You are right, the text I quoted mentions boundary-layer thickness as an important factor.
Though before I would glue VG's (howitzer) on the plane I'd try turbolator tape or sanding with 350 or 400 lengthwise in front of the inlet . Anything to energize the flow and thin out the b-layer.
This may be another easy test for Ed - reversible too!
Ed, try turbolator tape inside your ducts starting at some point and moving 1/4" wise around from it.
If you hit the right spot, separation should be delayed, flow more efficient, cooler tems.
Then you close the cowl-flaps and run faster!
Another one would be to sand the inner surfaces lengthwise towards the radiator - should "streamline" and energize the boundary-flow - sometimes "as smooth as possible" is NOT the best way :)
TJ
On 5/2/07, marv@lancair.net <marv@lancair.net> wrote:
I remember visiting a Velocity project a number of years ago that had a well-constructed NACA duct in an improper location and it simply didn't do the job. Rather than close it off and relocate it the builder installed a row of vortex generators in front of the duct about as far away as the duct was wide and it then worked like a charm. Perhaps not the most elegant solution but another case for more than one way to skin the proverbial cat. FWIW.
<Marv>
"Thomas Jakits" <rotary.thjakits@gmail.com
> wrote:
"""
just recently read about the Naca:
It can work VERY WELL, *IF*
a) You have the right location
...snip... """
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