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Date: Fri, 22 Oct 2004 19:03:15 -0500
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Cooling version 2.2
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Since you have 3' in front of the scoop opening, why not do the 
'streamline duct' thing with the opening closer to the leading edge? 
That way you could get more pressure recovery & likely reduce drag by 
moving the inlet outside the boundary layer at the same time.

Charlie
(not an aerodynamicist, but plan on staying at an Econolodge in FL next 
weekend)

Steve Brooks wrote:

>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.
>
>  
>