Return-Path: Received: from [24.25.9.103] (HELO ms-smtp-04-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.2b8) with ESMTP id 324141 for flyrotary@lancaironline.net; Fri, 16 Jul 2004 20:02:56 -0400 Received-SPF: error receiver=logan.com; client-ip=24.25.9.103; envelope-from=eanderson@carolina.rr.com Received: from EDWARD (clt25-78-058.carolina.rr.com [24.25.78.58]) by ms-smtp-04-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id i6H02PVw022019 for ; Fri, 16 Jul 2004 20:02:26 -0400 (EDT) Message-ID: <004c01c46b91$59b94300$2402a8c0@EDWARD> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: 11th test flight Date: Fri, 16 Jul 2004 20:02:28 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0049_01C46B6F.D2759680" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0049_01C46B6F.D2759680 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Dale , the problem with oil temps in the rotary is that the oil might be = able to stand considerably higher temps (particularly the synthetic oil = as you point out), but the engine suffers.=20 At least with the older and earlier 13B blocks, overheating could and = did cause damage at a temperature range far below where you would have = to worry about the oil decomposing. Overheating apparently caused the = seals to "chatter" against the housing as well as reportedly "shrinkage" = of the aluminum rotor housings. The guidelines were a maximum of 210F = after the oil cooler for the oil and 180F out of the engine block for = the coolant. Now, we have found that at least with the new blocks the = engines will apparently handle higher temps without adverse effects. = Apparently short excursions as high as 240F on the oil and 220-230F with = the coolant can be tolerated without damage - but, the feeling is that = extended operations at those temps is risking damage. The newer blocks seem to be considerably more tolerant of somewhat = higher temps reportedly due to changes in the castings, but I and others = have found to our dismay that exceeding that magic number (whatever it = may be) you do at risk. So that is why you will see more concern with = oil and coolant temps with the rotary at a lower temperature than would = normally cause concern with a reciprocating engine. Ed Ed Anderson RV-6A N494BW Rotary Powered Matthews, NC Steve ... re: the above underlined. I would say that what you have is just fine regarding your oil temp. = Remember that the "delta T" between where you are running and the = temperature at where it quits working is quite high. Especially if you = are using synthetic oil. Molbil I keeps lubricating quite well up past = 400 degrees and beyond. Thus, if you are running temps near 200 = degrees you have near a 200 degree temp spread (delta T) between what = the oil can take away and what it IS taking away in BTU's of heat = dissipation in a stable system. That is a pretty fat safety margin, = when you figure you can run 100 degrees hotter than what you are now and = still have 100 degrees left before lubrication failure is imminent. = Obviously, lower is better. Water cooling now is a different story. operating coolant at temps = near 200 while water boils at 212 ... gives you a delta T of just 12 = degrees to play with. I know you can kick it up by anti-freeze, = pressure on the system, etc. etc. but the bottom line is that you have = a lot narrower delta T range to deal with, and you are always working = the system a lot closer to near it's maximum potential for heat = dissipation. Just a thought, Dale Smith ------=_NextPart_000_0049_01C46B6F.D2759680 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Dale , the problem with oil temps in = the rotary is=20 that the oil might be able to stand considerably higher temps = (particularly the=20 synthetic oil as you point out), but the engine = suffers. 
 
 At least with the older and = earlier 13B=20 blocks,  overheating could and did cause damage at a = temperature range=20 far below where you would have to worry about the oil decomposing. = Overheating=20 apparently caused the seals to "chatter" against the housing as well as=20 reportedly "shrinkage" of the aluminum rotor housings.  The = guidelines were=20 a maximum of 210F after the oil cooler for the oil and 180F out of the = engine=20 block for the coolant.  Now, we have found that at least with the = new=20 blocks the engines will apparently handle higher temps without adverse=20 effects.  Apparently short excursions as high as 240F on the oil = and=20 220-230F with the coolant can be tolerated without damage - but, the = feeling is=20 that extended operations at those temps is risking damage.
 
The newer blocks seem to be = considerably more=20 tolerant of somewhat higher temps reportedly due to changes in the = castings, but=20 I and others have found to our dismay that exceeding that magic number = (whatever=20 it may be) you do at risk.  So that is why you will see more = concern with=20 oil and coolant temps with the rotary at a lower temperature than would = normally=20 cause concern with a reciprocating engine.
 
Ed
 
 
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
 Steve ... re: the above=20 underlined.

I would say that what you have is just fine=20 regarding your oil temp.  Remember that the "delta T" between = where you=20 are running and the temperature at where it quits working is quite = high. =20 Especially if you are using synthetic oil.   Molbil I keeps=20 lubricating quite well up past 400 degrees and = beyond.    Thus,=20 if you are running temps near 200 degrees you have near a 200 degree = temp=20 spread (delta T) between what the oil can take away and what it IS = taking away=20 in BTU's of heat dissipation in a stable system.    = That is a=20 pretty fat safety margin, when you figure you can run 100 degrees = hotter than=20 what you are now and still have 100 degrees left before lubrication = failure is=20 imminent.  Obviously, lower is better.

Water cooling now = is a=20 different story.   operating coolant at temps near 200 while = water=20 boils at 212 ... gives you a delta T of just 12 degrees to play=20 with.   I know you can kick it up by anti-freeze, pressure = on the=20 system, etc. etc.   but the bottom line is that you have a = lot=20 narrower delta T range to deal with, and you are always working the = system a=20 lot closer to near it's maximum potential for heat = dissipation.

Just a=20 thought,

Dale Smith

------=_NextPart_000_0049_01C46B6F.D2759680--