John,
For what it is worth, I tried using NACA Ducts as air intakes a few
years back and had performance problems. (as it turned out there were
other problems) I talked to Tom Burkland about the ducts and as I
remember, he said that they were not designed as intakes, but simple
openings, that did not spoil the aerodynamics, allowing air to be pulled
in by means of a fan. I have noticed the ducts being employed on
aircraft engine cowlings, both forward and reverse, but I don't know if
they are using some kind of blower in connection with them. Maybe they
are just vent openings.
I know that the location of the duct is critical. I had a duct in the
passenger side window of our car for a time. It worked well up to about
50 mph and then gave no air to the inside of the car. I am now using the
ducts as air intake for the cooling system and using a radiator fan to
move the air. It seems to work OK.
If you are planning to use them as air intakes for the motor, my
thinking is that you can get clean air, but probably no increase in
volume (no boost).
Good Luck!
Tom, Redding CA - #216 D/CC
John Beckett wrote:
> Mike
>
> My history may be way off base here, but I thought that NACA was the early
> version of NASA. That the testing on these ducts was late 1940's. And yes
> aviation was trying to crack the sound barrier at that time. Have noticed on
> 747's and the like, which are sub-sonic, that they do use the NACA duct on
> the fuselage. But as you mention all this doesn't mean that they will work
> correctly.
>
> JB
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