Propeller Construction Flashcards
What is the most common wood used for propellers?
Birch
Do fixed pitch propellers require input from pilot?
No
How many layers of wood form a blank?
5
How long must a blank rest to allow for equal distribution? What is it called after this process?
1 week. White
Why are small holes drilled in each tip of a wood propeller?
Release moisture and allow wood to breathe
What are the two controls of a controllable pitch propeller? What do they do?
Throttle control - controls power output of engine. Propeller control - Regulates engine and propeller RPM
What does doped fabric or polyurethane paint do to protect the wooden propellers?
Provides UV and mechanical protection
What are the 3 types of hubs used to mount wooden propellers on the engine crankshaft?
- forged steel hub on splined crankshaft
- tapered forged steel hub on tapered crankshaft
- bolted to steel flange on a splined crankshaft
What is bonded to leading edges of composite blades to protect from impact damage?
Nickel or stainless steel erosion shields
What a constant speeding propeller? How is it controlled?
Automatically changes blade pitch to maintain constant RPM. Constant speed unit governor
Why is a support fitted at the front end of the propeller hub in regards to spinner installation?
Centring purposes
Does the spinner have a high dynamic load?
Yes
What 3 materials could the spar be made off in construction of composite propellers with a metal spar? What does the spar do?
Titanium, aluminium alloy or stainless steel. Absorbs centrifugal forces and bending loads
What 3 materials could the shell be made off in construction of composite propellers with a metal spar? What does the shell do?
Fibreglass, Kevlar or carbon fibre. Gives torsional rigidity
How can minor adjustments be made on composite blades without a metal spar?
Balanced horizontally with lead wall placed into hollow balancing tube and covered with rubber plug
When are metal propellers used? What metal propeller material is most used? Why?
On a/c with greater engine power. Aluminium alloy. Better engine cooling
How do you make steel metal propellers lighter?
Make them hollow
What point do you number stations from? What increments are stations measured in?
Root to tip. 6 inch
What are the 3 most common shaft types?
Tapered, splined and flanged
Where are tapered shafts most commonly found?
Small, older, low powered piston engines
Where is a splined shaft most commonly used?
High output radial engines
How are sizes of splined shafts identified?
SAE (society of automotive engineers) number
Where are flanged shafts most commonly used?
Modern reciprocating and turboprop engines
What horsepower engines are SAE 20 splines used on? SAE 30? SAE 40? SAE 50? SAW 60 and 70?
200hp. 300-400hp. 500-600hp. 1000hp. Larger engines
Can you repair a spinner? If so how?
Yes. Stop drilling
