Oilguy

Has anyone ever heard of or used Air Tabs?
http://www.airtab.com

I found them while I was looking up information for building a new trailer... I was looking for a aero nose cone and found information about these things... On the outside they seem to make sense and their feedback seem consistant with their claims... Except the guy with the 03 black dodge dually...( I don't believe that at all!)
I just wonder if anyone in here has ever heard anything good or bad or has ever used them before...
Anyway....
Got distracted from my primary goal... so now I need to find a aero nose cone/bubble for the new trailer I am building...
Any ideas for that would be great too!

Oilguy

PaulDaisy

I am skeptical. These things, aka vortilons, have been in use in aviation for decades, with the purpose of breaking the laminar flow and prevent stall propagation by creating vortices around airfoils. With air velocities seen in towing I am very suspicious they would provide significant improvement. It is the blunt nose and butt of the trailer that creates drag and turbulent suction, and no matter how much you would disturb the flow at the edges of a brick, it will not turn it into an aerodynamic bullet.
Having said this, I have not used this product, so my post is pure speculation. But I would not buy it, based on my, whatever limited, understanding of airfoils and air flow.
-P

Oilguy

Yeah... I am skeptical too... But not ready to dismiss it as a joke yet.
I understand that a brick is not aerodynamic but can a device on the outside of the brick cause the drag on the rear of the brick to change and give it a cone like effect? I know this won't change the forward side but I am building a new trailer and I am going to build it with a V design with a downward sloped nose style. Basically try to make it as bullet like as I can.
I also wonder what they would do on the roof of a truck? I wonder if they would have the same effect as a bedcover?
They guaranty a mileage increase... small amount...But...
Anyway.... Just wondering outloud.....

XLR8R

I've heard mixed results at best.

PaulDaisy

I am interested in this too, but from what I learned so far, the short answer is, no. Otherwise the trucking companies would be all over an invention like that to save millions on fuel by reducing drag. All sorts of spoilers are put on cars to kill rear turbulent zone, and some do help at least to lower down the stagnant zone (helps to keep dust off of rear windshield on vans and SUVs, for example). But I have not seen any solutions that would improve the turbulence in the rear while not introducing more drag than helping the cause.
-P

XLR8R

As velocity through a fluid medium (i.e. air or water) increases, the effects of parasitic drag, aerodynamic drag and non-laminar flow become more pronounced.

A "teardrop" style extension to the rear of a box van will increase mileage; smooth, non-riveted or bolted skin will help; in short anything that causes the body to be more slippery, that is - to cause the fluid to flow around it as if it wasn't there.

Aren't the air-tabs designed to reduce laminar-flow turbulence and reduce the parasitic drag common at the rear of most box trailers/RVs? They should work in theory, but I doubt positive results are measurable outside of prolonged interstate speeds.

GAmes

I pulled a 22 ft cargo trailer that had a rounded front and air tabs from CA, then to LA, then to AZ. My fuel mileage was about the same as any other cargo trailer that I have hooked to. Of course, I never pulled it without the air tabs, but I wasn't impressed.

JimmieD

I don't know if there's anything on the net about it but the Kamm Theory is very well established. Dr. Kamm found that a spoiler strategically located at top rear of a vehicle improved stability and reduced overall drag, even causing an improvement in low speed aerodynamics.

The air flows over top of vehicle and then at the rear it is lifted by a very mild spoiler. The frontal area of a vehicle is the usual place to look for high pressure zones, and then next the rear spoiler. With this spoiler of proper size and angle the air is lifted, and then a vortex is created. The swirling downward flow of air in the vortex as it curls over top like a cresting wave creates a positive pressure at rear of vehcle where normally it is negative pressure. It's a free kick in the seat of the pants and positively works.

The design was used in many European high buck cars and race cars, then Chevrolet introduced it to the masses on their Chevy Vega! Since then many vans have incorporated the design into their body style, though most folks don't know it. It is not a large, high-mount spoiler, but is rather low in height, like 2"-3" at most. It works.

bmoeller

http://www.airtab.com/

I've seen a few rigs with the tabs. They've only been out on the market for a few years.

Oilguy

Yeah... I have searched the net to see if I could find anything on them (good or bad) and there is a lot of information about the theory and application in the aviation industry but I can't find any good information outside of their website that confirms or kills their claims.
I will keep looking... I would rather find someone that has documented proof that they work on a vehicle operating at under 150 miles per hours....

OG

whitebuffalo

a member on the DiRT mailing list has done a signifigant amount of research concerning drag and mpg. He pointed out several links that helped explain the effectiveness of the airtabs. it turns out mitsubishi did extensive research on their use
http://www.mitsubishi-motors.com/cor...004/16E_03.pdf

http://www.theautochannel.com/news/2...40100.2-lg.jpg

also, he pointed out that you can make them yourself for around $.30 each by using his template.

http://www.dodgetrucks.org/gallery/s...cat=500&page=1

also, he pointed out that hundreds of thousands of dollars were spent by the govt investigating reduced drag http://www.eere.energy.gov/vehiclesa...06/05_ross.pdf