Air Tabs

[d30gaijin]

Has anyone tried these out on there CT and do Air Tabs work good on the road while driving??

BK,

Someone on this forum had them on their CT but I don't recall whose build it was. Reading the testimonials on the Air Tabs web site it sure appears that they work to improve stability and even a small boost in MPG.

Don

[SteveB]

I had them on my 5x8. Unfortunately, I did not take before and after data. I probably got caught up in the buzz. I think if they did work we would see them on every UPS truck, FedEx truck, all square back trailers, etc.......
Steve

[bdosborn]

I was interested in airtabs awhile back. I did quite a bit of reading on the big RV forums and came away with two conclusions:

-Mileage gains were slim to none.
- Some noted better stability for long trailers when being passed by semis.

I thought it was too small a gain for the price (they are surprisingly expensive) and passed on them. However, YMMV.

Bruce

[roadinspector]

http://www.airtab.com/AirtabFuelSaverCalculator.xls

Here is a link to calculate your savings from the airtab website. When I calculated mine sometime back, the cost of the airtabs vs. fuel savings did not even come close to breaking even. It would cost more for the airtabs than the fuel savings.

Earnest

[d30gaijin]

BK,

This is the build on this forum that has Air Tabs installed. It is Prem's build thread. Page down towards the bottom: http://tnttt.com/viewtopic.php?f=42&t=25377&start=45

Don

[bdosborn]

I ran the Airtab spreadsheet on my trailer, based on 51 airtabs. That's how many it looks like Prem has on his trailer. Prem says he got a substantial mileage increase, the Airtab website says you can expect a 4% increase. It would be a 66 month payback for my setup according to the spreadsheet.



Bruce

[d30gaijin]

I ran the Airtab spreadsheet on my trailer, based on 51 airtabs. That's how many it looks like Prem has on his trailer. Prem says he got a substantial mileage increase, the Airtab website says you can expect a 4% increase. It would be a 66 month payback for my setup according to the spreadsheet.
Bruce

Bruce,

Those things are expensive! $2.59 for a piece of (likely) injection moulded plastic with what, double sided sticky tape? I see what you mean about adding them to a CT. One would have to do a boatload of hauling their CT at high speed to recoup the cost. 66 months? I don't even know if we'll have our same CT in 66 months? I mean, like we're already looking at an upgrade in size and quality and we haven't even finished what we've got yet.

Thanks for the info and spread sheet.

Don

[bigbendhiker]

I don't even know if we'll have our same CT in 66 months? I mean, like we're already looking at an upgrade in size and quality and we haven't even finished what we've got yet.

Don

Wow, I can't wait to see your next build!

[8ball_99]

I sort of have the same thoughts as above. If they really worked I'm pretty sure every UPS, Fed EX and big rig would have them. I haven't seen a single commercial vehicle running them.. Those trucks are on the road constantly. If even the 4% was true I'm pretty sure commercial trucks would be running them.. Cause yeah 3 bucks a pop ain't cheap but if you drove 5 -6 days a week it wouldn't take long to be worth it... For camping folk I don't see it. I know we only average a few hundred miles a month pulling are cargo..

[angib]

AirTabs are just a brand name of (expensive, but nicely made) vortex generator. You can make something similar from trapezoidal bits of aluminum sheet bent in a vice and some mounting tape - here's a nice Australian car article about them. Note that microlight aircraft use bent-aluminum VGs and this is the shape that NASA has tested, so don't get hoodwinked by AirTab propaganda about their VG shape. VGs are cheap enough to be worth trying out - though fuel records of less than 1,000 miles are unlikely to be accurate enough to measure the change.

Vortex generators work by injecting energy into the boundary layer in the form of turbulence. So they always use energy and the question is do they deliver enough aerodynamic benefit to pay back that energy? Towing a trailer is one place where they could deliver such a benefit by 'connecting' the tow vehicle and trailer together into one aerodynamic body. In practice I can't see a TTT achieving that, since the ideal would be for it to be really close to the tow vehicle, like with less than a foot gap. Some semi-trailer cabs and trailers are getting very close together and have the same cross section - then vortex generators look like they should be able to deliver real benefits.

But as a stick them anywhere to any vehicle tool - forget it.

[bdosborn]

Here's Prem's set up:

:fan:
I painted and installed 51 AirTabs (for tractor trailer rigs) on the back of my cargo trailer. They give better fuel efficiency by breaking the rolling vortex of wind behind the trailer at highway speeds, as noted in previous post and company's website.




Prem

He says he's getting a pretty significant mileage gain, maybe its because has a cargo trailer with a square back and not a teardrop.

237 miles using 21 gallons = 11.25MPG

I was getting 9.5MPG towing the trailer before the AirTabs.



AirTabs only work effectively over 45MPH. There were many times when I was under 40MPH towing on the trip. I was never on an Interstate for that test run, so one could expect even more fuel efficiency gain for a long trip on the open road. The vehicle gets 12-13 not towing on the open road.

Prem

Bruce

[High Desert]

Interesting discussion guys. A fellow I work with just installed a set f these today on a semi tractor, across the roof and on the rear edges of the side fairings as an experiment. It's set up like Andrew mentioned, this is one with less than 24" of gap between tractor & trailer. He's always trying new angles to improve efficiency. As I've been following this thread it caught my attention so I'm looking forward to his results. Not completely relevant to TT's but should be of some interest.

[angib]

A fellow I work with just installed a set f these today on a semi tractor, across the roof and on the rear edges of the side fairings as an experiment. It's set up like Andrew mentioned, this is one with less than 24" of gap between tractor & trailer.

In this case, I think what happens is that the turbulent-but-energised 'sheet' of vortices coming off the AirTabs forms a curtain that flows from the cab onto the trailer, so isolating the gap between the two and making the air think it is one long vehicle. I would be very surprised if the same effect could be achieved by trying to connect the much longer distance from a tow vehicle to a TTT.