I will if the airtab guy says it's OK. Waiting to hear back.

That seems to be the case, doesn't it.

Could you show me a pic of this non-vortex type? This is the first I've heard of that behaviour. My understanding is that the airtab style also creates vortices.

The Airtabs have a definate direction to face and create a clockwise vortex and counter clockwise vortex and should be placed 4 inches apart. The idea is to prevent reverse air flow back against the rear of the vehicle which represents drag and turbulance. I wish the improvement was greater to justify the cost but I guess at some point I will get a few and try them.

Vortex Strakes
 

Here's an SAE paper that describes how "vortex strakes" can be used to create an "aerodynamic boattail" behind semitrailers. See p. 13 for pics.

https://www.solusinc.com/pdf/2003-01-3377.pdf

Blue skies,

Patrick

a pic and the pattern for the airtab clones is here:

https://www.gassavers.org/showthread.php?t=1351

I don't think the airtab type create vortexes...since the vanes oppose one another....


the vgs I used on the roof are a different pattern....and do create vortexes.

According to the airtabs website (in "How do they work"), they create vortices.

Yes. Metro, I've been running my airtabs for sometime now, and when I drive through the rain, and a vehicle is behind me with thier lights on...I can significantly see the votices. Also, whenever I cruise down a dirt road above 40mph I can see them.

All I can say is that they are symetrical, but the air hitting between the vanes is bumped up...might create a spin? Maybe there is an interaction between this higher pressure and the lower pressure air between the airtabs?

the typical vg obviously creates a spin.....

FYI: Porsche 914 club forum - racer claims use of airtabs cut 1/2 second off his lap times by reducing rear lift:

https://www.914club.com/bbs2/index.php?s=&showtopic=52170

vgs for Vettes:

https://www.greenwoodcorvettes.net/gc4/vortex.htm

https://www.greenwoodcorvettes.net/gc...structions.htm

Info given to me by Ron Davidson at Airtabs. (Posted with permission)