From: "Finn Lassen finn.lassen@verizon.net" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Re: Butterfly cowl flap
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
References: <list-127925@logan.com>
Message-ID: <194b8b8b-dc25-d1f1-4fde-21ba8a2d3120@verizon.net>
Date: Sat, 3 Jul 2021 17:12:14 -0400
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This thread is very interesting:
https://vansairforce.net/community/showthread.php?t=68241&page=15
Post #145 has pictures. Of course Dan Horton's work turn out to be works 
of art.

Also https://vansairforce.net/community/showthread.php?t=36695&page=6 
post #58. Talks about sealing space between spinner and cowling. In 
typical RVs turbulent and hot air apparently comes /out/ of that crack 
and messes up air going into the inlets. Seems to be a relatively easy 
target. As for sealing space for bottom cowling (hard to do and still be 
able to remove the bottom cowling, Tracy mentioned making a screw-on 
cuff. I think on his RV-4 he has something that clamps to the PSRU just 
behind the prop flange.

Finn

On 7/3/2021 4:51 PM, Matt Boiteau mattboiteau@gmail.com wrote:
> I don't have any cowl flaps at the moment. But want to design 
> something to try to start to optimize the cowl for speed.
>
> - Matt Boiteau
>
>
> On Wed, Jun 30, 2021 at 11:08 PM Finn Lassen finn.lassen@verizon.net 
> <mailto:finn.lassen@verizon.net> <flyrotary@lancaironline.net 
> <mailto:flyrotary@lancaironline.net>> wrote:
>
>     I read through all posts since 2010 containing "cowl flap".
>
>     Both Charlie and Matt mentioned butterfly cowl flap.
>
>     I understand it's hinged in the middle, but having a hard time
>     visualizing it. When open, is the front then lowered into the outside
>     air stream? If so, doesn't the rear part of the flap then block the
>     opening from inside to outside of cowling?
>
>     If the front instead opens into the cowl (and rear down into the
>     outside
>     air stream), doesn't the front then block the air inside the
>     cowling. Or
>     maybe that's just a problem for me because my oil cooler goes all the
>     way down to the bottom of the cowling ...
>
>     Any pictures?
>
>     Finn
>
>     ---
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>
>     --
>     Homepage: http://www.flyrotary.com/
>     Archive and UnSub:
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>     <http://mail.lancaironline.net:81/lists/flyrotary/List.html>
>


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    <div class="moz-cite-prefix">This thread is very interesting:<br>
<a class="moz-txt-link-freetext" href="https://vansairforce.net/community/showthread.php?t=68241&amp;page=15">https://vansairforce.net/community/showthread.php?t=68241&amp;page=15</a><br>
      Post #145 has pictures. Of course Dan Horton's work turn out to be
      works of art.<br>
      <br>
      Also
      <a class="moz-txt-link-freetext" href="https://vansairforce.net/community/showthread.php?t=36695&amp;page=6">https://vansairforce.net/community/showthread.php?t=36695&amp;page=6</a>
      post #58. Talks about sealing space between spinner and cowling.
      In typical RVs turbulent and hot air apparently comes <i>out</i>
      of that crack and messes up air going into the inlets. Seems to be
      a relatively easy target. As for sealing space for bottom cowling
      (hard to do and still be able to remove the bottom cowling, Tracy
      mentioned making a screw-on cuff. I think on his RV-4 he has
      something that clamps to the PSRU just behind the prop flange.<br>
      <br>
      Finn<br>
      <br>
      On 7/3/2021 4:51 PM, Matt Boiteau <a class="moz-txt-link-abbreviated" href="mailto:mattboiteau@gmail.com">mattboiteau@gmail.com</a> wrote:<br>
    </div>
    <blockquote type="cite" cite="mid:list-127925@logan.com">
      <meta http-equiv="content-type" content="text/html; charset=utf-8">
      <div dir="ltr">I don't have any cowl flaps at the moment. But want
        to design something to try to start to optimize the cowl for
        speed.
        <div><br clear="all">
          <div>
            <div dir="ltr" class="gmail_signature"
              data-smartmail="gmail_signature">
              <div dir="ltr">
                <div>
                  <div dir="ltr">- Matt Boiteau</div>
                </div>
              </div>
            </div>
          </div>
          <br>
        </div>
      </div>
      <br>
      <div class="gmail_quote">
        <div dir="ltr" class="gmail_attr">On Wed, Jun 30, 2021 at 11:08
          PM Finn Lassen <a href="mailto:finn.lassen@verizon.net"
            moz-do-not-send="true">finn.lassen@verizon.net</a> &lt;<a
            href="mailto:flyrotary@lancaironline.net"
            moz-do-not-send="true">flyrotary@lancaironline.net</a>&gt;
          wrote:<br>
        </div>
        <blockquote class="gmail_quote" style="margin:0px 0px 0px
          0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">I
          read through all posts since 2010 containing "cowl flap".<br>
          <br>
          Both Charlie and Matt mentioned butterfly cowl flap.<br>
          <br>
          I understand it's hinged in the middle, but having a hard time
          <br>
          visualizing it. When open, is the front then lowered into the
          outside <br>
          air stream? If so, doesn't the rear part of the flap then
          block the <br>
          opening from inside to outside of cowling?<br>
          <br>
          If the front instead opens into the cowl (and rear down into
          the outside <br>
          air stream), doesn't the front then block the air inside the
          cowling. Or <br>
          maybe that's just a problem for me because my oil cooler goes
          all the <br>
          way down to the bottom of the cowling ...<br>
          <br>
          Any pictures?<br>
          <br>
          Finn<br>
          <br>
          ---<br>
          This email has been checked for viruses by Avast antivirus
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