Propulsion System Classification Questions and Answers

Statement I: A propeller is unsuitable for high subsonic cruise.

Statement II: Blade tip speed combines rotational and forward velocity and reaches the speed of sound first.

In the light of the above statements, choose the correct answer.

Statement I: A turbojet is the best choice for a long range subsonic airliner.

Statement II: It produces a high exhaust velocity relative to the flight speed.

In the light of the above statements, choose the correct answer.

Arrange these engine types in order of increasing suitable flight speed:

1. Reciprocating engine with propeller

2. Turboprop

3. High bypass turbofan

4. Turbojet or low bypass turbofan

5. Ramjet and scramjet

Select the correct sequence.

Arrange the stages of a gas turbine cycle in the order the air passes through them:

1. Intake and diffuser slow the incoming air

2. Compressor raises the pressure

3. Combustor adds heat at nearly constant pressure

4. Turbine extracts work to drive the compressor

5. Nozzle accelerates the gas to produce thrust

Select the correct sequence.

Arrange these engine types in order of increasing bypass ratio:

1. Turbojet, with no bypass at all

2. Low bypass turbofan on a combat aircraft

3. High bypass turbofan on a transport

4. Turboprop, treating the propeller as a very large fan

Select the correct sequence.

Arrange these steps in selecting an engine type for a new aircraft:

1. Establish the design cruise speed and altitude

2. Identify the types whose efficiency peaks in that regime

3. Compare fuel consumption, weight and installed drag

4. Assess noise, cost and certification requirements

5. Select the type and begin detailed matching

Select the correct sequence.

Arrange these events as an air breathing engine climbs to altitude:

1. Ambient density falls with height

2. The mass flow the engine can process falls

3. Thrust falls roughly in proportion

4. Falling ambient temperature partly improves the cycle

5. The net thrust lapse is gentler than density alone predicts

Select the correct sequence.

Consider the following engine and output pairs:

Turbojet - Thrust entirely from the exhaust jet

Turboprop - Mostly shaft power to a propeller

Turboshaft - Shaft power to a load other than a propeller

Turbofan - Thrust entirely from the core exhaust

How many of the pairs given above are correctly matched?

Consider the following pairs of engine and defining feature:

Ramjet - No compressor or turbine

Scramjet - Combustion in supersonic flow

Rocket - Carries its own oxidiser

Turbofan - No compressor

How many of the pairs given above are correctly matched?

Consider the following pairs of quantity and definition:

Specific thrust - Thrust per unit air mass flow

Thrust specific fuel consumption - Fuel flow per unit thrust

Bypass ratio - Bypass flow divided by core flow

Overall efficiency - The sum of thermal and propulsive efficiency

How many of the pairs given above are correctly matched?