Tested: Airtabs on a mini van, A-B-A - no measurable effect

[roflwaffle]

Failboat! Btw, what's up w/ the successive mpg increase in your close tests, needz moar warm?

[MetroMPG]

Good question. Could have been still warming up, though the outside temperature was actually falling slightly while I was driving back and forth and back and forth.

Van was getting lighter too, as I burned up fuel doing the tests

But in the end, I don't think it's statistically significant: standard deviation in all the A runs was 0.36 mpg

[Big Dave]

Thanks for enlightening the masses.

[Unforgiven]

interesting.

[Tundra Boy]

This is by now a dead thread I guess, based on the last posting date. However, I have a couple comments.........

While the test methodology was decent, why only test at 55 mph? Is that the speed you regular thread contributers drive? How about at say... 75 mph.

Secondly, you tested a vehicle that already was good for 33 mpg. Obviously not to many aerodynamic issues to begin with.

I wandered in here looking to improve the lousy mileage that I get with my Tundra; which is currently getting around 14 mpg.

I have read quite a bit of another thread regarding the streamlined toppers that several have made. I have seen some mention of approaches such as Kamm back but little or no mention of the Coanda effect for example.

Most of your efforts seem like a throwback to the 1930's and the streamlining teardrop efforts of that era.

You have not done anything to convince me that the Airtab approach is without merit. I guess that I may actually risk some of my own precious resources to find out for myself.

I think that many of you are close to engaging in pack mentality at this point, having so much time and effort invested in one particular approach that incidentally seems to greatly detract from the functionality that led to the purchase of a pick-up truck in the first place.

There. How was that for my first introductory post? Kind of like a fart in church I suppose.

Cheers!

[mwebb]

DIY vortex generators... - GasSavers.org - Helping You Save at the Pump Hypermiling and Fuel Efficiency Forum

another take on the subject , with many fun to read links

as per Mitsubishi testing the vortex generators on the pontiac van were probably placed in the wrong place ....
but a lancer is not a van ...

[Angmaar]

Thank you for testing these.

[RobertSmalls]

Originally Posted by Tundra Boy

Secondly, you tested a vehicle that already was good for 33 mpg. Obviously not to many aerodynamic issues to begin with...

I literally lolled at this one. 33mpg at 55mph is not very good, and I'd say the vehicle has enormous room for aerodynamic improvement.

Originally Posted by Tundra Boy

Most of your efforts seem like a throwback to the 1930's and the streamlining teardrop efforts of that era.

Aerodynamics is a somewhat mature field. The Germans studied and wrote extensively about the ideal low drag body, which is in fact the shape you describe. If you wish to lower your drag, you'd be wise to study low-drag shapes.

One great thing about this forum is there are a large number of people willing to go to the effort of scientifically testing their mods. As a result, we have proven results. Not a cult; it's science.

So, yes, all of our designs try to approximate the same shape. But you'd expect that, since we're all subject to the same laws of physics.

Anyway, welcome aboard. There's a few other pickup truck modders here, and I'm sure you can learn some things from their builds.

[PaleMelanesian]

You might want to look at Ferrari, Lamborghini, McLaren, Bugatti, Saleen, Corvette, etc to see what works and doesn't. Guess what? They're all built on a teardrop streamlined shape, because that IS what works.

[doviatt]

Airtabs or vortex generators were not designed or intended to reduce drag or increase forward efficiency in any way (originally). I would guess the origination of this claim of efficiency came from the product web site for cars. We all should know they originally appeared on airplane wings to help keep airflow from separating from the wing for the purpose of lift. This being in a vertical direction. It only takes someone with a marketing mind, sitting on an airplane, looking out the windows, noticing those tabs, thinking "I wonder what those are for". Then his marketing mind starts to engage and his motive is "I can sell these, they look cool. What can I use as the selling point?" Since cars do not benefit from improved vertical lift near the stall speed at critical angle of attack...;-)
...make up something....

They just add more drag. Period. Even on those airplane wings they add more drag. The trade off is better near stall performance at low (landing speeds) with attached airflow. They have no benefit at higher cruise speed. Just more drag.

I'm glad the testing is being done though. All ideas should be tested.