RMIT飞行训练课件－propeller螺旋桨

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RMIT Instructor Rating Mass Briefs Issue 1 /2004 Page 1
PROPELLERS
Aim: To understand the principles and considerations in a propeller producing thrust.
Application: All stages of flight where the engine is running
Definitions:
 Blade
- an aerofoil which converts engine power into thrust.
 Blade Angle
- the angle between the blade chordline and the plane of rotation.
 Blade Back
- the cambered side of the blade.
 Blade Face
- the flat side of the blade.
 Helix Angle
- the angle between the resultant velocity of the blade and the plane of
rotation.
 Angle of Attack
- the angle between the chordline of the blade and the relative airflow.
 Torque
- resistance to motion in the plane of rotation.
Engine Torque
- Torque Produced by the engine, force that turns the propeller
Propeller Torque
- Caused by drag of the propeller blades, opposes propeller rotation
Principles:
- The combination of the forward velocity and rotational velocity creates a
helical motion of the propeller through the air.
Brief 25
RMIT Flight Training Propellers
RMIT Instructor Rating Mass Briefs Issue 1 /2004 Page 2
- The tip travels fastest due to greater distance travelled in same time. Root
travels slowest. Therefore varying lift (thrust) forces.
- To even out forces, blade is twisted to compensate. Blade angle at hub needs
to be much greater than blade angle at tip.
- Geometric pitch is how far the propeller would theoretically advance in one
revolution.
- Effective pitch is how far the propeller actually advances in one revolution.
- The difference between geometric and effective pitch is called slip.
Considerations:
 Propeller Damage
- usually occurs first on leading edge, cause it hits the air first.
- avoid high power settings on loose surfaces like gravel.
 Propeller Fatigue
- most likely to occur on blade face.
Brief 25
RMIT Flight Training Propellers
RMIT Instructor Rating Mass Briefs Issue 1 /2004 Page 3
 Efficiency
- fixed-pitch propellers are most efficient at only one airspeed and RPM
combination. The C172 is fitted with a cruise prop.
Airmanship:
- Always perform thorough pre-flight inspections on the propeller.
- Handle the engine smoothly.
- Low power settings on ground to avoid damage.
Brief 25
RMIT Flight Training Propellers

haoyu405

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猪也能飞

感谢楼主万分感谢感谢万分

xy8701

谢谢楼主，我正准备去RMIT读书