X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 64 [XX] (100%) BODY: contains text similar to "low payment" Return-Path: Received: from ms-smtp-01.southeast.rr.com ([24.25.9.100] verified) by logan.com (CommuniGate Pro SMTP 5.1.4) with ESMTP id 1738434 for flyrotary@lancaironline.net; Fri, 05 Jan 2007 11:52:17 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.100; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-100-190.carolina.res.rr.com [24.74.100.190]) by ms-smtp-01.southeast.rr.com (8.13.6/8.13.6) with SMTP id l05GpFU7006780 for ; Fri, 5 Jan 2007 11:51:15 -0500 (EST) Message-ID: <000701c730e9$b8d79d80$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Ideal cooling Date: Fri, 5 Jan 2007 11:51:18 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0004_01C730BF.CF9D5570" 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_0004_01C730BF.CF9D5570 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable 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_0004_01C730BF.CF9D5570 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
As you say, Al, there are stories, rumors, = misinterpreted=20 data and occasionally actually facts.  I guess my old brain cells = are=20 surely declining, but I just can't get it out of  my head that = EVANS=20 is rather like - a band aid- for a marginal cooling 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 210F.."
 
" ...Under normal conditions the engine = water=20 temperature (exiting the = engine) should=20 never exceed 180F.  = However, engine damage is not likely to occur even = up to 200F - IF the temperature rises slowly. If = it rises=20 quickly, however, due to broken hose, lost fan belt, etc., engine damage = is=20 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 = as long=20 as the coolant and oil are still circulating and carrying heat away - = you have=20 more of a margin than if the coolant suddenly disappeared through a = broken hose=20 {:>).  Not being in a frigid area,   I use a 25/75 EWG = mixture=20 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, would=20 not appear to offer much to us Rotary folks as our engine (if you can = believe=20 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 as=20 H20, then it sure seems to me that you would need to increase the flow = rate of=20 the rotary pump to compensate. While raising the temperature = of the=20 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 = coolant=20 flow rate) then looking at the Cp of pure water, 50/50 mix and NPG  = we=20 have
 
Cp H20 1.00  Cp 50/50 0.82 Cp NPG = 0.66.  Just to=20 make my point, if 180F is the steady state temp for an system with pure = H20 then=20 using Evans at the same flow rate, you would need to raise the = temperature from=20 180F to (1.00 - 0.66)/100 by 34 % or from 180F to 240F to remove the = same amount=20 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 rate=20 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 temps=20 then I agree Evan's offers some benefits as can be read on their=20 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
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 = functional=20 by using a different coolant is simply not going to work, but people = keep=20 trying.  If pure water is not doing the job, then using liquids = with a=20 lower heat specific is only going to make it worst. =20
 
The Egg guys have been very successful using the Evans coolant. = The fluid=20 is less efficient, so it inflates the operating temperature. But it = also=20 brings a new very high boiling point to the party. So instead of = operating at=20 the normal 200F temp, they operate at 215F. But the boil over temp is = way up=20 there...I forget, but something like 260F or so. As a result, they end = up with=20 greater safety margin. A very sound decision for their installation. = This=20 because boil over is sudden, catastrophic, and essentially = irreversible. When=20 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 = 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 can=20 I do to improve cooling? What can I do?" But this Evans brings a new = tool to=20 the party. It's a great way to determine if you have flow volume = problem. If=20 you have inadequate coolant flow, Evans dramatically negatively = effects you=20 cooling. I've measured, logged, and tested tons of cooling concepts.=20 Deliberately overheating engine, stuff like that. Tracy's data = strongly=20 suggests local boiling. (Bills? observation). Trapped air or low flow = are=20 leading causes. I strongly suspect low flow due to line restrictions. = I think=20 we've got lot's of guys operating with 70% less flow than the engine = normally=20 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=20 lift and cam timing.
Artificial intelligence in cockpit, N9032U = 240+ hours=20 from Portland, Oregon
Glass panel design, Subaru install, Prop = construct,=20 Risk assessment info:
htt= p://www.maddyhome.com/canardpages/pages/alwick/index.html
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