Airtabs - Where's the best place to get a deal on them?
 

I am seriously considering installing Airtabs on The Beast, but at $2.50 each that isn't going to be cheap. I tried looking at the Airtab webiste, and either you can buy direct from them, or a few dealers in Canada. There were only 1 or 2 USA dealers, and their shops were nowhere near me.

On a related note, has anyone tried mounting the airtabs on magnetic flexible vinyl (like the magnetic signs some businesses put on their vehicles)? I figure if they will stay on you could move them around and experiment.

-Jay

Figured I'd throw it out there because I looked at air tabs and decided to go with vorteckz instead just because of the price (https://vortekz.com/generators.htm) $20 for 10 and at least for my car the seemed to be more ascetically appealing...plus they came with a template for placing them...

^^^^ I just got the vortkez as well. I think they look awesome if anything (not like the airtabs... in my opinion)

One question are you going to place them straight or go with the 10 and 15 degree angle recommendations??

Anybody have any opinions??

I was going to follow the instructions and use the recommended angles...figure they would suggest the best possible way to see gains with them for multiple applications...without a wind tunnel or a testing facility its pretty much a shot in the dark...

I was thinking about going with Airtabs but yes, the aesthetics are glaring... but if they work then I really can't complain. Someone (CFG) told me that he used magnets on his tabs to attach them to the roof only.

Has anyone here done any back to back testing on these? I understand that they work on the Mitsubishi, but I would like to see some results on an aftermarket application.

I'm holding off putting them on the Del Sol right away, I am really hoping to see a dramatic improvement since I believe the turbulence created from the the air flowing over the roof is a big downfall of it...I'll be doing 2 tanks stock with the D15z1 in, then I'll do 2 with the front lip and grill block and then add the VGs to see if there is any gains...got my fingers crossed, after the VGs I am playing around with mounting the vx spoiler on the Del Sol it seems with a little work I can get it to mount and look pretty good and hopefully create a boat tail...anyways I'll be keeping track in a gas log and in my build thread so hopefully we will see some positive results from my Sol...

Try some of the aluminum metal tape used fer ducting as it's thinner. I think they mention that on their website... ;) Just don't go too fast or you might see it slip away... :eek:

It may be easier to remove the airtab, but how is it reusable after that? Isn't the adhesive on the back of the airtab expended at that point?

-Jay

I don't think you need to remove the adhesive backing to test it. You could contact the company to find out what they would recommend... ;)

They might even sell spare adhesives... :D

you could go to wal-mart and get the 3M heavy duty outdoor double sided tape for $3.60 (or there abouts) which is a 5 foot roll.

While you're in walmart for the tape, pick up the T-section tent pegs out of the camping section, cut the first 4 inches off a couple of packs of those and accidentally forget to order the air tabs.

The air tabs borrow heavily from the profile of the NACA duct:
https://en.wikipedia.org/wiki/NACA_duct

Here are some detailed profiles:
https://www.recumbents.com/wisil/nacaduct/naca-duct.htm

Now get yourself some sheets of pvc foam (or equivalent), double faced tape and an Xacto knife (or equivalent) and experiment. Note that the edges of the duct are sharp to precipitate flow separation and create the vortex.

An aero engineer's perspective on air tabs and vortex generators:

1. Vortex generators on aircraft are not 'shark fins'. Those are marketing gimics. VG are generally rectangular. 'Shark fins' act like delta wings which are designed to produce lift. You don't want lift. You want vortices. Hence, you want a very low aspect ratio wing (a rectangle slightly longer than it is high) angled at about 20 degrees to the prevailing wind.

2. [Big] Aircraft generally don't use VG to reduce drag. They use them to maintain controllability by preventing separation in front of control surfaces. You see VG in front of ailerons. You don't see them in front of flaps.

3. Of course, for every rule there is an exception. Some Boeing 737s have shark fin VG to try to reduce the body drag caused by the very short tail cone. But on an aircraft 12 feet in diameter, there may be six VGs. Not every four inches. And this was established on very big, very expensive wind tunnels.

4. Yes gliders are using very small vortex generator strips (mini-air tabs?) to reduce drag. But this may only work on gliders because of the obsessive care to the finish. Aircraft (and cars) that have to work for a living get dirty. And they drive through air that has been driven through by the hundred cars in front of them. The calm air that provides laminar flow probably doesn't exist during most commutes.

5. Vortex generators that stick above the surface add drag. They must be used judiciously. They are only valuable if they reduce more drag than they create. The car that is fuzzy with little shark fin VG has probably only succeeded in increasing its apparent volume. Yeah, yeah, yeah. Sharks have toothlike denticles that improve their movement through the water. If your car is moving through the water, you might want to contact your insurance company. Sharks have had 1/2 billion years to get it right. I don't have that much time.

So, VG produce drag and sometimes provide a net drag reduction. They need to be applied to a specific area to solve a specific problem. And a few being good does not equal more being better.

And yes, I do have some places on my cars where I would like to try them.

Why are people comparing them to aircraft and not the Mitsubishi Lancer?

If they're stuck on with adhesive, I recommend you do this: get a heat gun. Hold the tape so that the sticky side shines (reflects light). Heat the adhesive for a few seconds until it looks tacky (the shiny part will start to sweat). Press down on your car and hold for about 15 seconds.

That's how we install things like satellite radio antennas and they never come off, even in a car wash.

Just adding that the Vortekz come with double sided 3m adhesive pads and are guaranteed for 3 years...if they fall off they will send you a pack of 5 replacements...also helped in my decision making

So, ummm delta wings make low speed lift at high angles of attack how? Oh yes, by making a humungous vortex.

And those little 3M pads hold so well that you can grab any fin between 2 fingers and literally shake the entire car.

My friend that has Vortekz VGs on his A6 Avant has already gone though a car wash with them...he didn't loose any.

Another thing, from what I recall (correct me if im wrong) doesn't the Evo have the "shark fins" straight into the wind and not angled? (like the "Vortekz" people say, 15 degrees into the wind)...

'cuz the Lancer is a statistical sample of one, while aircraft have been using VGs for decades. Mitsubishi (formerly a very successful aircraft company) found a VG installation that worked for the Lancer's roofline. But VGs are application specific. If you own a Lancer, putting the same VG installation on should give you the same results. If you don't have a Lancer, your results may vary. How do you learn more? Look at other applications.

Delta wings make vortices to produce lift at high alphas. That doesn't mean that they are the most efficient vortex generator shape. Their application also relates to controllability (a big issue in airplanes), structural efficiency, supersonic drag, etc. Very low aspect ratio wings (rectangles with AR approaching one (= square)) have been proposed depending almost entirely on vortex generation for lift. They've even been test flown. None has ever achieved production or commercial success because they don't make good airplanes. But they do make good vortex generators.

Another thing I noticed about the commercial VG is that they are smooth and rounded. If vortices are what you want, they should be sharp and angular. You want the flow to separate cleanly at an edge. (Note description of NACA inlet referenced in previous post).

Don't forget the marketing aspects of these things too. Make little triangular VGs, you can call them "Shark Fins". Make more efficient rectangular VGs, and you can call them "Perch Fins" or "Bluegill Fins". You can see the problem there.

Take a close look...They're progressively angled as specified by Mitsu.:

https://us1.webpublications.com.au/st.../3059_11lo.jpg

Yeah, especially the one in the middle. :D

They're not sharp and angular as Mitsu specified. They are soft and rounded. If they produce vortices, they will probably be weak and poorly formed. Too round and they just make turbulence, which is what the antenna base in the middle is doing. Plus the leading edge of the bar is acting like a stall strip, tripping the airflow right at the point you're trying to keep it attached. Might be a good application for VGs. Might not be a good implementation of VGs.

I wonder if these would help on the roof of my Dodge GrandCaravan?

I would be hesitant to call aircraft an alternate application. Last time I checked aircraft weren't designed to cruise down the highway at 70mph. But if I ever want to get my car to takeoff and cruise at 500mph and 35000 ft, I'll look at what airplanes are doing.

We only have one example but it's not necessarily a bad one. I wouldn't be surprised if WRC cars had them.

You have other cheaper options besides airtabs like airflow systems, $10 for 25ft strip:

https://www.gassavers.org/showpost.ph...4&postcount=36

That's for the adhesive. Their VG's are $6.35 to $7.95 a foot depending upon width, plus adhesive.

Darnit! I did not understand that.

So that means their cheapest is $3/foot and you still need glue and paint (it's purple!)...

Most of the aircraft in the world travel less than 200 mph and lots barely make 100 mph. Reducing drag on a car is a convenience. Reducing drag on an airplane is a necessity.

I suspect not. I'm going to try and sharpen the trailing edge of the roof of my Caravan like the Honda Odessy. Sort of a little kamback. It seems to be a recurring theme on a whole host of current model cars. I've debated retrofitting the aft wing that some Caravans come with, but can't find out if it is functional or decorative.

In back of vans/suvs, there's many popular styles nowadays:

- downward sloping spoiler (bmw x3)
- spoiler/wing with a hole (toyota hilander)
- camback (prius, but not 2-box suv)

https://www.analogstereo.com/images/om/bmw_x.jpg
https://www.hibredtoyotas.com/toyota-...-spoiler-2.jpg
https://image.automotive.com/f/miscel...yssey-left.jpg
https://www.familycar.com/roadtests/T...2/LeftRear.jpg
https://www.etendance.com/images/Peug...is%20Aster.jpg
https://upload.wikimedia.org/wikipedi...ce_black_r.jpg

Unclear what's better and how it plays with the rest of the underbody aero.