Return-Path: Sender: (Marvin Kaye) To: flyrotary Date: Sat, 30 Nov 2002 15:31:09 -0500 Message-ID: X-Original-Return-Path: Received: from bree.pipcom.com ([204.92.62.3] verified) by logan.com (CommuniGate Pro SMTP 4.0.2) with SMTP id 1891582 for flyrotary@lancaironline.net; Sat, 30 Nov 2002 06:39:29 -0500 Received: (qmail 11289 invoked from network); 30 Nov 2002 11:39:29 -0000 Received: from ras3-26.pipcom.com (HELO new) (204.92.62.158) by bree.pipcom.com with SMTP; 30 Nov 2002 11:39:29 -0000 X-Original-Message-ID: <001901c29864$e9f208a0$5ed9fea9@new> From: "Peter Cowan" X-Original-To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Coolant loss : More cooling system test stuff. X-Original-Date: Sat, 30 Nov 2002 06:37:49 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 > > .Tracy and others, what is the theory behind so much liquid in the > external > > expansion tank? Thermal expansion of the initial coolant volume doesn't > > account for such a large overflow. So is vapor building up inside? If it > is > > there is no longer a liquid filled system. I don't get it. > > Peter > > I'm not 100% sure what is going on but I think you would be surprised how > much the 50-50 coolant expands with heat. I flight tested the new bottle > yesterday and verified that on cooldown the system was completely topped off > with coolant (no air at top of fill port.) This was never the case before. > > This also accounts for another anomaly I've noticed over the years. It > seemed like the water cooling was slightly better on the first flight after > topping off the system. I was never sure because the next flight was > usually on a different day, different temperature, humidity, etc. Now that > I've been paying close attention I have verified that only a few ounces > worth of air in the system makes a noticible degredation in cooling > performance (about 5 degrees worth). Not sure why this is happening > either but I'm happy with the results. With more experimentation the answer > will probably come out. > > Tracy Crook Yes, Ed, I agree with that explanation of the heating process but... If we put a pot of coolant on the stove and heated it to 190 I'd bet that the 7 or 8 litres wouldn't expand more than a couple of percent. Tracy aren't you seeing more than 10% expansion? We'd see vapor coming off which would be captured in our contained system. So if the thermal expansion is less than what you are getting in the overflow bottle doesn't there have to be vapor in the system? Peter.