X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 1 [X] Return-Path: Received: from sccrmhc12.comcast.net ([204.127.200.82] verified) by logan.com (CommuniGate Pro SMTP 5.1.3) with ESMTP id 1634735 for flyrotary@lancaironline.net; Sun, 03 Dec 2006 10:51:19 -0500 Received-SPF: none receiver=logan.com; client-ip=204.127.200.82; envelope-from=wschertz@comcast.net Received: from 7n7z201 (c-24-7-194-231.hsd1.il.comcast.net[24.7.194.231]) by comcast.net (sccrmhc12) with SMTP id <200612031550520120013o96e>; Sun, 3 Dec 2006 15:50:57 +0000 Message-ID: <000701c716f2$cee8abc0$e7c20718@7n7z201> From: "Bill Schertz" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Fw: [FlyRotary] Re: Radiator Expansion Tank Date: Sun, 3 Dec 2006 09:50:45 -0600 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0004_01C716C0.80E12880" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2869 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 This is a multi-part message in MIME format. ------=_NextPart_000_0004_01C716C0.80E12880 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Thanks Al, One more question. Does the bottom end pressure stay positive after you = have run the engine up and then reduced power? Bill Schertz KIS Cruiser # 4045 ----- Original Message -----=20 From: Al Gietzen=20 To: Rotary motors in aircraft=20 Sent: Friday, December 01, 2006 12:43 PM Subject: [FlyRotary] Re: Fw: [FlyRotary] Re: Radiator Expansion Tank Bill; Working just fine. I haven't noted a pressure over 30 psi, even at = the highest temps. Al Al, Now that you are flying, how is your series connection of coolant = bottles with pressure caps working? I have constructed something = similiar, and there was some discussion that claimed that it wouldn't = work. I would be interested in what you found out. Bill Schertz Subject: [FlyRotary] Re: Radiator Expansion Tank Al, Rusty and others. I've been a little confused with the set- up recommended. Do you have = a pressure cap on the Radiator as well as the Expansion tank and do you = have an overflow bottle attached to the expansion tank. I've also seen where the rad pressure cap is not on the rad but on the = return to the pump. I would really like to sort this out so that I get a clearer picture = of the correct set-up. Advice appreciated. George ( down under) George; My system has two pressure caps. The filler neck on the left in the = photo connects to the pump inlet side of the loop (lowest pressure = point). That neck has a 23 # cap; and when the system is full and = purged, there is never any air at that cap. Overflow from the main = filler is plumbed to the bottom of the overflow bottle. The overflow = bottle normally is maybe half to two-thirds air as required to = accommodate the expansion from cold to hot. It has a 15# cap. =20 The idea is to always have positive pressure on the inlet side of the = pump to inhibit cavitation. Without a pressure cap on the overflow = bottle, expansion of the coolant in the engine pressurizes the system as = it heats up. But with no air in the system, after the peak is reached, = the pressure goes back to zero (or slightly negative to draw coolant = back from the overflow bottle) any time the temperature drops a bit; as = when you reduce power after climb-out. There are no caps on the radiators (2) as they are mounted at lower = levels. There are air bleed lines from the highest point of the tank on = each rad that go back to the filler neck; which is always at the lowest = pressure in the loop so the air will go there. With both caps fully latched, it is possible for the pressure to peak = at about 38 psi (23 plus 15), at sea level, if the overflow bottle is = full (coolant fully expanded). This give more margin (higher boiling = temp) and less likely cavitation at extreme conditions. Generally there = is always residual air in the bottle that is compressing, so the = pressure doesn't reach peak. Caps are 'differential pressure' so at = higher altitude the absolute pressure in the system is lower. A similar, and simpler approach is to have an expansion tank that has = air in it connected directly to the system, say as a filler tank with a = pressure cap, that is only half full when cold. Pressure builds as = things heat up, up to the max cap pressure. The difference in my = approach is that the pressure builds very quickly to the system cap = pressure because the coolant is incompressible (not counting some = expansion of hose connectors). So even if the engine is not fully = warmed up and I give it full throttle on takeoff, the system is at least = 23 psi at the pump inlet. Same is true any time later when power (and = RPM) is increased. Hope this all makes sense, Al -------------------------------------------------------------------------= ----- -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ ------=_NextPart_000_0004_01C716C0.80E12880 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Thanks Al,
One more question. Does the bottom end = pressure=20 stay positive after you have run the engine up and then reduced=20 power?
Bill Schertz
KIS Cruiser # 4045
----- Original Message -----
From:=20 Al = Gietzen=20
Sent: Friday, December 01, 2006 = 12:43=20 PM
Subject: [FlyRotary] Re: Fw: = [FlyRotary]=20 Re: Radiator Expansion Tank

Bill;

 

Working = just=20 fine.  I haven=92t noted a pressure over 30 psi, even at the = highest=20 temps.

 

Al

 

Al,

Now that you are flying, = how is=20 your series connection of coolant bottles with pressure caps working? = I have=20 constructed something similiar, and there was some discussion that = claimed=20 that it wouldn't work. I would be interested in what you found=20 out.

Bill=20 Schertz

Subject:=20 [FlyRotary] Re: Radiator Expansion Tank

 

Al, Rusty = and=20 others.

 

I've=20 been a little confused with the set- up recommended. Do you have = a=20 pressure cap on the Radiator as well as the Expansion tank and do you = have an=20 overflow bottle attached to the expansion = tank.

I've=20 also seen where the rad pressure cap is not on the rad but on the = return=20 to the pump.

 

I=20 would really like to sort this out so that I get a clearer = picture=20 of the correct set-up.

 

Advice=20 appreciated.

 

George=20 ( down under)

 

George;

 

My=20 system has two pressure caps.  The filler neck on the left in the = photo=20 connects to the pump inlet side of the loop (lowest pressure = point). =20 That neck has a 23 # cap; and when the system is full and purged, = there is=20 never any air at that cap.  Overflow from the main filler is = plumbed to=20 the bottom of the overflow bottle.  The overflow bottle normally = is maybe=20 half to=20 two-thirds = air as=20 required to accommodate the expansion from cold to hot.  It has a = 15#=20 cap. 

 

The=20 idea is to always have positive pressure on the inlet side of the pump = to=20 inhibit cavitation.  Without a pressure cap on the overflow = bottle,=20 expansion of the coolant in the engine pressurizes the system as it = heats up.=20 But with no air in the system, after the peak is reached, the pressure = goes=20 back to zero (or slightly negative to draw coolant back from the = overflow=20 bottle) any time the temperature drops a bit; as when you reduce power = after=20 climb-out.

 

There=20 are no caps on the radiators (2) as they are mounted at lower = levels. =20 There are air bleed lines from the highest point of the tank on each = rad that=20 go back to the filler neck; which is always at the lowest pressure in = the loop=20 so the air will go there.

 

With=20 both caps fully latched, it is possible for the pressure to peak at = about 38=20 psi (23 plus 15), at sea level, if the overflow bottle is full = (coolant fully=20 expanded).  This give more margin (higher boiling temp) and less = likely=20 cavitation at extreme conditions. Generally there is always residual = air in=20 the bottle that is compressing, so the pressure doesn=92t reach = peak.  Caps=20 are =91differential pressure=92 so at higher altitude the absolute = pressure in the=20 system is lower.

 

A=20 similar, and simpler approach is to have an expansion tank that has = air in it=20 connected directly to the system, say as a filler tank with a pressure = cap,=20 that is only half full when cold.  Pressure builds as things heat = up, up=20 to the max cap pressure.  The difference in my approach is that = the=20 pressure builds very quickly to the system cap pressure because the = coolant is=20 incompressible (not counting some expansion of hose connectors). =  So even=20 if the engine is not fully warmed up and I give it full throttle on = takeoff,=20 the system is at least 23 psi at the pump inlet.  Same is true = any time=20 later when power (and RPM) is increased.

 

Hope=20 this all makes sense,

 

Al

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

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