Wind deflector between cabover and cab

sleepy you raise a good point about commercial companys not using airtabs..i think one reason they don't is the van bodies they haul are at the widest allowable width for maximum cargo load.. those skirts under otr trucks and trailer are so simple and fairly cheap i wonder why companies don't use them more often..

I was part of the scientific community for many years... we lived by certain rules: Honesty first and foremost. We always proved our developing ideas before we made them available to a limited number of others that were skilled in the area that we were working in, if that peer review didn't quite agree with our findings we went back to work on our project... if further peer review agreed with us, we then and only then made our concepts public.

I think that if you go through the body of work (TC modifications and projects) that I've presented on the forum over that last 10 years you will see that I've adhered to my scientific principals... every project has been detailed and has functioned as promised.

I try to avoid being critical of other peoples projects... unless I'm directly challanged... even then I try to explain my thoughts based on my experience and the information that is readily available.

I have never recommended that anyone should do something that I haven't done or wouldn't do myself.

All my life I have observed a few people encouraging others to "jump of the bridge" or to "lick the ice tray." You have seen it too... it is a form of bullying,

If these people want to see something tried they should do it themselves first.

I have watched some of the most gifted people that I've ever known leave the TC forum... and that is a shame, worse it is a crime to steal all that tallent away from the rest of us by the few members constantly argueing points that they may not have any real knowledge of... just because they can.

Dixie Lee Ray, a couple of years before she died, told me that she as a scientist couldn't argue with a non scientist... a scientists code of ethics limited them to the truth. (I was her host for 3 days when she came to Oak Ridge) She was Govenoir of Washington State and the head of the Atomic Energy Commission. She lived on Fox Island, WA with her sister Mirium.

Like me, or not... I always tell the truth! By the time you see my projects... they work as presented.

Chet xxxxxxxx (Sleepy)

Mythbusters and Consumer Reports both get it wrong from time to time. :) I can't say I've really noticed that much noise in my Supercab. I wonder if the noise is more common in Crew Cabs. The bugs are annoying though but also show up in the front of the overhang. I don't think it matters much what people use as long as it works for them.

It also looks like the sleepy air foil is too tall on a newer Ford with that camper, so it doesn't really look like an option on the Ford with Airtabs on that particular camper. Finally, the one with airtabs might have to drill since it doesn't have the trim that Lance's, Artic Fox, Host, etc, have.

Works for me and no drilled holes!

Wheelholder wrote:

It looks like both sides are determined to be correct. Sleepy has maintained the proof of his device, whereas the other side seems to be totally speculative.
Not a lot of money, if you have the extra to spend, then I say go for it and give us the comparison that we have received from Sleepy.

I'm not sure I'm following you. Sleepy has tried his own thing and says it works. Art has tried his own thing and says it works. We have one testimonial sample from each, not much data, and no comparison data. It isn't as though we have had Consumer Reports or Myth Busters in here doing an unbiased report with a bunch of instrumentation. They probably both do something. But neither seems likely to double your fuel milage while cutting the noise in half, otherwise you would see one of them on every camper - and I have yet to see either on any camper.

It would appear that Sleepy has "real life" experience as to the viability of his diverter. I seem to remember reading his thread when he made the diverter and he gave numbers as to the increase in fuel mileage.

Air tabs have been around for a while. Sleepy's explanation of them is also my understanding of their operation. They are designed to break up the turbulence at the rear of a vehicle. There are a lot of big rigs that utilize air tabs. I have seen quite a few on tractors as well as the trailers. A lot of time, they are hard to see as they are painted the same color as the vehicle.

It looks like both sides are determined to be correct. Sleepy has maintained the proof of his device, whereas the other side seems to be totally speculative.
Not a lot of money, if you have the extra to spend, then I say go for it and give us the comparison that we have received from Sleepy.

sleepy wrote:
I personally think that using the Airtabs incorrectly will usually cause more problems.

If I were going to use the Airtabs I would follow the manufacturers instructions.

sleepy

Well, we have an existence proof (Art's) that you could be wrong about them, and I gather you have no experience with them in this application yourself. I'd like to see more people try them and report their experience here.

Another possible explanation of why they might work: by adding vorticity to the air entering the narrow slot between cab and camper, the effect of skin friction would be greatly increased (the boundary layer much thickened) which could very effectively slow the air flow hitting the camper front wall. I note that the clearance on Art's rig is minimal, which would help with this effect.

This forum topic has been both entertaining and informative and I do thank all for their input. I have seen air tabs on trucks and was completely confused as to how they work so this has broadened my knowledge.

My plan at this point is to build an airfoil/deflector similar to Sleepy's style and then add air tabs to at least the top rear of the camper.

I have a pop up style so the jacks are on the outside of the camper not the front and back. otherwise I would be sure to add them to the sides.

side note: would air tabs provide enough diversion of air to help divert air around the jacks on the rear?

the other item I would like to design is a deflector/foil that diverts air around the side between the truck cab and square side of the front wall of the camper.

again thanks for all the information along with the entertainment.

sleepy wrote:
The Airtabs . . . are designed to create turbulence... when installed at the trailing edge of a trailer or the trailing edge of our square backed truck campers...

Airtabs might just work on the cabover bottom. . .
The evidence is anecdotal, but a truck camper friend experiences his sun-roof window being sucked open from the low pressure area created under the cabover.

(The window movement is limited, it pops up just a little.)

I am intensely curious about this subject and a bit frustrated at the lack of testable evidence.

The Airtabs are a different subject: I'll try to make sense of it using my studies when they first came out and a bit of a refresher.

They are designed to creat turbulance... when installed at the trailing edge of a trailer or the trailing edge of our square backed truck campers...

Their stated function is to break up the laminar air flowing along the side the trailer or truck camper... to keep from having the laminar slip stream flowing straight back from the rear of the trailer or truck camper. This laminar flow creats a low pressure an the back of the trailer or truck camper creating drag....

The Airtabs attemp to solve the drag by dumping the turbulant air into the space immediately behind the square backed trailer or truck camper. That turbalant air fills the area and reduces drag and as a bonus keeps the back clean (both good things).

The manufacturer supplies a templet that positions the airtabs as close the the trailing edge of the trailer or truck camper as possible and positions them very close together.

They don't mount them on the sides in the front of the trailer... the turbalnce would create drag along the sides instead of reducing it at the rear. a bad thing.

In my opinion... using the water hose "wind tunnel" from my last post above:

If you mount Airtabs between the cabover and the truck's cab they will channel every bit of (water) air possible into the area between the cab and cabover... with a high speed turbalance and no drop in pressure.

The area will be like a large number of blenders (equal to the number of Airtabs) Will the noise change when moving through the air at highway speeds to a more acceptable frequency?...I don't know. Will their be more bug reminants? I personally think that using the Airtabs incorrectly will usually cause more problems.

If I were going to use the Airtabs I would follow the manufacturers instructions.

sleepy