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Date: Mon, 19 Nov 2007 09:07:33 -0500
From: Ernest Christley <echristley@nc.rr.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: 16X Rotary Engine.
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Bob Tilley wrote:
> OK Tracy,
>
> I think 340 HP at 9,000 is an accurate estimate.
>
> When do we get the 3.25 or 3.5:1 ratio PSRU?  ;-)
>
> Bob
Could you fit a prop long enough to take advantage of that high a ratio?

Increasing the ratio allows you to turn the engine faster without 
turning a given prop faster, thereby putting more power into each turn 
of the prop.

-or-

It allows you to turn a prop slower at a given RPM.  This allows you to 
use a longer prop and still keep the tips subsonic.

I think most of us are limited in prop length by ground geometry.    RPM 
is held down to preserve the engine.  With an extra 50 to 75 Hp, most of 
us will be limited to adding a prop blade or twisting the blades for 
more pitch.