Vortex Generators / Hmmm Airtabs

[GasSavers_katman]

Originally Posted by JanGeo

Well I know a really boxy vehicle that shows greatly reduced MPG at higher speed that needs to be tested . . . my xB

And my Tahoe!

[mosier]

I know it may be some trouble to try the test again, but your vortex generators might be too close to the trailing edge to be of benefit. On plane wings, the generators are closer to the front of the wing, to keep the air attached over the surface of the wing. You might want to try moving them forward a few inches, and see if there is any difference.

One thing that might be of interest is this quick doc on the generators, on the wikipedia (http://en.wikipedia.org/wiki/Vortex_generator), where it says they actually increase drag.

[JanGeo]

Originally Posted by katman

And my Tahoe!

Yeah but what percentage of your fuel consumption is to air drag compared to other drags of your vehicle? I know my xB gets better MPG at lower speeds and drops off over 40mph. Also think about AirTabs for $2.50 each in clear, black or white which have been wind tunnel tested.

[GasSavers_katman]

Originally Posted by JanGeo

Yeah but what percentage of your fuel consumption is to air drag compared to other drags of your vehicle? I know my xB gets better MPG at lower speeds and drops off over 40mph. Also think about AirTabs for $2.50 each in clear, black or white which have been wind tunnel tested.

I've thought about Airtabs in the past but then thought about making some and then people post other cool stuff and I start thinking about that and I procrastinate and get nothing done!
With the brush guard stuff on the Tahoe, which I don't want to take off, I know aerodynamic mods would help, but I'm having problems deciding what to use that won't change the looks too much. Clear Airtabs are a definite possibility. I've wondered about belly pans but are they effective on vehicles with large ground clearances? I never use the luggage rack so I could remove the cross bars. Then I could add a Ram Implosion Wing!

[zpiloto]

Originally Posted by katman

Then I could add a Ram Implosion Wing!

Do you know anybody that tested that thing. It looks pretty hokie. It would be the ultimate whale tail. http://www.electrifyingtimes.com/Rob...Patterson.html

[ZugyNA]

I've studied the vg thing and have installed some.

I'd have to guess that the ones on the roof are in an area where the boundary layer has already separated to some extent....probably reducing their effectiveness. Maybe try moving them forward about a foot?

The ones on the deck lid are at a place where the air has pretty much separated for sure from the sharp drop at the window.

I had some on the roof of a hatchback with less slope...slightly different design of vg though...similar to the Mitsubishi kind. Found that silicone caulk is best for permanent mounting.

Good to see the accurate testing....and some positive results.


Here is a similar car with similar flows:

http://www.mitsubishi-motors.com/cor...004/16E_03.pdf


vgs:

http://www.thirdshift.com/jack/firefly/firefly18.html

http://www.thirdshift.com/jack/firefly/firefly19a.html

Notice that he has his version of vg mounted the other direction? This plane cruises at around 60 mph.

[zpiloto]

Originally Posted by ZugyNA

I've studied the vg thing and have installed some.

I'd have to guess that the ones on the roof are in an area where the boundary layer has already separated to some extent....probably reducing their effectiveness. Maybe try moving them forward about a foot?

The ones on the deck lid are at a place where the air has pretty much separated for sure from the sharp drop at the window.

I had some on the roof of a hatchback with less slope...slightly different design of vg though...similar to the Mitsubishi kind. Found that silicone caulk is best for permanent mounting.

Good to see the accurate testing....and some positive results.


Here is a similar car with similar flows:

http://www.mitsubishi-motors.com/cor...004/16E_03.pdf


vgs:

http://www.thirdshift.com/jack/firefly/firefly18.html

http://www.thirdshift.com/jack/firefly/firefly19a.html

Notice that he has his version of vg mounted the other direction? This plane cruises at around 60 mph.

Your right about the direction. I don't know how I screwed that up. I'll have to swing them around and retest. Mybe this weekend. I was disappointed with the original results. Maybe this will get it around 3%.