the engine d) Rotates the engine 7/9 is windmilling: in the normal direction and gives some thrust in reverse and gives drag in reverse and gives some thrust in the normal direction and gives drag Dr Tran Tien Anh@ HCMUT 39) For an aircraft with a right hand propeller the effect of slipstream rotation acting on the fin will cause: a) Yaw to the left b) Roll to the left c) Yaw to the right d) Nose up pitch 40) To counteract the effect of slipstream rotation on a single engine aircraft: a) The fin may be reduced in size b) A "T" tail may be employed c) The fin may be off-set d) The wings may have washout 41) The gyroscopic effect of a right hand propeller will give: a) A yawing moment to the left whenever the engine is running b) A yawing moment to the left when the aircraft rolls to the right c) A nose-up pitch when the aircraft yaws to the right d) A yaw to the right when the aircraft pitches nose up 42) The alpha range of a variable pitch propeller is between: a) Feather and flight fine pitch stop b) Feather and ground fine pitch stop c) Flight fine pitch stop and reverse stop d) Ground fine pitch and reverse stop 43) When the CSU (Constant Speed Unit) is running "on speed": a) The governor weight centrifugal force balances the CSU spring force b) The CSU spring force balances the oil pressure c) The governor weight centrifugal force balances the oil pressure d) The supply of oil to the CSU is shut off 44) If engine power is increased with the propeller lever in the constant speed range, rpm increase, then: a) The governor weights move out, blade angle decreases, rpm decrease, weights remain out b) The governor weights move in, blade angle increases, rpm decrease, weights move out c) The governor weights move out, blade angle increases, rpm decrease, weights move in d) The governor weights move out, blade angle increases, rpm decrease, weights move in, blade angle decreases again 45) A propeller blade is twisted along its length: a) To compensate for the Centrifugal Twisting Moment b) To maintain a constant angle of attack from root to tip of the blade c) To increase the thrust given by the tip d) To maintain constant thrust from root to tip 8/9 Dr Tran Tien Anh@ HCMUT 46) Propeller torque is: a) The tendency of the propeller to twist around its longitudinal axis b) The helical path of the propeller through the air c) The turning moment produced by the propeller about the axis of the crankshaft d) The thrust produced by the propeller 47) The greatest stress on a rotating propeller occurs: a) At the tip b) At about 75% of the length c) At the midpoint d) At the root e) 48) What happens to the pitch of a variable pitch propeller in order to maintain constant rpm when (i) IAS ( indicated airspeed) is increased and (ii) Power is increased? (i) (ii) a) b) c) d) increases decreases increases decreases decreases increases increases decreases 49) Propellers may have an “avoid” range of rpm: a) To avoid resonance peaks which could lead to fatigue damage to the propeller b) To avoid excessive propeller noise c) Because the engine does not run efficiently in that rpm range d) To avoid the possibility of detonation occurring in the engine 50) An “Auto- Feathering” system senses: a) Low rpm b) Decreasing rpm c) High torque d) Low torque 9/9 Dr Tran Tien Anh@ HCMUT ... dissociation and carburretion of fuel 22) Supercharging is essential in (a) diesel engines (b) gas turbines (c) petrol engines (d) aircraft engines (e) marine engines 23) The mean effective pressure