X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 2 [X] Return-Path: Received: from bay0-omc2-s29.bay0.hotmail.com ([65.54.246.165] verified) by logan.com (CommuniGate Pro SMTP 5.1.7) with ESMTP id 1932650 for flyrotary@lancaironline.net; Tue, 20 Mar 2007 12:22:29 -0400 Received-SPF: pass receiver=logan.com; client-ip=65.54.246.165; envelope-from=lors01@msn.com Received: from hotmail.com ([65.54.250.80]) by bay0-omc2-s29.bay0.hotmail.com with Microsoft SMTPSVC(6.0.3790.2668); Tue, 20 Mar 2007 09:21:41 -0700 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Tue, 20 Mar 2007 09:21:41 -0700 Message-ID: Received: from 4.171.147.161 by BAY115-DAV8.phx.gbl with DAV; Tue, 20 Mar 2007 16:21:37 +0000 X-Originating-IP: [4.171.147.161] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: water boiling point Date: Tue, 20 Mar 2007 12:21:32 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00C1_01C76AEA.4B944C10" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: MSN 9 X-MimeOLE: Produced By MSN MimeOLE V9.50.0034.2000 Seal-Send-Time: Tue, 20 Mar 2007 12:21:32 -0400 X-OriginalArrivalTime: 20 Mar 2007 16:21:41.0156 (UTC) FILETIME=[D7BBA640:01C76B0B] Return-Path: lors01@msn.com This is a multi-part message in MIME format. ------=_NextPart_000_00C1_01C76AEA.4B944C10 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Re: [FlyRotary] water boiling pointI understand Al W's fondness of the = "air spring" in the system. It does convey a lot of info to the pilot.=20 I especially did not like the coolant pressure dropping to zero when = reducing power and descending. I feel blind in this condition. This is = what you see when there is zero air in the system. I like the Moroso = expansion tanks because they can function as both air/coolant separator = and gives room for the air spring volume. =20 I think Al G's system gives you the spring as well but ramps up the = nominal pressure. If you've ever seen it, It's very pretty too! Tracy ----- Original Message -----=20 From: al p wick=20 To: Rotary motors in aircraft=20 Sent: Tuesday, March 20, 2007 1:12 AM Subject: [FlyRotary] Re: water boiling point Interesting points. If I added a 1/4 cup more coolant, then my = pressure would peak at 12 psi instead of 7. I like your theory. I'll = dial it in to higher psi on new engine. So you can adjust your normal = peak pressure using that method. The important concept is to not allow = the system to reach cap psi. This little change improves understanding = and safety. Yet you want a high psi cap just in case something goes = wrong. Safety margin. I know it sounds like trivial difference, but it = isn't. I've seen results of cavitation. Not on water pump, but others. Pretty = profound.=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 On Mon, 19 Mar 2007 15:59:47 -0800 "Al Gietzen" = > writes: Al W; I don't disagree with your concept, but I think there are other = considerations. The air volume number of 2 cups only applies to your system. The 7 = psig you mention implies that you only get a bit over =BD cup expansion = of coolant. In my system I know I get at least 6 times that much. In addition to the boiling point protection, there is the = consideration of pump cavitation. When I was designing my system, I = recall some pretty awful photos (on the ACRE list) of what cavitation = can do a pump impellor. Since we generally run at high rpm, it's likely = an issue. =20 And "ideal" pressure depends on where you measure it, and where the = cap pressure is. There is likely at least a few psi difference between = the pump inlet and the outlet. If the 7 psig (gauge pressure) you = mention is on the outlet side, then it may be close to 0 psig at the = inlet, and considerably lower behind the vane in the pump. At 180F water = flashes to steam bubbles at about -7 psig (8 psia), so there could be a = have high probability of cavitation. And that's at sea level. If the 7 = psig is at the pump inlet, you'd be a bit better off. That's why I designed my system to have a 'cap pressure' of 23 psig = on the pump inlet side, why I have no air under that cap, and why I have = a pressure cap on the expansion bottle; so even when the coolant temp is = decreasing, and the cap pressure is 0 psig, there is still some positive = pressure at the pump inlet. Of course designing for this consideration = takes care of the boiling protection as well, and provides some margin = for altitude, since we generally fly considerably above sea level. It = has worked fine for me so far. Concerning masking a compression leak, I = think whether the pressure is 7 or 27 it is negligible compared to = combustion pressures. =20 I don't know that this is necessary, right, wrong, or ideal; but it = made sense to me. Al G There's one coolant design that's substantially better than the = others. I discovered it when doing severe ground testing...deliberately = overheating my engine.=20 Three basic requirements: 1) Place your radiator cap and reservoir above engine. The higher = the better. This allows trapped air in system to rise out of the flow = and stay there.=20 2) Put a 24 psi cap on the system. You can throw away your overflow = stuff. Not needed. 3) Always keep around 2 cups of air under the cap. This is the key = item. It brings a big safety advantage. It allows you to use coolant = pressure to predict well in advance how good your system is doing. It = minimizes pressure. Mine never exceeds 7 psi. But if something goes = wrong, then my pressure rises and I gain boilover protection due to the = increase in system pressure. -al wick Cozy IV -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_00C1_01C76AEA.4B944C10 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Re: [FlyRotary] water boiling point
I understand Al W's  fondness of the "air spring" in the = system. =20 It does convey a lot of info to the pilot. 
 
 I especially did not like the coolant pressure dropping to = zero when=20 reducing power and descending. I feel blind in this condition.  = This is=20 what you see when there is zero air in the system.  I like the = Moroso=20 expansion tanks because they can function as both air/coolant = separator and=20 gives room for the air spring volume.   
 
I think Al G's system  gives you the spring as well but = ramps up=20 the nominal pressure.  If you've ever seen it, It's very pretty = too!
 
Tracy
----- Original Message -----
From: al p wick
To: Rotary motors in = aircraft
Sent: Tuesday, March 20, 2007 = 1:12=20 AM
Subject: [FlyRotary] Re: water = boiling=20 point

Interesting points. If I added a 1/4 cup more coolant, then my = pressure=20 would peak at 12 psi instead of 7. I like your theory. I'll dial it in = to=20 higher psi on new engine. So you can adjust your normal peak pressure = using=20 that method. The important concept is to not allow the system to reach = cap=20 psi. This little change improves understanding and safety. Yet you = want a high=20 psi cap just in case something goes wrong. Safety margin. I know it = sounds=20 like trivial difference, but it isn't.
 
I've seen results of cavitation. Not on water pump, but others. = Pretty=20 profound.
 

-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
 
On Mon, 19 Mar 2007 15:59:47 -0800 "Al Gietzen" <ALVentures@cox.net> = writes:

Al=20 W;

 

I don't = disagree=20 with your concept, but I think there are other=20 considerations.

 

The air = volume=20 number of 2 cups only applies to your system.  The 7 psig you = mention=20 implies that you only get a bit over =BD cup expansion of = coolant.  In my=20 system I know I get at least 6 times that much.

 

In = addition to=20 the boiling point protection, there is the consideration of pump = cavitation.=20  When I was designing my system, I recall some pretty awful = photos (on=20 the ACRE list) = of what=20 cavitation can do a pump impellor.  Since we generally run at = high rpm,=20 it's likely an issue.  

 

And = "ideal"=20 pressure depends on where you measure it, and where the cap pressure = is.  There is likely at least a few psi difference between the = pump=20 inlet and the outlet.  If the 7 psig (gauge pressure) you = mention is on=20 the outlet side, then it may be close to 0 psig at the inlet, and=20 considerably lower behind the vane in the pump. At 180F water = flashes to=20 steam bubbles at about -7 psig (8 psia), so there could be a have = high=20 probability of cavitation.  And that's at sea level. If the 7 = psig is=20 at the pump inlet, you'd be a bit better off.

 

That's = why I=20 designed my system to have a 'cap pressure' of 23 psig on the pump = inlet=20 side, why I have no air under that cap, and why I have a pressure = cap on the=20 expansion bottle; so even when the coolant temp is decreasing, and = the cap=20 pressure is 0 psig, there is still some positive pressure at the = pump inlet.=20  Of course designing for this consideration takes care of the = boiling=20 protection as well, and provides some margin for altitude, since we=20 generally fly considerably above sea level. It has worked fine for = me so=20 far.  Concerning masking a compression leak, I think whether = the=20 pressure is 7 or 27 it is negligible compared to combustion = pressures.=20  

 

I don't = know that=20 this is necessary, right, wrong, or ideal; but it made sense to=20 me.

 

Al=20 G

 

There's one=20 coolant design that's substantially better than the others. I = discovered it=20 when doing severe ground testing...deliberately overheating my = engine.=20

 

Three = basic=20 requirements:

 

1)=20 Place your radiator cap and reservoir above engine. The higher the = better.=20 This allows trapped air in system to rise out of the flow and stay = there.=20

2)=20 Put a 24 psi cap on the system. You can throw away your overflow = stuff. Not=20 needed.

3)=20 Always keep around 2 cups of air under the cap. This is the key = item. It=20 brings a big safety advantage. It allows you to use coolant pressure = to=20 predict well in advance how good your system is doing. It minimizes=20 pressure. Mine never exceeds 7 psi. But if something goes wrong, = then my=20 pressure rises and I gain boilover protection due to the increase in = system=20 pressure.

 -al=20 wick
Cozy IV

 

 

 

-al wick
Cozy IV powered by = Turbo Subaru=20 3.0R with variable valve lift and cam timing.
Artificial = intelligence in=20 cockpit, N9032U 240+ hours from Portland, Oregon
Glass panel = design, Subaru=20 install, Prop construct, Risk assessment=20 = info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
=
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