X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 50 [XX] Return-Path: Received: from ms-smtp-04.southeast.rr.com ([24.25.9.103] verified) by logan.com (CommuniGate Pro SMTP 5.1.8) with ESMTP id 2016472 for flyrotary@lancaironline.net; Sun, 29 Apr 2007 15:04:35 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.103; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-103-061.carolina.res.rr.com [24.74.103.61]) by ms-smtp-04.southeast.rr.com (8.13.6/8.13.6) with SMTP id l3TI39Wp011351 for ; Sun, 29 Apr 2007 14:03:12 -0400 (EDT) Message-ID: <000601c78a88$cecdaf00$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" Subject: Cooling Effectiveness Date: Sun, 29 Apr 2007 14:04:16 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0003_01C78A67.46303EE0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3028 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0003_01C78A67.46303EE0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Seems a bit quite on the list, so though I would throw this out for = discussion. On my way back from Louisiana, I decided to see if I could determine how = close I was to an optimum cooling configuration for my installation and = power. At 9500 MSL the OAT was showing 46F. At 8 gph fuel burn (my normal = cruise power setting =3D approx 88 HP) the oil and coolant temps (no = thermostat) were showing 165F. I increased to my max power setting at = that altitude and when things stabilized, I was burning 12.5 GPH = (approx 133 hp). I noted that my oil and coolant temps had both = stabilized at 195F. 200F for oil and coolant are my personal limits = for long duration extended power settings - I will accept upto 220F on = coolant for a limited time period during/after take off. My conclusion is that my cooling system is fairly close to optimum (for = my installation) in that at full power cruise I am only 5F deg short of = my set limits. I do have a cooling deficit during high power take off = until I hit 120 mph IAS. At that point, the cooling air flow is = sufficient to bring down the temps combined with a modest power = reduction after reaching a safe altitude. Naturally, cooler OAT would have reduce the temps and higher OAT would = have brought it closer to my set temperature limit. Since I normally do not fly at my max power cruise settings, a case = could be made that my cruise cooling capacity is excessive for my needs = at cruise - but, reducing the capacity would then made the cooling = deficit on take off more severe - in fact, unacceptable I am certain.=20 Seeing some of the nice custom radiators now available at a reasonable = price from an number of sources such and Ed K (Tech Welding), I am of = the opinion that replacing my decade + old GM evaporator cores (designed = for Freon vice water) would improve the over all cooling effectiveness = and particularly on take off. The very dense GM core fins work best = with high dynamic pressure (higher IAS) available to force air through = them. The wider spacing fins of radiators made for water would = likely permit more air mass at lower airspeeds and enhance cooling = during take off. Perhaps someday, I'll replace the old 13B with a Renesis and find more = power and that I need a bit more cooling. That would probably be the = time I would consider replacing the GM cores, but after successfully = flying behind them for a decade they are like old friends. =20 Anyone else have comments about their cooling system - satisfaction - = dissatisfaction? Anyone there? Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.dmack.net/mazda/index.html . =20 Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.dmack.net/mazda/index.html ------=_NextPart_000_0003_01C78A67.46303EE0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Seems a bit quite on the list, so though I would = throw=20 this out for discussion.
 
On my way back from Louisiana, I decided to see = if I could=20 determine how close I was to an optimum cooling configuration for my=20 installation and power.
 
At 9500 MSL the OAT was showing 46F.  At 8 = gph fuel=20 burn (my normal cruise power setting =3D approx 88 HP) the oil and = coolant temps=20 (no thermostat) were showing 165F.  I increased to my max power = setting at=20 that altitude  and when things stabilized,  I was burning = 12.5=20 GPH (approx 133 hp).   I noted that my oil and coolant temps = had=20 both stabilized at 195F.   200F for oil and  = coolant=20 are my personal limits for long duration extended power settings - I = will accept=20 upto 220F on coolant for a limited time period during/after take=20 off.
 
My conclusion is that my cooling system is = fairly close to=20 optimum (for my installation)  in that at full power cruise I am = only 5F=20 deg short of my set limits.  I do have a cooling deficit during = high power=20 take off until I hit 120 mph IAS.  At that point, the cooling air = flow is=20 sufficient to bring down the temps combined with a modest power = reduction after=20 reaching a safe altitude.
 
Naturally, cooler OAT would have reduce the = temps and=20 higher OAT would have brought it closer to my set temperature=20 limit.
 
Since I normally do not fly at my max power = cruise=20 settings, a case could be made that my cruise cooling capacity is = excessive for=20 my needs at cruise - but, reducing the capacity would then made the = cooling=20 deficit on take off more severe - in fact, unacceptable I am=20 certain. 
 
Seeing some of the nice custom radiators now = available at=20 a reasonable price  from an number of sources such and Ed K = (Tech=20 Welding), I am of the opinion that replacing my decade + old GM = evaporator cores=20 (designed for Freon vice water) would improve the over all cooling = effectiveness=20 and particularly on take off.  The very dense GM core fins work = best with=20 high dynamic pressure (higher IAS) available to  force air = through=20 them.  The wider spacing fins of  radiators made for = water=20   would likely permit more air mass at lower airspeeds and enhance = cooling=20 during take off.
 
Perhaps someday, I'll replace the old 13B with a = Renesis=20 and find more power and that I need a bit more cooling.  That = would=20 probably be the time I would consider replacing the GM cores, but after=20 successfully flying behind them for a decade they are like old = friends. =20
 
Anyone else have comments about their cooling = system -=20 satisfaction - dissatisfaction?
 
Anyone there?
 
Ed
 
Ed Anderson
Rv-6A N494BW Rotary = Powered
Matthews,=20 NC
eanderson@carolina.rr.comhttp:/= /members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.dmack.net/mazda= /index.html
 
. 
 
 
 
 
 
 
Ed Anderson
Rv-6A N494BW Rotary = Powered
Matthews,=20 NC
eanderson@carolina.rr.comhttp:/= /members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.dmack.net/mazda= /index.html
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