X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [199.185.220.223] (HELO priv-edtnes28.telusplanet.net) by logan.com (CommuniGate Pro SMTP 4.3.5) with ESMTP id 1022105 for flyrotary@lancaironline.net; Sun, 26 Jun 2005 12:21:45 -0400 Received-SPF: pass receiver=logan.com; client-ip=199.185.220.223; envelope-from=echolakeresort@telus.net Received: from boucher-oddle24 ([207.194.127.16]) by priv-edtnes28.telusplanet.net (InterMail vM.6.01.04.04 201-2131-118-104-20050224) with SMTP id <20050626162058.EYIL7254.priv-edtnes28.telusplanet.net@boucher-oddle24> for ; Sun, 26 Jun 2005 10:20:58 -0600 MIME-Version: 1.0 Message-Id: <42BED5E5.000003.03760@BOUCHER-ODDLE24> Date: Sun, 26 Jun 2005 09:20:53 -0700 (Pacific Standard Time) Content-Type: Multipart/Alternative; boundary="------------Boundary-00=_TE9PG6G0000000000000" X-Mailer: IncrediMail (3001609) From: "Echo Lake Fishing Resort (Georges Boucher)" References: To: Subject: Re: [FlyRotary] Re: Coolant Leak X-FID: FLAVOR00-NONE-0000-0000-000000000000 X-Priority: 3 --------------Boundary-00=_TE9PG6G0000000000000 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Dave You mean expiation not vaporization don't you?=0D Georges B. =0D =0D -------Original Message-------=0D =0D From: Rotary motors in aircraft=0D Date: 06/25/05 20:13:34=0D To: Rotary motors in aircraft=0D Subject: [FlyRotary] Re: Coolant Leak=0D =0D Ok, here is my guess:=0D =0D =0D On 6/25/05, John Slade wrote: =0D OK, Dave. If that makes sense, explain this.... :)=0D After start-up - 29 psi (24 psi cap)=0D =0D coolant is expanding rapidly. The pressure rating of most caps is a roug= h estimate at best. It is determined by the metal spring. That metal spri= ng will also change the force it applies based on it's temperature (though I= am not sure which direction and how much). =0D =0D =0D Run-up 25 PSI=0D =0D Coolant is still expanding though possibly at a slower rate and/or the spring is now also warm and exerting less force.=0D =0D =0D Two trips around the pattern - zero PSI the entire time=0D =0D Now you are getting good air flow after climb out and the temp drops a little from its peak value, so the volume of coolant contracts and sucks = a little back in from the overflow - zero psi.=0D =0D =0D third downwind - 8 PSI.=0D =0D Now you have reached steady state temperature, or perhaps a second slight rise in temp as the overall under cowl temp rises (all heat sinks under t= he cowl become saturated with heat). Also, there is continuous vaporizatio= n of the coolant, which rapidly re condenses after leaving the hottest area= s. The amount of this vaporization is a function of the pressure and temp. = So it will seek some equilibrium at a pressure that is greater than zero. i= e. more vaporization increases the pressure, which in turn limits amount of vaporization. =0D =0D =0D taxi back to hangar - 10 PSI.=0D =0D Perhaps slightly warmer now (especially in those backward flying airplane= s) and the vaporization:pressure equilibrium has shifted a little.=0D =0D =0D After cool down - coolant still full to the brim.=0D =0D Yea, no reason for me to think you have a leak. (I can convince myself = of anything :-)=0D =0D -- =0D Dave Leonard=0D Turbo Rotary RV-6 N4VY=0D http://members.aol.com/_ht_a/rotaryroster/index.html=0D http://members.aol.com/vp4skydoc/index.html =0D =20 --------------Boundary-00=_TE9PG6G0000000000000 Content-Type: Text/HTML; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Dave  You mean expiation not vaporization don't you?
Georges B. 
 
-------Original Message-------
 
Date: 06/25/05 20:= 13:34
Subject: [FlyRotar= y] Re: Coolant Leak
 
Ok, here is my guess:

On 6/25/05, Jo= hn Slade <sladerj@bellsou= th.net> wrote:=20
OK, Dave. If that = makes sense, explain this.... :)
   = After start-up - 29 psi (24 psi cap)
 
coolant is expanding rapidly.  The pressure rating of most caps= is a rough estimate at best.  It is determined by the met= al spring.  That metal spring will also change the force it applies = based on it's temperature (though I am not sure which direction and how m= uch).

   = Run-up  25 PSI
 
Coolant is still expanding though possibly at a slower rate and/or t= he spring is now also warm and exerting less force.

   = Two trips around the pattern - zero PSI the entire time
 
Now you are getting good air flow after climb out and the temp drops= a little from its peak value, so the volume of coolant contracts and suc= ks a little back in from the overflow - zero psi.

   = third downwind - 8 PSI.
 
Now you have reached steady state temperature, or perhaps a second s= light rise in temp as the overall under cowl temp rises (all heat sinks u= nder the cowl become saturated with heat).   Also, there i= s continuous vaporization of the coolant, which rapidly re condenses afte= r leaving the hottest areas. The amount of this vaporization is a functio= n of the pressure and temp.  So it will seek some equilibrium at a p= ressure that is greater than zero.  ie. more vaporization increases = the pressure, which in turn limits amount of vaporization.
   = taxi back to hangar - 10 PSI.
 
Perhaps slightly warmer now (especially in those backward flying air= planes) and the vaporization:pressure equilibrium has shifted a little.
   = After cool down - coolant still full to the brim.
 
Yea, no reason for me to think you have a leak.   (I can c= onvince myself of anything  :-)
 
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