Trailer Mod Drawing to Scale

[aerostealth]

This is a scale drawing of the top of my Apex trailer to show the added mods for improved aerodynamic trailer towing. The scale is 1 ft per grid line. The trailer body increases from 19.5 ft long to nearly 26 ft including both the projected front and back modification. The side width is 90 inches or 7.5 wide. The second image at the right shows a side view of the boat tail only which is showing the top angle of 25 degrees to scale. The two side panels and the bottom panel will be at a 10 degree angle as shown.

I have seen in other threads a rationale for the trailer manufacturer to optimize interior space in trailers as a reason not to improve the aerodynamics of trailers. It is my position that this rationalization is not legitimate. As can be seen by my drawing the rear boat tail could be light in weight and made fold-able for storage when not in use. The front fascia can be light weight paneling also which would cover the propane tanks, and act as an additional storage area for light weight object like bed rolls etc.

The manufacturer really does not have a good reason not to include modifications like this into their trailer designs. With fascia surrounds for the AC unit if top mounted, and under belly enclosures to clean up the air under the trailer they would have a much better product that could cost the buyer up to 30% less in fuel cost to tow. You can not tell me that this would not sell if it was understood by the buyers. The manufacturer could incorporate these features much better then a Ecomodder tinkerer can after the the trailer design has been finalized. They could do it better, in a more durable fashion, and with a more pleasing aesthetics then most of us can in our garage. I think such a product enhancement could breathe some new life in this moribund industry.

The real reason it is not being done is fundamental lack of comprehension and insight into the physical laws governing low speed aerodynamics and its importance. In short they just are not all that sharp of pencil in their chosen field of trailer designing.

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[slowmover]

Conventional travel trailers have an economic life of approximately six years. It will be sold or traded at that point. It may have as much as 30k miles on it in that time, but I suspect it is less more than the majority of the time.

The suspension is flat dangerous. Aero is a ways behind this need to correct farm wagon suspensions. Even horse-drawn coaches from 150-yrs ago were better. This has to do with the trailer staying on the road.

My divergence from your point is minor. Both should be done. But until roof and wall seal lasts more than that six to ten years, it doesn't much matter about either of our objections given the few low stress miles covered.

[aerostealth]

My major point is that all this aero is better done during the design and manufacturing process. The unit cost goes way down due to assembly line techniques and then the actual cost of only a few hundred dollars is buried in the purchase price. The competitive advantage of having a product that requires 10% to 30% less fuel to tow is a no brainer and should appeal to any real capitalist who is worth his salt.

[slowmover]

Chrome and glitz sells cars. Chrysler products out handled, out braked and usually out accelerated GM and Ford in the 1960s. But was last in sales.

Trailers are sold on floor plans. Slide outs.

The big picture is that subsidized fuel makes an RV possible. And I've posted at LEAST a dozen times over the past dozen years an overall economical approach to having the more fuel efficient tow vehicle and trailer on WOODALLS. Hundreds of views of those posts, thousands overall. Think I've ever had a PM to ask more details? My combined rig is cheaper than nearly any conventional pairing, burns less fuel and will last far longer.

The appeal of the latest class of RV -- the toy hauler -- is that it carries yet more vehicles to burn yet more fuel. Requires a $70k pickup to tow it. Etc.

[aerostealth]

Sorry, I own a trailer and fuel cost are a primary consideration on every trip. So is it with the majority of TV owners. I am sure there are well heeled owners out there for which fuel cost are not a real consideration but I would bet they constitute a minor percentage of really big rig owners. Oddly enough better aero would contribute to better handling. I think this rationalizations for observed facts really just discounts the near total ignorance in this country for applied aerodynamics.

[slowmover]

Fuel cost consideration. Yes, along with handling safety. Question would be why anyone would choose an inefficient truck and trailer to start with when with not a great deal of reading one could have come up with a more efficient combination. And with lower depreciation. Better road performance. Don't answer, it isn't meant to be personal; it is, however, the general dilemma. Finance costs are the reason generally given for choices made. Brand new junk is more affordable, it is said, than a used quality trailer due to monthly loan note.

The "cost" of the RV is nights aboard over time owned. For most Americans it will be around thirty nights per year over six years. Fuel falls short of being as significant as lost market value. Add in the higher operating cost of, say, a pickup over a Camry or Accord to the above. This is seen as normal. As to vacation fuel, the advice is, "live with it".

There is not an "affordable" quality aero trailer as things are seen. Not of a reasonable size for a family. Age forty eight with one child or more. A twenty five foot Bigfoot or Airstream -- even used -- is not considered. Yet a ten year old example of either is competitive in price. And is less than halfway through a two dozen year lifespan.

But RVers aren't inclined to keep annual fuel cost records. To find where the family budget can be cut to finance vacation travel. Neither by keeping an old car longer, or in modifying solo duty driving. (Yes, one can find examples, I know of several with older Airstream trailers and older turbodiesel trucks. But they and I have tolerance for maintenance and repairs). Apparently vacations are to be free of any sort of work the rest of the year. Some minor upkeep at worst. And then trade vehicles after Mother Nature takes her toll.

At maybe 5000-miles/year, saving on fuel is seen as $450 in the difference between 10 and 15 mpg at $2.50 per gallon. It is not seen as worth trying to save $3000 in six years. The kids'll be grown and gone, or we'll move up to a motorhome, or what have you.

Floor plans and glitz. Carry my Harley in the back. Drive around the rest of the year in an empty DRW 4WD 9000-lb pickemup.

Hell, I can't even get others to find interest in cents-per-mile calculations on fuel by itself, much less the total costs. If there is a simpler way of understanding improvements, I'd like to know it. Takes away concern over the absolute number and focuses it on the percentage improvements.

Modifications to the existing trailer are seen as, first, unsightly, and, second, as an unnecessary waste of time to save so little.

The link to John Bridges modified trailer pics is case in point. A very good thread on Woodalls a half dozen years ago. But no follow up by others. I'd say that thread and Orbywans modified Class C on this forum the two best "how to" threads of the past decade. Anyone with a square box could use info from each.

Bridge begins his mods on a post in his forums off topic Mud Room entitled "The Great North American Tour of '07". Post #53. The links to the specifics of the mods are dead. Maybe one could contact him. A five month trip where a $7000 fuel cost was expected. He was happy with changes made. (He now pulls a 40' 5er with a turbodiesel truck).

See also the Woodalls 2010 thread: "Nose Cone Installation on TT" and "Wind Deflector on TT".

2009 thread: "Revised Wind Deflector"

[aerostealth]

Given the constraints of my inquiry all I am saying is that existing trailer design can be improved upon by aerodynamic modifications to make them use up to 30% less energy to tow with an increase in stability. The question to "Should they even exist" while interesting is moot within this frame of referance. It still begs the question as to why modifications that cost me around 1% of the purchase price of the trailer yet can save from 10 to 30% of the fuel cost are not a viable design option from the manufacturer. The answer is of course it could be. I have heard these various counter arguments about finance cost, cost per mile, ownership taste and goals and they just don't explain this glaring market place failure. The who purpose of Ecomodder is centered on this efficiency question and trailers are a good subset of this question. The real reason for this market failure is ignorance on both sides of the market, that is push and pull.

[aerohead]

I'm gonna go with a National Building Code for all recreational vehicles based upon thermodynamics.
The National Home Builders Association members cannot construct a home in the United States unless it meets certain minimum Federal criteria for thermal insulation to control its heating fuel economy/kW-h economy,National Plumbing Codes,National Electrical Codes.
The aerodynamic drag factor of an RV is the same to fuel economy as R-Factor and U-Value is to heating and cooling.
Electric and gas appliances are also subject to Federal standards.
I'm for huge government meddling in the marketplace,with onerous government regulations which mandate the equivalent of draconian CAFE standards for all RVs sold in the USA.
Consumers can remain as ignorant as they like,but they'll be structurally forbidden from purchasing a product which would be the engineering equivalent of a bingo ditch,trash incinerator, or toxic spill; and expect their neighbors to just absorb the insult.
Manufacturers would be totally free to build whatever they like as long as the minimum requirements were met.A level playing field.

[Hersbird]

What about trailers that seldom if ever move? Like the tiny house craze. In a way they are promoting smaller more efficient living but they put them on wheels often to skirt government authority on building codes. I've thought of a tiny house cabin if I ever am blessed with a mountain top peice of land so I could also move it out of any potential wildfire danger.

[Hersbird]

While I don't doubt the stats given by slowmover in regards to camper usage, I have to wonder if the lack of use is partly due to the lack of efficiency. The buyers probably intend to use them more but when faced with $4 gas and 8 MPG they end up spending $100 on gas for a weekend getaway. Add $25 a night at least to camp and you end up $75/night. Not to mention ll the hassles of a camper. Next thing you know you end up in hotels on the short trips and use the camper once a year. I have thought about renting a storage lot closer to the recreation area but we like to spread our trips around.