New ppt Props Flashcards
Allows propeller to produce thrust in reverse direction to produce deceleration (braking). Negative blade angles. (the greater the RPM the greater the reverse thrust)
Reverse pitch
what changes the blade angle pitch on a constant-speed prop?
prop governor
how is the propeller mounted in a low power or piston engine aircraft?
crankshaft
an older type of Adjustable-pitch propeller that can only be adjusted on the ground with the engine off.
Ground-Adjustable Propellers
the flat part of the blade that faces the pilot
Blade face
transition point to reverse
Disking- Neutral/Zero pitch
contains propeller information and is where it attaches to the engine
Blade hub
the frequency at which the system will vibrate if it is excited by a single pulse
Resonant Frequency
A ______ propeller is mounted to the aft end of an engine and push the airplane through the air
Pusher
The propeller is able to convert about __% of the brake horsepower to thrust horsepower
85%
The actual distance the propeller travels in one revolution through the air (friction drag & weight)
Effective Pitch
A small “Bite” of air ( T/O, climb)
Fine pitch (High RPM)
will automatically maintain a constant RPM for changes in flight conditions (tailwind, headwind, air pressure/temperature changes.
Constant-Speed Propellers
When a propeller is connected to an engine and produces thrust, aerodynamic and mechanical forces causes the propeller to?
Vibrate
may have their pitch adjusted in flight, but each setting must be made manually by pilot.
Controllable-Pitch Propellers
are designed to optimize a particular RPM and forward motion
Fixed-Pitch Propellers
What is the purpose of the propeller ?
To convert engine brake horsepower to thrust horsepower
caused by a low pressure area forward of the blade axis in rotation and Rotates the blades to a higher blade angle, decreasing RPM (COARSE PITCH)
Stalling degrees on prop blade?
If exceeded to 15 degrees
The difference between the Geometric and Effective Pitches. The less the losses the more efficient the propeller.
Prop Slip
Caused by the resistance of the air to propeller rotation. Bends blades in opposite direction of rotation
Blades trying to remain in parallel rotation to the propeller plane of rotation and Rotates the blades to a lower angle (toward 0, which increases RPM) (FINE PITCH)
Some propeller engine combinations have a critical operating range where vibrations forces are too great to stay in. _______ wil indicate this range.
Tachometer
A ______ propeller is mounted to the front of the engine and pulls the airplane through the air
Tractor
Why is the blade twisted ?
So it can Compensate for difference in rotational speed of the propeller blade and allows for more even distribution of thrust
Selection that allows blades to be moved to pitch angle of almost +90 degrees in event of engine shut-down (reduces drag). RPM = 0 (failed engine)
Feather
Allows a big “Bite” of air for cruise.
Coarse pitch (Low RPM)
how is the propeller mounted in a high power or turboprop engine aircraft?
gear reduction system
Caused by propeller weight tending to throw the blades away from the centre of rotation (hub). This is the strongest force acting on the propeller
What safety precautions should you take before working on or rotating a propeller ?
Mixture to Cut off
Magneto switch to Off
Fuel selector valve to off
Ground the p- leads
Remove the spark plug leads
Most effective angle of attack for a prop blade?
2 & 4 degrees
A fixed-pitch propeller to optimize takeoff and climb but slower and less efficient cruise (Example blade angle of attack 2 degrees)
Climb Propeller
the distance the propeller should travel in one revolution through a solid (no losses).
Geometric Pitch
the cambered side of the blade similar to a wings upper surface
blade back
Caused by thrust loads. Compression and tension acting upon the blades and Bends the blades forward in the line of flight
A fixed-pitch propeller with a high blade angle to optimize cruise and high altitude flight. Longer takeoff and slower, less efficient climb (Example blade angle of attack 4 degrees).
Cruise Propeller
A compromise between a Climb and Cruise propeller (Example blade angle of attack 3 degrees).
Standard Propeller
