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Keith Tanner
Keith Tanner MegaDork
3/5/17 9:24 p.m.
plance1 wrote: In reply to Keith Tanner: How about bringing back that na widebody kit?

It's a Mazda Competition E-Prod body kit. Not ours to sell in the first place. You can buy the whole damn car if you'd like, it's for sale as a caged roller.

Appleseed
Appleseed MegaDork
3/6/17 7:16 a.m.

Keith is right. NACA ducts need sharp, right angles to work. Like sharp enough to almost cut you sharp.

Duke
Duke MegaDork
3/6/17 8:04 a.m.
Appleseed wrote: Keith is right. NACA ducts need sharp, right angles to work. Like sharp enough to almost cut you sharp.

At the bottom of the inlet as well as the top?

stafford1500
stafford1500 HalfDork
3/6/17 9:14 a.m.
Duke wrote:
Appleseed wrote: Keith is right. NACA ducts need sharp, right angles to work. Like sharp enough to almost cut you sharp.
At the bottom of the inlet as well as the top?

Yes, all of the edges except the back on the top surface need to be sharp. Very sharp, like almost cut yourself sharp. There is a pair of votrexs (vorticii) that roll up along the edges to help pull the flow down into the duct. Done right you can get about 95% of the total pressure in the inlet. It will be less than having a duct at the front center of the car, but better than using underhood air pressure/temperature.
The back top edge needs to be radiused.
Keith is right about the shape being a simple shape to lay out. Look for NACA duct shape and you will find some examples...

stafford1500
stafford1500 HalfDork
3/6/17 9:23 a.m.

If you want the technical data to build your own shape and all the theory behind the ducts look for NACA techical Note 2323 published in 1951. Lots of math, but worth the read if you like that sort of thing. It should be freely available thru the NASA/LARC sites.

alfadriver
alfadriver MegaDork
3/6/17 9:57 a.m.
stafford1500 wrote: If you want the technical data to build your own shape and all the theory behind the ducts look for NACA techical Note 2323 published in 1951. Lots of math, but worth the read if you like that sort of thing. It should be freely available thru the NASA/LARC sites.

Found it- http://naca.central.cranfield.ac.uk/reports/1951/naca-tn-2323.pdf

or here- https://ntrs.nasa.gov/search.jsp?R=19890067876

Fitzauto
Fitzauto Dork
3/6/17 10:42 a.m.

This is why I love this place. I love reading about stuff like that and y'all always have links at the ready.

Woody
Woody MegaDork
3/19/17 8:04 a.m.

I've started adding the 3D printed NACA duct to my spare headlight cover. More details here: Miata Wintercrosser: M-Edition, Page 8

 photo IMG_8766_zpsthjrdhwz.jpg

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