X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [24.25.9.102] (HELO ms-smtp-03-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTP id 970532 for flyrotary@lancaironline.net; Sat, 04 Feb 2006 22:01:06 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.102; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-025-165.carolina.res.rr.com [24.74.25.165]) by ms-smtp-03-eri0.southeast.rr.com (8.13.4/8.13.4) with SMTP id k1530JXO017482 for ; Sat, 4 Feb 2006 22:00:21 -0500 (EST) Message-ID: <001a01c62a00$539aac50$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: NPG Coolant Temperature vs 50/50 Date: Sat, 4 Feb 2006 22:00:31 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Virus-Scanned: Symantec AntiVirus Scan Engine Thanks, Bob. A flaw in my calculation for sure. The deltaT would certainly (we hope {:>) not be in the 180F range. So now, instead of 180F + 13%, it would be more like 183-187F. On the other hand, Al indicated a coolant temp of 215F is more the norm. Of course, the Subaru would undoubtedly be running a higher coolant temp even with the 50/50 mixture because it would be more efficient and the block can stand it. My error in any case, thanks for catching it. Ed ----- Original Message ----- From: "Bob White" To: "Rotary motors in aircraft" Sent: Saturday, February 04, 2006 9:48 PM Subject: [FlyRotary] Re: NPG Coolant Temperature vs 50/50 > Hi Ed, > > You need to look at a 13% increase in delta T. If Delta T is in the > range of 20 to 50 deg., the increase is only 2.6 to 6.5 deg. I don't > remember report of lesser temperature, but the increase wouldn't be > that great. > > Bob W. > > > On Sat, 4 Feb 2006 20:56:49 -0500 > "Ed Anderson" wrote: > >> Hi Al, >> >> Appreciate your (anybody else welcome also) views on one other thing that >> is still bothering me about the use of NPG. >> >> Given that NPG+ has a specific heat of 0.66 at 212F or 20% less than >> the 0.82 for the 50/50 mixture and given that NPG+ is approx 7% more >> dense than the 50/50 - then that for the same flowrate for both it would >> seem that NPG still has a 13% lesser overall capacity for heat transfer >> (at the same temps 212F and flow rates). >> >> Also assume that the engine is produce the same heat load (Q),lets take >> alook at what temperature we might see with NPG+ compared to the 50/50 >> solution. We have from the oldie but goody Q = c*M*DeltaT the ability to >> solve for the temperature increase, DeltaT. >> >> Delta T = Q/cM, now if the combined effects of c and m provide 13% less >> heat transfer capability than the 50/50 mixture that would indicated that >> to carry away the same Q at the same flow rate, the delta T of NPG+ would >> need to increase by 13%. So if I were getting 180F with the 50/50 for >> the same Q load (and flow rate) then with NPG+, I would expect 180 *1.13 >> = 203F. Yet, if I understood correct we have reports that lesser >> temperatures results noted by users of NPG - this leaves me a bit >> puzzled. >> >> If my assumption is correct thus far, then I am at a loss to understand >> the reports of lesser cooling temps when using NPG+, it would seem just >> the opposite would happen, that is - the coolant temperature would >> increase. >> >> Now, If the coolant temp with NPG+ actually does remain the same (or >> decreased) for the same Q and flow rate, then it could indicate the >> engine heat load is not being carried away as well as with the 50/50. IF >> the reports of lesser cooling temps occurs when switching to NPG+ are >> correct, then it would appear to me that the engine must then be >> operating under a higher heat load (i.e heat not being transfer to the >> radiators as effectively) . This doesn't even take into consideration >> the possibly lesser flow rate of NPG+ for the same pump speed as the >> 50/50 due to its higher 3 times higher viscosity (at 212F). >> >> Yes, I have no problem understanding that boil-over has been >> eliminated - but, is NPG actually cooling as well as coolant temps may >> lead one to believe? I mean with NPG, I could have a excessive block >> temperature and still not have boil-over - but my rotary engine would >> likely have suffered damage. >> >> What am I missing? Inquiring minds (even old ones) want to know {:>) >> >> Ed A >> > > > -- > http://www.bob-white.com > N93BD - Rotary Powered BD-4 (first engine start 1/7/06) > Custom Cables for your rotary installation - > http://www.roblinphoto.com/shop/ > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ >