Bill,

Actually, where the scoops are located, they are outside of the fuselage,
and the only thing in front of them are the wing strakes.  I didn't measure
from the strake leading edge to the scoop inlet, but I would estimate that
it is between 3 to 4 feet.  I guess that would mean that there is a boundary
layer of about .6 to .8 inches present at that location.

If the boundary layer air becomes an issue, I will either put a small air
dam ahead of the scoop, or as I did with the NACA, install a vortex
generator ahead of the scoop.

I thought that I might have a photo that shows the scoop in relation to the
wing, but looking at the ones that I took, none really show it very well.

Regards,
Steve

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On
Behalf Of Bill Dube
Sent: Wednesday, October 20, 2004 8:19 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Cooling version 2.2


At 05:55 PM 10/20/2004 -0400, you wrote:
 

Attached are a couple of photos of my lower cowling. It is minus 2 small
armpit scoops, and plus 2 larger scoops.
   

        I notice that these scoops include the boundary layer with the air
they scoop in. Isn't this a problem, especially near the fuselage?

        The boundary layer grows at something like a 0.2 inch per foot of
length. This rule of thumb would imply that you would need to space the
side of the scoop about 3 to 4 inches from the fuselage. The upper lip
should be something like 1.5 inches off the underside of the wing.

        If you don't space the scoop away from the surface of the
airplane, you create a lot of drag and you don't take in much air.

        Perhaps there is some key point I'm missing.