I read you Buly,
just recently read about the Naca:
It can work VERY WELL, IF
a) You have the right location
b) it does not hurt to help with augmentation (exhaust)
c1) You make the Naca as it is supposed to be made:
Inlet lip radius and angle are VERY critical
c2) sharp corners on the side walls, if they are "nice and smoothly rounded" it will not work!
I hazard a guess - a small negative angle for the sharp edge might help?
Idea being that a strong vortex is created that will pull more air in.
d) Air must be a safe distance from the inlet, before it can be expanded/slowed down to avoid immediate feedback.
e) Boundary layer thickness is an important performance parameter
The real problem is to get the quality of the edges and the inlet lip (radius and angle to the slipstream) as high as possible and the whole duct dimensionally correct for the application.
It is definitely easier to get a Ram Air Intake into the breeze and be happy.
Naca is for the nit-picks that want the last ounce of drag removed :)) !!
If it just looks like a Naca, but the details don't work - no joy.
I doubt that any of the "ready made - one size fits all" Naca's really work....
For details:
follow the link for a 62 page pdf note: this is 16 MB!!
around page 30 you get some good pictures
If anyone need it I can email it direct....
Here is a good discussion:
Watch it! You might get addicted:))
TJ
On 5/2/07, Bulent Aliev <atlasyts@bellsouth.net> wrote:
> John,
>
> are you crazy, you can't do that - Naca's don't work! No one ever
> told you?
>
> TJ :)
>
> PS: Don't tell your airplane!
>
NACA's don't work well with radiators. John's works only because he
has a big honkin lip (scoop) to force air inside the NACA.
Also the "super-size" radiator and double oil coolers help too. Real
NACA scoop does not have a lip extending into the breeze.
And NO! I'm not PL's agent :)
Buly
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