Ordered Airtabs today!
 

I ordered my set of black airtabs today https://www.airtab.com/

Im planning to install them as seen here to start:

https://www.airtab.com/Images/gallery/Paulst/2.JPG

https://www.airtab.com/Images/gallery/Paulst/3.JPG

Exerpt of his experience with these....
We've increased our fuel mileage by about 9mpg on a full load, from 11-12 MPG to 20-21 mpg. We pull fast, heavy and long most of the time. With the Airtabs as installed, wind noise is reduced and the trailer stability is phenomenal. Evidence the Airtabs are working is most noted in rainy weather, in cross winds and meeting larger semi-trailers on two lane highways. The unloaded truck will get 25 mpg but with Airtabs fitted as per our pictures, we are getting 32-34 mpg. The Airtabs on the top rear of the cab eliminate 80% of the bugs on the front of the trailer. If you watch the bugs, they tell you where the air is going. The Airtabs on the hood of the truck keeps the windshield cleaner and reduces wind noise with the windows open.

There are 67 Airtabs on the truck and 95 on the trailer. A small investment for this kind of fuel economy and stability, not to mention the extra horsepower. It seems with Airtabs we aren't bucking wind, but directing it. This outfit gets a lot of curious looks but these results prove the Airtabs usefulness. The savings on a 1000 mile trip fully loaded would be approximately 35 gallons of fuel. At $3.00 per gallon, that's $105.

Ill post back installation pics and eventually MPG data once available for anyone interested in how these do. This could be a good front wheel skirt replacement option for just about any car possibly and maybe a front windshield deflector? For me, Im hoping it does that as well as also help around the back of the cab and bed maybe... anyway - I have them coming, will see how they do.

-Jeff

He Jeff, when you get them... Can you possible take some detailed pictures of them (preferably with a ruler or some sort of scale for dimensions) before they are installed?

I'd like to model them and do some CFD on their specific design (or as close as I can get) for application on a human powered vehicle... It'll probably be useful to others too. I have to do research anyway, so it seems like a good idea to start with a commercial product :p


Out of curiosity -- how did that gentleman find the separation points on his truck?

Separation points? meaning how far apart to space them is what I think your asking. If so, Im not sure how he did it, but the airtabs themselves come with 2 spacing templates, fill them both up, then move the first template beyond the 2nd (becoming the 3rd) and so on - like leapfrog. I will be using this method as closely as possible. I expect something to hinder complete compliance, but it will be close.

I will be glad to get some close up pictures with a ruler. It will be late next week at the earliest.

So air tabs add energy to the boundary layer much like the tabs on airplane wings or dimples on a golf ball do (in fact, exactly like they do). Separation is a fluid (in this case air) interaction where the flow that is attached to the skin of the vehicle (boundary layer) just lets go. It was discovered that if you give this layer a little bit of energy slightly BEFORE this separation occurs - you effectively move the separation point further back. In the case of a plane wing - you create more lift and thus lower the stall speed.

The easiest way to see what I'm talking about....
https://www.gassavers.org/attachment....1&d=1192830726

Notice how the red dye just lets go :)

Mitsubishi posted a paper on this - showing a reduction in cD by 6 points (.006) when they placed their vortex generators (basically, air tabs) 100mm in front of the separation point.

The trick is, and the focus of research, is how tall to make them. Optimal height is equal to the height of the boundary layer. But, the height of the layer increases with velocity. Make them too tall, and all you do is create turbulence -- make them too short, and they don't add much/enough energy to be effective :/

Thanks :thumbup: Much appreciated :) I guess it would be beneficial to mention that a top, side and front is the most helpful :)

FWIW I am running AirTabs on my hard top and I haven't noticed any quantifiable increase on FE. YMMV

https://lostleagues.com/wp-content/up...at_lines_2.gif

9mpg improvement just from airtabs sounds like a stretch to me. I've spent a lot of time on the road towing a lot of equipment, box trailers, backhoes, etc. There just wasn't that much difference. Pulling the backhoe mileage went down only 2-3mpg.

That said it doesn't mean that I don't want to try them. I'm seriously considering getting some to try on my saturn. I just don't know if there the right size for my application.

Red, my guess would be that the airflow has not reattached to the roof before it hits the air tab. I've looked at the jeeps before and there quite possibly one of the most unaerodynamic vehicles out there. I imagine that they would work better on the sides of the jeep. D

I'd be interested to see a documented increase in MPG related to installing this product. To me it seems like a miracle product for anything other than sustained driving at a highways speed, but I'm quite the skeptic.

And mar a perfectly vertical surface? :D Always worth a shot

Ask and you shall receive :p Okay, so it's not mpg increase - it's decrease in cD. It's also not for this specific product, it's for Mitsubishi's design (which is a basic delta wing foil).

Let me know if that link is dead ;)
https://www.mitsubishi-motors.com/cor...004/16E_03.pdf

The juicy images

Left with - Right without
https://www.primitiveengineering.com/...ex_gen_cfd.jpg
^^ Notice the Blue low pressure zone on the windscreen is larger without the VG's.
Left with - Right without
https://www.primitiveengineering.com/...g_pressure.JPG
Despite the lower pressure just behind the VG's (deeper blues), Mitsubishi got a decrease in cD - notice how the larger green area behind the VG's compared to without.

Here's Mitsu's Design
https://www.primitiveengineering.com/...vortex_top.jpg

Here's what you might find on a plane
https://www.primitiveengineering.com/...mg/vg_wing.jpg

I too was skeptical until reading that paper -- I had thought the velocities needed to have an effect needed to be much higher...

Oh, I also forgot to mention -- you can also find VG's under aircraft flaps - for increased stability at lower speeds ;)
https://www.nasa.gov/centers/langley/.../Micro-VG.html

I feel it also necessary to state that this is in no way an endorsement for the Airtab product. Flow control does work, intelligently designed - anyone can make something look cool - but that doesn't mean it works. Claiming to lower mpg is ballsy in my opinion - the much safer (and likely more accurate) claim is that it can reduce cD when properly installed.

Great article. But I still hold that I am skeptical to see what actual results will be seen in MPG with these.

From what I understood, these airtabs should speed up the airflow and smooth it to lower the CD. So would these work on any part of the vehicle that doesn't flow as well as it could such as the wheels, or even on the back of a hatchback civic? I would assume it would given the principle of how they work, but I would guess there would also need to be flow testing done to prove there effectiveness (and to make sure they don't do more harm than good) to be sure of it.

A hidden thread:

https://www.gassavers.org/showthread.php?t=1482

The 1st PDF shows research on how high to make them, angle to use, and where to put them. This testing was done at highway speeds.

Thanks for that ZugyNA - I'll read through it all sometime this week. I decided to purchase the product instead of attempting to make them for 2 reasons:

1. It seems that the shape and angles need to be just right, and Im not that patient or precise...
2. Multiply #1 by 75 VGs that would have to be produced and you'd have one frustrated F150 owner.

Im looking forward to posting actual driving test data for the board.

THEY WORK - at least...
 

on my truck. I imagine it has a greater impact on the shape of a truck / van than it would on an already much more aero car.

First - the scale pics, as requested:

https://www.doodlebuckets.com/epnc/IMG_2283.JPG

https://www.doodlebuckets.com/epnc/IMG_2284.JPG

https://www.doodlebuckets.com/epnc/IMG_2285.JPG

https://www.doodlebuckets.com/epnc/IMG_2286.JPG

https://www.doodlebuckets.com/epnc/IMG_2287.JPG

https://www.doodlebuckets.com/epnc/IMG_2288.JPG

https://www.doodlebuckets.com/epnc/IMG_2289.JPG



Then - pics of them installed on the F150 (I may take the time to paint them red later - but most likely not.)

https://www.doodlebuckets.com/epnc/IMG_2290.JPG

https://www.doodlebuckets.com/epnc/IMG_2291.JPG

https://www.doodlebuckets.com/epnc/IMG_2292.JPG

https://www.doodlebuckets.com/epnc/IMG_2293.JPG

https://www.doodlebuckets.com/epnc/IMG_2294.JPG


Finally the stats on the test route...that being a 45/55 mph bypass stretch with stoplights out, a 65 mph interstate out, 65 mph interstate back, and 45/55 mph bypass back.

Before (all current mods except Airtabs), according to SGII
23.6 / 22.6 / 20.6 / 23.7

After airtabs installed, according to SGII
25.7 / 24.3 / 22.0 / 25.6

Appears to be a solid 2 mpg gain (7-9% increase).... It was also pretty cool to "see" them working. I drove under a falling leaf. It would normally have hit my windshield and bounced over. Today, I saw it falling and then get rushed up over the windshield without ever hitting it, so it would appear that the tabs on the hood are indeed directing airflow over the windshield to some extent. Granted, this was one lousy leaf... it will be interesting to see if this trend continues (lots of falling leaves this time of year), and if I have the same experience noted by the other guy - a cleaner windshield...:thumbup:

Cheers
-Jeff

Damn, you ordered a buttload of them things...

Any chance you'd be interested in doing a string test and filming while driving before and after?

I have to think about making some for my crx now...zugy NA's write up is pretty good, dunno how I never saw it before, :p

I think that would be difficult to do for three reasons...

1st - the tabs are stuck on pretty good, I "could' get them off, but I'd be afraid of them not reattaching as well once they were pried off. This would disappoint me greatly and cost me more money (in the way of new adhesive of some sort).

2nd - I dunno how to do a string test, but Im sure someone could describe the proper method. I would be willing to do it if Im able on the existing setup. Perhaps windtunnel test results could be found on google somewhere for a stock F150 (I can try to find that). If not, here is a stock dodge that provides some evidence of a before - albeit not my exact truck.

https://web.archive.org/web/200304142...er/Tonneau.htm

3rd - I dont own a camera, and would need to get someone to assist me that does. I assume that the filming also needs to be done by a chase car? So I just need to find the right assistant (someone with a camera who is willing to help me out)

Let me know how to do the testing, and if this would provide any value to folks, and Ill see about pursuing it.

Eh, don't worry about it. I'm sure treb will mock one up and run it through his water machine a school in a few days time anyway, :)

Just use someone else's fee-zoh (f150) for the control string test...

Thanks for those pictures - thanks for the extra measurements too - I can make a spline to get pretty close to that curvy shape :) They help a whole lot :)

I wish, I don't have direct access to the water tunnel anymore :/ Perhaps within a few months, I can see about using it though (when it's filled for other classes) :D

Oh, poo...I wish all my friends weren't crappy econ majors and mehbe I could make them do something like that...

Maybe I just didn't use enough of em on the Heep.....

Jeff, any noticeable increase/decrease of wind noise? Stability changes? Anything blowing around?

I dont know that I have noticed any stability changes, but Ill get a better feel for that after a long hwy 95 trip tomorrow. It may seem a little more stable, but I may just be thinking that based on what Ive read - the power of suggestion you know. Really hard to say. I havnt noticed any less wind noise either - but the radio is usually on too. I will listen for it on said hwy 95 trip.

Where do you live on 95?

Raleigh, NC area...traveling up to Baltimore

Ah, you're way down from me then, I'm from jersey.

yup, opposite ends, maybe we'll cross paths one day

Man, I put 5, just 5 white ones on a white Jeep Liberty, and couldn't bite the bullet and mount them everywhere...I have to applaud you for diving in like that.

Wow! Great results for the ford truck!

Hopefully your results continue to show an increase in MPG to show this is more than a one-time event. Good luck with your better MPG quest!

Maybe I'll look into some of these for the VX. I'm sure they can't hurt!

I often travel the bypass portion of my test route. Two more trips out and back along this stretch showed 25.x mpg. So it has been repeated a few times. Ill update the group with more after the road trip.

Now that's what I call just diving in! Wondering where you got the idea for using the tabs on the hood?

From the airtab display gallery...

https://www.airtab.com/Images/photogallery/gallery1.htm

https://www.airtab.com/Images/gallery/Paulst/2.JPG

https://www.airtab.com/Images/gallery/Paulst/3.JPG

the price is a ripoff.
you could make airtabs for 20 cents a piece with a vacuum molding machine. my friend had one in his garage. you put a part on the plate and a sheet of 1/8th inch plastic is heated up untill it almost melts. the its placed on the plate and a vacuum opens and sucks the hot plastic sheet down onto the airtab so it follows its contours. when the plastic cools you pull the sheet off, cut around the part and you have an exact copy for 20 cents.
if you guys are serious about airtabs, just buy one and take it to someone who does vacuum molding. have them make you 50 or 100 or heck 5000 and sell the extras on ebay.

Just arrived from the 333 mile trip from Raleigh to Baltimore.

Previously, this tri yielded a 22.3 MPG hwy run...arriving with just over 1/4 tank left.

Today, with airtabs and wheel covers, it increased to 26.7 MPG...arriving with about 1/2 tank left!

Very exciting gains. I will update you guys with the leg home info if you want. Then I'll drop it.... they work, at least on my truck. Take care all.

jeffreymccoy -

Wow! Yes, more info please.

CarloSW2

CFG83 you need these on your wagon. the .36cd is screaming for them. I'm just not sure if they'll help me.

Interesting results. Can you dig up a weather comparison between the two trips for us?

:thumbup:

Yeah, you could do that but you'd probably be violating the copyright on their design and it certainly is morally questionable at best. The price might seem steep to you, but I'm sure that significant R&D went into developing the product and they are trying to recoup their investment. How'd you like it if you developed a product and some punk stole your design? People develop products to make $$$. Take that away from them and the good ideas will stop coming, period. Do something productive with your life, don't spin your wheels thinking up ways to rip off legit businesses. I own a small business so I know what its like to try to make a buck. Its hard enough without people like you dreaming up ways to steal an idea that (a.) you would never have thought of and (b.) probably don't even understand. If you don't like the price, don't buy the product.

i am curious too, especially with the winter summer blend mix ups as a possibility. :/

How much do you think was the wheel covers? It'd be interesting to know.

On 8/8/2007:
https://www.wunderground.com/history/...q_statename=NA

Temperature:
Mean Temperature 79 °F / 26 °C 63 °F / 17 °C
Max Temperature 93 °F / 33 °C 74 °F / 23 °C 87 °F / 30 °C (1990)
Min Temperature 65 °F / 18 °C 51 °F / 10 °C 35 °F / 1 °C (1964)
Degree Days:
Heating Degree Days 0 4
Month to date heating degree days 0 28
Since 1 July heating degree days 3 49
Cooling Degree Days 14 2
Month to date cooling degree days 77 22
Year to date cooling degree days 2035 1496
Growing Degree Days 28 (Base 50)
Moisture:
Dew Point 65 °F / 18 °C
Average Humidity 66
Maximum Humidity 93
Minimum Humidity 38
Precipitation:
Precipitation 0.00 in / 0.00 cm 0.11 in / 0.28 cm 2.54 in / 6.45 cm (1996)
Month to date precipitation 0.13 0.94
Year to date precipitation 26.35 34.80
Snow:
Snow 0.00 in / 0.00 cm - - ()
Since 1 July snowfall 0.0
Snow Depth 0.00 in / 0.00 cm
Sea Level Pressure:
Sea Level Pressure 30.03 in / 1017 hPa
Wind:
Wind Speed 2 mph / 3 km/h (SSE)
Max Wind Speed 8 mph / 13 km/h
Max Gust Speed 13 mph / 21 km/h
Visibility 10 miles / 16 kilometers
Events Fog



Today, 8/22/2007:
https://www.wunderground.com/history/...q_statename=NA

Actual: Average : Record :
Temperature:
Mean Temperature 70 °F / 20 °C 58 °F / 14 °C
Max Temperature 83 °F / 28 °C 70 °F / 21 °C 86 °F / 30 °C (1947)
Min Temperature 56 °F / 13 °C 46 °F / 7 °C 26 °F / -3 °C (1974)
Degree Days:
Heating Degree Days 0 8
Month to date heating degree days 23 114
Since 1 July heating degree days 26 135
Cooling Degree Days 4 0
Month to date cooling degree days 133 39
Year to date cooling degree days 2091 1513
Growing Degree Days 20 (Base 50)
Moisture:
Dew Point 54 °F / 11 °C
Average Humidity 63
Maximum Humidity 83
Minimum Humidity 41
Precipitation:
Precipitation 0.00 in / 0.0 cm 0.09 in / 0.23 cm 0.62 in / 1.57 cm (1958)
Month to date precipitation 0.30 2.35
Year to date precipitation 26.52 36.21
Snow:
Snow 0.00 in / 0.00 cm - - ()
Since 1 July snowfall 0.0
Snow Depth 0.00 in / 0.00 cm
Sea Level Pressure:
Sea Level Pressure 30.23 in / 1025 hPa
Wind:
Wind Speed 3 mph / 6 km/h ()
Max Wind Speed 15 mph / 24 km/h
Max Gust Speed 17 mph / 27 km/h
Visibility 10.0 miles / 16.1 kilometers



Little cooler this week than 2 weeks ago, and slightly less humidity. Pretty close to the same, even avg wind was close 3 vs 2, although gusts were a little different. Overall, similary conditions between the 2 days, nice sunny fall days....