X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao08.cox.net ([68.230.241.31] verified) by logan.com (CommuniGate Pro SMTP 5.0.3) with ESMTP id 871489 for flyrotary@lancaironline.net; Sun, 11 Dec 2005 12:35:16 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.31; envelope-from=ALVentures@cox.net Received: from BigAl ([68.7.14.39]) by fed1rmmtao08.cox.net (InterMail vM.6.01.05.02 201-2131-123-102-20050715) with ESMTP id <20051211173302.KQST26964.fed1rmmtao08.cox.net@BigAl> for ; Sun, 11 Dec 2005 12:33:02 -0500 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Radiator Expansion Tank Date: Sun, 11 Dec 2005 09:34:36 -0800 Message-ID: <000001c5fe79$288e4ec0$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C5FE36.1A6B0EC0" 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 V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C5FE36.1A6B0EC0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable =20 Hi Al; While my system is laid out somewhat differently (not withstanding = the EWP), I too have 2 pressure caps, one 22psi cap on the system and a 15 = psi cap on the overflow bottle. My overflow bottle is a new snowmobile = coolant bottle that I had surplus and it happened to have a 1bar cap one it. Now = I had expected to see compound pressures on my system (22+15=3D37), but = have never seen greater than 23 psi. (On my latest flight it appears that the coolant press reg has failed as it read 0 psi even when I loosened the = cap and found plenty of pressure). In your post you state that it is possible to reach 38 psi, then you = go on to say that on take-off your system is at least 23 psi. So my = question is have you ever seen any compound pressures in your system (greater than = 23 psi ???) =20 Yes; both during pressure test and during operation. During a pressure test, the gauge on my little battery powered air pump read 40 psi when = air was escaping from the overflow bottle. Unless something else is = happening, the pressures are additive. The cap controls the pressure difference between what is under the cap, and what is downstream at the overflow. = The overflow from my filler neck cap connects to the overflow bottle. When there is no pressure in the overflow bottle the system pressure goes up quite rapidly to about 23# as the engine warms. As more coolant is = forced into the overflow bottle, and that pressure builds, the system pressure increases.=20 =20 I haven't bothered to observe; but as the coolant temp drops, I expect = the pressure drops quite rapidly to about the pressure that is in the = overflow bottle. =20 Al ------=_NextPart_000_0001_01C5FE36.1A6B0EC0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Hi = Al;

While my system is laid out somewhat differently (not = withstanding the EWP), I too have 2 pressure caps, one 22psi cap on the system and a = 15 psi cap on the overflow bottle. My overflow bottle is a new snowmobile = coolant bottle that I had surplus and it happened to have a 1bar cap one it. Now = I had expected to see compound pressures on my system (22+15=3D37), but have = never seen greater than 23 psi. (On my latest flight it appears that the coolant = press reg has failed as it read 0 psi even when I loosened the cap and found = plenty of pressure).

In your post you state that it is possible to reach 38 psi, = then you go on to say that on take-off your system is at least 23 psi. So my question is have you ever seen any compound pressures in your system = (greater than 23 psi ???)

Yes; both during pressure test = and during operation. During a pressure test, the gauge on my little = battery powered air pump read 40 psi when air was escaping from the overflow = bottle. Unless something else is happening, the pressures are additive. The cap = controls the pressure difference between what is under the cap, and what is = downstream at the overflow. The overflow from my filler neck cap connects to = the overflow bottle. When there is no pressure in the overflow bottle = the system pressure goes up quite rapidly to about 23# as the engine warms. = As more coolant is forced into the overflow bottle, and that pressure builds, = the system pressure increases.

I haven’t bothered to = observe; but as the coolant temp drops, I expect the pressure drops quite rapidly to = about the pressure that is in the overflow bottle.

Al

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