Chad Robinson wrote:

With respect to NACA scoops, I understand why they are bad for cooling, but
does this mean they should be eliminated completely, or should they still be
used for other air requirements - air to the intake manifold, cooling the
cockpit, etc.? I haven't gotten to the point of making the scoop, so should I
just ignore it entirely, or go ahead and make it and just glass a cover over
it until/unless it's needed?

Regards,
Chad

For modest air requirements like cockpit ventilation they seem to be
OK.
What is surprising to me is nobody seems to use them for what they
were designed for in the first place and that is an internal device 
such as a carb inlet that is drawing air in. Apparently you get 
more HP with a conventional scoop such as found on the Vans RV series, 
the P38 and the Me 109 to overcome any additional drag that these type
scoops may have compared to a NACA scoop. Net result higher top speed.

BTW Tracy Crook has one of these type scoops on his rotary powered RV4
and 
his top speed is around 214 MPH.
 
Paul Lamar
 
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