X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.121] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTP id 2500241 for flyrotary@lancaironline.net; Wed, 21 Nov 2007 23:07:01 -0500 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.121; envelope-from=eanderson@carolina.rr.com Received: from edward2 ([24.74.103.61]) by cdptpa-omta05.mail.rr.com with SMTP id <20071122040624.LFIX8432.cdptpa-omta05.mail.rr.com@edward2> for ; Thu, 22 Nov 2007 04:06:24 +0000 Message-ID: <000601c82cbd$66f40b90$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Naca Report on Radiator Thickness Date: Wed, 21 Nov 2007 23:08:56 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 Work on the Cozy, Ron. Because then something useful will get done for certain {:>) Ed ----- Original Message ----- From: "Ron Springer" To: "Rotary motors in aircraft" Sent: Wednesday, November 21, 2007 9:20 PM Subject: [FlyRotary] Re: Naca Report on Radiator Thickness > Well, engineering judgement tells me that your drag > increase is still too low. Now I'll just have to prove > it by looking at that report, or elsewhere. > Sounds like a good project for the long holiday > weekend, or I could just work on my Cozy ... it will > be a tough call! > > Ron > > --- Ed Anderson wrote: > >> >> Ok, Ron, I went back and looked at the drag aspects >> again. It looks like >> the calculation was accurate, however, I think this >> will put it into a >> better perspective than before. >> >> The frontal drag at 120 mph for the 1 square foot >> radiator (using just the >> frontal area - no drag coefficient) was >> >> 37.63 lbf/ft^2, the "internal skin" drag of the 4" >> thick radiator was 6.7 >> lbf/ft^2. The skin drag for the 1" thick rad was >> 4.28 lbf/ft^2. So >> comparing the 6.7 with the 4.28 was where I came up >> with the 58% increase in >> skin drag. >> >> However, adding the frontal and skin drag factors >> for the "total" drag, I >> get 37.62 lbf/ft^2 + 4.28 lbf/ft^2 = 40.98 lbf/ft^2 >> total drag for the 1" >> rad. For the 4" rad 37.62 + 6.7 = 44.32 lbf/ft^2, >> so based on that it >> appears that the total drag was increased by >> 41.90/44.32 = 5.5% more total >> drag for the 4" radiator than for the 1" radiator. >> It might be a tad bit >> less than that due to the 5% decrease in mass flow >> on the frontal area of >> the thicker rad. >> >> At least that is the way it appears to me. >> >> Ed >> >> >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: >> > http://mail.lancaironline.net:81/lists/flyrotary/List.html >> > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html