Return-Path: Received: from [24.25.9.102] (HELO ms-smtp-03-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.3c3) with ESMTP id 855405 for flyrotary@lancaironline.net; Tue, 05 Apr 2005 08:07:31 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.102; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-185-127.carolina.res.rr.com [24.74.185.127]) by ms-smtp-03-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id j35C6hY5015838 for ; Tue, 5 Apr 2005 08:06:44 -0400 (EDT) Message-ID: <001e01c539d7$f0c56f70$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Cooling -Learned a lot Date: Tue, 5 Apr 2005 08:06:46 -0400 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 6.00.2800.1106 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Virus-Scanned: Symantec AntiVirus Scan Engine You're welcome, Michael Glad you found a source for the book. Like I say it takes a bit of digging into, I had to re-read some sections several times to fully understand (I think {:>)) the essence of their findings. Ed ----- Original Message ----- From: "Michael Burke" To: "Rotary motors in aircraft" Sent: Tuesday, April 05, 2005 12:40 AM Subject: [FlyRotary] Re: Cooling -Learned a lot > Ed, > Many thanks for your reply. > I too have been searching the net for a definitive text on liquid cooled > aircraft engine, theory and design but have not been able to find anything > directly related to the subject of liquid cooled engines. Plenty of books on > Fluid Dynamics pertaining to jet engine design. > Thanks for the link to the supplier in Asia, I found in other posts, as I'm > in Australia I'll buy direct from them. > > I'm not actually building anything yet (except confidence and knowledge). > I'm at that stage of trying to reconcile what I can really like as opposed > to what I can really afford. Short list is, RV8, Mustang II, Aerocad, or > Team Tango, maybe Cozy IV if parts are available. Mazda Renesis will be the > power source for whichever kit I choose. I'm just so grateful there are so > many guys working out all the problems with rotary engine installation who > are willing to share their knowledge. > > Michael. > > > > ----- Original Message ----- > From: "Ed Anderson" > To: "Rotary motors in aircraft" > Sent: Monday, April 04, 2005 10:36 PM > Subject: [FlyRotary] Re: Cooling -Learned a lot > > > > I have only read this one book (actually chapter 12) on liquid aircraft > > cooling, its seems to be the ONE. It is not light reading, but chapter > 12 > > presents the liquid cooling challenge for aircraft in what appears to me > to > > be a fairly complete manner. You do have to did into it a bit. No, the > book > > has been out of print for decades. I finally got a bound Xerox copy from > a > > foreign source with good legibility but that was about the best I could > say. > > Pages were out of order, upside down, etc. but like I said the information > > was legible. > > > > The book is "Aerodynamics of Propulsion" by Kuchemann and Weber better > know > > as "K&W" > > published by McGraw-Hill in 1953. I searched long and hard for a copy and > I > > found none in the typical out of print book sellers. > > > > There is one other book Hoerner Fluid Dynamics that is reported to be a > > good one as well, but I have not acquired that one as yet. > > > > > > I'll have to see if I can find my source for K&W, it was back a few years > > ago and I have had a couple of harddisk crashes since then. > > > > Ed > > ----- Original Message ----- > > From: "Michael Burke" > > To: "Rotary motors in aircraft" > > Sent: Monday, April 04, 2005 2:47 AM > > Subject: [FlyRotary] Re: Cooling -Learned a lot > > > > > > > Ed is this book the"Holy Grail" on liquid cooled aircraft engines. Is it > > > still available from book stores, if not where can it be purchased. > > > Many Thanks, > > > Rotary Newbie, > > > Michael. > > > > > > ----- Original Message ----- > > > From: "Ed Anderson" > > > To: "Rotary motors in aircraft" > > > Sent: Monday, April 04, 2005 12:14 AM > > > Subject: [FlyRotary] Cooling -Learned a lot > > > > > > > > > > Too right, Jerry > > > > > > > > My first 40 hours or so were in the marginal cooling zone. {:>). As > > > other > > > > things in this hobby, there are so many variables that interact, that > > what > > > > may appear simply at first, is almost always a bit more complex. I > > > > say(Cooling Axiom 1) if you have enough cooling surface area and air > > mass > > > > flow then it WILL cool. However, you may incur a high penalty in > > > cooling > > > > drag - which may not be as important for draggy airframes (such as > > > biplanes) > > > > as it is to sleeker airframes. Also a system that adequately cools > an > > > > engine producing 150 HP may not cool an engine producing 180 HP. > > Picking > > > > your cooling design point is important. Optimizing for cruise and > your > > > will > > > > be less than optimum for take and climb. Optimize for climb and you > > will > > > > probably have more cooling drag than required at cruise. Compromise, > > > > compromise - cowl flaps are sometimes used to try to have the best of > > both > > > > worlds. > > > > > > > > Some folks advocate a thinner, larger surface area core -which is > great > > > for > > > > slow moving automobiles stuck in traffic with low dynamic pressure > > > > potential, but I think is not the optimum for most aircraft. Once you > > > trip > > > > the airflow and turn it turbulent you have incurred most of the drag > > > > penalty. Larger surface area cores disrupt a larger airstream and > incur > > > > more drag. Yes, thicker cores produce a bit more drag than the SAME > > > frontal > > > > area thinner cores. But, with a thicker core you can use a core with > > > > smaller frontal area. > > > > > > > > The NASCAR radiator's average 3" thick and on the long tracks where > > > speeds > > > > are higher some even go up to 7" thick. My contention is their > > operating > > > > environment is more akin to ours than regular automobiles moving at > > slower > > > > speeds. You know that the NASCAR folks will spend $$ for just a tiny > > > > advantage - so clearly they don't use thick cores because it is a > > > > disadvantage. But, some folks will continue to point to the large thin > > > > radiators designed for environments with much lower dynamic pressure > as > > > > being the way to go. Will it cool? sure it will (Cooling axiom 1 > > above). > > > > Is it the lowest drag option for an aircraft of the RV/TailWind type, > I > > am > > > > convinced it is not. > > > > > > > > The diffuser makes a considerable amount of difference and can made > the > > > > difference between a system that cools adequately and one which does > > not. > > > > The biggest culprit that lessens cooling effectiveness is turbulent > > eddies > > > > that form inside the duct due to flow detachment from the walls. > These > > > > eddies in effect act to block effective airflow through part of the > > core. > > > > So keeping the airflow attached to the sides of the diffusers is > crucial > > > for > > > > good cooling from two standpoints. A good diffuser will reduce airflow > > > > velocity through the core which will reduces cooling drag. Pressure > > > across > > > > the core is increased which further enhances cooling. > > > > > > > > I have gone from a total of 48 sq inches opening (total) for my two GM > > > cores > > > > and that provided marginal cooling - down to 28 sq inches (total) with > > > > adequate cooling with an engine now producing more HP. Experimenting > > with > > > > the diffuser shape made the difference. > > > > > > > > The K&W book (Chapter 12) really provided the insight to how and which > > > > diffuser shapes provided the better dynamic recovery. The Streamline > > duct > > > > was shown to be able to provide up to 82% recovery of the dynamic > > > pressure. > > > > Some folks reading the chapter misinterpreted the chart to show only > 42% > > > > recovery where there chart was actually only showing the pressure > > recovery > > > > contribution due to the duct walls and did not include the > contribution > > > due > > > > to the core. On the same chart, an equation (which apparently gets > > > ignored) > > > > clearly shows that the TOTAL pressure recovery is 82%. > > > > > > > > I have taken the Streamline duct as a starting point, but since I do > not > > > > have the space to provide the 12-14" for a proper Streamline duct, I > did > > > > some "creative" things to try to insure that there was no separation > > even > > > > though my walls diverge more rapidly than the Streamline duct. Won't > > > claim > > > > mine are as good as a Streamline, but they clearly are much better > than > > > the > > > > previous design which basically just captured the air and forced it > > > through > > > > the cores. > > > > > > > > FWIW > > > > > > > > Ed Anderson > > > > RV-6A N494BW 275 Rotary Hours (Plugs Up) > > > > Matthews, NC > > > > eanderson@carolina.rr.com > > > > > > > > > > > > ----- Original Message ----- > > > > From: "Jerry Hey" > > > > To: "Rotary motors in aircraft" > > > > Sent: Sunday, April 03, 2005 9:27 AM > > > > Subject: [FlyRotary] Re: phase I flight restrictions was:N19VX flys > > > > > > > > > > > > > It was not long ago that "cooling" was the major issue. Now it > seems > > > > > that we have learned enough to make several different configurations > > > > > work. I can't lay my finger on what it is we have learned but my > > > > > recommendation is to use smaller radiators and EWPs. Jerry > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >> Homepage: http://www.flyrotary.com/ > > > > >> Archive: http://lancaironline.net/lists/flyrotary/List.html > > > > > > > > > > > > > >> Homepage: http://www.flyrotary.com/ > > > >> Archive: http://lancaironline.net/lists/flyrotary/List.html > > > > > > > > >> Homepage: http://www.flyrotary.com/ > > >> Archive: http://lancaironline.net/lists/flyrotary/List.html > > > > > >> Homepage: http://www.flyrotary.com/ > >> Archive: http://lancaironline.net/lists/flyrotary/List.html