On 27 Oct 2004 17:43:27 -0700, (sidk) wrote:

Here is a link to a photo from last month's tuft-testing on my
Velocity with hopes that some clue would appear as to why my engine
cooling is worse than marginal. Tape was duct tape and some was on
for several months (waiting for weather, photographer, digital camera,
photoplane, etc...) and was a pain-in-the-butt to remove.
For the test, the left (pilot) side NACA has two VGs, the right side
none.

http://img35.exs.cx/img35/5182/HPIM0430.jpg

Sid Knox

Velocity N199RS

Sid, I hope that there are some other scoops somewhere besides the two
I see on top of the airplane. From what I've read over the years if
the two scoops I see are it for cooling, there are two really glaring
problems. 1. Naca scoops are really marginal for engine cooling
intakes, this is something that has been known for many years. 2.
Naca scoops do not work when placed in a low pressure region of the
fuselage. Your two scoops are on the downside of the rear of the
fuselage and for sure are in a low pressure area.

What works? Pitot type scoops placed in an area of positive pressure,
or out in the free air stream ala P-51 Mustang.

But if you have pitot type scoops on the belly of your airplane,
nevermind.

Corky Scott