X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 26 Apr 2006 00:16:33 -0400 Message-ID: X-Original-Return-Path: Received: from smtp102.sbc.mail.mud.yahoo.com ([68.142.198.201] verified) by logan.com (CommuniGate Pro SMTP 5.0.9) with SMTP id 1080837 for lml@lancaironline.net; Tue, 25 Apr 2006 18:31:26 -0400 Received-SPF: none receiver=logan.com; client-ip=68.142.198.201; envelope-from=elippse@sbcglobal.net Received: (qmail 19314 invoked from network); 25 Apr 2006 21:48:35 -0000 Received: from unknown (HELO Computerroom) (elippse@sbcglobal.net@71.148.2.182 with login) by smtp102.sbc.mail.mud.yahoo.com with SMTP; 25 Apr 2006 21:48:35 -0000 X-Original-Message-ID: <000501c668b2$05166920$b6029447@Computerroom> From: "Paul Lipps" X-Original-To: "Marv Kaye" Subject: prop tips X-Original-Date: Tue, 25 Apr 2006 14:48:39 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0002_01C66877.56E6C8C0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2869 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2869 This is a multi-part message in MIME format. ------=_NextPart_000_0002_01C66877.56E6C8C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Colyn! The prop scales up or down. I recently did a design for a = four-blade CS, 55" diameter, 500+ hp, 400 mph. Very high efficiency. = Prop tips are mounted on a long lever. One lb of drag at the tip of a 3 = ft radius consumes three times as much hp as one lb at 1 ft radius. = There is no lift at the tip, but the drag, which is proportional to = chord, is still there! Sweeping the tip doesn't get rid of the drag, nor = does making the blade thinner, which is also what sweeping a blade does; = it makes the blade look thinner. Thinner blades also have lower L/D! = Keeping tip chord at zero and tip Mach at or below 0.85 is the ticket! = In my equations I compare thrust-to-torque ratio every inch along the = blade. On my designs it decreases somewhat near the tip, but stays = fairly constant all the way into the root. On standard wide-chord = blades, it really goes to Hell at the tips! ------=_NextPart_000_0002_01C66877.56E6C8C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Colyn! The prop scales up or down. I recently = did a design=20 for a four-blade CS, 55" diameter, 500+ hp, 400 mph. Very high = efficiency. Prop=20 tips are mounted on a long lever. One lb of drag at the tip of a 3 ft = radius=20 consumes three times as much hp as one lb at 1 ft radius. There is no = lift at=20 the tip, but the drag, which is proportional to chord, is still there! = Sweeping=20 the tip doesn't get rid of the drag, nor does making the blade thinner, = which is=20 also what sweeping a blade does; it makes the blade look thinner. = Thinner blades=20 also have lower L/D! Keeping tip chord at zero and tip Mach at or = below=20 0.85 is the ticket!  In my equations I compare = thrust-to-torque ratio=20 every inch along the blade. On my designs it decreases somewhat near the = tip,=20 but stays fairly constant all the way into the root. On standard=20 wide-chord blades, it really goes to Hell at the=20 tips!
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