X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [216.52.245.18] (HELO ispwest-email1.mdeinc.com) by logan.com (CommuniGate Pro SMTP 5.0.7) with ESMTP id 964444 for flyrotary@lancaironline.net; Wed, 01 Feb 2006 22:34:15 -0500 Received-SPF: none receiver=logan.com; client-ip=216.52.245.18; envelope-from=wschertz@ispwest.com Received: from 7n7z201 (unverified [63.13.186.70]) by ispwest-email1.mdeinc.com (Vircom SMTPRS 4.3.456.0) with SMTP id for ; Wed, 1 Feb 2006 19:31:54 -0800 X-Modus-BlackList: 63.13.186.70=OK;wschertz@ispwest.com=OK X-Modus-RBL: 63.13.186.70=0000274C X-Modus-Trusted: 63.13.186.70=NO Message-ID: <016301c627a9$347f92d0$0400000a@7n7z201> From: "William" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Suitability of NPG for Rotary Engine use Date: Wed, 1 Feb 2006 21:31:06 -0600 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_015E_01C62776.CF337CC0" 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 This is a multi-part message in MIME format. ------=_NextPart_000_015E_01C62776.CF337CC0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable The other thing that occurred to me in reading Dave's account is that he = ran it on the ground, getting stable temperatures. It was only after = taking off, climbing to altitude, and then leveling off that he had the = temperature excursion and the problem. ** speculation/theory** On the ground, the cooling from the prop blast would be relatively low, = therefore the glycol could circulate and warm up. During climb -- engine = generating a lot of power, air speed higher than taxi, but still not at = max flow of air through the radiators. Now you get to altitude, level = off, speed up, increase the flow of air (and resultant cooling) through = the radiator, and lower the power setting somewhat. ??Can you?? get = into a situation where the radiator is cooling the glycol so much that = it gets viscous and starts slowing down/blocking flow passages?? I don't = know, but I had the following observation on a cold morning in December: I was driving my wife's PT-cruiser at steady speed on an interstate with = the temperature on the outside measuring -15*F. The temperature gauge in = the car would rise to the thermostat set point, hold for a short time, = and then drop off. This cycle repeated as long as I was maintaining = constant power input. When I would go off the Interstate, going through = town at ~30mph, the temperature would stabilize at thermostat setting, = solid as a rock. My *hypothesis* of what was going on was: 1. At low speeds, the radiator/thermostat combination could assume a = steady state condition. 2. At highway speeds, the high rate of very cold air flowing through the = radiator would supercool the coolant, and when the thermostat opened the = cold coolant would cause the engine temperature to drop a few degrees, = then the thermostat would close and the temperature would slowly climb = back to the thermostat setting. I have watched for this behavior at less = extreme conditions, and if there it is not noticable. Bill Schertz KIS Cruiser # 4045 ----- Original Message -----=20 From: Ed Anderson=20 To: Rotary motors in aircraft=20 Sent: Wednesday, February 01, 2006 7:49 PM Subject: [FlyRotary] Re: Suitability of NPG for Rotary Engine use Thanks, Bill Just thought it might be useful to some who might be considering it = why NPG just might not be well suited to the stock rotary coolant = system. Yes, I noticed that the chart did not measure the viscosity of the NPG = at the same temps as they did the 50/50 mixture. Might be a legitimate = reason for that but escapes me. I suspect the viscosity goes much = higher at lower temps. No problem with a running engine, but starting a = really cold block might offer some problems as you suggest. Especially = given the small diameters of some of the GM cores channels. Could be = that Dave simply was not getting any significant cooling due to minimal = flow. I recall him saying the temps went up all of a sudden and wonder = if the coolant "trapped" in the block might not have reached very high = temps before managing to "burst" lose and send the temp sensor soaring. Ed ----- Original Message -----=20 From: William=20 To: Rotary motors in aircraft=20 Sent: Wednesday, February 01, 2006 6:40 PM Subject: [FlyRotary] Re: Suitability of NPG for Rotary Engine use Excellent write-up Ed, I would be particularly leery of NPG in a = severely cold climate with small channels in the heat exchanger. High = viscosity and small channels can lead to high pressure drop -- low flow. = This then becomes unstable, if the flow becomes low, the fluid in the = radiator can become colder, leading to higher viscosity, lower flow, = higher pressure drop, all the while the engine portion can be = overheating. Note that the viscosity for NPG+ is >10 times that of 50-50 EG/water = at 50*F, a really interesting number would be the viscosity at 0*F = (Where Dave was flying). It could be that the pump cannot generate = enough pressure drop to force the fluid through the radiator if it gets = cold. On plain (room temperature) water, the Mazda pump can generate ~20 = psi at zero flow at 5500 rpm. Bill Schertz KIS Cruiser # 4045 ----- Original Message -----=20 From: Ed Anderson=20 To: Rotary motors in aircraft=20 Sent: Wednesday, February 01, 2006 9:31 AM Subject: [FlyRotary] Suitability of NPG for Rotary Engine use Things have been a little dull on the list, since Dave reported on = his "adventure".=20 Also, I recently received a phone call from a rotary enthusiast = (not on the list) about the use of Evans NPG (Propylene Glycol) in = rotary engines. I did a bit of research and my conclusion was the = rotary engine was not well suited to benefit from the properties of NPG = in its stock coolant system configuration. =20 That the use of 100% glycol would require increased coolant flow = rates by 10-15% and more coolant pump power would be required (hard to = quantify this one but it appears in the range of 15-25% more). Also the = hazard of fire due to a leak on hot exhaust would be increased (this = would apply to a 100% mixture of either Ethylene or Propylene glycol). = There are benefits to using NPG, however, in my opinion the effort = needed to change the rotary cooling configuration to safely use it = makes the cost effectiveness of the conversion questionable. The apparent success of Evans NPG in reciprocating engines is not = in conflict with my assessment about its suitability for the rotary = engine. Attached is some supporting (I believe) facts to support this = opinion (and that is all it is). Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com -------------------------------------------------------------------------= - -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net/lists/flyrotary/ -------------------------------------------------------------------------= --- -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ ------=_NextPart_000_015E_01C62776.CF337CC0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
The other thing that occurred to me in = reading=20 Dave's account is that he ran it on the ground, getting stable = temperatures. It=20 was only after taking off, climbing to altitude, and then leveling off = that he=20 had the temperature excursion and the problem.
 
** speculation/theory**
On the ground, the cooling from the = prop blast=20 would be relatively low, therefore the glycol could circulate and warm = up.=20 During climb -- engine generating a lot of power, air speed higher than = taxi,=20 but still not at max flow of air through the radiators. Now you get to = altitude,=20 level off, speed up, increase the flow of air (and resultant cooling) = through=20 the radiator, and lower the power setting somewhat.  ??Can you?? = get into a=20 situation where the radiator is cooling the glycol so much that it gets = viscous=20 and starts slowing down/blocking flow passages?? I don't know, but I had = the=20 following observation on a cold morning in December:
 
I was driving my wife's PT-cruiser at = steady speed=20 on an interstate with the temperature on the outside measuring -15*F. = The=20 temperature gauge in the car would rise to the thermostat set point, = hold for a=20 short time, and then drop off. This cycle repeated as long as I was = maintaining=20 constant power input. When I would go off the Interstate, going through = town at=20 ~30mph, the temperature would stabilize at thermostat setting, solid as = a rock.=20 My *hypothesis* of what was going on was:
 
1. At low speeds, the = radiator/thermostat=20 combination could assume a steady state condition.
 
2. At highway speeds, the high rate of = very cold=20 air flowing through the radiator would supercool the coolant, and when = the=20 thermostat opened the cold coolant would cause the engine temperature to = drop a=20 few degrees, then the thermostat would close and the temperature would = slowly=20 climb back to the thermostat setting. I have watched for this behavior = at less=20 extreme conditions, and if there it is not noticable.
 
Bill Schertz
KIS Cruiser # 4045
----- Original Message -----
From:=20 Ed=20 Anderson
Sent: Wednesday, February 01, = 2006 7:49=20 PM
Subject: [FlyRotary] Re: = Suitability of=20 NPG for Rotary Engine use

Thanks, Bill
 
Just thought it might be useful to some who = might be=20 considering it why NPG just might not be well suited to the stock = rotary=20 coolant system.
 
Yes, I noticed that the chart did not measure = the=20 viscosity of the NPG at the same temps as they did the 50/50 = mixture. =20 Might be a legitimate reason for that but escapes me.  I suspect = the=20 viscosity goes much higher at lower temps.  No problem with a = running=20 engine, but starting a really cold block might offer some problems as = you=20 suggest.  Especially given the small diameters of some of the GM = cores=20 channels.  Could be that Dave simply was not getting any = significant=20 cooling due to minimal flow.  I recall him saying the temps went = up all=20 of a sudden and wonder if the coolant "trapped" in the block might not = have=20 reached very high temps before managing to "burst" lose and send the = temp=20 sensor soaring.
 
 
Ed
----- Original Message -----
From:=20 William=20
To: Rotary motors in = aircraft=20
Sent: Wednesday, February 01, = 2006 6:40=20 PM
Subject: [FlyRotary] Re: = Suitability of=20 NPG for Rotary Engine use

Excellent write-up Ed, I would be = particularly=20 leery of NPG in a severely cold climate with small channels in the = heat=20 exchanger. High viscosity and small channels can lead to high = pressure drop=20 -- low flow. This then becomes unstable, if the flow becomes low, = the fluid=20 in the radiator can become colder, leading to higher viscosity, = lower flow,=20 higher pressure drop, all the while the engine portion can be=20 overheating.
 
Note that the viscosity for NPG+ is = >10=20 times that of 50-50 EG/water at 50*F, a really interesting number = would be=20 the viscosity at 0*F (Where Dave was flying). It could be that the = pump=20 cannot generate enough pressure drop to force the fluid through the = radiator=20 if it gets cold. On plain (room temperature) water, the Mazda pump = can=20 generate ~20 psi at zero flow at 5500 rpm.
 
Bill Schertz
KIS Cruiser # 4045
----- Original Message ----- =
From:=20 Ed Anderson
To: Rotary motors in = aircraft=20
Sent: Wednesday, February = 01, 2006=20 9:31 AM
Subject: [FlyRotary] = Suitability of=20 NPG for Rotary Engine use

Things have been a little dull on the = list, since=20 Dave reported on his "adventure". 
 
 Also, I recently received a phone = call from a=20 rotary enthusiast (not on the list) about the use of Evans NPG = (Propylene=20 Glycol) in rotary engines.  I did a bit of research and my = conclusion=20 was the rotary engine was not well suited to benefit from the = properties of NPG in its stock coolant system=20 configuration.  
 
 That the use of 100% glycol would=20  require increased coolant flow rates by 10-15% and more = coolant=20 pump power would be required (hard to quantify this one but it = appears in=20 the range of 15-25% more).  Also the hazard of fire due to a = leak on=20 hot exhaust would be increased (this would apply to a 100% mixture = of=20 either Ethylene or Propylene glycol).  There are benefits to = using=20 NPG, however, in my opinion the effort needed to change =  the=20 rotary cooling configuration to safely use it makes the cost = effectiveness=20 of the conversion questionable.
 
The apparent success of Evans NPG in = reciprocating=20 engines is not in conflict with my assessment about its = suitability for=20 the rotary engine.
 
Attached is some supporting (I believe) = facts to=20 support this opinion (and that is all it is).
 
Ed
 
Ed Anderson
Rv-6A N494BW Rotary=20 Powered
Matthews, NC
eanderson@carolina.rr.com

--
Homepage:  http://www.flyrotary.com/
Archive = and=20 UnSub:  =20 http://mail.lancaironline.net/lists/flyrotary/

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Homepage:  http://www.flyrotary.com/
Archive = and=20 UnSub:  =20 = http://mail.lancaironline.net/lists/flyrotary/
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