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Old 12th August 2008 | 10:22
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BroomstickPilot
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Joined: Apr 2002
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From: Surrey, England
VP or Constant speed?

Would somebody please enlighten me.

All of the above posts refer to what is described as a 'VP prop'.

However, some of them, (notably Guppy's reference to setting prop speed,) clearly suggest to me that what is being discussed is in fact the 'constant speed prop'.

My understanding has always been that these are two different things.

The pitch of a VP prop is set by the pilot, who then has to alter the pitch during the flight as appropriate at each stage of his/her flight. At any throttle setting and rpm, the prop remains at the same pitch unless the pilot sees fit to change it.

The constant speed prop, by contrast, is provided with a governor which changes the pitch of the prop automatically. On takeoff, the pilot first sets the prop speed required and then follows it up with throttle, on throttling back the throttle is pulled first and then the prop speed. But within any setting of throttle and prop speed, the maintenance of prop speed is automatic.

I would suppose that these days a true VP prop is a rarety except on vintage aeroplanes such as, I suppose, the Harvard.

But are we correct to use the same term for any wobbly prop?

Please enlighten.

Broomstick.
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