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Message-ID: <4B9057D5.3030400@gmail.com>
Date: Thu, 04 Mar 2010 19:01:09 -0600
From: Dave <david.staten@gmail.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] The stalled propeller blade
References: <list-4152731@logan.com>
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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.