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Date: Wed, 20 Oct 2004 18:18:48 -0600
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
From: Bill Dube <bdube@al.noaa.gov>
Subject: Re: [FlyRotary] Cooling version 2.2
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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.