X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao107.cox.net ([68.230.241.39] verified) by logan.com (CommuniGate Pro SMTP 5.1.9) with ESMTP id 2093625 for flyrotary@lancaironline.net; Sat, 09 Jun 2007 15:01:56 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.39; envelope-from=alventures@cox.net Received: from fed1rmimpo02.cox.net ([70.169.32.72]) by fed1rmmtao107.cox.net (InterMail vM.7.05.02.00 201-2174-114-20060621) with ESMTP id <20070609190113.WZVU12556.fed1rmmtao107.cox.net@fed1rmimpo02.cox.net> for ; Sat, 9 Jun 2007 15:01:13 -0400 Received: from BigAl ([72.192.132.90]) by fed1rmimpo02.cox.net with bizsmtp id 9X1E1X0071xAn3c0000000; Sat, 09 Jun 2007 15:01:14 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Oil temp limit Date: Sat, 9 Jun 2007 12:02:25 -0800 Message-ID: <000001c7aad1$19a44030$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C7AA8E.0B810030" 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 V6.00.2900.3028 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C7AA8E.0B810030 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Thanks; Lyn, Ed, and Dave, One thing to note is that, because the cooling is air flow limited, the = oil delta T is not large - when the temp after the cooler is 220F, the pan = temp is about 235F, redrive exit about 240F. The Castrol 20-50 shows no signs = of any effect. At reduced power climb I'm at about 5000-5200 rpm; and 70% power, or = less. So probably not damaging anything. My oil cooler in the wing root is up-flow air. I installed a simply = spray system, a la Tracy, at the outlet side (top, because it was easy) for = ground cooling, and have found it not that big a help; and not needed since I installed an aux fan to keep the coolant temps down. Installing a spray system on the air inlet side spraying up for in-flight is much more difficult, requiring removal of wing (or engine). I've got about 8 more hours for phase 1 completion, and it may be more important to work on my skills and enjoyment right now, than on the airplane. Although having a tendency (A.K.A.; curse) toward being a "perfectionist", it bothers me when things aren't working quite right. Al The limit has to do with temperature, time, and limiting component.=20 At typical cruise conditions I have coolant temps of 160-170F and oil = temps about 20 degrees higher. Short term climb out (1000 - 2000') I see oil getting up 215 -220 and coolant around 200. If I continue climb, I need = to reduce power to keep them at those levels; which means climb rates of 500-700 FPM with OAT of 65F, and maybe a bit less if OAT is higher. I = don't like being limited to that climb rate when I have power for considerably more; but the real question is: Is that temp level an issue if sustained = for 10-15 minutes? And what is it affecting? I expect to make some modification to improve airflow through the = cooler, just deciding if it is urgent or if it can wait for another 10 -20 hrs = of flying. Anytime I go east from my airport I have to climb from 1400' to about 7000' to clear high terrain. Thanks, Al The object of controlling oil temperature is that temps above 160 = degrees begins to reduce power as rotor face temps begin to limit cylinder = filling.=20 =20 Second,=20 The oil temperatures in the wedge will be very much higher than the temperature being reported on the gage. The bearing area is way over = sized for the stress levels involved and at the low RPM in aviation use, the bearings will not fail from stress.=20 =20 However the soft overlay on the bearing face has a low melting point. = Oil moving off the bearing carries away the heat from wedge oil. In racing = the higher oil pressures used, helps perform this function.=20 =20 Some racers just machine off the overlay and run on the copper. Good = bearing material, and a high melting point. Extra clearance allows more oil flow = for a given pressure. =20 The rotor face can run as high as 400 degrees, and the oil is removing = most of that. =20 By the time you get to 230 degrees in the sump you are walking on thin = ice, as far as rotor bearings is concerned. You could go higher with less throttle (stress from wedge heat) but in the end I think you need more = oil cooling.=20 =20 The race car needs 90 water tops and 190 oil tops. At 100 PSI.=20 =20 Lynn E Hanover=20 =20 =20 _____ =20 See what's free at AOL.com = .=20 ------=_NextPart_000_0001_01C7AA8E.0B810030 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Thanks; Lyn, = Ed, and Dave,=

One thing to note is that, = because the cooling is air flow limited, the oil delta T is not large - when the = temp after the cooler is 220F, the pan temp is about 235F, redrive exit about 240F. = The Castrol 20-50 shows no signs of any effect.

At reduced power climb I’m = at about 5000-5200 rpm; and 70% power, or less.  So probably not = damaging anything.

My oil cooler in the wing root is up-flow air.  I installed a simply spray system, a la = Tracy, at the = outlet side (top, because it was easy) for ground cooling, and have found it not = that big a help; and not needed since I installed an aux fan to keep the coolant = temps down. Installing a spray system on the air inlet side spraying up for = in-flight is much more difficult, requiring removal of wing (or = engine).

I’ve got about 8 more hours = for phase 1 completion, and it may be more important to work on my skills = and enjoyment right now, than on the airplane.  Although having a = tendency (A.K.A.; curse) toward being a “perfectionist”, it bothers me when = things aren’t working quite right.

Al

The limit has to do with temperature, time, and limiting component. =

 At typical cruise conditions I have coolant temps of 160-170F and oil temps = about 20 degrees higher.  Short term climb out (1000 – 2000’) = I see oil getting up 215 -220 and coolant around 200.  If I continue = climb, I need to reduce power to keep them at those levels; which means climb = rates of 500-700 FPM with OAT of 65F, and maybe a bit less if OAT is higher. =  I don’t like being limited to that climb rate when I have power for considerably more; but the real question is: Is that temp level an issue = if sustained for 10-15 minutes? And what is it affecting?

I expect to make some modification to improve airflow through the cooler, = just deciding if it is urgent or if it can wait for another 10 -20 hrs of = flying. Anytime I go east from my airport I have to climb from 1400’ to = about 7000’ to clear high terrain.

 Thanks,

 Al

The object of controlling oil temperature is that temps above 160 degrees = begins to reduce power as rotor face temps begin to limit cylinder filling. =

 

Second,

The oil temperatures in the wedge will be very much higher than the temperature = being reported on the gage. The bearing area is way over sized for the stress = levels involved and at the low RPM in aviation use, the bearings will not fail = from stress.

 

However the soft overlay on the bearing face has a low melting point. Oil moving = off the bearing carries away the heat from wedge oil. In racing the higher = oil pressures used, helps perform this function.

 

Some racers just machine off the overlay and run on the copper. Good bearing = material, and a high melting point. Extra clearance allows more oil flow for a = given pressure.

 

The rotor face can run as high as 400 degrees, and the oil is removing most = of that.  

By the time you get to 230 degrees in the sump you are walking on thin ice, as = far as rotor bearings is concerned. You could go higher with less throttle = (stress from wedge heat) but in the end I think you need more oil cooling. =

 

The race car needs 90 water tops and 190 oil tops. At 100 PSI. =

 

Lynn E Hanover 

 

 



See what's free = at AOL.com. =

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