Paul,

Thanks for the input.

Ref para. 1:   The "convex shape" mentioned was on the outside of the duct leading to the front edge of the rad.  I
would think that internally the duct should be larger than the entrance, to slow the air down.

Joe Graham

That is the beauty of the wedge shaped section over the rad. No classic diffuser
is required. It is far more compact than a classic diffuser which requires
2.5 times the rad dimension for its length. The classic diffuser is not practical 
for our use unless you want to put the rad in the aft fuselage. Cutting large holes
in the bottom of your RV will guarantee that Van will shoot you the first
times he sees it and you :) The airplane should be designed for such a 
diffuser right from the get go just like the P51 was. 

I tested this wedge shaped diffuser on the top of a Dodge Caravan awhile 
back and it works great. Other people have used it successfully to cool 
large Chev V8's such as Engineair.

Check out the book called Compact Heat Exchangers by Kay & London.

Paul Lamar
 
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