X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from outbound-mail.dca.untd.com ([64.136.47.15] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with SMTP id 2370796 for flyrotary@lancaironline.net; Fri, 05 Oct 2007 12:50:08 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.136.47.15; envelope-from=alwick@juno.com Received: from Penny (71-32-247-85.ptld.qwest.net [71.32.247.85]) by smtpout01.dca.untd.com with SMTP id AABDSN42VAE5GF9A for (sender ); Fri, 5 Oct 2007 09:49:23 -0700 (PDT) Message-ID: From: "Al Wick" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: Coolant Water Pressure Date: Fri, 5 Oct 2007 09:49:19 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0092_01C80735.003F51F0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6000.16480 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6000.16480 X-ContentStamp: 48:24:3922862792 X-MAIL-INFO:579d9db97101a180d90509b9f509d53138391109306deddd7130113930cd302574ad19559d15b9b5b9857104d5b00d048001a5ad7d211405a1290d099120e9e941443d00e1e5ad0095f4f18ded208df131d5bde5f0a9b4fdd0a4b0a46df524619975c931f4d4d45435d1b4a1dd1d5d3449f094155585d1859d29795538458511d9d950b59d380414a07460a1 X-UNTD-OriginStamp: L941HVjjYzDhN3itp//mkD1Zui8Ftk+IEYOVRAfVx6zHPiqxU8gpVw== X-UNTD-Peer-Info: 10.171.42.31|smtpout01.dca.untd.com|smtpout01.dca.untd.com|alwick@juno.com This is a multi-part message in MIME format. ------=_NextPart_000_0092_01C80735.003F51F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable >at 22 psi the air would likely occupy even more space The opposite is true. Air space reduces substantially when you increase = pressure. Think of coolant as a solid, and air as a giant spring. When = you add btu's to coolant, it immediately responds by expanding. This = causes the air molecules to compress...a lot. There are some fun exhibits at the science museum I volunteer at we use = to demonstrate air/ water compression. An eye dropper inside a pop = bottle. When you squeeze the pop bottle, the eye dropper plummets to the = bottom. When you let go, dropper rises to surface. The pressure increase = when you squeeze bottle causes air in dropper to compress(less air = volume). This allows water to displace that air....dropper is now = heavier and falls to bottom.=20 It's really ironic. You can design a system that seems to work fine. You = fly with that for years with no failures( well I guess you could call = the pinging and high temps a failure). But a small change can greatly = reduce your risk. There's a lot of value to changing your air bleed = design to one that dynamically removes air. No shrader valve, no = repeated cooling cycles to remove air. By "dynamic" I mean that it = automatically removes air from the system. No muss no fuss.=20 As you design system, just pretend their is air at the top of each = component. Then find simple way to allow that air to move to higher = component in system. So, my radiator is lowest point in system. If I = place my radiator tube near the top of radiator, then all air naturally = leaves rad and flows to engine. Next I look at highest coolant passage = in engine. In my case I had to drill and tap a little 1/4 npt into the = coolant manifold, then run tube from there up to highest point in = system. Suddenly I've got a system that automatically removes all air = immediately. Try as I can, I can no longer trap air anywhere. If I = develop compression leak that pumps air into system, it has much less = effect, because it rises out of the coolant flow. When I drain and = refill, it all immediately and rapidly fills, I can get every drop back = into the system. Dynamic air bleed is a safety advantage, easy to accomplish. Each of = these safety advantages adds up mathematically.=20 Likewise, contrary to popular theory, leaving two cups of air under cap = increases safety. You can prove that to yourself with simple experiment = I described earlier.=20 -al wick ----- Original Message -----=20 From: Ed Anderson=20 To: Rotary motors in aircraft=20 Sent: Friday, October 05, 2007 9:07 AM Subject: [FlyRotary] Re: Coolant Water Pressure 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.... -Al Wick Cozy IV powered by Turbo Subaru 3.0R with variable valve lift and cam = timing.=20 Artificial intelligence in cockpit, N9032U 240+ hours from Portland, = Oregon Glass panel design, Subaru install, Prop construct, Risk assessment = info: http://www.maddyhome.com/canardpages/pages/alwick/index.html ------=_NextPart_000_0092_01C80735.003F51F0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
>at 22 psi the air would likely occupy even = more=20 space
 
The opposite is true. Air space reduces = substantially when=20 you increase pressure. Think of coolant as a solid, and air as a = giant=20 spring. When you add btu's to coolant, it immediately responds by = expanding.=20 This causes the air molecules to compress...a lot.
 
There are some fun exhibits at the science = museum I=20 volunteer at we use to demonstrate air/ water compression. An eye = dropper inside=20 a pop bottle. When you squeeze the pop bottle, the eye dropper plummets = to the=20 bottom. When you let go, dropper rises to surface. The pressure increase = when=20 you squeeze bottle causes air in dropper to compress(less air volume). = This=20 allows water to displace that air....dropper is now heavier and falls to = bottom.=20
 
It's really ironic. You can design a system that = seems to=20 work fine. You fly with that for years with no failures( well I guess = you could=20 call the pinging and high temps a failure). But a small change can = greatly=20 reduce your risk. There's a lot of value to changing your air bleed = design to=20 one that dynamically removes air. No shrader valve, no repeated cooling = cycles=20 to remove air. By "dynamic" I mean that it automatically removes air = from the=20 system. No muss no fuss.
 
As you design system, just pretend their is air = at the top=20 of each component. Then find simple way to allow that air to move to = higher=20 component in system. So, my radiator is lowest point in system. If I = place my=20 radiator tube near the top of radiator, then all air naturally leaves = rad and=20 flows to engine. Next I look at highest coolant passage in engine. In my = case I=20 had to drill and tap a little 1/4 npt into the coolant manifold, then = run tube=20 from there up to highest point in system. Suddenly I've got a system = that=20 automatically removes all air immediately. Try as I can, I can no longer = trap=20 air anywhere. If I develop compression leak that pumps air into system, = it has=20 much less effect, because it rises out of the coolant flow. When I drain = and=20 refill, it all immediately and rapidly fills, I can get every drop back = into the=20 system.
 
Dynamic air bleed is a safety advantage, = easy to=20 accomplish. Each of these safety advantages adds up mathematically.=20
Likewise, contrary to popular theory, leaving = two cups of=20 air under cap increases safety. You can prove that to yourself with = simple=20 experiment I described earlier.
 
-al wick
 
----- Original Message -----
From:=20 Ed=20 Anderson
Sent: Friday, October 05, 2007 = 9:07=20 AM
Subject: [FlyRotary] Re: = Coolant Water=20 Pressure

 
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=20 part 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=20 and refilling coolant, not being as knowledgeable as I am now, I = almost cooked=20 the engine, because I assumed that when the header tank was full - the = engine=20 had all the coolant it could take.  Rapidly climbing coolant = temps and=20 pinging of hot engine cooling off soon make it clear that just because = the=20 header tank was full didn't mean a whole lot.  Of course, I = noticed after=20 each run up that the coolant level in the header tank would decrease=20 permitting me to put more coolant in.  That finally made me = realize what=20 the problem was - would have been very nice to have this list around = back then=20 {:>)
 
 
 
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=20 initial pressure of 21-22 psi immediately on engine start, dropping = off=20  quickly to zero and then gradually climbing  back to 5 - 7 = psi as=20 the coolant 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=20 it often takes burping the engine to get the air out.
 
Ed
----- Original Message -----
From:=20 Thomas Jakits
To: Rotary motors in = aircraft=20
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=20 not 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 - this way there is next to no space where air can get = trapped,=20 just a small bubble atop the standpipe, won't be big enough to cause = any=20 cooling detriment.
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=20 big 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=20 load of cold air inthe cooler! As it heats up the air-bubble expands = and=20 reduces 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=20 hot approx 2/3 of the way up and then they are much cooler - = indicating=20 that the remaining 1/3 of my core is filled with air.  It = generally=20 takes me 3 runups reaching 5000 rpm before I can touch =20 the core tanks and find them hot all the way from top to=20 bottom.  So depending on your radiator set up that might be = something=20 you can quickly check.
 
 
snipped....

=
 
-Al Wick
Cozy IV powered by Turbo Subaru 3.0R with variable = valve lift=20 and cam timing.
Artificial intelligence in cockpit, N9032U 240+ = hours from=20 Portland, Oregon
Glass panel design, Subaru install, Prop construct, = Risk=20 assessment info:
htt= p://www.maddyhome.com/canardpages/pages/alwick/index.html
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