3. Propulsion Systems

Question 1

What types of Engines are there?

Answer 1

Turbojet, Turbofan, Turboprop, Ramjet/Scramjet

Question 1

Whats the difference in bypass ratio for Turbojet and Turbofan

Answer 1

Turbojet: BPR ~ = 0, Turbofan BPR > 0

Question 2

What type of Engine Interfaces exits

Answer 2

Engine and nacelle (comercial), Engine and fuselage (military jet)

Question 3

What does the Interface Control Document define in terms of engine interfaces?

Answer 3

Installation, System Connections, Power Offtakes

Question 4

What are some benefits of eliminating the pneumatic bleed?

Answer 4

• more efficient, aircraft does not draw as much power off the engine in cruise -> lower fuel consumption, Significant simplification due to elimination of pneumatic system

Question 5

Whats the Control Problem when dealing with Engines?

Answer 5

to control fuel flow and air flow of the engine to operate it at its optimum efficiency

Question 6

What are some functions provided by the Full Authority Digital Engine Control?

Answer 6

optimized engine efficiency, protection from operation outside engine limits, coordination of engine/aircraft control functions, saves weight, reduces pilot workload, reduces maintenance cost

Question 7

What are some benefits of the FADEC

Answer 7

enhance basic control functions (start, idle, acceleration, stability thrust), optimize engine control (cooling, bleed air control, anti-surge), enhance engine protection(thrust limitation, critical speed and pressure), improved pilot/engine interface, improved reliability and safety

Question 8

Which engine parameters are displayed to the pilots

Answer 8

Engine Speed (N1, N2, N3), Engine temperatures, Engine Pressure Ratio, Engine Vibration, Thrust or Torque

Question 9

List all the types of jet fuel and their applied field

Answer 9

A1: Standard for civil aviation, A: similar to A1 only in US, B: lighter fuel, enhanced cold-temperature performance, lower flame point (military)

Question 10

What are Dry Bays used for?

Answer 10

Dry bays exist to stop the engine to explode in the case of an uncontained rotor burst, zone normal to the engine axis is called rotor burst zone and is not suitable for tanks

Question 11

How much additional room does the fuel tank need to have to account for expansion?

Answer 11

At least 2%, must be impossible to fill this space with the fueling system, alternatively tank vents

Question 12

What type of fuel transfers exist and what are they used for?

Answer 12

Forward and aft transfer (modify cog), inboard and outboard fuel transfer (reduce bending moments and hence structural fatigue)