Return-Path: Received: from fed1rmmtao01.cox.net ([68.230.241.38] verified) by logan.com (CommuniGate Pro SMTP 4.2b8) with ESMTP id 324747 for flyrotary@lancaironline.net; Sat, 17 Jul 2004 12:09:01 -0400 Received-SPF: error receiver=logan.com; client-ip=68.230.241.38; envelope-from=ALVentures@cox.net Received: from BigAl ([68.107.116.221]) by fed1rmmtao01.cox.net (InterMail vM.6.01.03.02 201-2131-111-104-20040324) with ESMTP id <20040717160830.OBST7910.fed1rmmtao01.cox.net@BigAl> for ; Sat, 17 Jul 2004 12:08:30 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: 11th test flight Date: Sat, 17 Jul 2004 09:08:59 -0700 Message-ID: <000001c46c18$5e942ac0$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C46BDD.B23552C0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C46BDD.B23552C0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Subject: [FlyRotary] Re: 11th test flight =20 You dasn't ever want to run straight H2O in your cooling system. I just went out to the shop and checked a container label for engine = coolant (Wal-Mart variety). Sez boiling point for 50/50 mixture with H2O is 265 deg.F. Put a 16 psi cap on that and it goes up some more. =20 Yes; the boiling point goes up; but the 'specific heat' - the ability of = the fluid to absorb heat - goes down by roughly the same percentage; thus = for the same flow rate, you are removing about 25% less heat. It is further aggravated because of higher viscosity, it also reduces flow rate. = Lowering the specific heat (a.k.a., heat capacity) and the flow rate increases = the temp change through the engine and rad, increases thermal stress and may reduce radiator effectiveness. =20 So there is a tradeoff. But you're right, don't run straight water. = The ethylene-glycol coolant comes with corrosion inhibitors; so if you don't dilute with e-g, by all means add corrosion inhibitors. =20 The argument for using e-g/water or not is probably case dependant, it depends on what is the limiting factor in your cooling system. But I'd = say that if you are having cooling difficulties with e-g/water coolant, try straight water with inhibitors. It may make things better. =20 Al ------=_NextPart_000_0001_01C46BDD.B23552C0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Subject: [FlyRotary] Re: 11th test flight

You = dasn't ever want to run straight H2O in your cooling system.

I just = went out to the shop and checked a container label for engine coolant (Wal-Mart = variety). Sez boiling point for 50/50 mixture with H2O is 265 = deg.F.

Put a 16 = psi cap on that and it goes up some more.

Yes; the boiling point goes up; = but the ‘specific heat’ – the ability of the fluid to absorb heat - goes down = by roughly the same percentage; thus for the same flow rate, you are = removing about 25% less heat. It is further aggravated because of higher = viscosity, it also reduces flow rate. Lowering the specific heat (a.k.a., heat capacity) and the flow rate increases the temp change through the engine = and rad, increases thermal stress and may reduce radiator = effectiveness.

So there is a tradeoff. But = you’re right, don’t run straight water. The ethylene-glycol coolant = comes with corrosion inhibitors; so if you don’t dilute with e-g, by all = means add corrosion inhibitors.

The argument for using e-g/water = or not is probably case dependant, it depends on what is the limiting factor in = your cooling system. But I’d say that if you are having cooling difficulties with e-g/water coolant, try straight water with = inhibitors. It may make things better.

Al

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