X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 26 Apr 2006 10:59:26 -0400 Message-ID: X-Original-Return-Path: Received: from imo-m28.mx.aol.com ([64.12.137.9] verified) by logan.com (CommuniGate Pro SMTP 5.0.9) with ESMTP id 1081621 for lml@lancaironline.net; Wed, 26 Apr 2006 10:20:35 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.9; envelope-from=CustomACProp@aol.com Received: from CustomACProp@aol.com by imo-m28.mx.aol.com (mail_out_v38_r7.5.) id q.3db.aaf30a (48576) for ; Wed, 26 Apr 2006 10:12:59 -0400 (EDT) From: CustomACProp@aol.com X-Original-Message-ID: <3db.aaf30a.3180d9eb@aol.com> X-Original-Date: Wed, 26 Apr 2006 10:12:59 EDT Subject: Re: [LML] prop tips X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1146060779" X-Mailer: 9.0 SE for Windows sub 5026 X-Spam-Flag: NO -------------------------------1146060779 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Reading between the lines about the propeller; Torque turns the propeller? And horsepower is just a way to tell how much gas will be burned? Seems right to me. Jim Ayers In a message dated 04/25/2006 9:21:47 PM Pacific Daylight Time, elippse@sbcglobal.net writes: 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! -------------------------------1146060779 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

Reading between the lines about the propeller;

Torque turns the propeller?

And horsepower is just a way to tell how much gas will be burned?

Seems right to me.

Jim Ayers

In a message dated 04/25/2006 9:21:47 PM Pacific Daylight Time,=20 elippse@sbcglobal.net writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>

Colyn! The prop scales up or down. I recently did=20= a=20 design for a four-blade CS, 55" diameter, 500+ hp, 400 mph. Very high=20 efficiency. Prop tips are mounted on a long lever. One lb of drag at the t= ip=20 of a 3 ft radius consumes three times as much hp as one lb at 1 ft radius.= =20 There is no lift at the tip, but the drag, which is proportional to chord,= is=20 still there! Sweeping the tip doesn't get rid of the drag, nor does making= the=20 blade thinner, which is also what sweeping a blade does; it makes the blad= e=20 look thinner. Thinner blades also have lower L/D! Keeping tip chord a= t=20 zero and tip Mach at or below 0.85 is the ticket! In my equatio= ns I=20 compare thrust-to-torque ratio every inch along the blade. On my designs i= t=20 decreases somewhat near the tip, but stays fairly constant all the way int= o=20 the root. On standard wide-chord blades, it really goes to Hell at th= e=20 tips!

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