Return-Path: Received: from ns5.rokland.us ([67.15.10.31] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP-TLS id 573625 for flyrotary@lancaironline.net; Sun, 19 Dec 2004 23:07:48 -0500 Received-SPF: none receiver=logan.com; client-ip=67.15.10.31; envelope-from=bob@bob-white.com Received: from bgp01386375bgs.brodwy01.nm.comcast.net ([68.35.160.229] helo=localhost) by ns5.rokland.us with smtp (Exim 4.43) id 1CgEpF-0006Z6-CG for flyrotary@lancaironline.net; Sun, 19 Dec 2004 22:07:13 -0600 Date: Sun, 19 Dec 2004 21:07:11 -0700 From: Bob White To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: George Graham glide update Message-Id: <20041219210711.7d639025.bob@bob-white.com> In-Reply-To: References: X-Mailer: Sylpheed version 1.0.0rc (GTK+ 1.2.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Antivirus-Scanner: Clean mail though you should still use an Antivirus X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - ns5.rokland.us X-AntiAbuse: Original Domain - lancaironline.net X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - bob-white.com X-Source: X-Source-Args: X-Source-Dir: I suspect they would be different. To hazard a guess, a free spinning prop is doing less work than a prop turning a motor, so it should provide less drag. But a fixed pitch prop in either condition would want to turn somewhere in the range of speed you would be gliding at. A prop at flat pitch would need to speed up to a very high rpm to match the forward speed of the plane. If the prop can't keep up with the forward speed of the plane, it will effectively be pushing backward creating extra drag. At least that's my armchair analysis. Bob White On Sun, 19 Dec 2004 18:10:25 -0800 (PST) Tom wrote: > I wonder if a free-spinning prop on a broken tranny would not have the > same drag as a spinning prop which is turning the motor? I'd be > inclined to say they would differ. > > Tom > > > --- Bob White wrote: > > > Somenone else recently reported a spinning prop having negligable > > effect on engine out glide. (Dave Leonard maybe?). I'm thinking > > that the biggest effect occurs with a C/S prop that goes to flat > > pitch when it looses oil pressure. I think twins often use > > feathering props for that reason. > > > > Bob White > > > > On Sun, 19 Dec 2004 15:41:53 -0500 > > "Tracy Crook" wrote: > > > > He glided about 20 miles from an altitude of only 5000 ft with the > > prop > > freewheeling! I've heard several times that a freewheeling prop > > (no engine drag on it) would generate lots of drag. Another sacred > > cow shot down : ) > > > > > > Tracy > > > > -- > > http://www.bob-white.com > > N93BD - Rotary Powered BD-4 (soon) > > > > >> Homepage: http://www.flyrotary.com/ > > >> Archive: http://lancaironline.net/lists/flyrotary/List.html > > > > > > > __________________________________ > Do you Yahoo!? > Yahoo! Mail - Helps protect you from nasty viruses. > http://promotions.yahoo.com/new_mail > > >> Homepage: http://www.flyrotary.com/ > >> Archive: http://lancaironline.net/lists/flyrotary/List.html > > -- http://www.bob-white.com N93BD - Rotary Powered BD-4 (soon)