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Date: Mon, 21 Dec 2009 15:39:34 -0500
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Message-ID: <1b4b137c0912211239t24262bafud40f83a4bec1cdc5@mail.gmail.com>
Subject: Re: [FlyRotary] Air Flow Question
From: Tracy Crook <tracy@rotaryaviation.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Content-Type: multipart/alternative; boundary=000feaea1ad15bdeaf047b431691

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I assume you mean 400% of the inlet cross sectional *area*.    CFM air in =
CFM air out so 45 kts is about right given your numbers.  But I think the
weak point in your assumptions is that the air entering the inlet is going
at 180 kts. (or whatever your TAS is). There will likely be some external
diffusion going on so that column of air velocity may not  = TAS.   The
pressure required to force air through a typical oil cooler at 45 kts is
probably a lot higher than you are likely to achieve.  Just a gut feel, I
could be wrong.

Just as a reference point, my oil cooler face area to inlet area ratio is
650 %.  Inlet is ~16 sq.in. The radiator face to inlet ratio is 560 %.
Are these the right numbers to use?  Don't know yet but today's RV-8 flight
gave me excellent oil & water temps (167 / 157) on a 55 deg day.  Still have
lots of cooling outlet cleanup work to do and still flying without all my
intersection fairings in place so I expect cooling to only get better.

I cleaned the exterior of my O2 sensor with brake parts cleaner for today's
flight but it was still dead.  Didn't try removing it to clean the hot end
though.

Tracy (Whooo Hooo!  no smoke today.   I'm closer to taking this thing
somewhere you can see it Ed!  )

On Mon, Dec 21, 2009 at 2:03 PM, Thomas Mann <tmann@n200lz.com> wrote:

>   If I have a volume of air entering my scoop at 180 kts and expand the
> volume of the chamber by 400% can I expect the speed of the airflow to drop
> to 45 kts at that point?
>
>
>
> T Mann
>
>

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I assume you mean 400% of the inlet cross sectional <u>area</u>.=A0=A0=A0 C=
FM air in =3D CFM air out so 45 kts is about right given your numbers.=A0 B=
ut I think the weak point in your assumptions is that the air entering the =
inlet is going at 180 kts. (or whatever your TAS is). There will likely be =
some external diffusion going on so that column of air velocity may not=A0 =
=3D TAS.=A0=A0 The pressure required to force air through a typical oil coo=
ler at 45 kts is probably a lot higher than you are likely to achieve.=A0 J=
ust a gut feel, I could be wrong.<br>
<br>Just as a reference point, my oil cooler face area to inlet area ratio =
is 650 %.=A0 Inlet is ~16 <a href=3D"http://sq.in">sq.in</a>. The radiator =
face to inlet ratio is 560 %.=A0=A0=A0 Are these the right numbers to use?=
=A0 Don&#39;t know yet but today&#39;s RV-8 flight gave me excellent oil &a=
mp; water temps (167 / 157) on a 55 deg day.=A0 Still have lots of cooling =
outlet cleanup work to do and still flying without all my intersection fair=
ings in place so I expect cooling to only get better.=A0 <br>
<br>I cleaned the exterior of my O2 sensor with brake parts cleaner for tod=
ay&#39;s flight but it was still dead.=A0 Didn&#39;t try removing it to cle=
an the hot end though.<br><br>Tracy (Whooo Hooo!=A0 no smoke today. =A0 I&#=
39;m closer to taking this thing somewhere you can see it Ed!=A0 )<br>
<br><div class=3D"gmail_quote">On Mon, Dec 21, 2009 at 2:03 PM, Thomas Mann=
 <span dir=3D"ltr">&lt;<a href=3D"mailto:tmann@n200lz.com">tmann@n200lz.com=
</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_quote" style=3D"border=
-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-lef=
t: 1ex;">









<div bgcolor=3D"white" link=3D"blue" vlink=3D"blue" lang=3D"EN-US">

<div>

<blockquote style=3D"border-style: none none none solid; border-color: -moz=
-use-text-color -moz-use-text-color -moz-use-text-color black; border-width=
: medium medium medium 1.5pt; margin: 5pt 0in 5pt 3.75pt; padding: 0in 0in =
0in 4pt;">


<div>

<p class=3D"MsoNormal"><span style=3D"font-size: 11pt; color: rgb(31, 73, 1=
25);">If I have a volume of air entering my scoop at 180 kts and
expand the volume of the chamber by 400% can I expect the speed of the airf=
low
to drop to 45 kts at that point?</span></p>

<p class=3D"MsoNormal"><span style=3D"font-size: 11pt; color: rgb(31, 73, 1=
25);">=A0</span></p>

<p class=3D"MsoNormal"><span style=3D"font-size: 11pt; color: rgb(31, 73, 1=
25);">T Mann</span></p>

</div>

</blockquote>

</div>

</div>


</blockquote></div><br>

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