What should US Travel Trailer makers do?

[Tourigjm]

this may have been posted before.
its one of my professors

Ken Visser Research Page

[fud2468]

I wonder if this could be placed on a van or SUV and get similar results.
Ray mac.

[Big Dave]

I’ve thought about this – strictly for the 1-percentile that puts 25,000 miles a year on an RV (race crews, etc).

Using my truck as the tractor. Mine is lower than usual and only SRW, so the cab shows 79.9” wide and 72” above grade. At the top of the bed (48” above grade) it tapers in on a 34 degree angle to be only 48” wide at the top of the cab.

The Bowlus Road Chief was 80” wide (todays RVs are at least 96” wide).

Start with a 79” wide Hi-Lo design. (Using my truck’s dimensions) have its road operating height no more than 71”. In camp it deploys higher. Compensate for loss of space (by making it narrow) with some additional length. Taper it in at truck-cab angle at the top. Now nothing “shows” in the air stream – just a small step at the interface.

Given the cites posted by trebuchet, I wouldn’t go wild on the shape – just avoid the A/C tumor on top and round the edges a la Airstream.

[4536]

Check out patent # 6959958 by Tourigjm's Professor Visser. He combines the use to vector generators and enclosed and open panels mounted to the rear doors of the trailer to obtain a significant reduction in drag. When multiple panels are used, they appear to taper inward at a 20degree angle from the rear of the trailer. The "dirtier" the front of the tractor/trailer combo, the bigger the reduction in drag. You should be able to find it Patent Storm.com. You will have to register but the process is fast and free.

[chaster]

Perhaps this is a naive (or dumb) idea, but how come nobody just puts an inflatable boat tail on the back of trailers?

Make it out of the same material used in those bouncy houses that kids like to play in. No worries about hitting stuff (it'll bend/deform), and just collapse it when not on the road or when there are clearance issues...

*scratches head* how come nobody does this? Seems like it would be pretty inexpensive and it wouldn't compromise interior space or construction techniques...?

Chaster

[4536]

Its not dumb. I have seen pictures of similar devices made out of rubber or plastic materials. The drawbacks are remembering to deflate them or open the doors to which they are attached before getting to close to a loading docks and other objects. Also they cost some $ and only last about 5 years.

Another problem is that independent truckers ( who pay the fuel bills on the runs they make) often don't own the tractors they haul. One solution is government requirements or incentives to tractor manufacturers.

[chaster]

Originally Posted by 4536

Its not dumb. I have seen pictures of similar devices made out of rubber or plastic materials. The drawbacks are remembering to deflate them or open the doors to which they are attached before getting to close to a loading docks and other objects. Also they cost some $ and only last about 5 years.

Another problem is that independent truckers ( who pay the fuel bills on the runs they make) often don't own the tractors they haul. One solution is government requirements or incentives to tractor manufacturers.

Hm, okay, so how about the following ideas to address these challenges:

1) I realize they would cost money to make, but it seems that if they were mass manufactured (like inflatable rafts, beds, etc.) are then they could be made for a relatively low cost (say, less than $300). If they save 10% on fuel bills, the trucker would make that back in probably just a couple long hauls.

2) I know that the truckers often don't own the tractors, but seeing as how these are essentially add-ons that the trucker would attach to the back of the trailer during a long haul (using some sort of clips), and trailers are fairly standard in dimensions (), it seems that the truckers could add these on to their loads themselves.. I don't see why the manufacturers have to be the supplier?... Or maybe my ignorance is showing through.. heh..

[4536]

I agree. There is no doubt that alot of $ and fuel could be saved on long hauls. As fuel prices significantly increase, as I suspect they will, there will be more motivation to make changes. A fair number of independent truckers have made improvements to their tractors and some fleet owners have made changes to their tractor/trailor combs, but it might be tricky to come up with a way to attach a device to some one elses trailor without putting mounting holes in it that might cause leaks when the device is removed.

Now if the aerodynamic aftermarket industry and the trucking industry or the government could come with standard mounting plates to be attached to the rear of existing and new tractors, I think that significant progress could be made.

If they do not, they will face incresing competition from the railroad industry that can deliver more cargo at less cost as fuel prices rise. Warren Buffet, one of the most successful investors of our era is betting on the railroad industry.

[slowmover]

Most travel trailers only travel about 500 miles a year. Unless you are one of those exceptions that travels more. The aero advantage is not worth the sacrifice of cost and interior space.

Travel trailers vary greatly in design and application. Most are sold, these days, to those with time (older, no children at home). Since the de-regulation of airlines in 1978, the tremendous increase in commercial truck traffic at the same time, and the decline in the average Americans income (since 1972; against increased fixed costs), the day of all-aluminum, aerodynamic trailers has pretty well passed. Cheaper, easier to fly & rent for many. But such was once not the case, as the better trailers were bought by families for extensive travel. This is to say that the high end travel trailers were meant to be used for decades, with excellent road manners, and low overall cost of ownership.

I'm third generation, looking for yet another. My folks kept theirs for 27-years. As to the "practicality" of the right travel trailer (TT), aero has significant advantages not only in fuel economy. Rounded edges/corners/fully enclosed undersides means winds just roll off of them. I have seen ordinary "boxes" heeling over like sailboats, and accidents from strong winds are not rare. Same for being parked. More than once I have seen an aero trailer advertised as being a survivor of multiple hurricanes (FL) where others blew away or blew apart.

Most important is in handling the headwinds of tractor-trailers, especially when on a two-lane and several trucks coming the other way are traveling close together . . the effect of multiple bow waves is an accident coming at you (if the trailer is a box). A "sway-eliminating" hitch is only just good enough (such as Pro Pride).

Aero-formed with light, strong construction has no equal. When the trailer also has independent suspension, the combination cannot be beat (assuming also disc brakes) for roadworthiness.

I am aware of no space reduction on trailers from, say, 1960 to 1990 (the ones from the 1930's to the early 50's were towed behind seriously underpowered cars).

A fuel economy gain of 20% is ordinary. When the TV (tow vehicle) is intelligently matched, the gains can be better if one is perfectionistic about all details related to "steady state" highway operation (my term). A turbodiesel is the best in that case. (The Europeans received the Chrysler 300 in wagon form with a near-perfect TD engine that could have been a heckuva TV for North America, at a reasonable price).

The gains are in fuel economy, unit life, and on-road performance. They must be balanced. (And you would never see me buy a square white box as they fall apart after a half-dozen years, have terrible road manners, poor insulation, etc).

The better ones (Arctic Fox) may last a bit longer, but suffer from the shoebox design that never allows one to feel as if he were sitting outside once parked. Unfortunately the AWARD trailers had serious deficiencies. CASITA is one brand of tiny trailers that is well received.

If someone were so inclined, a good project helpful to all would be to design an alternative air-conditioner shroud, as those roof units are used on all types. That the manufacturers have low-profile units now only illustrates the problem.

There are plenty of us (a small subset, granted) who have, or will, travel full time with extended parking contemplated for living. Also, being on the Gulf Coast I see a good trailer as being nothing more than prudent. The number of people in the future needing affordable portable housing will only increase, IMO. Aero is part of that. One should not need a pickup to tow a 7,000-lb trailer.

[Bicycle Bob]

J. Baldwin, long-time Tech editor for Whole Earth, resided happily for many years in an Airstream. It was known as "the Silver Turd."
I've had tentative plans for a bus or trailer conversion with all the utilities lined up on one side, and the other wall folding down into an extended floor, with an arch-rib greenhouse structure filling the resulting gap.