Buy a new 5th wheel, ripe project for a boat tail

[aerostealth]

[freebeard]

That basically the stuff. Foamed plastic instead of recycled thermoplastic. Thinner skins. How thick do you think that foil coating is? Will you have scraps to experiment with?

The first obvious question is "can you bend it?" Maybe a wringer that has a big roller on the bottom and a small one on the top, to lightly crush the foam on the inside of the curve.

You can make seams by cutting 1/8-1/4" slots in the foam and using splines. Glue or rivets staggered side to side.

Are you going to laminate loose fiberglass cloth? If you completed the foam structure and sewed up a fiberglass 'sock', you could pull it in tension over the whole surface with clamps and then resin it in place. It would be stronger and probably require less putty and sanding to get a finished surface.

[aerostealth]

We are building a Achmed boat tail which has strait sides. The roof has a slight curvature to it for a high center. I may try to curve the top piece a little.

[slowmover]

Don't forget rolling resistance. RV are notorious for improper amount of bearing grease and pre set. Figure that axle alignment is not correct. Adding shock absorbers and improved Spring equalizers is also worthwhile as direct and indirect mpg improves. A corrected baseline, in other words.

If tires are ST type, I'd change em out pronto for LT tires of greater loAd reserve. Centramatic balancers also worthwhile.

All of these will lessen effort at the steering wheel. More positive feedback.

Looking forward to how things go.

[freebeard]

Try this on a scrap: Lay a piece on a flat surface and roll it wit a brayer (hard rubber roller) or rolling pin. It's thin enough I think that might be enough to put a curve in it.

[skyking]

Just found this, much like what I will do with ours.

My plan is to put a permanent 6~8" extension on the back that gets things pointed in the right direction, provides a nice box cavity when the tail is not on, and has the attach points on it.
I will make mine about 6' long and have a total of 6 pieces that will lay across the back on the bumper when not in use. I can petal-shape them to get some curvature.
One consideration is the clearance and tail lights. I have a trailer plug on the back of my 5th wheel that I will make a set of lights for.

[freebeard]

I just got a roll-around Office Depot crate w/ retractable handle and wheels. Translating it's folding scheme to the back of a motor home, the deck would fold up; the sides would bifold and pull the rear wall forward; and then the [curved] top cap would fold down to cover the whole thing.

Going from a cube to a trapezoidal prism; I'd need to experiment to confirm, but it seems like if the hinge in the sides is off-center it would still collapse.

That would lap correctly to shed rainwater. Top over sides over deck.

Since semi-permeable surfaces on the back of a box van are a thing; maybe it would be more aerodynamic as a screened porch. Two birds with one win.

[aerostealth]

Have to see it.

[freebeard]

http://www.amazon.com/Rubbermaid-3N83-Collapsible-Cargo-Crate/dp/B0011NCTJU

The lid is actually a separate piece.

[aerostealth]

Here is a side view of the trailer after we got back yesterday from getting the trailer braking problem diagnosed and fixed. You may note we took the rear shelf, bumper, and spare tire off.

We set out heading south with a 13 mph tailwind. We pulled up to 11.3 mpg with that making my actual airspeed equivalent to 50 mph. Round trip we drove 95 miles and averaged 9.3 mpg at the top of the driveway. These are computer generated numbers, but they are very encouraging none the less.

An 18% improvement in mpg from a 36% reduction in wake area gets me up to 11 mpg, which is impressive for a rig this size. I am looking at trimming the bumpers on each side by about 6 inches which will stop them from sticking out into the air stream. We were very pleased with the new numbers we registered yesterday.