Return-Path: Received: from [24.25.9.100] (HELO ms-smtp-01-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 2801017 for flyrotary@lancaironline.net; Sat, 06 Dec 2003 10:13:08 -0500 Received: from o7y6b5 (clt78-020.carolina.rr.com [24.93.78.20]) by ms-smtp-01-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id hB6FD4xk022832 for ; Sat, 6 Dec 2003 10:13:05 -0500 (EST) Message-ID: <002d01c3bc0a$f4c74220$1702a8c0@WorkGroup> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Expansion Chambers Date: Sat, 6 Dec 2003 10:09:33 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_002A_01C3BBE1.0BB73E60" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_002A_01C3BBE1.0BB73E60 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable /jug/container. Well -- I also recommend a 21-24 psi radiator cap. =20 Thanks, Ed, Al & Mark for you're input.=20 I think I'll go with the simplest solution first, then add an = expansion chamber if that doesn't work. I'm thinking of getting one of those plastic overflow bottles with a = screen washer bottle fitted up next to it from a breakers yard. I'd = mount this high on the firewall. It would be simple to pipe the screen = washer to the plenum for use in hot day climb-out. Any thoughts? 21-24 PSI seems a bit high for the cap, though. I have a 16lb cap. Do = you think I should change it? John John, Regarding the radiator cap capacity. The radiator cap is a = "gauge" pressure cap in that it relies on atmospheric pressure along = with its spring to help it hold the coolant in. At altitude, with less = atmospheric pressure, the overall capability of the cap is lower. Also, = reportedly they tend to loose a bit of their capacity after a few = heating/cooling cycles. I tried 16 PSI cap and found I lost coolant on each flight. Once the = cap releases fluid that lowers pressure inside the radiators which if = hot enough can then send a big surge through the cap and overflow your = overflow bottle. I have recommend to a couple of folks who reported loosing cooling = using 16 psi caps to go to a higher capacity cap and that solved their = problem. In addition, most of the literature on coolants indicate that = you would like to keep the coolant pressure high enough so that the = coolant (water) would not have a tendency to boil even at temps above = 212F. =20 So you can try your 16 psi cap, but if you find yourself loosing = fluids (even with an overflow bottle) on flights, then try a higher = capacity radiator cap. Here is what on radiator maker says about radiator caps Radiator Caps In a cooling system, a higher pressure equates to a higher boiling = point for the coolant. Higher coolant pressures also transfer heat from = the cylinder heads more efficiently. We recommend using a radiator cap = with the highest pressure rating that the radiator is designed to = accept. In general, performance radiators will accept 22-24 PSI, and = professional racing radiators will accept a 29-31 PSI. The coolant will typically only build to 16-18 PSI, due to expansion = up to 200=B0F. However, if the engine does overheat due to external = factors, the pressure inside the cooling system could reach as high as = 28 PSI. Once the radiator cap has opened and vented coolant, the engine = will not cool down until it has been turned off. The radiator cap is = basically a "safety valve", so always use the highest pressure radiator = cap that the radiator will tolerate. If you are unsure of the pressure = rating for your radiator, check with the manufacturer for the maximum = recommended operating pressure. I don't quite understand their statement about the engine not cooling = down after venting until you turn it off. I would think that reducing = power and therefore heat into the coolant would cause the problem to = subside - assuming you have any coolant remaining {:>), perhaps their = statement "..and Vented Coolant" means ALL the coolant. Evaporator cores have a burst pressure around 250 psi, so that is not = your limitation. I would hesitate using more than 21-24 psi as I would = be concerned about pushing water out around the water pump shaft. In any case, your decision as always {:>) Ed Ed Anderson RV-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com ------=_NextPart_000_002A_01C3BBE1.0BB73E60 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
 /jug/container.  Well -- I also recommend a 21-24 = psi radiator=20 cap.    
Thanks, Ed, Al & Mark for you're = input. 
I=20 think I'll go with the simplest solution first, then add an expansion = chamber=20 if that doesn't work.
I'm=20 thinking of getting one of those plastic overflow bottles with a = screen=20 washer bottle fitted up next to it from a breakers yard. = I'd mount this=20 high on the firewall. It would be simple to pipe the screen washer to = the=20 plenum for use in hot day climb-out. Any thoughts?
 
21-24 PSI seems=20 a bit high for the cap, though. I have a 16lb cap. Do you think I = should=20 change it?
John
 
John, Regarding=20 the radiator cap capacity.  The radiator  cap is = a "gauge"=20 pressure cap in that it relies on atmospheric pressure along with its = spring=20 to help it hold the coolant in.  At altitude, with less = atmospheric=20 pressure, the overall capability of the cap is lower.  Also, = reportedly=20 they tend to loose a bit of their capacity after a few heating/cooling = cycles.
 
I = tried 16 PSI cap=20 and found I lost coolant on each flight. Once the cap releases fluid = that=20 lowers pressure inside the radiators which if hot enough can then send = a big=20 surge through the cap and overflow your overflow = bottle.
 
I = have recommend=20 to a couple of folks who reported loosing cooling using 16 psi caps to = go to a=20 higher capacity cap and that solved their problem.  In addition, = most of=20 the literature on coolants indicate that you would like to keep the = coolant=20 pressure high enough so that the coolant (water) would not have a = tendency to=20 boil even at temps above 212F. 
 
So = you can try=20 your 16 psi cap, but if you find yourself loosing fluids (even with an = overflow bottle) on flights, then try a higher capacity radiator=20 cap.
 
Here = is what on=20 radiator maker says about radiator caps
 
Radiator Caps
In a cooling system, a = higher=20 pressure equates to a higher boiling point for the coolant. Higher = coolant=20 pressures also transfer heat from the cylinder heads more efficiently. = We=20 recommend using a radiator cap with the highest pressure rating that = the=20 radiator is designed to accept. In general, performance radiators will accept 22-24=20 PSI, and professional racing radiators will = accept a=20 29-31 PSI.

The coolant will typically only build = to 16-18=20 PSI, due to expansion up to 200=B0F. However, if the engine does = overheat due to=20 external factors, the pressure inside the cooling system could reach = as high=20 as 28 PSI. Once the radiator cap has opened and vented coolant, the = engine=20 will not cool down until it has been turned off. The radiator cap is = basically=20 a "safety valve", so always use the = highest=20 pressure radiator cap that the radiator will = tolerate. If=20 you are unsure of the pressure rating for your radiator, check with = the=20 manufacturer for the maximum recommended operating=20 pressure.
 
I don't quite understand their statement about the = engine not=20 cooling down after venting until you turn it off.  I would = think=20 that reducing power and therefore  heat into the coolant would = cause the=20 problem to subside - assuming you have any coolant remaining {:>), = perhaps=20 their statement "..and Vented Coolant" means ALL the=20 coolant.
 
Evaporator cores have a burst pressure around 250 = psi, so that=20 is not your limitation.  I would hesitate using more than 21-24 = psi as I=20 would be concerned about pushing water out around the water pump=20 shaft.
 
In any case, your decision as always=20 {:>)
 
Ed
Ed Anderson
RV-6A N494BW = Rotary=20 Powered
Matthews, NC
eanderson@carolina.rr.com
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