Propeller Systems (Variable Pitch) Flashcards
What are the definitions of the following terms?
Coarse Pitch
Fine Pitch
Feather Pitch
Revering Pitch
How is pitch changed in a variable speed prop?
Via a hydraulic system using engine oil controlled by the propeller governor to change the pitch of the blades
In a non-feathering system (single engines), the pitch is increased with increased oil pressure
In a full-feathering system (multi-engines), the pitch is decreased with increased oil pressure
As you add oil to a full-feathering system, what happens to the pitch of the blades?
The pitch is decreased/becomes more fine
As you add oil into a non-feathering system, what happened to the pitch of the blades?
The pitch increases/becomes more coarse
What kind of pitch would moving the lever full-forward give?
Fine = Low angle of incidence = low/small angle of attack
What do you use in aircraft with a variable prop instead of RPM?
Manifold Pressure
If the outside air pressure is 29.92, what will the Manifold Pressure guage read at full throttle?
Just below 30”. The MP guage should be reading close to whatever the pressure it. There is a little bit of loss but should be close.
If the throttle is pulled to idle, what will the MP guage read regardless of the outside air pressure?
Super low, around 10”
When there is a MP guage, what do it and the RPM guage mean now?
MP: The power I have availible
RPM: How efficiently I am using that power with the pitch of my prop
What is the perfect angle of attack for a prop blade?
2 to four degrees
While within the governing range, if there are any changes in engine power and/or airspeed, the governer will…
Maintain a steady RPM if a constant-speed propeller system is used
What drives the propeller blades of a full-feathering system towards coarse pitch?
Counterweights and internal springs
Oil pressure boosted by the governor has the purpose of moving the propeller towards…
coarse pitch in a single-engine aeroplane
As the oil pressure drops on a constant-speed non-feathering system, the governor would make the propeller…
full fine
What happens to a centrifugal counterweight and springs propeller system when the engine quits during flight?
Because the engine is still windmilling, the gear still drives the governor. The governor will still operate as usual and change the blade angle so as to keep the RPM setting.
So the blades move towards the selected propeller RPM by becoming more fine