Return-Path: Received: from [24.25.9.102] (HELO ms-smtp-03-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 2790459 for flyrotary@lancaironline.net; Fri, 05 Dec 2003 20:51:04 -0500 Received: from o7y6b5 (clt78-020.carolina.rr.com [24.93.78.20]) by ms-smtp-03-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id hB61p0wR001443 for ; Fri, 5 Dec 2003 20:51:02 -0500 (EST) Message-ID: <002401c3bb9a$ebef6bc0$1702a8c0@WorkGroup> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Expansion Chambers Date: Fri, 5 Dec 2003 20:47:33 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0021_01C3BB71.01DC01C0" 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_0021_01C3BB71.01DC01C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi John, Sorry, John. Thanks for the vote of confidence. Was working on = understanding K&W, duct and heat exchangers and seeing so many reponses = to your inqurey that I figured you probably didn't need another input.=20 I tend to agree with the initial advise you received. If your radiator = cap is at the highest point of your cooling system then I believe that = all you need is an overflow bottle/jug/container. Well -- I also = recommend a 21-24 psi radiator cap. That is all that I use. The = overflow catches any -- well, overflow. Needless to say your overflow = bottom must be vented to the atmosphere. The system on my aircraft is = so effective in removing the air from the cooling system after a couple = of flights, no air remains- in fact, that causes a condition that first = caused me to think I had a engine problem. So I might as well mention it = in case anyone else runs into it. What apparently happens is as long as there is a small amount of air = trapped in your system then compression of that air can/will occur. = However, once all the air is expelled from the system, you get to a = condition (verified that Tracy Crook also encounter it - don't know of = anyone else reporting it) I call cold fluid Hyraulic lock in that there = apparently is apparently no more air available for compression. So when = the engine and cooling system components cool down, that contraction = squeezes the coolant (and discharges some into the overflow). So what = remains in the engine has no room for any further expansion. Note: An = expansion chamber would probably preclude this phenomona, but at = additonal weight and complexity. I first noticed that after about 3 flights (during which that process = apparently expells any significant remains air after a refill of the = coolant system) that immediately (within 3 seconds) upon starting the = engine that my coolant pressure would go to 18-20 psi - long before the = coolant heating could possibly have caused it. I ,at first thought, I = had a combustion leak between the rotor chamber and cooling system and = was having the coolant system pressurized by combustion gas (that is one = of the symptoms of a cooling "O" ring failure). However, there was no = loss of fluid, no indications of combustible in coolant (frequently will = see what looks like thin oily sluge on top of the coolant) and once = airborne (or the engine heated up) the pressure would drop back to a = nominal 4-9 psi (depending on power setting and OAT - note: I do no use = a thermostat). =20 Tracy confirmed the same condition (and we have different cooling = system, his in parallel, mine in series, his with 5/8" lines me with 1" = lines, etc.). I believe that what we are seeing was the cooling pressure = sensor diaphram being pressurized by the kinetic energy in the cold = coolant flow perturbed by the water pump and coolant flow. Since = without any air in the system and the fuild occuping all the space, any = small pressure pertubation is no longer absorbed by the "shock absorber" = of a bit of air in the system and it shows up immediately on the = pressure sensor. Once the engine heats up then apparently there is = enough expansion in components through out the system that the pressure = drops back down. Since we are basically talking about a liquid, as you = know very, very little compressibility occurs. Don't really know if that is the reason - perhaps some hydraulic fluid = experts could offer further comment. my $ 0.02 worth Ed =20 Ed Anderson RV-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com ----- Original Message -----=20 From: "John Slade" To: "Rotary motors in aircraft" Sent: Friday, December 05, 2003 11:10 AM Subject: [FlyRotary] Re: Expansion Chambers > Calling Ed Anderson: > Ed, It's not that I disrespect others, but I've come to respect you're > opinions on matters rotary. See what you get for all you're hard work! > I recently posted a question about the need for an overflow bottle and > expansion chamber and how they should be plumbed. I was kinda hoping = to get > you're opinion. > Regards, > John Slade >=20 >=20 > >> Homepage: http://www.flyrotary.com/ > >> Archive: http://lancaironline.net/lists/flyrotary/List.html ------=_NextPart_000_0021_01C3BB71.01DC01C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi John,
 
   Sorry, = John. Thanks for the=20 vote of confidence.  Was working on understanding K&W, duct and = heat=20 exchangers and  seeing so many reponses to your inqurey that I = figured=20 you probably didn't need another input. 
 
 I tend to agree with the initial = advise you=20 received.  If your radiator cap is at the = highest=20 point of your cooling system then I believe that all you need = is an=20 overflow bottle/jug/container.  Well -- I also recommend a 21-24 = psi=20 radiator cap.   That is all that I use. The overflow = catches=20 any -- well, overflow.  Needless to say your overflow bottom = must be=20 vented to the atmosphere.   The system on my aircraft is so = effective=20 in removing the air from the cooling system after a couple of flights, = no air=20 remains- in fact, that causes a condition that first caused me to think = I had a=20 engine problem. So I might as well mention it in case anyone else runs = into=20 it.
 
What apparently happens is as long as = there is a=20 small amount of air trapped in your system  then compression of = that air=20 can/will occur.  However, once all the air is expelled from the = system, you=20 get to a condition (verified that Tracy Crook also encounter it - don't = know of=20 anyone else reporting it) I call cold fluid Hyraulic lock in that there=20 apparently is apparently no more air available for compression. So = when the=20 engine and cooling system components cool down, that contraction = squeezes the=20 coolant (and discharges some into the overflow).  So what remains = in the=20 engine has no room for any further = expansion.  Note:=20 An expansion chamber would probably preclude this phenomona, but at = additonal=20 weight and complexity.
 
I first noticed that after about 3 = flights (during=20 which that process apparently expells any significant remains air after = a refill=20 of the coolant system) that immediately  (within 3 seconds) upon = starting=20 the engine that my coolant pressure would go to 18-20 psi - long before = the=20 coolant heating could possibly have caused it.  I ,at first = thought, I had=20 a combustion leak between the rotor chamber and cooling system and was = having=20 the coolant system pressurized by combustion gas (that is one of the = symptoms of=20 a cooling "O" ring failure).  However, there was no loss of fluid, = no=20 indications of combustible in coolant (frequently will  see what = looks like=20 thin oily sluge on top of the coolant)  and once airborne (or the = engine=20 heated up)  the pressure would drop back to a nominal 4-9 psi = (depending on=20 power setting and OAT - note: I do no use a thermostat).  =
 
Tracy confirmed the same condition (and = we have=20 different cooling system, his in parallel, mine in series, his with 5/8" = lines=20 me with 1" lines, etc.). I believe that what we are = seeing was=20 the cooling pressure sensor diaphram being pressurized by the kinetic = energy in=20 the cold coolant flow perturbed by the water pump and coolant = flow.  Since=20 without any air in the system and the fuild occuping all the space, any = small=20 pressure pertubation is no longer absorbed by the "shock absorber" of a = bit of=20 air in the system  and it shows up immediately on the pressure = sensor. Once the engine heats up then apparently there is enough = expansion=20 in components through out the system that the pressure drops back down. = Since we=20 are basically talking about a liquid, as you know very, very little=20 compressibility occurs.
 
Don't really know if that is the reason = - perhaps=20 some hydraulic fluid experts could offer further comment.
 
my $ 0.02 worth
 
Ed
 
   
Ed Anderson
RV-6A N494BW Rotary=20 Powered
Matthews, NC
eanderson@carolina.rr.com
----- Original Message -----
From: "John Slade" <sladerj@bellsouth.net>
To: "Rotary motors in aircraft" = <flyrotary@lancaironline.net>
Sent: Friday, December 05, 2003 11:10=20 AM
Subject: [FlyRotary] Re: Expansion=20 Chambers

> Calling Ed Anderson:
> Ed, It's not that I = disrespect others,=20 but I've come to respect you're
> opinions on matters rotary. See = what you=20 get for all you're hard work!
> I recently posted a question about = the=20 need for an overflow bottle and
> expansion chamber and how they = should be=20 plumbed. I was kinda hoping to get
> you're opinion.
>=20 Regards,
> John Slade
>
>
> >> =20 Homepage:  http://www.flyrotary.com/
>=20 >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html ------=_NextPart_000_0021_01C3BB71.01DC01C0--