17.1

Question 1

What is the hub

Answer 1

Central part of the propeller which carries the blade

Question 2

What is the blade

Answer 2

Aerofoil section that attaches to the hub

Question 3

What is the butt

Answer 3

Base of blade where root ends

Question 4

Waht is the blade root/shank

Answer 4

Thickened portion of the blade nearest to hub

Question 5

What is the blade station

Answer 5

Distance mesaured from centre (in cm or in)

Question 6

Define coarse pitch

Answer 6

The blade angle moves away from plane of rotation

Question 7

Define fine pitch

Answer 7

The blade angle moves towards plane of rotation

Question 8

What are the two components of force that operate on the blade

Answer 8

Thrust and torque that generate a resultant force

Question 9

What varies the amount of air displaced

Answer 9

Pitch/blade angle

Question 10

What changes in the revolution, when the blade pitch is changed

Answer 10

The distance travelled becomes more or less

Question 11

What does alpha range mean

Answer 11

The blade pitch operates within the coarse and fine range

Question 12

Define angle of advance

Answer 12

Measured angle from plane of rotation to relative air flow

Question 13

What causes windmilling

Answer 13

Negative thrust and negative torque

Question 14

When is beta range used

Answer 14

When on ground e.g. engine start and reverse thrust

Question 15

What is required to move the throttle lever into reverse thrust

Answer 15

Lever must be lifted to clear detent

Question 16

Why is the angle of indcidence varied on a propeller

Answer 16

To maintain angle of attack/thrust distribution (tip moves faster than root)

Question 17

How do you calculate slip

Answer 17

Geometric pitch - effective pitch

Question 18

Define geometric pitch

Answer 18

The distance a propeller should theoretically travel

Question 19

What is thrust bending

Answer 19

The forward pushing force due to the thrust generated

Question 20

What is torque bending

Answer 20

The rotational force that tries to bend the blade opposite to rotational direction

Question 21

What is the aerodynamic twisting moment

Answer 21

The pressure acting on a blade that forces it to become coarser

Question 22

How does centrifugal twisting moment work

Answer 22

The propellers mass tries is thrown out to the edge making it finer pitch

Question 23

Where aer the highest vibrational loads found

Answer 23

80% of its length

Question 24

What is blade solidity

Answer 24

The total area covered by the blade propellers

Question 25

What effect does torque have on the aircraft

Answer 25

During low speed there is a large yawing effect in the direction of the torque load

Question 26

As a propeller rotates, what happens to the A.O.A of up and down going blades

Answer 26

Upgoing will reduce (less thrust) Downgoing will increase (more thurst)

Question 27

What engine is described as the critical engine

Answer 27

The engine generating less thrust (e.g. in engine failure)

Question 28

Define resonant frequency

Answer 28

Natural maximum vibration

Question 29

What is blade washout

Answer 29

The twisting of the tip at a greater angle to the root

Question 30

What are the normal propeller efficiency values

Answer 30

80%-90%