X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 2 [X] Return-Path: Received: from ms-smtp-05.southeast.rr.com ([24.25.9.104] verified) by logan.com (CommuniGate Pro SMTP 5.1.7) with ESMTP id 1876197 for flyrotary@lancaironline.net; Thu, 01 Mar 2007 09:54:58 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.104; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-103-061.carolina.res.rr.com [24.74.103.61]) by ms-smtp-05.southeast.rr.com (8.13.6/8.13.6) with SMTP id l21ErtAF017579 for ; Thu, 1 Mar 2007 09:53:56 -0500 (EST) Message-ID: <001d01c75c11$70fa9be0$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] diffusers Date: Thu, 1 Mar 2007 09:53:57 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001A_01C75BE7.87E1BE80" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3028 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_001A_01C75BE7.87E1BE80 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable John, I would go with the 22 1/4 sq inches. For these reasons: 1. Your engine may produce more power than the one I run with - = requiring more heat rejection. 2. It is easier to neck down the opening (than widen it) if it turns = out you have more than what is necessary - or do nothing 3. My cowl exit area is probably a bit larger than most which may = produce less back pressure enabling smaller opening to flow more air. Ball up your fist and see if you can stick it through the narrowest = opening - it should just almost go (that is if you have the same size = hands I do {:>)) How's that for a standard of measure? Ed ----- Original Message -----=20 From: John Downing=20 To: Rotary motors in aircraft=20 Sent: Thursday, March 01, 2007 9:39 AM Subject: [FlyRotary] diffusers Ed, If I add the extension, indicated with cardboard w/lines, I have = the original 22 1/4 sq. in's. If I block off the cowl openings to match = the diffuser, I will have 18 7/8 sq. inches. The neck at the smallest = point is approximately 15 sq. inches as close as I can determine by my = barn door math. Which is the better way to go, opening wise, the larger = or the smaller opening. If these numbers are in the ball park, I'll lay = up the glass. Thankyou JohnD -------------------------------------------------------------------------= ----- -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ ------=_NextPart_000_001A_01C75BE7.87E1BE80 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
John, I would go with the 22 1/4 sq = inches.  For=20 these reasons:
 
1.  Your engine may produce more power than = the one I=20 run with - requiring more heat rejection.
2.  It is easier to neck down the opening = (than widen=20 it)  if it turns out you have more than what is necessary - or do=20 nothing
3.  My cowl exit area is probably a bit = larger than=20 most which may produce less back pressure enabling smaller opening to = flow more=20 air.
 
Ball up your fist and see if you can stick it = through the=20 narrowest opening - it should just almost go (that is if you have the = same size=20 hands I do {:>))  How's that for a standard of = measure?
 
 
Ed
----- Original Message -----
From:=20 John=20 Downing
Sent: Thursday, March 01, 2007 = 9:39=20 AM
Subject: [FlyRotary] = diffusers

Ed,  If I add the extension, = indicated with=20 cardboard w/lines, I have the original 22 1/4 sq. in's.  If I = block off=20 the cowl openings to match the diffuser, I will have 18 7/8 sq. = inches. =20 The neck at the smallest point is approximately 15 sq. inches as close = as I=20 can determine by my barn door math.  Which is the better way to = go,=20 opening wise, the larger or the smaller opening.  If these = numbers are in=20 the ball park, I'll lay up the glass.  Thankyou  = JohnD

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