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Date: Tue, 9 Feb 2010 19:44:52 -0500
Message-ID: <1ab24f411002091644x3ba834dawb02eaa624b7689ce@mail.gmail.com>
Subject: Less power, more speed.
From: Lynn Hanover <lehanover@gmail.com>
To: flyrotary@lancaironline.net
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Prop efficiency climbs (so I'm told) until it reaches speed of sound, so I
believe some try to take the prop  as close to 3,000 rpm as possible, yet
some stay a conservative 2,700 rpm, what do you suggest, given all the
variables.
George (down under)

Calculating the propeller tip speed just gets you close, because the airflow
over the forward side of the blade reaches supersonic before the blade
speed.

The spreadsheets for calculating all of this neat airplane stuff (by John
Roncz) are available on the EAA web page.


If you have no spreadsheet, you can download one from Open Office.org
 for free. Or the whole office suite. Works great. Compatible with
everything, free.

You can fill in the dimensions of your plane and prop data and crank out the
actual performance data within a percent or so. Scary accurate.

Lynn E. Hanover

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<div><font face=3D"Arial" size=3D"2">Prop efficiency climbs (so I&#39;m tol=
d) until it reaches speed of sound, so I believe some try to take the prop=
=A0 as close to 3,000 rpm as possible, yet some stay a conservative 2,700 r=
pm, what do you suggest, given all the variables.</font></div>

<div><font face=3D"Arial" size=3D"2">George (down under)</font></div>
<div>=A0</div>
<div>Calculating the propeller tip speed just gets you close, because the a=
irflow over the forward side of the blade reaches supersonic before the bla=
de speed.</div>
<div>=A0</div>
<div>The spreadsheets for calculating all of this neat airplane stuff (by J=
ohn Roncz) are available on the EAA web page. </div>
<div>=A0</div>
<div>=A0</div>
<div>If you have no spreadsheet, you can download one from Open Office.org<=
/div>
<div>=A0for free. Or the whole office suite. Works great. Compatible with e=
verything, free. </div>
<div>=A0</div>
<div>You can fill in the dimensions of your plane and prop data and crank o=
ut the actual performance data within a percent or so. Scary accurate.</div=
>
<div>=A0</div>
<div>Lynn E. Hanover</div>

--000e0cd1e218ad8e45047f3457a8--