Quote:
Originally Posted by slowmover
Shape is important, and I'll leave that to others better versed. Height is the highway mpg killer, before all others. After that is the need for radiused wall joins. Rolled. Top & bottom. Enclosed undercarriage. (This done, don't worry about adding Coleman Mach 8 roof air and/or Fantastic Fans).
Go have a long look at the UHaul 12'x6'x6' trailer. Great utilitarian shape. Great towing manners with tandem axle. Wide spread axle (roll center problems minimized as leaf springs are joined to axles beneath or outboard of side walls). Low ground clearance.
I used this behind my truck on two 700-mile round trips. Four legs. Two each loaded and empty. Same load. Same road and conditions. Truck is 8k solo, and combined rig was 13k. Solo mpg was always 24 (up to 27). Trailer empty was 19-mpg. Trailer loaded was 18-mpg. Always at 58-mph and never a tailwind. Gulf Coast Texas. And always traversing Houston.
About a 25-30% penalty. Doesn't get better than that. But it might with help from this crowd. Truck has cab height topper and trailer roof was same height.
I'd pretty much copy that trailer, but give it a rounded bullet nose. And an EM approved swing away tail. I'd also change to torsion axles (wheel face is now equivalent to leaf join at axle per roll center). A Towtector to build an interface upon.
And Polymetal. Somewhere. (I ain't ragging you, Freedom-of-the-Beard)
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Yes, hight is a killer, thats why i decided on a pop-up instead of a one piece.
With the radiuses that was my second biggest mistake. I used 2x4's to build the frame and intended to router a radius onto all sides. I completely forgot and cant go back and do it now. Quite unbelievable really...
I am going to have to try to think of a way to round those without changing whats built.
Was planning to make side skirts, the bottoms of them should be rounded too?
With the undercarriage i was thinking cloroplast or something light to smooth it out. However i really want/don's want to put a big water tank and a spare tire under the trailer. We need a fair bit of water for our trip, i want to keep the weight low, it needs to be by the axle and i have other things i also want by the axle inside the trailer. With the spare tire too... dont want anything under there catching wind but i have to be real careful how i load my trailer to keep the tongue weight right and keep it from being a see-saw.
Thanks for the tip on the u-haul! There is a location close to me, i will go have a look at them.
I towed a 5x5x8 u-haul before i started to see if this style of car could do it. It weighed 900 pounds empty which was about as much as i wanted to pull with the hitch i had on the car. I put an extra 500 pounds in the car and headed for the biggest hills i could find. Its like a parachute but i got 25 usmpg pushing the car real hard trying to keep it at 60-70mph or whatever 5500rpm would get me to on hills. Iirc 50mph was the most i slowed down to on the biggest hill.
That was to see if the car would overheat, what my worst possible fuel milage would be, and how it handled. It handled suprisingly well considering how light the tongue weight was (only 50 pounds!) And i slowed down on an empty strech of road, went to the middle and started swinging it. Trailer was very stable and immediatly went straight when i stopped moving the wheel. I was very impressed with the u-haul!
Not so impressed with my '02 civic though. I towed the u-haul home on flat ground with it only 50km. Oil temps went super high immediatly and it blew the head gasket. I thought there was no way the little car would do it and almost didnt even bother trying. but it stayed cool that day and even stopped the trailer as fast or faster than the civic!
With the axle style- i made a hurried choice and cant return this one now.
This was a 2000 pound trailer, i plan for its final loaded weight to be 1700 pounds max. I intend to drive it like you would an otr semi at 130,000 pounds. I like that, however i dont want to be going down big hills at 20mph. I installed front brakes on the car that are nearly twice as big as oem and i bought a 3500 pound braked axle and installed it on the trailer. The axle was on sale cheap. I didnt find out about tortion axles being better till after i had installed it... Im going to stick with this axle i think. Leaf springs seem to ride fairly well when loaded near their max weight and all my weight in the trailer will be very low down. Nothing at all higher than 2ft above the floor.
Thanks for the towtector tip. I had been considering something stretchy to go from the bottom of the car bumper to the underside of the trailer to help airflow and to deflect rocks. Is that a good or bad idea?
Quote:
Originally Posted by freebeard
Eh?
How did you know I was going to post this picture again? I should go out and get another scrap and try the braked edge again. Had it been scored or rabbeted on the backside it wouldn't have ruptured the outer skin:
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I saw that before when i was on this forum almost a year ago, what is it? I cant remember. Can you send me a link to the thread where you talked about it?