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Yes, thanks Jeff for clarifying "Eds Workbook".
I believe that different solutions work for different cases, no - one-fit-all in the case of aircraft cooling. As several have already mentioned their are 3 key elements of our cooling systems. I might add there is a 4th - Risk Tolerance.
The 1st/number uno requirement is to remove adequate heat from the engine (in our case via a coolant). If your systems doesn't do that, then the rest is for naught.
Having said that - the next (2nd) requirement in my book is to ensure that the radiator sheds sufficient heat from the coolant to the air flow that permits the heat level of the engine to be maintain within a satisfactory (small) range. Too cold and you loose some power/fuel efficiency and too hot -well, you know what that will lead to.
The 3rd element is to do 1 and 2 with minimum possible drag. Now, trying to optimize the three key elements so that the total system meets your objective is where a lot of experimenting (and dare I say some "Luck") comes in. The key difficulty is trying to "simplify" some fairly esoteric properties and equations so that they are understood well enough to aim us in the right direction in our practical application. I dare say few of us have the resources or access to the test beds/laboratories that produce the studies that we attempt to comprehend and apply.
Saving the 4th for last - your approach is likely to be influenced a great deal by your risk tolerance. For some having the temperature exceed 180F might be too risky. I was content to takeoff and climb-out so long as coolant temp did not exceed 220F and would decrease from that during cruise climb. Some would not feel comfortable doing that. But, for me the reduce drag at speeds where I spent most of the time flying was worth a bit higher temps on take off.
Now, I greatly admire Tracy Crooks ability to assess and accept risk factors that I could not bring myself to do.
Example, I used expensive/heavy 1" stainless steel braided hose with heavy fittings welded to the coolant cores. In contrast, I saw Tracy successful use light weight stretch bands clamps, rubber hose and some of his coolant fittings were epoxied to the cooling core. Too risky for my taste, but on the other hand Tracy undoubtedly had the best performing RV-4 and Rv-8 around. I've not heard of any of his "risky" approaches ever failing, but they would have made me a bit more than anxious if I flew with them. So whether you consciously assess your risk factor or not it will be there influencing your decisions and choices.
But, hey guys, if it were easy there would be no challenge and there would be a reduce sense of satisfaction at succeeding when you finally get it nailed down.
Ed
------ Original Message ------
From: "Jeff Whaley jwhaley@datacast.com" <flyrotary@lancaironline.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: 7/22/2021 7:51:01 AM
Subject: [FlyRotary] Re: Inlet cooling article
Ed's cooling workbook sits on Ed's bookshelf and inside his head ... just a metaphor never published, except for the advice he has presented to this forum over the years. Great to see you Ed adding a few 02 cents worth lately.
I will never claim to have all the answers but I have managed to get my installation to operate at cruise settings with an OAT of 100F and a cruise speed of only 100 mph.
My journey has been a long and hard one, so I've been reluctant to stick my neck out too far on this forum ... however at the risk of being harshly judged by my peers, below is a link to a playlist of youtube videos I've put out there on the subject ... you may or may not like them ... you may or may not learn anything from them ... I think they are worth sharing or they wouldn't exist ... my latest edition will be released early Saturday morning.
Jeff
https://www.youtube.com/playlist?list=PLYDy_YhIDvshT9--FR37aywJbyD1UXNof
I know only from the cooling book of the late Paul Lamar
Has purchased one from him when was on his rotaryforum years ago.
https://www.aircraftspruce.com/catalog/bvpages/coolYourWankel.php
Le Roux
Sent from my iPhone
Le Roux Breytenbach
This is the first time I've heard of Ed's workbook!
All a bit late for me at this stage, but would be interested in reading through it as I've still git sooooo much to learn.
Steve Iz
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