Lecture 19

Question 1

How do non-air-breathing engines operate?

Answer 1

Carries all the needed oxygen within their fuel
Generates heat by chemical reaction between fuel and an oxidizer

Question 2

List the types of air-breathing reaction (turbine) engines*

Answer 2

Turbojet
Turboprop
Turboshaft
Turbofan

Question 3

How does a turbojet engine operate?*

Answer 3

Takes air in through the air inlet
Compresses the air
Mix compressed air with fuel
Air and fuel mixture ignited and burned
Hot gases passes through turbine
Air forced out of a specially shaped exhaust nozzle forming a high-speed jet

Question 4

What are turboprop engines?*

What are the two methods to drive the prop?

Answer 4

Drives a propeller
A derivative of the turbojet engine

Connecting the propeller to the compressor using a reduction gearbox
Connecting the propeller to a turbine separate from the core engine, resulting in reverse flow (Free-Turbine Engine)

Question 5

What are turboshaft engines?

Answer 5

Commonly used for helicopters
More efficient at constant RPM required by helicopters
Reduction gearbox is remote from the engine

Question 6

What are turbofan (bypass) engines?*

What are some pros to this design?

Answer 6

Turbojet engines with a large fan at the inlet

Increased propulsive efficiency
Lower Noise
Lower fuel consumption

Question 7

What are the three types of turbofan engines?*

What is a bypass ratio?

Answer 7

Low-Bypass Engine (smaller fan)
High-Bypass Engine (larger fan)
Ultra-High-Bypass Engine
Be able to tell the difference by looking at them**

Ratio of the mass or air moved by the fan to the mass of air moved by the core engine
Air from the fan section flows around the outside of the core engine
Higher bypass = higher efficiency