Mailing List flyrotary@lancaironline.net Message #28556
From: Monty Roberts <montyr2157@alltel.net>
Subject: Heat exchangers.
Date: Sun, 18 Dec 2005 22:22:10 -0600
To: <flyrotary@lancaironline.net>
Monty here is my back of the envelope calculations.    If you are going to produce apporx 220HP steady State at cruise (which I assume you are if cruising at 250MPH) then you will need to dump close to 10,000 BTU /Min waste heat via radiators and oil coolers.  My calculations indicates that at 250 MPH cruise you will should have no problem getting rid of that much heat with that dynamic pressure and core area(assuming your ducts are doing their  job).
 
  However, my calculations also indicate you may have to hit as much as 150-160 MPH before your cooling is able to keep up with the heat rejection.  So don't know how long it will take you get to that speed from take off, but better carry  a bit of spray bar water.  Of course, you could pull back on the throttle and ease the heat load in a slower climb to cruise altitude.
 
Ed A
 
Thanks Ed,
 
You are the Ed I was after sorry for the confusion Ed K.  I also was not very clear about the number of heat exchangers. There would be 1 12X12X4 in block in each wing. We agree on the heat flow, my calcs were somewhere around 10800 BTU/min at full tilt. 150-160 mph is fine for climb. How long to get to that speed? Something that weighs less than 2000 lbs and has 250 Hp gets there....quick. 
 
Looks like the Ford cores will not work. I cut the end tank off one of them this evening. It has a lot of internal baffles and is a 3 pass design. It would probably be way too restrictive if used as a radiator. IF not for the baffles they would be great. It is actually a much better design for an EVAPORATOR than the GM units. Why did Ford have to pick this particular thing to make better than GM. Just to pick on me I guess.
 
Anybody seen any GM cores that are 4 in thick with 9 inches between tanks?
 
Monty
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