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Old 07-03-2024, 03:32 PM   #11 (permalink)
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Originally Posted by aerohead View Post
1) For a 'rigid' construction, the Highway Patrol is going to cite you for illegal length for anything beyond 48" of elongation.
Curious where you are getting this 48" number from and what the point of reference is. There a plenty of vehicle out there with massive extensions past the rear axles.

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Old 07-03-2024, 03:38 PM   #12 (permalink)
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By extreme good fortune and a little guile I I got my hands on the first built from the ground up Electric Van in the US. It's a GM/Brightdrop Zevo 600. I have had it since Sept 23. It's pretty fantastic. 178 kWh battery & AWD. Range is 275 miles in the winter (MN) and 360 summer.
Very cool vehicle and project. AT first glance without you listing angles it looks to me like the angle of your tail is too steep.
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Old 07-05-2024, 10:34 AM   #13 (permalink)
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' curious '

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Originally Posted by JSH View Post
Curious where you are getting this 48" number from and what the point of reference is. There a plenty of vehicle out there with massive extensions past the rear axles.
As a reaction to the Arab Oil Embargos of 1973 and '79, the USDOT added a 'work-around' to their own Class-8 length restrictions for semi-trailers, as long as it was for energy efficiency.
NASA and the major tractor manufacturers knew from their own research that, 'elongating' the trailer body with a boat tail would absolutely improve mpg.
They allowed four-feet for 'rigid' tails, and five-feet for inflatable tails ( Fachsenfeld, circa 1935, at the FKFS, Stuttgart, Germany ).
BMW and the Wagonner's Trucking Company have used rigid four-foot, FRP tails on their 18-wheelers.
Continuum Dynamics held to four-feet with their $425,000, DARPA-funded semi-trailer box-cavity, measured by NASA, at Ames, Palo Alto, CA.
You'll notice that the 'rigid panel' 'Trailer Tail', as used primarily with Messila Valley Trucking, held to a four-foot tail, although they've continuously lobbied in the US and EU for 'longer' tails, known to provide larger mpg gains. The 'Trailer Tail' is kind of a 'folding' version of Continuum's box-cavity.
Bruce Ruefer, an 'inventor' of Lubbock, Texas, was the last 'champion' of the inflated tail that I know of. Texas Tech University tried to help him with their Aero Lab in the mid-1990s.
I'm not in any 'official loop' as far as data goes, so I have no knowledge that the federal govt. has ever changed their length allowances.
I'm in the 'go ahead and boat-tail camp,' and beg for forgiveness if ever 'cited' for a violation. ( full executive immunity for ecomodding )
I added a four-foot inflated boat tail to AeroStealth's Toyota T-100 in 1995, and along with a half-tonneau, and rooftop storage container on the floor of the truck bed, experienced over 30-mpg for the first time in the T-100.
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Old 07-05-2024, 11:38 AM   #14 (permalink)
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As a reaction to the Arab Oil Embargos of 1973 and '79, the USDOT added a 'work-around' to their own Class-8 length restrictions for semi-trailers, as long as it was for energy efficiency.....
Class 8's do have overall length restrictions but a Brightdrop is not even close to a Class 8. The 600 is available with a 9990 (Class 2) or 11000 GVW. (Class 3). It is also only 290 inches long. (24.2 ft)

For reference this is a Holiday Rambler Vacationer Series RV. 36 feet long with an absolutely MASSIVE rear overhang. (It is built on a Class 4 Ford step-van chassis)

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Old 07-05-2024, 11:54 AM   #15 (permalink)
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' rear overhang'

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Originally Posted by JSH View Post
Class 8's do have overall length restrictions but a Brightdrop is not even close to a Class 8. The 600 is available with a 9990 (Class 2) or 11000 GVW. (Class 3). It is also only 290 inches long. (24.2 ft)

For reference this is a Holiday Rambler Vacationer Series RV. 36 feet long with an absolutely MASSIVE rear overhang. (It is built on a Class 4 Ford step-van chassis)

The DOT length restrictions have nothing to do with 'rear overhang', only 'how much' added length is allowed for an 'existing' structure.
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If one added a 'Trailer Tail', or 'other' 48-inch boat-tail to the rear of some RV, I don't believe that there'd be any 'push back' from the constabulary.
If the tail were an 'inflated' length of 60", I don't believe there'd be any objection.
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If an RV owner wanted to pull a 'trailer', in the form of a 100%-length boat-tail, no government body would legally have a thing to say about it.
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My brother had a 36', Ford chassis-based RV motorhome that he could have boat-tailed. It's 6.5-mpg @ 55-mph ( with the V-10 ) hastened it's 'sale.' It was a losing proposition from day-one.
Orbywan's Ford-based RV motorhome achieved 14.5-mpg, with his full aero kit.
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Old 07-05-2024, 01:30 PM   #16 (permalink)
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It was a losing proposition from day-one.
So I'm off the hook for scratching his floor in Ogden?
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Old 07-05-2024, 05:08 PM   #17 (permalink)
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Quote:
Originally Posted by aerohead View Post
The DOT length restrictions have nothing to do with 'rear overhang', only 'how much' added length is allowed for an 'existing' structure.
A 24 foot van is nowhere near any kind of length limit. The OP is building an RV based on a van chassis - normal RV rules apply. The length limit for an RV is 40 feet.

If he builds a solid structure and puts the taillights on the rear of that structure he is good as long as the overall length is less than 40 feet.

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My brother had a 36', Ford chassis-based RV motorhome that he could have boat-tailed. It's 6.5-mpg @ 55-mph ( with the V-10 ) hastened it's 'sale.' It was a losing proposition from day-one.
I friend of mine had one of those too and he did 6 mpg at 55 mph loaded or unloaded. Needless to say it didn't travel very far and he most used it parked on a piece of property as a summer "cabin".
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Old 07-05-2024, 05:46 PM   #18 (permalink)
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My motor home got 10MPG, but in the end what it lacked was a parking space.

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If he builds a solid structure and puts the taillights on the rear of that structure he is good as long as the overall length is less than 40 feet.
I'd add wheelie bars.
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Old 07-06-2024, 09:20 PM   #19 (permalink)
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My latest drawing. Maximalist. Probable realistic length is 47" to lights and 89 - 91" total.
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Old 07-07-2024, 12:30 AM   #20 (permalink)
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Will you, or how will you, cap the top and bottom?

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