X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 09 Apr 2006 00:40:59 -0400 Message-ID: X-Original-Return-Path: Received: from smtp108.sbc.mail.mud.yahoo.com ([68.142.198.207] verified) by logan.com (CommuniGate Pro SMTP 5.0.9) with SMTP id 1062138 for lml@lancaironline.net; Sat, 08 Apr 2006 01:40:19 -0400 Received-SPF: none receiver=logan.com; client-ip=68.142.198.207; envelope-from=elippse@sbcglobal.net Received: (qmail 67688 invoked from network); 8 Apr 2006 05:39:33 -0000 Received: from unknown (HELO Computerroom) (elippse@sbcglobal.net@71.157.179.55 with login) by smtp108.sbc.mail.mud.yahoo.com with SMTP; 8 Apr 2006 05:39:33 -0000 X-Original-Message-ID: <000501c65ace$d0c19c30$37b39d47@Computerroom> From: "Paul Lipps" X-Original-To: Subject: fixed-pitch prop X-Original-Date: Fri, 7 Apr 2006 22:39:31 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0002_01C65A94.22E795E0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0002_01C65A94.22E795E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Actually, Scotty, I do have a fixed-pitch prop. But my prop has very = little drag; I have to use a lot of braking to bring it to a stop (on = the ground, of course!). And this with an idle rpm of 680! I'm sure you, = with all your knowledge of things aerodynamic, have a copy of = "Aerodynamics For Naval Aviators". Look on page 149 where it compares = wind-milling vs stopped drag vs pitch. It turns out that a prop with 23 = deg. to 60 deg. pitch has less drag wind-milling than stopped. My = effective pitch, from VMPH X 1056 / rpm, usually computes to 76". That = works out to 27 deg at the 75% radius of a 63" diameter prop. That, = along with the minimal area of my prop beyond 12" radius, is the reason = it has so little drag. 'True, even though my 235 has a best L/D of 15:1 = at 110 mph IAS, it probably won't get that with the engine off. One of = these days I'll have to shut off the engine, at altitude, and see if the = prop will even wind-mill, and what kind of glide I do get! Paul ------=_NextPart_000_0002_01C65A94.22E795E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Actually, Scotty, I do have a fixed-pitch = prop.  But=20 my prop has very little drag; I have to use a lot of braking to bring it = to a=20 stop (on the ground, of course!). And this with an idle rpm of 680! I'm = sure=20 you, with all your knowledge of things aerodynamic, have a copy of = "Aerodynamics=20 For Naval Aviators". Look on page 149 where it compares = wind-milling vs=20 stopped drag vs pitch. It turns out that a prop with 23 deg. = to 60=20 deg. pitch has less drag wind-milling than stopped. My effective = pitch,=20 from VMPH X 1056 / rpm, usually = computes to=20 76". That works out to 27 deg at the 75% radius of a 63" diameter prop. = That,=20 along with the minimal area of my prop beyond 12" radius, is the reason = it has=20 so little drag. 'True, even though my 235 has a best L/D of 15:1 at = 110 mph=20 IAS, it probably won't get that with the engine off. One of these days = I'll have=20 to shut off the engine, at altitude, and see if the prop will even=20 wind-mill, and what kind of glide I do get! =20 Paul
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