X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 1 [X] Return-Path: Received: from bay0-omc1-s23.bay0.hotmail.com ([65.54.246.95] verified) by logan.com (CommuniGate Pro SMTP 5.1.4) with ESMTP id 1740771 for flyrotary@lancaironline.net; Sat, 06 Jan 2007 12:02:19 -0500 Received-SPF: pass receiver=logan.com; client-ip=65.54.246.95; envelope-from=lors01@msn.com Received: from hotmail.com ([65.54.250.75]) by bay0-omc1-s23.bay0.hotmail.com with Microsoft SMTPSVC(6.0.3790.2668); Sat, 6 Jan 2007 08:59:59 -0800 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Sat, 6 Jan 2007 08:59:58 -0800 Message-ID: Received: from 4.171.174.228 by BAY115-DAV3.phx.gbl with DAV; Sat, 06 Jan 2007 16:59:54 +0000 X-Originating-IP: [4.171.174.228] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Ideal cooling Date: Sat, 6 Jan 2007 11:59:48 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0052_01C7318A.2A1A6810" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: MSN 9 X-MIMEOLE: Produced By MSN MimeOLE V9.50.0034.2000 Seal-Send-Time: Sat, 6 Jan 2007 11:59:48 -0500 X-OriginalArrivalTime: 06 Jan 2007 16:59:58.0942 (UTC) FILETIME=[192A37E0:01C731B4] Return-Path: lors01@msn.com This is a multi-part message in MIME format. ------=_NextPart_000_0052_01C7318A.2A1A6810 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I have never heard any advice from the people at Racing Beat that was at = all suspect and it usually sanity checks with logic, reason and past = experience. Likewise Lynn H's rotary advice. So I won't re-hash all = the reasons for the temperature recommendations for the rotary here. On the subjects of EVANS coolant and boiling, only thing I would add is = that the significance of NUCLEATE boiling in cooling the rotary has been = largely overlooked. This is a good and necessary factor in the upper = power ranges (> 150 HP) on rotaries as opposed to film or bulk boiling = which is a very bad thing. EVANS eliminates these bad types of boiling = but my concern is that it also eliminates the good nucleate boiling. = Why it is especially important on the rotary is due to the fact that it = has to dissipate 6 combustion chambers worth of heat in only two chamber = walls. In other words, the heat flux is 3 times what it is in 4 stroke = piston engines. The lack of nucleate boiling will not show up immediately or even in 100 = hours of flight. It will eventually show up as cracks around sparkplug = bosses, excessive coking on rotor housings, short TBOs and other = problems. These problems would not usually show up in automotive (non = racing) use but are especially prevalent in aviation applications. Tracy Crook ----- Original Message -----=20 From: Ed Anderson=20 To: Rotary motors in aircraft=20 Sent: Friday, January 05, 2007 11:51 AM Subject: [FlyRotary] Re: Ideal cooling As you say, Al, there are stories, rumors, misinterpreted data and = occasionally actually facts. I guess my old brain cells are surely = declining, but I just can't get it out of my head that EVANS is rather = like - a band aid- for a marginal cooling system. I do agree catastrophic boil-over is something to be avoided. But, = IF the problem is your system can't keep up with your heat dissipation = needs, then the system needs to be fixed, substituting a coolant with = less heat carrying capacity and raising the operating temperature just = does not seem the right course of action - in my opinion. =20 Responding to you question about the rotary limitations. In the = rotary's case, the old conventional wisdom probably goes back to data = published by Racing beat way back when - I still have the article. To = quote excerpts from the article: "...oil temperature entering the engine should never be allowed to = exceed 210F.." " ...Under normal conditions the engine water temperature (exiting the = engine) should never exceed 180F. However, engine damage is not likely = to occur even up to 200F - IF the temperature rises slowly. If it rises = quickly, however, due to broken hose, lost fan belt, etc., engine damage = is likely." I suspect that later model engines are not as sensitive and I have had = my coolant as high as 240F for very short periods and oil as high as = 220F. I could not tell of any adverse effects - however, as soon as I = detected the excursion I quickly backed off the power. My normal Max is = 200F for the oil and 220F for the coolant, but again only on climbout at = high power on a hot day. I suspect as long as the coolant and oil are = still circulating and carrying heat away - you have more of a margin = than if the coolant suddenly disappeared through a broken hose {:>). = Not being in a frigid area, I use a 25/75 EWG mixture rather than the = 50/50 normally quoted. So a coolant like the EVANS which can indeed operate at higher = temperatures with much higher boiling point than water, would not = appear to offer much to us Rotary folks as our engine (if you can = believe what the experts claim) simply can not tolerate the higher = operating temps. =20 If the fluid can not carry as much heat per unit volume as H20, then = it sure seems to me that you would need to increase the flow rate of the = rotary pump to compensate. While raising the temperature of the fluid = alone will indeed transport additional heat, lets look at what it takes. = Assuming the mass flow is the same (no increase/decrease in coolant = flow rate) then looking at the Cp of pure water, 50/50 mix and NPG we = have Cp H20 1.00 Cp 50/50 0.82 Cp NPG 0.66. Just to make my point, if = 180F is the steady state temp for an system with pure H20 then using = Evans at the same flow rate, you would need to raise the temperature = from 180F to (1.00 - 0.66)/100 by 34 % or from 180F to 240F to remove = the same amount of heat.=20 But pure water is not a practical cooling fluid (corrosion, etc), so = taking a common 50/50 mixture we have (0.83 -0.66)/0.83 =3D 20% or from = 180F to 216F and that is to keep the heat removal the same. If the = heat load (50/50) climbed to 200F then the Evan's equivalent required = would be 240F. However, if we increase the coolant flow rate by 20%-24%, then Evans = can transport the same heat load with no temperature rise. IF I were = going to consider using it in a rotary, I definitely would attempt to = increase the flow rate. But, I don't know how the different viscosity = of the Evans fluid would affect the caviation point, etc - I suspect = that it would lower it. Seems you can ever affect just one factor when = you make a change{:>) But, at least, an increase flow rate may keep = the operating temp point below a critical maximum. =20 So if you engine can tolerate the increase operating temps then I = agree Evan's offers some benefits as can be read on their website. However, the higher operating temperature point stresses the entire = system and in the case of the rotary is likely to put it into a very = questionable operating regime. At least,that's the way it appears to = me. FWIW Ed ----- Original Message -----=20 From: al p wick=20 To: Rotary motors in aircraft=20 Sent: Friday, January 05, 2007 10:20 AM Subject: [FlyRotary] Re: Ideal cooling On Fri, 5 Jan 2007 07:46:37 -0500 "Ed Anderson" = > writes: Trying to make an inadequate cooling system functional by using a = different coolant is simply not going to work, but people keep trying. = If pure water is not doing the job, then using liquids with a lower heat = specific is only going to make it worst. =20 The Egg guys have been very successful using the Evans coolant. The = fluid is less efficient, so it inflates the operating temperature. But = it also brings a new very high boiling point to the party. So instead of = operating at the normal 200F temp, they operate at 215F. But the boil = over temp is way up there...I forget, but something like 260F or so. As = a result, they end up with greater safety margin. A very sound decision = for their installation. This because boil over is sudden, catastrophic, = and essentially irreversible. When it blows, it blows. Rumor has it that the same solution on your engine would not add = safety margin, but actually reduce it. I'm skeptical of that personally, = but don't have facts to evaluate. It just sounds fishy that there are = components so sensitive to a mere 15F change in temp. I know how these = theories can get started and hang around for lack of facts. So I don't = know one way or the other, just skeptical. But here's the cool thing. We tend to think along the lines of "What = can I do to improve cooling? What can I do?" But this Evans brings a new = tool to the party. It's a great way to determine if you have flow volume = problem. If you have inadequate coolant flow, Evans dramatically = negatively effects you cooling. I've measured, logged, and tested tons = of cooling concepts. Deliberately overheating engine, stuff like that. = Tracy's data strongly suggests local boiling. (Bills? observation). = Trapped air or low flow are leading causes. I strongly suspect low flow = due to line restrictions. I think we've got lot's of guys operating with = 70% less flow than the engine normally sees, and that puts them right on = the edge of this problem. FWIW. -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_0052_01C7318A.2A1A6810 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
I have never heard any advice from the people at Racing Beat that = was at=20 all suspect and it usually sanity checks with logic, reason and past=20 experience.  Likewise Lynn H's rotary advice.  So I won't = re-hash=20 all the reasons for the temperature recommendations for the rotary = here.
 
On the subjects of EVANS coolant and boiling, only thing I would = add is=20 that the significance of NUCLEATE boiling in cooling the rotary has been = largely=20 overlooked.  This is a good and necessary factor in the upper power = ranges=20 (> 150 HP) on rotaries as opposed to film or bulk boiling which is a = very bad=20 thing.  EVANS eliminates these bad types of boiling but my concern = is that=20 it also eliminates the good nucleate boiling.  Why it is especially = important on the rotary is due to the fact that it has to dissipate 6 = combustion=20 chambers worth of heat in only two chamber walls.  In other words, = the heat=20 flux is 3 times what it is in 4 stroke piston engines.
 
The lack of nucleate boiling will not show up immediately or = even in=20 100 hours of flight.  It will eventually show up as cracks around = sparkplug=20 bosses, excessive coking on rotor housings, short TBOs and other=20 problems.   These problems would not usually show up in = automotive=20 (non racing) use but are especially prevalent in aviation = applications.
 
Tracy Crook
----- Original Message -----
From: Ed Anderson
To: Rotary motors in = aircraft
Sent: Friday, January 05, 2007 = 11:51=20 AM
Subject: [FlyRotary] Re: Ideal=20 cooling

As you say, Al, there are stories, rumors,=20 misinterpreted data and occasionally actually facts.  I guess my = old=20 brain cells are surely declining, but I just can't get it out of =  my=20 head that EVANS is rather like - a band aid- for a marginal cooling=20 system.
 
  I do agree catastrophic boil-over is = something to=20 be avoided.  But, IF the problem is your system can't keep up = with your=20 heat dissipation needs, then the system needs to be fixed, = substituting a=20 coolant with less heat carrying capacity and raising the = operating=20 temperature just does not seem the right course of action = - in my=20 opinion. 
 
Responding to you question about the rotary=20 limitations.  In the rotary's case, the old conventional wisdom = probably=20 goes back to  data published by Racing beat way back when - I = still have=20 the article.  To quote excerpts from the article:
 
 "...oil temperature entering the engine should never be allowed to = exceed=20 210F.."
 
" ...Under normal conditions the = engine water=20 temperature (exiting the=20 engine) should never exceed 180F.  However, engine damage is not likely to occur = even up=20 to 200F - IF the temperature rises = slowly. If=20 it rises quickly, however, due to broken hose, lost fan belt, etc., = engine=20 damage is likely."
 
I suspect that later model = engines are not as=20 sensitive and I have had my coolant as high as 240F for very short = periods and=20 oil as high as 220F.  I could not tell of any adverse = effects  -=20 however, as soon as I detected the excursion I quickly backed off the=20 power.  My normal Max is 200F for the oil and 220F for the = coolant, but=20 again only on climbout at high power on a hot day.  I suspect=20 as long as the coolant and oil are still circulating and carrying = heat=20 away - you have more of a margin than if the coolant suddenly = disappeared=20 through a broken hose {:>).  Not being in a frigid area,  =  I=20 use a 25/75 EWG mixture rather than the 50/50 normally = quoted.
 
So a coolant like the EVANS which can indeed = operate at=20 higher temperatures with much higher  boiling point than = water,=20 would not appear to offer much to us Rotary folks as our engine (if = you can=20 believe what the experts claim) simply can not tolerate the higher = operating=20 temps.   
 
If the fluid can not carry as much heat per = unit volume=20 as H20, then it sure seems to me that you would need to increase the = flow rate=20 of the rotary pump to compensate. While raising the = temperature of=20 the fluid alone will indeed transport additional heat, lets look at = what it=20 takes.  Assuming the mass flow is the same (no increase/decrease = in=20 coolant flow rate) then looking at the Cp of pure water, 50/50 mix and = NPG  we have
 
Cp H20 1.00  Cp 50/50 0.82 Cp NPG = 0.66.  Just=20 to make my point, if 180F is the steady state temp for an system with = pure H20=20 then using Evans at the same flow rate, you would need to raise the=20 temperature from 180F to (1.00 - 0.66)/100 by 34 % or from 180F to = 240F to=20 remove the same amount of heat. 
 
 But pure water is not a practical = cooling fluid=20 (corrosion, etc), so taking a common 50/50 mixture we have (0.83 = -0.66)/0.83 =3D=20 20% or from 180F to 216F and that is to keep the heat removal the = same. =20 If  the heat load (50/50) climbed to 200F then the Evan's = equivalent=20 required would be 240F.
 
However,  if we increase the coolant =  flow=20 rate by 20%-24%, then Evans can transport the same heat load = with no=20 temperature rise.  IF I were going to consider using it in a = rotary, I=20 definitely would attempt to increase the flow rate.  But,=20 I don't know how the different viscosity of the Evans fluid = would=20 affect the caviation point, etc  - I suspect that it would lower=20 it.  Seems you can ever affect just one factor when you = make a=20 change{:>)   But, at least, an increase flow rate may = keep the=20 operating temp point below a critical maximum. =20  
 
So if you engine can tolerate the increase = operating=20 temps then I agree Evan's offers some benefits as can be read on their = website.
 
However, the higher operating temperature = point stresses=20 the entire system and in the case of the rotary is likely to=20 put it into a very questionable operating = regime.  At=20 least,that's the way it appears to me.
 
FWIW
 
Ed
 
 
----- Original Message -----
From:=20 al = p wick=20
To: Rotary motors in = aircraft=20
Sent: Friday, January 05, = 2007 10:20=20 AM
Subject: [FlyRotary] Re: = Ideal=20 cooling

On Fri, 5 Jan 2007 07:46:37 -0500 "Ed Anderson" <eanderson@carolina.rr.com&g= t;=20 writes:
Trying to make an inadequate cooling = system=20 functional by using a different coolant is simply not going to = work, but=20 people keep trying.  If pure water is not doing the job, then = using=20 liquids with a lower heat specific is only going to make it = worst. =20
 
The Egg guys have been very successful using the Evans coolant. = The=20 fluid is less efficient, so it inflates the operating temperature. = But it=20 also brings a new very high boiling point to the party. So instead = of=20 operating at the normal 200F temp, they operate at 215F. But the = boil over=20 temp is way up there...I forget, but something like 260F or so. As a = result,=20 they end up with greater safety margin. A very sound decision for = their=20 installation. This because boil over is sudden, catastrophic, and=20 essentially irreversible. When it blows, it blows.
 
Rumor has it that the same solution on your engine would not = add safety=20 margin, but actually reduce it. I'm skeptical of that personally,=20 but don't have facts to evaluate. It just sounds fishy that = there are=20 components so sensitive to a mere 15F change in temp. I know how = these=20 theories can get started and hang around for lack of facts. So I = don't know=20 one way or the other, just skeptical.
 
But here's the cool thing. We tend to think along the lines of = "What=20 can I do to improve cooling? What can I do?" But this Evans brings a = new=20 tool to the party. It's a great way to determine if you have flow = volume=20 problem. If you have inadequate coolant flow, Evans dramatically = negatively=20 effects you cooling. I've measured, logged, and tested tons of = cooling=20 concepts. Deliberately overheating engine, stuff like that. Tracy's = data=20 strongly suggests local boiling. (Bills? observation). Trapped air = or low=20 flow are leading causes. I strongly suspect low flow due to line=20 restrictions. I think we've got lot's of guys operating with 70% = less flow=20 than the engine normally sees, and that puts them right on the edge = of this=20 problem.
 
FWIW.
 

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