Engines

Question 1

What is specific fuel consumption?

Answer 1

Fuel burn per hour / engine thrust

Question 2

What is the combustion cycle of a jet/gas turbine?

Answer 2

Induction
Compression
Combustion
Expansion
Exhaust

Question 3

What is the compression ratio of a gas turbine engine?

Answer 3

Change in pressure between inlet and outlet parts of an individual compressor stage or complete compressor section of an engine.

Question 4

What is the bypass ratio of an engine?

Answer 4

Ratio of the total airmass flow through the fan stage to the airmass flow that passes through the turbine (HP) section

Question 5

How does a fan engine differ from a bypass engine?

Answer 5

The cold bypass airflow and hot engine core airflow are discharged separately

Question 6

What are the advantages of a fan engine?

Answer 6

1. Smaller eng size
2. Better propulsive efficiency
3. Better fuel consumption
4. Reduction in engine noise
5. Contamination is centrally discharged through the bypass duct so avoiding the hot core.

Question 7

What advantage does a triple-spool eng have with regard to n1 fan compressor size?

Answer 7

It can be made much larger and closer to its optimal design.

Question 8

What is the benefit of all spools moving independently?

Answer 8

All can work closer to their optimal performance speed.

Question 9

What does a flat rated engine provide?

Answer 9

A Constant rate of thrust up to a fixed temperature (Tref)

Question 10

What is the benefit of flying at the highest alt possible?

Answer 10

1. Minimum cruise airframe drag

2. Best engine Specific fuel consumption