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Old 09-04-2016, 02:36 PM   #15
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Given the comments about rooftop equipment creating disturbance that may counteract or significantly limit the products effectiveness, I am wondering if only using them vertically on the rear of the RV would be enough to reduce the push created by passing trucks?
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Old 09-04-2016, 03:45 PM   #16
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And they look so good.


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Old 09-04-2016, 04:25 PM   #17
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Originally Posted by AKOne View Post
When I saw these installed a Motorhome, the aviation part of me was standing there scratching my head

What do you fly? A Shorts Skyvan?
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Old 09-04-2016, 04:52 PM   #18
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It strikes me that if you are using this product as an aide to gain more miles per gallon, then their primary function would be to reduce air drag.

One cause of drag is protuberances, and voids like between cab and camper, and around air conditioners on top... Another is the large wake from a square tail and the low pressure in like has also been discussed.

I can see how these tabs may break up the air walls and wake walls, and therefore help to reduce drag. This may help to increase MPG.

I can even understand how this 'broken' wall of air may help others on the road not deal with a solid wall of air pressure coming off our motor homes.

I was going to say that I could not see how this will have any impact on the passing truck who's wake hits my motor home and pushes it sideways...

As I was typing, I am wondering if the small swirlees coming off my motor home may actually help to break up that wall of air as it hits the side of my motor home as the truck passes. (or I pass it).

In this case, I would think the tabs would need to be near the front of my motor home... The tabs in the preceding picture were at the rear.

Is there a placement for optimum mileage improvement? A different placement for optimum stability against trucker air push?

I would love to know what people think...
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Old 09-05-2016, 07:18 AM   #19
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The toad will also aid in breaking up the vacuum behind the motorhome, varying of course by size and shape of both the MH and the toad. Some MH owners claim better mileage when towing than when not.
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Old 09-05-2016, 11:39 AM   #20
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The toad will also aid in breaking up the vacuum behind the motorhome, varying of course by size and shape of both the MH and the toad. Some MH owners claim better mileage when towing than when not.
This is purely anecdotal, and far too short a test to mean anything concrete, but in June I made a trip to a particular camp ground about 100 miles away.

In August, I made the exact same trip.

In August I towed my Lincoln MKX (SUV) and I had not towed anything in June. The MKX weighs close to 5000 pounds.

In August, my miliage appeared to be approximately 1/10 of a mile per gallon better than in June.

There are far too many factors for such a short trip, but with the heavy toad, I was expecting a heavy negative impact on my MPG. Instead it went the other way, a tiny bit...

Perhaps the car behind did help with the drag...
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Old 09-05-2016, 12:17 PM   #21
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They do more to prevent buffeting than to increase gas mileage - but the two go hand in hand a bit.

Protuberances, etc on the top of the MH have little bearing on what the airtabs are trying to do.

Follow a truck in the rain. You'll see alternating vortices that shed off each side of the trailer in an alternating sequence. If you look closely, it also corresponds to a certain amount of sway.

For those marines in the audience, if you look off the back of an Amphib while under way you see the same thing in the wake.

The airtabs keep the flow from detaching as abruptly and producing the vortices, reducing sway and drag.

For a semi - the base drag f the tractor and interactions with the front of the trailer, underbody drag, and wheel drag are bigger contributors than the base drag of the trailer, so the fixes go there first. The ducktails are probably a larger improvement than the airtabs but not really applicable to RVs and light trailers.

The airtabs price is too high in relation to the benefits to an RV owner for gas mileage, but are helpful for handling.
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Old 09-05-2016, 12:57 PM   #22
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Meet a couple in a Tiffin Allegro 36'. Their claim was less cross wind buffeting, less push with passing trucks, and improved MPG, by about .5 as I remember.
He was a civil engineer, his wife drives their RV. She said his claims were good. Documented Mpg results. First time I got it from a good source, not a review.
He painted them with exact colors from Tiffin. Looked good.
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Old 09-05-2016, 01:41 PM   #23
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Meet a couple in a Tiffin Allegro 36'. Their claim was less cross wind buffeting, less push with passing trucks, and improved MPG, by about .5 as I remember.
He was a civil engineer, his wife drives their RV. She said his claims were good. Documented Mpg results. First time I got it from a good source, not a review.
He painted them with exact colors from Tiffin. Looked good.
That's what I am searching for... Not so much mpg improvement, but I want to reduce the push I get from passing trucks. If it just does that well, it would be worth the price for the reduction in driver tension and fatigue. Would like to hear from more end users experience.
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Old 09-05-2016, 02:04 PM   #24
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Old 09-05-2016, 02:16 PM   #25
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I want to reduce the push I get from passing trucks. If it just does that well, it would be worth the price for the reduction in driver tension and fatigue. Would like to hear from more end users experience.
Your money would be better spent on Watts Links and X Braces for your coach versus Air Tabs.

Read through THIS iRV2.com thread (which is lengthy but worthwhile) and then talk to Van Williams. You will be AMAZED at the difference and no more driver fatigue or trucker push.

Dr4Film ----- Richard
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Old 09-05-2016, 07:25 PM   #26
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The explanation of vortexes off the rear of the MH are fine, but how do tabs impact the inrush of air coming off the truck in the next lane?

If the technical posts that were trying to explain why trucks use tabs on the tractors more than the trailers are valid, and surely some on this thread are not convinced, I maintain that putting tabs on a motor home rear end is not explained on how it improves the push from a passing truck...

I might even buy that if the passing truck has the tabs, and if some of the contradicted verbiage is actually true, I still cannot see how it applies to the handling of the motor home.

For me, I guess if no one answers this oft asked question, I will have to hope that all trucks that pass me have the tabs on them. Then, I guess I will have a smoother ride...
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Old 09-06-2016, 06:37 AM   #27
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Watts Links

Quote:
Originally Posted by Dr4Film View Post
Your money would be better spent on Watts Links and X Braces for your coach versus Air Tabs.

Read through THIS iRV2.com thread (which is lengthy but worthwhile) and then talk to Van Williams. You will be AMAZED at the difference and no more driver fatigue or trucker push.

Dr4Film ----- Richard
I'd like to follow up on your suggestions. Could you provide me a link? Not sure who Van Williams is either. Thx for your help!
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Old 09-06-2016, 06:56 AM   #28
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I guess whatever device you are using to read iRV2.com, it does not show the the hot link I had posted in my previous post (The word THIS was a Hot Link to the thread).

Below is the thread for the Watts Link & Cross Braces plus a way to contact Van Williams.

Wandering, sway bars, alignment, ride height, oh my!!

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