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 971210 for flyrotary@lancaironline.net; Sun, 05 Feb 2006 17:17:51 -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 k15MH4Dp004046 for ; Sun, 5 Feb 2006 17:17:05 -0500 (EST) Message-ID: <001501c62aa1$e50d6780$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: NPG Coolant Temperature vs 50/50 Date: Sun, 5 Feb 2006 17:17:04 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0012_01C62A77.FBED8540" 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_0012_01C62A77.FBED8540 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I think I'll pass on the boil -over, getting to the age where too much = fun can be dangerous {:>). Yes, many of us do use a coolant pressure gauge. It told me when I = recently compromised the coolant "O" ring due to a trapped piece of apex = seal on the side of the rotor (hasty rebuild)which created sufficient = friction to locally fry the Teflon Coated "O" ring. I think I have the = honor of being the only known case of frying one of those. My coolant = pressure started to climb on long trip from NC to Mississippi, it = increased approx 1/2" psi every 45 minutes. My the time I got to = Charlies, the pressure was reading 18-19 Psi. So second time had to = rebuild engine down in Louisiana in June. I suspect that you are correct, Al. The operating temperatures = recommended my Mazda long ago are undoubtedly conservative especially = with regard to the capability of various "O" rings to withstand the = heat.=20 However, I am not certain what else might occur as a result of over = heating. I have read that overheating can cause the apex seal to = chatter and create wear on the rotor housing. I have seen speculation = that uneven heating of the block might cause it to "banana" and bearings = to wear/seize. One story is that the aluminum rotor housing will = "shrink" if over heated (actually it appears that the aluminum housing = might indeed tend to "crush" under pressure of tension bolts and = overheated metal) and was one of the things to check/measure during an = rebuild. =20 I would think that folks in the racing crowd would know first hand of = damage overhead engines might incur. Lynn???? As I indicated, I and several others have exceeded those limits by = healthy margins for limited time without indications of damage. However, I for one have had too many engine rebuilds for other reasons = to intentionally cook one to destruction - I'll defer to someone else to = do that {:>) All this talk about boil-over has me thinking about a cool drink and = going to neighbors to watch super bowl game (actually, we turn on the = set and then never get around to watching it ). Check in later. Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com ----- Original Message -----=20 From: al p wick=20 To: Rotary motors in aircraft=20 Sent: Sunday, February 05, 2006 2:50 PM Subject: [FlyRotary] Re: NPG Coolant Temperature vs 50/50 Boil over. Man is that fun!=20 I deliberately caused boil over with multiple high speed taxi tests. I = think I did it three times. When it happens, there's no stopping it. You = loose substantial quantity fluid and all of the engine components are = heat soaked. I don't know if there would be any value to shutting off = engine, then restarting. Likely not. Lack of fluid movement would likely = cause even greater coolant loss. Certainly lots of things you can do to prevent it. Some simple ones = like throw away overflow bottle and operate cooling system with 2 cups = of air under cap. Big asset, as it allows you to use coolant pressure as = advance indicator of system integrity. Yeah, I know you guys think your = sys behaves different. I am skeptical. I sure would review those oil and coolant temp limits. I find that so = hard to believe. Maybe long ago. I'd dig into "what component fails, how = does it fail (like how long does it take)". Stuff like that. If failure = mode is gradual coolant loss past o-ring, I'd instrument that then test = it. Force it to happen. With the modern advances in material properties, = I just can't believe 230F coolant can affect an o-ring anymore. You = know? -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 On Sat, 4 Feb 2006 21:56:27 -0500 "Ed Anderson" = writes: 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). = 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 -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_0012_01C62A77.FBED8540 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
I think I'll pass on the boil -over, = getting to the=20 age where too much fun can be dangerous {:>).
 
Yes, many of us do use a coolant = pressure=20 gauge.  It told me when I recently compromised the coolant "O" ring = due to=20 a trapped piece of apex seal on the side of the rotor (hasty = rebuild)which=20 created sufficient friction to locally fry the Teflon Coated "O" = ring.  I=20 think I have the honor of being the only known case of frying one of=20 those.  My coolant pressure started to climb on long trip from NC = to=20 Mississippi, it increased approx 1/2" psi every 45 minutes.  My the = time I=20 got to Charlies, the pressure was reading 18-19 Psi.  So second = time had to=20 rebuild engine down in Louisiana in June.
 
I suspect that you are correct, = Al.  The=20 operating temperatures recommended my Mazda long ago are undoubtedly=20 conservative especially with regard to the capability of various "O" = rings to=20 withstand the heat. 
 
 However, I am not certain what=20 else might occur as a result of over heating.  I have read = that=20 overheating can cause the apex seal to chatter and create wear on = the rotor=20 housing.  I have seen speculation that uneven heating of the block = might=20 cause it to "banana" and bearings to wear/seize.  One story is = that=20 the aluminum rotor housing will "shrink" if over heated (actually it = appears=20 that the aluminum housing might indeed tend to "crush" under = pressure of=20 tension bolts and overheated metal) and was one of the things to=20 check/measure during an rebuild. 
 
I would think that folks in the racing = crowd would=20 know first hand of damage overhead engines might incur.  =20 Lynn????
 
  As I indicated, I and several = others have=20 exceeded those limits by healthy margins for limited time without = indications of=20 damage.
 
However, I for one have had too many = engine=20 rebuilds for other reasons  to intentionally cook one to = destruction - I'll=20 defer to someone else to do that {:>)
 
All this talk about boil-over has me = thinking about=20 a cool drink and going to neighbors to watch super bowl game (actually, = we turn=20 on the set and then never get around to watching it ).
 
Check in later.
 
Ed
 
Ed Anderson
Rv-6A N494BW Rotary=20 Powered
Matthews, NC
eanderson@carolina.rr.com
----- Original Message -----
From:=20 al p = wick
Sent: Sunday, February 05, 2006 = 2:50=20 PM
Subject: [FlyRotary] Re: NPG = Coolant=20 Temperature vs 50/50

Boil over. Man is that fun!
I deliberately caused boil over with multiple high speed taxi = tests. I=20 think I did it three times. When it happens, there's no stopping it. = You loose=20 substantial quantity fluid and all of the engine components are heat = soaked. I=20 don't know if there would be any value to shutting off engine, then=20 restarting. Likely not. Lack of fluid movement would likely cause even = greater=20 coolant loss.
 
Certainly lots of things you can do to prevent it.  Some = simple ones=20 like throw away overflow bottle and operate cooling system with 2 cups = of air=20 under cap. Big asset, as it allows you to use coolant pressure as = advance=20 indicator of system integrity. Yeah, I know you guys think your sys = behaves=20 different. I am skeptical.
 
I sure would review those oil and coolant temp limits. I find = that so=20 hard to believe. Maybe long ago. I'd dig into "what component fails, = how does=20 it fail (like how long does it take)". Stuff like that. If failure = mode=20 is gradual coolant loss past o-ring, I'd instrument that then = test it.=20 Force it to happen. With the modern advances in material properties, I = just=20 can't believe 230F coolant can affect an o-ring anymore. You = know?
 

-al wick
Artificial intelligence in cockpit, Cozy IV = powered by=20 stock Subaru 2.5
N9032U 200+ hours on engine/airframe from = Portland,=20 Oregon
Prop construct, Subaru install, Risk assessment, Glass panel = design=20 info:
htt= p://www.maddyhome.com/canardpages/pages/alwick/index.html
 
 
 
On Sat, 4 Feb 2006 21:56:27 -0500 "Ed Anderson" <eanderson@carolina.rr.com&g= t;=20 writes:
Ok, Al
 
That as you said, explains = it.  My=20 recollection of reported coolant temps were clearly in error and = what you=20 cited about coolant temps using NPG does correlate.  My mind is = happy!
 
I have fortunately never = experienced cascade=20 boil-over and hope never to do so, clearly a terrifying and hopeless = feeling=20 to encounter why flying.  Shutting off the engine in such a = situation=20 might bring things back under control - if you have plenty of=20 altitude.  But, I would assume most boil overs happen = after a high=20 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 -=20 Japan to be exact.  Mazda provided that 180F coolant temps (out = of the=20 block) and 210F Oil temps (into the block) were the limits.  = These can=20 also be found in Racing Beat's technical catalog.   I have = on=20 occasion - and for very limited amounts of time - had oil temps as = high as=20 230F and coolant as high as 250F.  These were cases where = coolant was=20 still flowing and pressurized.  After the first incident with = an 86 N/A=20 block, I found I had coolant "O" ring compromised (coolant leaking = into=20 combustion chamber), I then switched to the Teflon Enscapulate = Silicon "O"=20 rings and on the one or two occasions when the temps reached 220F = oil and=20 230F coolant - there appeared to be no damage.
 
I believe that those limits were = established=20 for the mid 1980 era 13Bs and that block coolant galley improvements = and=20 casting changes (as well as use of higher temps rubber seals) have = probably=20 raised the permissible operating temperature.  But, I do not = know of=20 anyone who has tested an engine to destruction to find out=20 {:>)
 
Ed
----- Original Message ----- =
From:=20 al p = wick=20
To: Rotary motors in = aircraft=20
Sent: Saturday, February = 04, 2006=20 9:32 PM
Subject: [FlyRotary] Re: = NPG Coolant=20 Temperature vs 50/50

The Egg guys no longer operate at the normal 200F when they = install=20 NPG. I don't recall the exact number, but they operate around 215F = (cruise). Which explains most of your theoretical differences. =
They gain a significant safety bonus in the boil over temp. = That=20 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=20 efficiency of the fluid.
 
I've heard you guys describe the importance of operating = coolant=20 around 185F or so? Are you sure of that limit? Is that just a = recommended=20 thing, or hard and fast limit. I'm always skeptical of stuff = like=20 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=20 of NPG. 
 
Given that NPG+ has a specific = heat of 0.66=20 at 212F or  20% less than  the 0.82 for the 50/50 = mixture=20 and 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=20 NPG still has a 13% lesser overall capacity for heat transfer =  (at=20 the same temps 212F and flow rates).
 
Also assume that the engine is = produce the=20 same heat load (Q),lets take alook at what temperature we might = see with=20 NPG+ compared to the 50/50 solution.  We have from the = oldie but=20 goody Q =3D c*M*DeltaT the ability to solve for the temperature = increase,=20 DeltaT.
 
Delta T =3D Q/cM, now if the = combined effects=20 of c and m  provide 13% less heat transfer capability than = the=20 50/50 mixture that would indicated that to carry away the same Q = at the=20 same flow rate, the delta T of NPG+ would need to increase by = 13%. =20 So if I were getting 180F with the 50/50 for the same Q load = (and flow=20 rate) then with NPG+,  I would expect 180 *1.13 =3D = 203F.  Yet,=20 if I understood correct we have reports  that lesser=20 temperatures results noted by users of NPG - this leaves me a = bit=20 puzzled.
 
If my assumption is correct = thus far, then=20 I am at a loss to understand the reports of lesser cooling temps = when=20 using NPG+, it would seem just the opposite would happen, that=20 is - the coolant  temperature would=20 increase. 
 
Now,  If the coolant temp = with NPG+=20 actually does  remain  the same (or decreased) for the = same Q=20 and flow rate,  then it could indicate the engine heat load = is not=20 being carried away as well as with the 50/50.  IF the = reports of=20 lesser cooling temps occurs when switching to NPG+  = are=20 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=20 radiators as effectively) .  This doesn't even take into=20 consideration the possibly lesser flow rate of NPG+ for the same = pump=20 speed as the 50/50 due to its higher 3 times higher viscosity = (at=20 212F). 
 
 Yes, I have no problem = understanding=20 that boil-over has been eliminated - but, is NPG actually = cooling as=20 well as coolant temps may lead one to believe? I mean with = NPG, I=20 could have a excessive block temperature and still not have = boil-over -=20 but my rotary engine would likely have suffered = damage.
 
 What am I missing? = Inquiring minds=20 (even 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,=20 Risk assessment, Glass panel design=20 = info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
=
 

-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
= ------=_NextPart_000_0012_01C62A77.FBED8540--