X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 2 [X] Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 01 Apr 2007 13:42:29 -0400 Message-ID: X-Original-Return-Path: Received: from imo-d21.mx.aol.com ([205.188.144.207] verified) by logan.com (CommuniGate Pro SMTP 5.1.8) with ESMTP id 1960938 for lml@lancaironline.net; Sun, 01 Apr 2007 13:29:01 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.144.207; envelope-from=REHBINC@aol.com Received: from REHBINC@aol.com by imo-d21.mx.aol.com (mail_out_v38_r8.1.) id q.cf6.d161c2e (39332) for ; Sun, 1 Apr 2007 13:28:06 -0400 (EDT) From: REHBINC@aol.com X-Original-Message-ID: X-Original-Date: Sun, 1 Apr 2007 13:28:05 EDT Subject: Re: [LML] Re: Thielert Diesel Centurion 4.0 X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1175448485" X-Mailer: 9.0 for Windows sub 5126 X-Spam-Flag: NO -------------------------------1175448485 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 4/1/2007 12:09:49 PM Eastern Standard Time, walter@advancedpilot.com writes: Ya think? The cooling drag increase can be in the 15-20% range. Now, calculate the increased HP required to overcome that increase in drag. It's not insignificant. Were this simple to address the diesel aircraft would be faster and more efficient than they are. Walter Sorry Walter, I didn't intend to talk over anyones head. Here's how you calculate the power change. We'll use Scott's estimate of 20% for cooling drag as a fraction of total drag and your upper range estimate of 20% increase in cooling drag for a diesel compared to a gas engine. The increase in total drag due to cooling for the diesel installation is then 20% * 20%, which yields a total drag increase of 4%. Power is a function of drag * velocity. Assuming velocity is held constant, then the power requirement will vary directly with the change in drag. Thus the required power increase for the additional drag will be 4% as well. If you need help with any other concepts, just ask. I'm sure someone on the list here will be happy to help you. Rob ************************************** See what's free at http://www.aol.com. -------------------------------1175448485 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

In a message dated 4/1/2007 12:09:49 PM Eastern Standard Time, walter@a= dvancedpilot.com writes:

Ya think? <g>

The cooling drag increase can be in the 15-20% range= . Now, calculate the increased HP required to overcome that increase i= n drag. It's not insignificant. Were this simple to address the=20= diesel aircraft would be faster and more efficient than they are.

Walter

Sorry Walter,

I didn't intend to talk over anyones head. Here's how you calculate the= power change. We'll use Scott's estimate of 20% for cooling drag as a=20= fraction of total drag and your upper range estimate of 20% increase in cool= ing drag for a diesel compared to a gas engine. The increase in total d= rag due to cooling for the diesel installation is then 20% * 20%, which= yields a total drag increase of 4%.

Power is a function of drag * velocity. Assuming velocity is=20= held constant, then the power requirement will vary directly with=20= the change in drag. Thus the required power increase for the additional= drag will be 4% as well.

If you need help with any other concepts, just ask. I'm sure someone on= the list here will be happy to help you.

Rob

See what's free at AOL.com. -------------------------------1175448485--