Return-Path: Received: from relay03.roc.ny.frontiernet.net ([66.133.131.36] verified) by logan.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 3051893 for flyrotary@lancaironline.net; Mon, 01 Mar 2004 00:37:27 -0500 Received: (qmail 31525 invoked from network); 1 Mar 2004 05:37:26 -0000 Received: from unknown (HELO frontiernet.net) ([170.215.99.215]) (envelope-sender ) by relay03.roc.ny.frontiernet.net (FrontierMTA 2.3.6) with SMTP for ; 1 Mar 2004 05:37:26 -0000 Message-ID: <4042CC11.41925462@frontiernet.net> Date: Sun, 29 Feb 2004 23:37:21 -0600 From: Jim Sower X-Mailer: Mozilla 4.77 [en] (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: PROP Free Spinning or WindMilling??? References: Content-Type: multipart/alternative; boundary="------------3027F897AF8E9A1C8BE5F532" --------------3027F897AF8E9A1C8BE5F532 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit That wasn't very well articulated. At zero lift, there is some parasite drag, but you never see zero lift so it's the induced drag that dominates, and except at cruise you're at pretty high Cl, so induced drag is quite high. You quit reading too soon. Go over the rest of the post and tell me where I went wrong. WALTER KERR wrote: > At > zero lift it has some parasite drag, but it's the induced drag > that dominates. > > Hi Jim, Doesn't make better sense to me, I fell off > the sled with the opening statement that at zero > lift the induced drag dominates, and I have a degree > in aero engineering :>) If I can remember back to > aero 101 in the 50's, the induced drag is a function > of lift coef. squared and would be zero at zero > angle of attack. I believe the prop runs at a high > negative angle of attack when it is windmilling with > load and approachs the zero lift angle of attack > when freewheeling. When the prop is loaded or > stopped, the disk theory does not apply, it only the > drag of the stick. Bernie Kerr > -- Jim Sower ... Destiny's Plaything Crossville, TN; Chapter 5 Long-EZ N83RT, Velocity N4095T --------------3027F897AF8E9A1C8BE5F532 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit That wasn't very well articulated.  At zero lift, there is some parasite drag, but you never see zero lift so it's the induced drag that dominates, and except at cruise you're at pretty high Cl, so induced drag is quite high.  You quit reading too soon.  Go over the rest of the post and tell me where I went wrong.

WALTER KERR wrote:

<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /> At zero lift it has some parasite drag, but it's the induced drag that dominates.
Hi Jim, Doesn't make better sense to me, I fell off the sled with the opening statement that at zero lift the induced drag dominates, and I have a degree in aero engineering :>)  If I can remember back to aero 101 in the 50's, the induced drag is a function of lift coef. squared and would be zero at zero angle of attack. I believe the prop runs at a high negative angle of attack when it is windmilling with load and approachs the zero lift angle of attack when freewheeling. When the prop is loaded or stopped, the disk theory does not apply, it only the drag of the stick. Bernie Kerr

--
Jim Sower ... Destiny's Plaything
Crossville, TN; Chapter 5
Long-EZ N83RT, Velocity N4095T
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