wake reduction

[donee]

Hi All,

Those are quite interesting videos! That vortex generator just drives the air into the floor dramatically. You know they gotta be generating allot of drag to do that.

The issue with such techniques is tuning them to get the air to just deflect lightly, and curve away from the roadway and go parallel with it. Rather than as was seen in the video. And do that with a minimum of vortex generator. Otherwise the drag reduced by eliminating the tail tumble of the air, will just be overcome by the drag of the vortex generator.

Streamlining is a much more reliable method for those without the windtunel and force gauges needed to tune up vortex generators to the specific vehicle application.

I found some downloads on that web page. In his own report from 2004 he reports no VG's resulted in less drage (40 degree boattail).

http://www.vortaflow.com/consulting/...unt%20body.pdf

And that he was going to investigate smaller VG's.

[Patrick]

Yes. If you read the guy's paper on his website, he admits that the drag is actually greater with the vortex generators than without them.

[AeroModder]

Vortex generators are far more effective in reducing rear lift, unless you have them along the sides of a large, square rear end, like a semi.

[Tygen1]

Originally Posted by aerohead

Laack,GOOGLE the Mercedes above in the title box and see what they did.

I see they extended the decklid with the giant wing...but are you saying the wing helped with drag reduction?

[aerohead]

Originally Posted by Tygen1

I see they extended the decklid with the giant wing...but are you saying the wing helped with drag reduction?

Tygen,what caught my eye,was both the fairing at the top of the backlight which softens the curvature off the roof allowing 'clean' air to strike the wing,both above and below,and the boot extension,which runs straight back as far as the end of the bumper.
This is kind of a permutation of the Merkur XR4Ti bi-wing spoiler,where they look to manage the separated flow both high and low.
If the wing was just symmetrical,with no induced lift,It could serve as a re-attachment point and work to
'sculpt' the wake a bit.
I found an article on the 1988 Holden Commodore VL SS Group ASV by Tom Walkinshaw who created 18-aero add-ons for the car,dropping Cd from 0.43,to 0.32.
He extended a rear spoiler as far as the bumper and raised it about 7.5-inches ( 187.5 mm ) at the trailing edge.He also extended the C-pillars back to it to create the 'birdbath on the boot' also used on the Mustang GT.
The extreme spoiler on Mike Murillo's Pro-Stock '93 Mustang notchback,is as long as the trunklid itself,projecting straight back with zero upsweep.
And for protection to pedestrians,you just put a couple of SIMPSON drag chutes under it,sticking out a little bit.
If that doesn't 'man-it-up' enough,then I don't know what will!