Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Sun, 03 Apr 2005 22:04:23 -0400 Message-ID: X-Original-Return-Path: Received: from secure5.liveoakhosting.com ([64.49.254.21] verified) by logan.com (CommuniGate Pro SMTP 4.3c3) with ESMTP-TLS id 853798 for lml@lancaironline.net; Sun, 03 Apr 2005 21:27:09 -0400 Received-SPF: none receiver=logan.com; client-ip=64.49.254.21; envelope-from=walter@advancedpilot.com Received: (qmail 8067 invoked by uid 2520); 4 Apr 2005 01:18:26 -0000 Received: from 68.227.132.71 by secure5.liveoakhosting.com (envelope-from , uid 2020) with qmail-scanner-1.25st (clamdscan: 0.83/762. perlscan: 1.25st. Clear:RC:0(68.227.132.71):. Processed in 1.398331 secs); 04 Apr 2005 01:18:26 -0000 Received: from ip68-227-132-71.br.br.cox.net (HELO ?10.0.1.3?) (68.227.132.71) by secure5.liveoakhosting.com with SMTP; 4 Apr 2005 01:18:24 -0000 Mime-Version: 1.0 (Apple Message framework v619.2) In-Reply-To: References: Content-Type: multipart/alternative; boundary=Apple-Mail-5--1020688251 X-Original-Message-Id: <46bdd3bb7fdc54535f63bf83422696ec@advancedpilot.com> From: Walter Atkinson Subject: Re: [LML] Oil and Warming up X-Original-Date: Sun, 3 Apr 2005 20:26:21 -0500 X-Original-To: "Lancair Mailing List" X-Mailer: Apple Mail (2.619.2) --Apple-Mail-5--1020688251 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=ISO-8859-1; format=flowed Mark: I'd say we agree just about 100% on this issue. I like to see 200dF on=20= the coolest CHT before applying takeoff power. Walter On Apr 3, 2005, at 4:29 PM, Mark Ravinski wrote: Walter,=A0=A0 =A0Gary, =A0 First let me thank you for all the great posts that I've found so=20 informative over the years. And thank you Marv.=A0 The benefits can't be overstated. =A0 Some of the reasoning behind my choice of warming up comes from the=20 information available concerning starting a cold engine. Here in the northeast, preheating is many times required.=A0 ( I use 32=20= deg F as a guide but others differ. ) Without this preheat, cylinder walls can be scored because the aluminum=20= piston will expand more and faster than the steel cylinders, which are=20= distorting under the stress of the rapid heating.=A0 Clearances are=20 reduced not allowing enough oil for the rings or even binding the=20 pistons. This scenario is obviously worse for a tight engine. =A0 Walter, your concerns on keeping the CHT's cooler seem to be more of a=20= summer operations concern.=A0 I couldn't agree more and do rush to the=20= end of the runway in warm weather.=A0 Temp is always at least 100f.=A0 = Your=20 reference to Lycoming's position on this eludes me.=A0 My Lycoming=20 Operators Manual specifically calls for a "warm up" as part of the=20 ground check and has instructions for doing so.=A0 However, no=20 temperature information is given other than in "operating conditions"=20 where there is a note not to run below 140F for continuous operation. =A0 Gary,=A0 The cooling effects of the oil are more limited with less = flow.=A0=20 There is a squirt tube that directs an oil on the bottom of each piston=20= and excess flow to the valve mechanism helps cool the cylinder heads.=A0=20= I know=A0=A0the oil carries a fair portion of the cooling load but have = no=20 data or numbers. =A0 As an engineer, I'm assuming that the faster the cylinders are heated=20 the more internal stress occurs.=A0 (Which leads to cracks) Most of us aren't looking at the CHT's during to first part of takeoff=20= roll but I know the temps are climbing really fast. I'll bet some data might be provided by anyone with a data recorder=A0(=20= Like Greyhawk for instance) who could quantify the rate of change of=20 CHT's on takeoff as opposed to other phases of flight.=A0 My bet is that=20= it's the fastest changing part of the flight. I've chosen 100F as a reasonable starting point.=A0 The warmer the = engine=20 is before full power is added the slower will be the rate of change. If anyone can show me how to do it better, I'd appreciate it. What temperature would you hang your hat on Walter - as ideal? =A0 Mark Ravinski N360KB 1320 hrs =A0 =A0 If you have any data to support that contention, I would really=20 appreciate seeing it. I know of no such data and do not share your=20 concern. As a matter of fact, waiting until the cylinders are a higher=20= temperature before takeoff, only serves to end up with a hotter CHT=20 during initial climb. I'd rather keep the cylinders cool. TCM,=20 Lycoming, Pratt & Whitney, and Wright all seem to agree with that. I=20 think they're right. Walter =A0 =A0 =A0 =A0 --Apple-Mail-5--1020688251 Content-Transfer-Encoding: quoted-printable Content-Type: text/enriched; charset=ISO-8859-1 Mark: I'd say we agree just about 100% on this issue. I like to see 200dF on the coolest CHT before applying takeoff power.=20 Walter On Apr 3, 2005, at 4:29 PM, Mark Ravinski wrote: ArialWalter,=A0=A0 = =A0Gary, =A0 ArialFirst let me thank you for all the great posts that I've found so informative over the = years. ArialAnd thank you Marv.=A0 The benefits can't be overstated. =A0 ArialSome of the reasoning behind my choice of warming up comes from the information available concerning starting a cold engine. ArialHere in the northeast, preheating is many times required.=A0 ( I use 32 deg F as a guide but others differ. ) ArialWithout this preheat, cylinder walls can be scored because the aluminum piston will expand more and faster than the steel cylinders, which are distorting under the stress of the rapid heating.=A0 Clearances are reduced not allowing enough oil for the rings or even binding the = pistons. ArialThis scenario is obviously worse for a tight engine. =A0 ArialWalter, your concerns on keeping the CHT's cooler seem to be more of a summer operations concern.=A0 I couldn't agree more and do rush to the end of the runway in warm weather.=A0 Temp is always at least 100f.=A0 Your reference to Lycoming's position on this eludes me.=A0 My Lycoming Operators Manual specifically calls for a "warm up" as part of the ground check and has instructions for doing so.=A0 However, no temperature information is given other than in "operating conditions" where there is a note not to run below 140F for continuous operation. =A0 ArialGary,=A0 The cooling effects of the oil are more limited with less flow.=A0 There is a squirt tube that directs an oil on the bottom of each piston and excess flow to the valve mechanism helps cool the cylinder heads.=A0 I know=A0=A0the oil carries a fair portion of the cooling load but have no data or = numbers. =A0 ArialAs an engineer, I'm assuming that the faster the cylinders are heated the more internal stress occurs.=A0 (Which leads to cracks) ArialMost of us aren't looking at the CHT's during to first part of takeoff roll but I know the temps are climbing really fast. ArialI'll bet some data might be provided by anyone with a data recorder=A0( Like Greyhawk for instance) who could quantify the rate of change of CHT's on takeoff as opposed to other phases of flight.=A0 My bet is that it's the fastest changing part of the flight. ArialI've chosen 100F as a reasonable starting point.=A0 The warmer the engine is before full power is added the slower will be the rate of change. ArialIf anyone can show me how to do it better, I'd appreciate it. ArialWhat temperature would you hang your hat on Walter - as ideal? =A0 ArialMark = Ravinski ArialN360KB 1320 = hrs Arial=A0 Arial=A0 Times New RomanIf you have any data to support that contention, I would really appreciate seeing it. I know of no such data and do not share your concern. As a matter of fact, waiting until the cylinders are a higher temperature before takeoff, only serves to end up with a hotter CHT during initial climb. I'd rather keep the cylinders cool. TCM, Lycoming, Pratt & Whitney, and Wright all seem to agree with that. I think they're right. Times New RomanWalter =A0 =A0 =A0 =A0 --Apple-Mail-5--1020688251--