Kitplane published a wonderful article this month January 2004
page 66 by Mike Hirshfield. Pick a copy soon as they are going fast. 
I agree with Mike 95%.  Nice summary of what we have been talking 
about for the last three or four years.

On the other hand Jan EAA Sport Aviation
page 34 had an article by Divid Lednicer and Neal Willford that 
was totally unrealistic. Just ask the average RV builder to remove
the lower fuselage skin so a proper P51 type scoop and Kuchemann & Weber 
theoretically perfect duct  can be installed in the aft fuselage. Dick Van G would 
personally shoot you. Neal and David are where we were three or four years
ago prior to the oblique diffuser ideas of Kays & London.

I'll make a couple of points here but there can and will be more discussion
on these two article in the future.

1. If the scoop is on the front of the airplane there is no need for
a boundary layer air bleed. That eliminates the frontal area increase due
a P51 type scoop. If it is a pusher you have no choice but to
use a P51 type scoop to bypass the thick boundary layer. Again
NACA scoops are not recommended for heat exchangers.

2. No way is there room in the average tractor cowl for a theoretically 
perfect K & M style duct as shown this illustration from the Sport AV art. 
Particularly with a tricycle landing gear configuration. I have added some
comments and scale dimensions in red. This is why it is essential
when planning your engine installation and liquid cooling system to make 
SCALE 3D drawings or a full size mock up. 

Paul Lamar
 
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