Propeller Construction

Question 1

What is the most common wood used for propellers?

Answer 1

Birch

Question 2

Do fixed pitch propellers require input from pilot?

Answer 2

No

Question 3

How many layers of wood form a blank?

Answer 3

5

Question 4

How long must a blank rest to allow for equal distribution? What is it called after this process?

Answer 4

1 week. White

Question 5

Why are small holes drilled in each tip of a wood propeller?

Answer 5

Release moisture and allow wood to breathe

Question 6

What are the two controls of a controllable pitch propeller? What do they do?

Answer 6

Throttle control - controls power output of engine. Propeller control - Regulates engine and propeller RPM

Question 7

What does doped fabric or polyurethane paint do to protect the wooden propellers?

Answer 7

Provides UV and mechanical protection

Question 8

What are the 3 types of hubs used to mount wooden propellers on the engine crankshaft?

Answer 8

• forged steel hub on splined crankshaft
• tapered forged steel hub on tapered crankshaft
• bolted to steel flange on a splined crankshaft

Question 9

What is bonded to leading edges of composite blades to protect from impact damage?

Answer 9

Nickel or stainless steel erosion shields

Question 10

What a constant speeding propeller? How is it controlled?

Answer 10

Automatically changes blade pitch to maintain constant RPM. Constant speed unit governor

Question 11

Why is a support fitted at the front end of the propeller hub in regards to spinner installation?

Answer 11

Centring purposes

Question 12

Does the spinner have a high dynamic load?

Answer 12

Yes

Question 13

What 3 materials could the spar be made off in construction of composite propellers with a metal spar? What does the spar do?

Answer 13

Titanium, aluminium alloy or stainless steel. Absorbs centrifugal forces and bending loads

Question 14

What 3 materials could the shell be made off in construction of composite propellers with a metal spar? What does the shell do?

Answer 14

Fibreglass, Kevlar or carbon fibre. Gives torsional rigidity

Question 15

How can minor adjustments be made on composite blades without a metal spar?

Answer 15

Balanced horizontally with lead wall placed into hollow balancing tube and covered with rubber plug

Question 16

When are metal propellers used? What metal propeller material is most used? Why?

Answer 16

On a/c with greater engine power. Aluminium alloy. Better engine cooling

Question 17

How do you make steel metal propellers lighter?

Answer 17

Make them hollow

Question 18

What point do you number stations from? What increments are stations measured in?

Answer 18

Root to tip. 6 inch

Question 19

What are the 3 most common shaft types?

Answer 19

Tapered, splined and flanged

Question 20

Where are tapered shafts most commonly found?

Answer 20

Small, older, low powered piston engines

Question 21

Where is a splined shaft most commonly used?

Answer 21

High output radial engines

Question 22

How are sizes of splined shafts identified?

Answer 22

SAE (society of automotive engineers) number

Question 23

Where are flanged shafts most commonly used?

Answer 23

Modern reciprocating and turboprop engines

Question 24

What horsepower engines are SAE 20 splines used on? SAE 30? SAE 40? SAE 50? SAW 60 and 70?

Answer 24

200hp. 300-400hp. 500-600hp. 1000hp. Larger engines

Question 25

Can you repair a spinner? If so how?

Answer 25

Yes. Stop drilling