X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [24.25.9.100] (HELO ms-smtp-01-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTP id 970533 for flyrotary@lancaironline.net; Sat, 04 Feb 2006 21:57:03 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.100; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-025-165.carolina.res.rr.com [24.74.25.165]) by ms-smtp-01-eri0.southeast.rr.com (8.13.4/8.13.4) with SMTP id k152uGNN026180 for ; Sat, 4 Feb 2006 21:56:18 -0500 (EST) Message-ID: <001601c629ff$c2a01c30$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: NPG Coolant Temperature vs 50/50 Date: Sat, 4 Feb 2006 21:56:27 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0013_01C629D5.D9769D00" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0013_01C629D5.D9769D00 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Ok, Al That as you said, explains it. My recollection of reported coolant = temps were clearly in error and what you cited about coolant temps using = NPG does correlate. My mind is happy! I have fortunately never experienced cascade boil-over and hope never to = do so, clearly a terrifying and hopeless feeling to encounter why = flying. Shutting off the engine in such a situation might bring things = back under control - if you have plenty of altitude. But, I would = assume most boil overs happen after a high powered takeoff on a hot day, = so altitude may be lacking. I can certainly understand why that would induce someone to go to the = NPG coolant. =20 Long, Long ago and in a place far, far away - Japan to be exact. Mazda = provided that 180F coolant temps (out of the block) and 210F Oil temps = (into the block) were the limits. These can also be found in Racing = Beat's technical catalog. I have on occasion - and for very limited = amounts of time - had oil temps as high as 230F and coolant as high as = 250F. These were cases where coolant was still flowing and pressurized. = After the first incident with an 86 N/A block, I found I had coolant = "O" ring compromised (coolant leaking into combustion chamber), I then = switched to the Teflon Enscapulate Silicon "O" rings and on the one or = two occasions when the temps reached 220F oil and 230F coolant - there = appeared to be no damage. I believe that those limits were established for the mid 1980 era 13Bs = and that block coolant galley improvements and casting changes (as well = as use of higher temps rubber seals) have probably raised the = permissible operating temperature. But, I do not know of anyone who has = tested an engine to destruction to find out {:>) Ed ----- Original Message -----=20 From: al p wick=20 To: Rotary motors in aircraft=20 Sent: Saturday, February 04, 2006 9:32 PM Subject: [FlyRotary] Re: NPG Coolant Temperature vs 50/50 The Egg guys no longer operate at the normal 200F when they install = NPG. I don't recall the exact number, but they operate around 215F = (cruise). Which explains most of your theoretical differences.=20 They gain a significant safety bonus in the boil over temp. That = safety margin is what it's all about. At least from the risk = perspective.=20 So by operating at a higher Delta T, they compensate for the reduced = efficiency of the fluid.=20 I've heard you guys describe the importance of operating coolant = around 185F or so? Are you sure of that limit? Is that just a = recommended thing, or hard and fast limit. I'm always skeptical of stuff = like that. -al wick On Sat, 4 Feb 2006 20:56:49 -0500 "Ed Anderson" = writes: Hi Al, Appreciate your (anybody else welcome also) views on one other thing = that is still bothering me about the use of NPG. =20 Given that NPG+ has a specific heat of 0.66 at 212F or 20% less = than the 0.82 for the 50/50 mixture and given that NPG+ is approx 7% = more dense than the 50/50 - then that for the same flowrate for both it = would seem that NPG still has a 13% lesser overall capacity for heat = transfer (at the same temps 212F and flow rates). Also assume that the engine is produce the same heat load (Q),lets = take alook at what temperature we might see with NPG+ compared to the = 50/50 solution. We have from the oldie but goody Q =3D c*M*DeltaT the = ability to solve for the temperature increase, DeltaT. Delta T =3D Q/cM, now if the combined effects of c and m provide = 13% less heat transfer capability than the 50/50 mixture that would = indicated that to carry away the same Q at the same flow rate, the delta = T of NPG+ would need to increase by 13%. So if I were getting 180F with = the 50/50 for the same Q load (and flow rate) then with NPG+, I would = expect 180 *1.13 =3D 203F. Yet, if I understood correct we have reports = that lesser temperatures results noted by users of NPG - this leaves me = a bit puzzled. If my assumption is correct thus far, then I am at a loss to = understand the reports of lesser cooling temps when using NPG+, it would = seem just the opposite would happen, that is - the coolant temperature = would increase.=20 Now, If the coolant temp with NPG+ actually does remain the same = (or decreased) for the same Q and flow rate, then it could indicate the = engine heat load is not being carried away as well as with the 50/50. = IF the reports of lesser cooling temps occurs when switching to NPG+ = are correct, then it would appear to me that the engine must then be = operating under a higher heat load (i.e heat not being transfer to the = radiators as effectively) . This doesn't even take into consideration = the possibly lesser flow rate of NPG+ for the same pump speed as the = 50/50 due to its higher 3 times higher viscosity (at 212F).=20 Yes, I have no problem understanding that boil-over has been = eliminated - but, is NPG actually cooling as well as coolant temps may = lead one to believe? I mean with NPG, I could have a excessive block = temperature and still not have boil-over - but my rotary engine would = likely have suffered damage. What am I missing? Inquiring minds (even old ones) want to know = {:>) Ed A -al wick Artificial intelligence in cockpit, Cozy IV powered by stock Subaru = 2.5 N9032U 200+ hours on engine/airframe from Portland, Oregon Prop construct, Subaru install, Risk assessment, Glass panel design = info: http://www.maddyhome.com/canardpages/pages/alwick/index.html ------=_NextPart_000_0013_01C629D5.D9769D00 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Ok, Al
 
That as you said, explains it.  My = recollection of reported coolant temps were clearly in error and what = you cited=20 about coolant temps using NPG does correlate.  My mind is=20 happy!
 
I have fortunately never experienced = cascade=20 boil-over and hope never to do so, clearly a terrifying and hopeless = feeling to=20 encounter why flying.  Shutting off the engine in such a situation = might=20 bring things back under control - if you have plenty of altitude.  = But, I=20 would assume most boil overs happen after a high powered takeoff on = a hot day, so altitude may be lacking.
 
 I can certainly understand why = that would=20 induce someone to go to the NPG coolant. 
 
Long, Long ago and in a place far, far = away - Japan=20 to be exact.  Mazda provided that 180F coolant temps (out of the = block) and=20 210F Oil temps (into the block) were the limits.  These can also be = found=20 in Racing Beat's technical catalog.   I have on occasion - and = for=20 very limited amounts of time - had oil temps as high as 230F and coolant = as high=20 as 250F.  These were cases where coolant was still flowing and=20 pressurized.  After the first incident with an 86 N/A block, I = found I had=20 coolant "O" ring compromised (coolant leaking into combustion chamber), = I then=20 switched to the Teflon Enscapulate Silicon "O" rings and on the one or = two=20 occasions when the temps reached 220F oil and 230F coolant - there = appeared to=20 be no damage.
 
I believe that those limits were = established for=20 the mid 1980 era 13Bs and that block coolant galley improvements and = casting=20 changes (as well as use of higher temps rubber seals) have probably = raised the=20 permissible operating temperature.  But, I do not know of anyone = who has=20 tested an engine to destruction to find out {:>)
 
Ed
----- Original Message -----
From:=20 al p = wick
Sent: Saturday, February 04, = 2006 9:32=20 PM
Subject: [FlyRotary] Re: NPG = Coolant=20 Temperature vs 50/50

The Egg guys no longer operate at the normal 200F when they = install NPG.=20 I don't recall the exact number, but they operate around 215F = (cruise). Which=20 explains most of your theoretical differences.
They gain a significant safety bonus in the boil over temp. That = safety=20 margin is what it's all about. At least from the risk perspective. =
So by operating at a higher Delta T, they compensate for the = reduced=20 efficiency of the fluid.
 
I've heard you guys describe the importance of operating coolant = around=20 185F or so? Are you sure of that limit? Is that just a recommended = thing,=20 or hard and fast limit. I'm always skeptical of stuff like = that.
 
-al wick
 
 
On Sat, 4 Feb 2006 20:56:49 -0500 "Ed Anderson" <eanderson@carolina.rr.com&g= t;=20 writes:
Hi Al,
 
Appreciate your (anybody else = welcome also)=20 views on one other thing that is still bothering me about the = use of=20 NPG. 
 
Given that NPG+ has a specific heat = of 0.66 at=20 212F or  20% less than  the 0.82 for the 50/50 = mixture and=20 given that NPG+ is  approx 7% more dense than the 50/50=20 - then that for the same flowrate for both it would seem = that NPG=20 still has a 13% lesser overall capacity for heat transfer  (at = the same=20 temps 212F and flow rates).
 
Also assume that the engine is = produce the same=20 heat load (Q),lets take alook at what temperature we might see with = NPG+=20 compared to the 50/50 solution.  We have from the oldie but = goody Q =3D=20 c*M*DeltaT the ability to solve for the temperature increase,=20 DeltaT.
 
Delta T =3D Q/cM, now if the = combined effects of=20 c and m  provide 13% less heat transfer capability than the = 50/50=20 mixture that would indicated that to carry away the same Q at the = same flow=20 rate, the delta T of NPG+ would need to increase by 13%.  So if = I were=20 getting 180F with the 50/50 for the same Q load (and flow rate) then = with=20 NPG+,  I would expect 180 *1.13 =3D 203F.  Yet, if I = understood=20 correct we have reports  that lesser temperatures results = noted by=20 users of NPG - this leaves me a bit puzzled.
 
If my assumption is correct thus = far, then I am=20 at a loss to understand the reports of lesser cooling temps when = using NPG+,=20 it would seem just the opposite would happen, that = is - the=20 coolant  temperature would increase. 
 
Now,  If the coolant temp with = NPG+=20 actually does  remain  the same (or decreased) for the = same Q and=20 flow rate,  then it could indicate the engine heat load is not = being=20 carried away as well as with the 50/50.  IF the reports of = lesser=20 cooling temps occurs when switching to NPG+  are correct, = then it=20 would appear to me that the engine must then be operating under a = higher=20 heat load (i.e heat not being transfer to the radiators as = effectively)=20 .  This doesn't even take into consideration the possibly = lesser flow=20 rate of NPG+ for the same pump speed as the 50/50 due to its higher = 3 times=20 higher viscosity (at 212F). 
 
 Yes, I have no problem = understanding that=20 boil-over has been eliminated - but, is NPG actually cooling as well = as=20 coolant temps may lead one to believe? I mean with NPG, I could = have a=20 excessive block temperature and still not have boil-over - but my = rotary=20 engine would likely have suffered damage.
 
 What am I missing? Inquiring = minds (even=20 old ones) want to know {:>)
 
Ed A
 
 

-al wick
Artificial = intelligence in=20 cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on=20 engine/airframe from Portland, Oregon
Prop construct, Subaru = install, Risk=20 assessment, Glass panel design=20 = info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
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