RMIT飞行训练课件－propeller螺旋桨
**** Hidden Message ***** RMIT Instructor Rating Mass Briefs Issue 1 /2004 Page 1<BR>PROPELLERS<BR>Aim: To understand the principles and considerations in a propeller producing thrust.<BR>Application: All stages of flight where the engine is running<BR>Definitions:<BR> Blade<BR>- an aerofoil which converts engine power into thrust.<BR> Blade Angle<BR>- the angle between the blade chordline and the plane of rotation.<BR> Blade Back<BR>- the cambered side of the blade.<BR> Blade Face<BR>- the flat side of the blade.<BR> Helix Angle<BR>- the angle between the resultant velocity of the blade and the plane of<BR>rotation.<BR> Angle of Attack<BR>- the angle between the chordline of the blade and the relative airflow.<BR> Torque<BR>- resistance to motion in the plane of rotation.<BR>Engine Torque<BR>- Torque Produced by the engine, force that turns the propeller<BR>Propeller Torque<BR>- Caused by drag of the propeller blades, opposes propeller rotation<BR>Principles:<BR>- The combination of the forward velocity and rotational velocity creates a<BR>helical motion of the propeller through the air.<BR>Brief 25<BR>RMIT Flight Training Propellers<BR>RMIT Instructor Rating Mass Briefs Issue 1 /2004 Page 2<BR>- The tip travels fastest due to greater distance travelled in same time. Root<BR>travels slowest. Therefore varying lift (thrust) forces.<BR>- To even out forces, blade is twisted to compensate. Blade angle at hub needs<BR>to be much greater than blade angle at tip.<BR>- Geometric pitch is how far the propeller would theoretically advance in one<BR>revolution.<BR>- Effective pitch is how far the propeller actually advances in one revolution.<BR>- The difference between geometric and effective pitch is called slip.<BR>Considerations:<BR> Propeller Damage<BR>- usually occurs first on leading edge, cause it hits the air first.<BR>- avoid high power settings on loose surfaces like gravel.<BR> Propeller Fatigue<BR>- most likely to occur on blade face.<BR>Brief 25<BR>RMIT Flight Training Propellers<BR>RMIT Instructor Rating Mass Briefs Issue 1 /2004 Page 3<BR> Efficiency<BR>- fixed-pitch propellers are most efficient at only one airspeed and RPM<BR>combination. The C172 is fitted with a cruise prop.<BR>Airmanship:<BR>- Always perform thorough pre-flight inspections on the propeller.<BR>- Handle the engine smoothly.<BR>- Low power settings on ground to avoid damage.<BR>Brief 25<BR>RMIT Flight Training Propellers 看 不 到 感谢楼主万分感谢感谢万分 谢谢楼主，我正准备去RMIT读书
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