Return-Path: Received: from [24.25.9.100] (HELO ms-smtp-01-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.2b8) with ESMTP id 322266 for flyrotary@lancaironline.net; Thu, 15 Jul 2004 09:41:54 -0400 Received-SPF: error receiver=logan.com; client-ip=24.25.9.100; envelope-from=eanderson@carolina.rr.com Received: from EDWARD (clt25-78-058.carolina.rr.com [24.25.78.58]) by ms-smtp-01-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id i6FDfKPg002022 for ; Thu, 15 Jul 2004 09:41:21 -0400 (EDT) Message-ID: <005301c46a71$6ab7dde0$2402a8c0@EDWARD> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: New Scoop Date: Thu, 15 Jul 2004 09:41:22 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0050_01C46A4F.E35781A0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0050_01C46A4F.E35781A0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageHi Rusty, K&W actually has a section on the analysis of the cooling component = of drag. I have skimmed over that section and would need to go back to = it to get a feel for what percentage of the total drag it might be for = an Rv. The sleeker and faster your design (i.e. the lower the external = drag factor) then the higher % of the total the cooling drag becomes. = So more important for the 200MPH+ crowd than say the 120 MPH and below = crowd. I know there are some fairly reliable overall estimates of the drag = of an RV (CAFE reports and others), so if an reasonably estimate of = cooling drag could be calculated then we could sort of determine how = much cooling drag is or is not affecting your overall performance. Your radiator cooling capacity would certainly appear to be more than = you need given your low coolant temps (assuming they are close to the = money) with your current set up. But, the 2.85 and higher rpm producing = more power will eat up some of that. On an average comparing the RPM Tracy gets with the 2.85, I would say = you will turn approx 1000 rpm more than the 2.17 that would mean in = increase of approx 20% more BTU you will need to get rid of. Of course = with the faster acceleration and climb rate you could have more cooling = air - or the "overcapacity" in cooling would permit you to climb at a = slower airspeed and steeper angle. So I wouldn't change anything - yet. Ed =20 Ed Anderson RV-6A N494BW Rotary Powered Matthews, NC ----- Original Message -----=20 From: Russell Duffy=20 To: Rotary motors in aircraft=20 Sent: Wednesday, July 14, 2004 8:42 PM Subject: [FlyRotary] Re: New Scoop If you design and tailored your cooling system for cooling in a steep = climb on a hot day, you will have excessive cooling capacity at cruise = (read - more cooling drag) than is necessary. =20 Hey Ed,=20 I agree of course that you would have more cooling drag, but do you = have any idea what the drag penalty would be for an RV style plane? =20 I personally want to be able to climb at 100 kts, full throttle, on = the hottest day, without ever exceeding any temps. At the moment, I = can, but the C drive and new prop may change things some. I seem to = have more excess water cooling, than oil cooling, and eventually, I may = have to close up part of the radiator inlets. =20 FWIW, the other day it was 92 degrees on the ground, and I climbed at = 100 kts to 8k ft, full throttle. The max oil temp was 195, and the max = water was 178. At 8000 ft, full throttle, temps settled in to be 183 = for oil, and 130 for water. That was at 196 mph TAS, with plenty of = fairing work left to be done. As for climb performance, I noticed that = the EM-2 flight timer was on 7 minutes when I leveled out at 8k ft. = That's OK for now, but I expect to see that time to 8k ft be less than 4 = min with the C drive. =20 Rusty (just got home with a motorcycle, more like a training bike) =20 ------=_NextPart_000_0050_01C46A4F.E35781A0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
Hi Rusty,
 
    K&W actually has = a section=20 on the analysis of the cooling component of drag.  I have skimmed = over that=20 section and would need to go back to it to get a feel for what = percentage of the=20 total drag it might be for an Rv.  The sleeker and faster your = design (i.e.=20 the lower the external drag factor) then the higher % of the total the = cooling=20 drag becomes.  So more important for the 200MPH+ crowd than say the = 120 MPH=20 and below crowd.
 
   I know there are some = fairly reliable=20 overall estimates of the drag of an RV (CAFE reports and others), so if = an=20 reasonably estimate of cooling drag could be calculated then we could = sort of=20 determine how much cooling drag is or is not affecting your overall=20 performance.
 
  Your radiator cooling capacity = would=20 certainly appear to be more than you need given your low coolant temps = (assuming=20 they are close to the money) with your current set up.  But, the = 2.85 and=20 higher rpm producing more power will eat up some of that.
On an average comparing the RPM Tracy = gets with the=20 2.85, I would say you will turn approx 1000 rpm more than the 2.17 that = would=20 mean in increase of approx 20% more BTU you will need to get rid = of.  Of=20 course with the faster acceleration and climb rate you could have more = cooling=20 air - or the "overcapacity" in cooling would permit you to climb at a = slower=20 airspeed and steeper angle.  So I wouldn't change anything -=20 yet.
 
Ed
 
 
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
----- Original Message -----
From:=20 Russell=20 Duffy
Sent: Wednesday, July 14, 2004 = 8:42=20 PM
Subject: [FlyRotary] Re: New = Scoop

If you design and tailored your cooling system for = cooling in=20 a steep climb on a hot day, you will have excessive cooling capacity = at cruise=20 (read - more cooling drag) than is necessary. 

Hey Ed,=20

I agree = of course that=20 you would have more cooling drag, but do you have any idea what the = drag=20 penalty would be for an RV style plane? 

I = personally want to be=20 able to climb at 100 kts, full throttle, on the hottest day, = without=20 ever exceeding any temps.  At the moment, I can, but the C = drive and=20 new prop may change things some.  I seem to = have more=20 excess water cooling, than oil cooling, and eventually, I may have=20 to close up part of the radiator = inlets.  

FWIW, = the other day it=20 was 92 degrees on the ground, and I climbed at 100 kts = to 8k=20 ft, full throttle.  The max oil temp was 195, and the max water=20 was 178.  At 8000 ft, full throttle, temps settled in = to be 183=20 for oil, and 130 for water.  That was at 196 mph TAS, with plenty = of=20 fairing work left to be done.  As for climb performance,=20 I noticed that the EM-2 flight timer was on 7 minutes when I = leveled out=20 at 8k ft.  That's OK for now, but I expect to see that time to 8k = ft be=20 less than 4 min with the C drive.  

Rusty = (just got home=20 with a motorcycle, more like a training=20 bike)  

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