X-Virus-Scanned: clean according to Sophos on Logan.com X-PolluStop-Diagnostic: (direct reply)\eX-PolluStop-Score: 0.00\eX-PolluStop: Scanned with Niversoft PolluStop 2.1 RC1, http://www.niversoft.com/pollustop Return-Path: Received: from mail22.syd.optusnet.com.au ([211.29.133.160] verified) by logan.com (CommuniGate Pro SMTP 4.3c4) with ESMTPS id 865841 for flyrotary@lancaironline.net; Tue, 12 Apr 2005 03:20:42 -0400 Received-SPF: none receiver=logan.com; client-ip=211.29.133.160; envelope-from=lendich@optusnet.com.au Received: from george (d211-31-83-17.dsl.nsw.optusnet.com.au [211.31.83.17]) by mail22.syd.optusnet.com.au (8.12.11/8.12.11) with SMTP id j3C7JhUT031815 for ; Tue, 12 Apr 2005 17:19:47 +1000 Message-ID: <002101c53f30$837eea00$11531fd3@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: RV10 Cowl Date: Tue, 12 Apr 2005 17:23:21 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001E_01C53F84.538B53C0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 This is a multi-part message in MIME format. ------=_NextPart_000_001E_01C53F84.538B53C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I could be wrong but I think the idea is to get the opening away from = the hub area as all it creates is a turbulence and blanketing effect. The minimization of the flat plate area dictates that you can't take it = too far from the hub area because of increased drag, created because of = a bigger frontal area. However just past the hub you get better flow - however the area between = the flange/ hub area and the rad inlet needs to be streamlined - hence = the concave recess between the two, which allows the air to flow = smoothly rearwards. The boundary layer is more of a concern as you move backwards along the = cowl and the fuselage. George ( down under)=20 Ernest Wrote: > You should have went with your first instinct in my opinion. Like = you said, > the boundary layer at that point does not exist in any measurable = thickness, > and your going to get increased drag from the vortices created in = the > intersecting surfaces. Something more like this? [JJJ RV10-COWL Rev 5] I'm not sure I like = this look totally either but it might improve the airflow a bit. I guess = the other option would be to put a center 'divider' something like this = [JJJ-RV10-COWL Rev4 & JJJ-RV10-COWL Rev 4-FULL VIEW] to get things = better streamlined, but it actually may increase the problem due to = rotational flow off the prop. Jarrett Johnson -------------------------------------------------------------------------= ----- >> Homepage: http://www.flyrotary.com/ >> Archive: http://lancaironline.net/lists/flyrotary/List.html ------=_NextPart_000_001E_01C53F84.538B53C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 I could be wrong but I think the = idea is to=20 get the opening away from the hub area as all it creates is a turbulence = and=20 blanketing effect.
 
The minimization of the flat plate area = dictates=20 that you can't take it too far from the hub area because of increased=20 drag, created because of a bigger frontal area.
 
However just past the hub you get = better flow -=20 however the area between the flange/ hub area and the rad inlet needs to = be=20 streamlined - hence the concave = recess between=20 the two, which allows the air to flow smoothly rearwards.
 
The boundary layer is more of a concern = as you move=20 backwards along the cowl and the fuselage.
George ( down = under) 
 
 
Ernest Wrote:
 
> You should have went with your = first=20 instinct in my opinion.  Like you said,
> the boundary = layer at=20 that point does not exist in any measurable thickness,
> and = your going=20 to get increased drag from the vortices created in the
> = intersecting=20 surfaces.
 
 
 
Something more like = this? [JJJ=20 RV10-COWL Rev 5]  I'm = not sure I=20 like this look totally either but it might improve the airflow a bit. = I guess=20 the other option would be to put a center 'divider' something like = this=20 [JJJ-RV10-COWL Rev4 &  JJJ-RV10-COWL = Rev=20 4-FULL VIEW]  to get things better streamlined, but it = actually=20 may increase the problem due to rotational flow off the = prop.
 
Jarrett Johnson

>>  Homepage: =20 http://www.flyrotary.com/
>>  Archive:  =20 = http://lancaironline.net/lists/flyrotary/List.html
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