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 5.1.12) with ESMTP id 2370709 for flyrotary@lancaironline.net; Fri, 05 Oct 2007 12:08:06 -0400 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-omta06.mail.rr.com with SMTP id <20071005160726.GBZC3972.cdptpa-omta06.mail.rr.com@edward2> for ; Fri, 5 Oct 2007 16:07:26 +0000 Message-ID: <001801c80769$dac60470$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: [FlyRotary] Re: Coolant Water Pressure Date: Fri, 5 Oct 2007 12:07:40 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0015_01C80748.538257F0" 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 This is a multi-part message in MIME format. ------=_NextPart_000_0015_01C80748.538257F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Tj Yes, the initial design of my cooling system as well as its components = go back to 1997. Lets just say,it seemed like a good idea at the time = and having no one around to advise me differently, I proceeded as = follows: At the time, using two GM cores I got from the junk yard, I simply cut = off the 3/8 - 1/2" aluminum tubing which were on the bottom of this = particular core configuration. Thin I drilled out the existing holes = and brazed in two AN-16 Male fittings. Since I did not have sufficient = room up front to run the coolant line connecting the two over the Ross = PSRU, I ran it under. So as you so correctly deduced, the inlet and = outlet are both on the bottom. No question it would have been better to = run the coolant in the bottom of one and out the top which would have = left no space in the core for air to accumulated.=20 Yes, at 22 psi the air would likely occupy even more space, but since I = do my runup with the cap off or loose, there is no pressure during the = process. So while I have never measured it and it probably varies from = one time to the next, there appears to be approx 1/3 of the top part of = each core which has air on the initial fire up of the engine - after a = complete drain and refill of the coolant system. =20 I must admit that the first several times of draining and refilling = coolant, not being as knowledgeable as I am now, I almost cooked the = engine, because I assumed that when the header tank was full - the = engine had all the coolant it could take. Rapidly climbing coolant = temps and pinging of hot engine cooling off soon make it clear that just = because the header tank was full didn't mean a whole lot. Of course, I = noticed after each run up that the coolant level in the header tank = would decrease permitting me to put more coolant in. That finally made = me realize what the problem was - would have been very nice to have this = list around back then {:>) After burping the system there is still small amount of air left, but = the overflow tank set gradually removes the remaining air over a couple = of flights. Then the hydraulic "lock" phenomena starts with initial = pressure of 21-22 psi immediately on engine start, dropping off quickly = to zero and then gradually climbing back to 5 - 7 psi as the coolant = heats up. But, other than having to "clear" the air out with a couple/three run = ups to 5000 rpm, it works just fine and has since 97. I occasionally = toy with the idea of putting in simple small air bleed on the top of = each - but, like I said, it works fine and other things to do {:>) Sounds like your approach will avoid my burping problem. However, Lynn = has mentioned that even in the car installation it often takes burping = the engine to get the air out. Ed ----- Original Message -----=20 From: Thomas Jakits=20 To: Rotary motors in aircraft=20 Sent: Friday, October 05, 2007 11:12 AM Subject: [FlyRotary] Re: Problem? [FlyRotary] Re: Coolant Water = Pressure Hi Ed, for sure I saw your installation before (numerous times...), but I do = not recall your exact pluming. Your description below sounds like inlet and outlet are facing down. At 22psi it should even be more like 1/2 the radiator with air :) Anyway, I assume waterflow is radical enough to strip the air out in 3 = trials. My system will have a bottom inlet and a top outlet. If it doesn't fit = the outlet may exit the bottom of the tank but will have an internal = standpipe - this way there is next to no space where air can get = trapped, just a small bubble atop the standpipe, won't be big enough to = cause any cooling detriment.=20 I still see BMW motorcycle oil-coolers mounted this way. Don't know = the exact make-up today, but the earliest ones where simple single pass = bottom feed bottom exit (cheapest solution and esthetically least = disturbing), a big problem to purge. 1/4 was useless because of trapped = air...=20 Furthermore, if the pump had a little leak or just a long time between = runs would drain the oil fro mthe cooler and at start-up you had a fresh = load of cold air inthe cooler! As it heats up the air-bubble expands and = reduces cooler volume even more...=20 Best Regards, TJ snipped.. In my case, if I do a complete drain and refill of the system, on = the first run up the core's tanks will be hot approx 2/3 of the way up = and then they are much cooler - indicating that the remaining 1/3 of my = core is filled with air. It generally takes me 3 runups reaching 5000 = rpm before I can touch the core tanks and find them hot all the way = from top to bottom. So depending on your radiator set up that might be = something you can quickly check.=20 snipped.... ------=_NextPart_000_0015_01C80748.538257F0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Tj
 
Yes, the initial design of my cooling system as = well as=20 its components go back to 1997. Lets just say,it seemed like a good = idea at=20 the time and having no one around to advise me differently, I proceeded = as=20 follows:
 
 At the time, using two GM cores I got from = the junk=20 yard,  I simply cut off the 3/8 - 1/2" aluminum tubing which were = on the=20 bottom of this particular core configuration. Thin  I drilled = out the=20 existing holes and brazed in two AN-16 Male fittings.  Since I did = not have=20 sufficient room up front to run the coolant line connecting the two over = the=20 Ross PSRU, I ran it under.  So as you so correctly deduced, the = inlet and=20 outlet are both on the bottom.  No question it would have been = better to=20 run the coolant in the bottom of one and out the top which would have = left no=20 space in the core for air to accumulated.
 
Yes, at 22 psi the air would likely occupy even = more=20 space, but since I do my runup with the cap off or loose, there is no = pressure=20 during the process.  So while I have never measured it and it = probably=20 varies from one time to the next, there appears to be approx 1/3 of the = top part=20 of each core which has air on the initial fire up of the engine - after = a=20 complete drain and refill of the coolant system. 
 
I must admit that the first several times of = draining and=20 refilling coolant, not being as knowledgeable as I am now, I almost = cooked the=20 engine, because I assumed that when the header tank was full - the = engine had=20 all the coolant it could take.  Rapidly climbing coolant temps and = pinging=20 of hot engine cooling off soon make it clear that just because the = header tank=20 was full didn't mean a whole lot.  Of course, I noticed after each = run up=20 that the coolant level in the header tank would decrease permitting me = to put=20 more coolant in.  That finally made me realize what the problem was = - would=20 have been very nice to have this list around back then = {:>)
 
 
 
After burping the system there is still small = amount of=20 air left, but the overflow tank set gradually removes the remaining air = over a=20 couple of flights.  Then the hydraulic "lock" phenomena starts with = initial=20 pressure of 21-22 psi immediately on engine start, dropping off =  quickly to=20 zero and then gradually climbing  back to 5 - 7 psi as the coolant=20 heats  up.
 
 
But, other than having to "clear" the air out = with a=20 couple/three run ups to 5000 rpm, it works just fine and has since = 97.  I=20 occasionally toy with the idea of putting in simple small air bleed on = the top=20 of each - but, like I said, it works fine and other things to do=20 {:>)
 
Sounds like your approach will avoid my burping=20 problem.  However, Lynn has mentioned that even in the car = installation it=20 often takes burping the engine to get the air out.
 
Ed
----- Original Message -----
From:=20 Thomas Jakits
Sent: Friday, October 05, 2007 = 11:12=20 AM
Subject: [FlyRotary] Re: = Problem?=20 [FlyRotary] Re: Coolant Water Pressure

Hi Ed,
 
for sure I saw your installation before (numerous times...), but = I do not=20 recall your exact pluming.
Your description below sounds like inlet and outlet are facing=20 down.
At 22psi it should even be more like 1/2 the radiator with air = :)
Anyway, I assume waterflow is radical enough to strip the air out = in 3=20 trials.
My system will have a bottom inlet and a top outlet. If it = doesn't fit=20 the outlet may exit the bottom of the tank but will have an internal = standpipe=20 - this way there is next to no space where air can get trapped, just a = small=20 bubble atop the standpipe, won't be big enough to cause any cooling = detriment.=20
I still see BMW motorcycle oil-coolers mounted this way. Don't = know the=20 exact make-up today, but the earliest ones where simple single pass = bottom=20 feed bottom exit (cheapest solution and esthetically least = disturbing), a big=20 problem to purge. 1/4 was useless because of trapped air...
Furthermore, if the pump had a little leak or just a long time = between=20 runs would drain the oil fro mthe cooler and at start-up you had a = fresh load=20 of cold air inthe cooler! As it heats up the air-bubble expands and = reduces=20 cooler volume even more...
 
Best Regards,
 
TJ

snipped..
 In my case, if I do a complete = drain and=20 refill of the system, on the first run up the core's tanks =  will be hot=20 approx 2/3 of the way up and then they are much cooler - indicating = that the=20 remaining 1/3 of my core is filled with air.  It generally = takes me 3=20 runups reaching 5000 rpm before I can touch  the core = tanks=20 and find them hot all the way from top to bottom.  So depending = on your=20 radiator set up that might be something you can quickly check.=20
 
 
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