X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 1 [X] Return-Path: Received: from ms-smtp-03.southeast.rr.com ([24.25.9.102] verified) by logan.com (CommuniGate Pro SMTP 5.1.4) with ESMTP id 1741956 for flyrotary@lancaironline.net; Sun, 07 Jan 2007 10:06:35 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.102; 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-03.southeast.rr.com (8.13.6/8.13.6) with SMTP id l07F5XGr012534 for ; Sun, 7 Jan 2007 10:05:33 -0500 (EST) Message-ID: <000701c7326d$4bd2d1c0$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Ideal cooling Date: Sun, 7 Jan 2007 10:05:40 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0004_01C73243.62A226A0" 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_01C73243.62A226A0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I agree, Al. Part of the value of this list is exactly the different = knowledge, experience and viewpoint of its members. There are so many = variables, its not hard to fixate on those which most support a = particular point of view(most often - our own viewpoint) {:>), until = alternative interpretations are presented for consideration. =20 I also agree that the "limits" on the rotary are probably conservative - = I mean I have hit 240F on the coolant (abeit for very short periods) - = did it shorten the life of the engine - don't know, hopefully not, but = nothing catastrophic happened, so I can live with it. But, on the other = hand, I don't have any more "authoritative" source on limits - so until = (as you point out) data to the contrary arrives, I will use the best I = have as guidelines. =20 I have overheated a rotary (caused me to lose the coolant "O" ring = seal), so I know it can happen - as others can attest to as well. There = is no question in my mind that the rotary is more heat sensitive than = most reciprocating engines - as Tracy pointed out - a lot more heat = density in parts of the block - which can quickly send temperatures = rocketing upward - if adequate cooling is not available. So others may = have more design leeway regarding the cooling system than the rotary. Evan's works, but other than catastrophic boiling protection, I fail = to see any material benefit and the potential adverse effect on the = rotary would just make me very hesitant. If I had a cooling problem, I = would always look into the design or installation first. My viewpoint = is if water can not provide adequate cooling then my system needs a = redesign. But, again, that is just my personal opinion - and we all = know what opinions are worth {:>) ED ----- Original Message -----=20 From: al p wick=20 To: Rotary motors in aircraft=20 Sent: Sunday, January 07, 2007 9:01 AM Subject: [FlyRotary] Re: Ideal cooling On Fri, 5 Jan 2007 11:51:18 -0500 "Ed Anderson" = writes: <> When I first looked into Evans years ago, saw the specific heat value, = then I too discounted it. I too thought it was a crutch for a bad = cooling design. At the time I reasoned that it would have to increase = drag. And it does...... if you assume all of the other factors are the = same. However, if the user just operated at a temperature 10 or 15F = higher than normal, then there is no drag increase. So as time has = passed, I realized it can be a significant safety advantage. Now I think = it's worthy of consideration. Tracy makes excellent point regarding = nucleation. That said, I too am resistant to using it. I never have, and prefer to = do everything I can to use conventional coolant and standard = temperatures. But if I'm unable to obtain the safety margin = conventionally, then I will definitely try it. Racing Beat article is interesting. But I try to keep in mind that = that's just some guy writing the article. So I always seek other = evidence. If the author included facts that supported logic, then I'd be = much less skeptical. I am familiar with Asian design practices. They put = a great deal of effort into reducing sensitivity to things like coolant = and oil temp. They know that increasing that margin by 5 or 10F, they = dramatically reduce warranty issues and improve customer satisfaction. = So if the engine was temperature sensitive in the past, they would put = lot's of effort into reducing that. Of course, I'm not encouraging running engine hotter. But I do = encourage skepticism.=20 -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_01C73243.62A226A0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
I agree, Al.  Part of the value of this = list is=20 exactly the different knowledge, experience and viewpoint of its = members. =20 There are so many variables, its not hard to fixate on those which most = support=20 a particular point of view(most often - our own viewpoint) {:>), = until=20 alternative interpretations are presented for consideration.  =
 
I also agree that the "limits" on the rotary are = probably=20 conservative - I mean I have hit 240F on the coolant (abeit for very = short=20 periods) - did it shorten the life of the engine - don't know, hopefully = not,=20 but nothing catastrophic happened, so I can live with it.  But, on = the=20 other hand, I don't have any more "authoritative" source on limits - so = until=20 (as you point out) data to the contrary arrives, I will use the best I = have as=20 guidelines. 
 
I have overheated a rotary (caused me to lose = the coolant=20 "O" ring seal), so I know it can happen - as others can attest to as = well. =20 There is no question in my mind that the rotary is more heat sensitive = than most=20 reciprocating engines - as Tracy pointed out - a lot more heat = density in=20 parts of the block - which can quickly send temperatures rocketing = upward - if=20 adequate cooling is not available.  So others may have more design = leeway=20 regarding the cooling system than the rotary.
 
  Evan's works, but other than catastrophic = boiling=20 protection, I fail to see any material benefit and the potential adverse = effect=20 on the rotary would just make me very hesitant.  If I had a cooling = problem, I would always look into the design or installation = first.  My=20 viewpoint is if water can not provide adequate cooling then my system = needs a=20 redesign.  But, again, that is just my personal opinion - and we = all know=20 what opinions are worth {:>)
 
ED
 
 
 
----- Original Message -----
From:=20 al p = wick
Sent: Sunday, January 07, 2007 = 9:01=20 AM
Subject: [FlyRotary] Re: Ideal=20 cooling

On Fri, 5 Jan 2007 11:51:18 -0500 "Ed Anderson" <eanderson@carolina.rr.com&g= t;=20 writes:
<<I do agree catastrophic boil-over is = something=20 to be avoided.  But, IF the problem is your system can't keep up = with=20 your heat dissipation needs, then the system needs to be fixed,=20 substituting a coolant with less heat carrying capacity and = raising=20 the operating temperature just does not seem the right course of = action=20 - in my opinion. 
>>
 
When I first looked into Evans years ago, saw the specific heat = value,=20 then I too discounted it. I too thought it was a crutch for a bad = cooling=20 design.  At the time I reasoned that it would have to increase = drag. And=20 it does...... if you assume all of the other factors are the same. = However, if=20 the user just operated at a temperature 10 or 15F higher than normal, = then=20 there is no drag increase. So as time has passed, I realized it can be = a=20 significant safety advantage. Now I think it's worthy of = consideration.=20 Tracy makes excellent point regarding nucleation.
 
That said, I too am resistant to using it. I never have, and = prefer to do=20 everything I can to use conventional coolant and standard = temperatures. But if=20 I'm unable to obtain the safety margin conventionally, then I will = definitely=20 try it.
 
Racing Beat article is interesting. But I try to keep in mind = that that's=20 just some guy writing the article. So I always seek other=20 evidence. If the author included facts that supported logic, = then=20 I'd be much less skeptical. I am familiar with Asian design practices. = They=20 put a great deal of effort into reducing sensitivity to things like = coolant=20 and oil temp. They know that increasing that margin by 5 or 10F, they=20 dramatically reduce warranty issues and improve customer satisfaction. = So if=20 the engine was temperature sensitive in the past, they would put lot's = of=20 effort into reducing that.
 
Of course, I'm not encouraging running engine hotter. But I do = encourage=20 skepticism.
 

-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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