Marc Wiese wrote:

I know Paul does not like them, BUT-

Those smaller NACA ducts can be made to work well with a couple of 1?
vgs placed 1? in front of the front lip, and tilted outward 3/4" at the
back. A vee shape. Like this. >, but make the front at least a ½? open.
This trips the boundary layer, creates vortices that are drawn down
close to the surface and into the opening, instead of the air smoothly
flowing over the opening a la standard boundary 1? from surface layer
flow.
At least that is my experience.
My guess is that larger ones can be made to do the same thing by adding
more pairs of vgs.

Paul, how about you use your manometer set up to test this!! I would
love to see numbers. I do know my oil cooler works better, cause I got a
40F drop in oil temp from a stock eom NACA fed oil cooler.

Also Velocity has done some testing on this and seems to think it works.

Marc Wiese

Sorry. No time to waste attempting to do something that NACA said is
not recommended. There are too many other way more important problems 
to solve. I would be glad to publish your results if you
want to build a prototype and test and document the pressure
recovery.

Paul Lamar
 
The AirCraft Rotary Engine NewsLetter.              Powered by Linux.
ACRE NL web site. Copyright 1998-2002 All world wide rights reserved.
http://home.earthlink.net/~rotaryeng/            http://www.linux.org