Aircraft Engines

Question 1

What is the cycle of an internal combustion engine?

Answer 1

Intake, compression, combustion, exhaust. Or ‘suck squeeze, bang, blow’

Question 2

An engine is a means of….

Answer 2

Converting engine power into propulsive force

Question 3

Propellers are usually classified by their position on an aircraft. Define them?

Answer 3

Push propellers are located on the rear whereas tractor propellers are located on the front, either on the wings or the nose.

Question 4

Outline the anatomy of a propeller.

Answer 4

The hub connects the propeller to the driveshaft/crankshaft. The shank is the section immediately next to the hub, it forms the thickest cross section and is where the most stress is exerted. The spinner is a cone on the front of the propeller that deflects air away from the hub and onto the blades.

Question 5

A blade is twisted in order to alter the?

Answer 5

Angle of attack, which would give a constant amount of lift despite the outer edge travelling faster than the parts close to the hub

Question 6

A blade is twisted in order to alter the?

Answer 6

Angle of attack, which would give a constant amount of lift despite the outer edge travelling faster than the parts close to the hub.

Question 7

The rotational velocity vector is equivalent to?

Answer 7

RPM (Repetitions Per Minute)

Question 8

What is the blade pitch?

Answer 8

The angle between the plane of rotation and the blade chord. Defined as either fine or coarse and affects the amount of work a propeller can do. You may get fixed or variable pitch propellers

Question 9

Aside from pitch, what other design element can alter propeller performance?

Answer 9

Number of blades

Question 10

What is a jet engine?

Answer 10

An engine that discharges a fast moving ‘jet’ of fluid to generate thrust.

Question 11

Which of newtons laws is does a jet engine fall in alignment with?

Answer 11

Third. For every action, there is an equal and opposite reaction.

Question 12

Name some components of a jet engine?

Answer 12

Compressor, Combustion chamber, turbine.

Question 13

There are 4 main types of jet engine. Name them?

Answer 13

Turbojet,
Turboshaft/turboprop,
Turbofan
Ramjet

Question 14

Ramjet is mainly?

Answer 14

High speed and military use. Utilises few moving parts.

Question 15

Name some advantages of jet engines?

Answer 15

Lower engine vibration, able to cruise above the weather, more power therefore better performance in terms of speed and noise, cheaper fuel.

Question 16

Name some disadvantages of fewer engines?

Answer 16

Initial ‘set-up’ cost, delay in engine take-up (spool time), higher stresses, less manoeuvrable at lower levels and have higher approach speeds.

Question 17

Turboprop engines are what?

Answer 17

Gas turbine engines whereby power produced is used to drive a propeller.

Question 18

Advantages of turboprop?

Answer 18

Quieter, performance envelope is most efficient for commuter type aircraft.

Question 19

Disadvantages of turboprop?

Answer 19

Generally lower cruising levels than jets. Expensive to manufacture. Higher frontal area = more drag.

Question 20

AVGAS means?

Answer 20

Aviation Gasoline. Used in smaller piston engine powered aircraft.

Question 21

AVTUR means?

Answer 21

Aviation Turbine Fuel of (ATF)