Read the last paragraph........... That's that!
Looks like I was wrong Mike. Sorry.
Might be OK for a turbo charger inlet as it is sucking.

Paul Lamar

 Mike Wills wrote:

Paul,

  In my case I'm not sure the picture is quite as bleak as you see it. The
test duct for the paper you are referring to was installed flush on a flat
surface. So has to rely entirely on the effect Bill described to ingest any
air at all. May be a significant issue if installing NACA ducts on a large
flat surface (like the belly of an airplane near the wing trailing edge).

  Now go back and look at the front view of my cowl. Obviously not a flat
surface. The fact that you can see the duct entry nose on would seem to
suggest that this duct will ingest some high velocity airflow. Unless you
assume significant problems with boundary layer ingestion. Personally I
have a hard time believing the boundary layer is any sort of a significant
issue for inlets located so far forward on the fuse.

  I'm not guaranteeing it'll work. I had enough doubts myself to add a
second cooler in the chin scoop. But I suspect that it will add some
significant amount of cooling and with 1 1/2 times the oil cooler area that
most guys are flying with I'm willing to gamble on it.

  As I said before, I couldnt accept the look (and obstructed view) of a
snorkel up there so I'm not changing it now. We'll see how well it works
(or doesnt) soon enough.

Mike Wills

Ed Anderson had one on the bottom of the cowl with much more of a slope.
Did not work. Changed to a snorkel and worked much better.
My suggestion is mock it up on a pick up truck with the oil cooler
and make some pressure recovery test. It is not a disaster.
A crescent shaped scoop above the prop spinner would not look
too bad.
 

Paul Lamar

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