Mailing List flyrotary@lancaironline.net Message #50242
From: Dave <david.staten@gmail.com>
Subject: Re: [FlyRotary] The stalled propeller blade
Date: Thu, 04 Mar 2010 19:01:09 -0600
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Lynn Hanover wrote:

 AOA, I think in terms of the wing producing max lift.  The AOA changes with elevator input.  A prop is not unlike a wing, but I still don’t have a grasp of what is causing AOA change in a fixed pitch prop.  But, usually I have to read things three or four times in order to “get it”.

Ok.. a "fixed" pitch prop can have a changing AOA.. heres how..

The pitch angle of the plane.. itself... along the crankshaft axis.. has an impact on how the prop sees the oncoming air, and hence varies the angle of attack of the prop blades.

An airplane flying at lower airspeeds in its regime will tend to fly nose high..

An airplane flying at higher airspeeds will tend to be nose level or even a tad nose down..

The same prop on the same plane at two different speeds will result in two different pitch angles and therefore two different angle of attacks.. which then have an effect on thrust.
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