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Message-ID: <1c23473f0512191506w7b03f4b2la61055043bc1eeb7@mail.gmail.com>
Date: Mon, 19 Dec 2005 15:06:26 -0800
From: David Leonard <wdleonard@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Props
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Oh, BTW Bully.  You will also note that at 6000 RPM the prop is doing 2750
which a lot of certified props will turn, even if 74"long.

Also, short prop are not necessarily less efficient, its just that the spee=
d
of peak efficiency is shifted to a higher airspeed, and probably that peak
is a little more narrow.

Dave Leonard


On 12/19/05, Buly <atlasyts@bellsouth.net> wrote:
>
> Yesterday somebody gave me the formulas to calculate the prop tip
> speed. I did some calculations and looks like us with the 2.17
> redrives are kind of painted in the corner. Hope I'm wrong, but if I
> want to keep the tips from going supersonic, I have to cut down the
> prop to 64" or keep the engine below 5500 RPM. The choice is either
> inefficient prop and adequate power, or efficient long prop and not
> getting all the power from the engine? Am I wrong?
> Buly
> atlasyts@bellsouth.net
>
>
>
>
> --
> Homepage:  http://www.flyrotary.com/
> Archive and UnSub:   http://mail.lancaironline.net/lists/flyrotary/
>



--
Dave Leonard
Turbo Rotary RV-6 N4VY
http://members.aol.com/_ht_a/rotaryroster/index.html
http://members.aol.com/_ht_a/vp4skydoc/index.html

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<div>Oh, BTW Bully.&nbsp; You will also note that at 6000 RPM the prop is d=
oing 2750 which a lot of certified props will turn, even if 74&quot;long.</=
div>
<div>&nbsp;</div>
<div>Also, short prop are not necessarily less efficient, its just that the=
 speed of peak efficiency is shifted to a higher airspeed, and probably tha=
t peak is a little more narrow.</div>
<div>&nbsp;</div>
<div>Dave Leonard<br><br>&nbsp;</div>
<div><span class=3D"gmail_quote">On 12/19/05, <b class=3D"gmail_sendername"=
>Buly</b> &lt;<a href=3D"mailto:atlasyts@bellsouth.net">atlasyts@bellsouth.=
net</a>&gt; wrote:</span>
<blockquote class=3D"gmail_quote" style=3D"PADDING-LEFT: 1ex; MARGIN: 0px 0=
px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">Yesterday somebody gave me the f=
ormulas to calculate the prop tip<br>speed. I did some calculations and loo=
ks like us with the=20
2.17<br>redrives are kind of painted in the corner. Hope I'm wrong, but if =
I<br>want to keep the tips from going supersonic, I have to cut down the<br=
>prop to 64&quot; or keep the engine below 5500 RPM. The choice is either
<br>inefficient prop and adequate power, or efficient long prop and not<br>=
getting all the power from the engine? Am I wrong?<br>Buly<br><a href=3D"ma=
ilto:atlasyts@bellsouth.net">atlasyts@bellsouth.net</a><br><br><br><br><br>
--<br>Homepage:&nbsp;&nbsp;<a href=3D"http://www.flyrotary.com/">http://www=
.flyrotary.com/</a><br>Archive and UnSub:&nbsp;&nbsp; <a href=3D"http://mai=
l.lancaironline.net/lists/flyrotary/">http://mail.lancaironline.net/lists/f=
lyrotary/</a><br></blockquote>
</div><br><br clear=3D"all"><br>-- <br>Dave Leonard<br>Turbo Rotary RV-6 N4=
VY<br><a href=3D"http://members.aol.com/_ht_a/rotaryroster/index.html">http=
://members.aol.com/_ht_a/rotaryroster/index.html</a><br><a href=3D"http://m=
embers.aol.com/_ht_a/vp4skydoc/index.html">
http://members.aol.com/_ht_a/vp4skydoc/index.html</a>=20

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