A few thought on lighter foamies.

[loaderman]

my foamie isapprox 500lb total, with mattress. that includes the frame, which is 265lbs.

1.The frame is over 1/2 the weight. Really need to make the frame lighter.
Been reading about moncoque and unibody designs.
For us the walls need to replace the frame, they are actually just really tall beams, and have the floor hang off the walls. Easy to do if your walls are between the wheels.
Working on how to do it when your going maximum width and have to go over the wheels with the body.

2.Also if you put foam in the floor it becomes a torsion box and you do not need heavy plywood or anywhere near as much for 'joists'/framing.

3. Instead of using wood or metal joists in the floor I am wondering about wrapping the edge of the Styrofoam with canvas and glue/paint. Say use 2x8 Styrofoam, wrap the edge with canvas (do not need to do whole surface). So every 2' you have a double layer of canvas. then put a 1x2 or whatever thickness your floor is around the perimeter and plywood on top and bottom. All glued of course.

[GPW]

How light do you need to make it ... I was thinking of motorcycle tires/rims for a real light one ...
The trailers are the heaviest item ... Good place to re-think a light er construction method ... like a tubing or Aluminum frame ... ?

[loaderman]

How light ? Perfect world - For me I am trying to build a big one 28' but want it light so I can pull it with a minivan that can tow 1800lbs. Would even settle for using a 1/2 ton.

For those wanting a really light smaller trailer motorcycle tires might be a good idea. Just remember they have to be able to carry the weight you are putting on them. You can get motorcycle tires/rims that mount like a car tire, they bolt on from one side.

Aluminum frame is a good possibility, especially if you construct it with a unibody design. Now aluminum is not cheap but on a smaller trailer you would not need a lot. Make the frame as part of the floors/walls. Often I see the trailer with cross braces and a full perimeter frame then another wood frame on top of that. Seems redundant.
As another note Aluminum takes special welding, although I have seen large trailers that were bolted together, using U-bolts and gussets/fish plates.

[GPW]

Drilling and bolting Aluminum is Easy ... welding it takes special eqpt. and skill ...
I always look through the vintage plans to see what the Old Timers did .... if it worked for them ...

[loaderman]

I agree. Some of the old time homemade ones had no frame. Basically build the cabin and attach wheels and a tow bar on the front. But I couldn't get that licensed here. So by making the frame part of the floor/walls I can reduce weight and keep the powers that be happy.

[loaderman]

Here is the idea I am thinkning on. Of course you scale the size of the aluminim L to your build.

[loaderman]

Here is the idea I am thinkning on. Of course you scale the size of the aluminim L to your build.

did not label it on diagram, under the floor joists there would be 1/8" plywood , the brown layer.

[dogeron52]

http://tnttt.com/album_ ... c_id=87519[img]


this is one approach

Dog52[/img]

[mezmo]

Hi dogeron52,

What is the link you got your album pic from? I've been trying to find
that web site but haven't been successful.

Thanks,

Cheers,
Norm/mezmo

[dogeron52]

http://www.epoxyworks.com/indexprojects.html

non marine use, projects from Jon Staudacher

Dog

[dogeron52]

I am trying to design a trailer similar to this. With a trail manor type top to fit in the garage.

Dog

[Wobbly Wheels]

I read much more than I post, but I figured I'd throw in a couple thoughts that have occurred to me while pondering this same idea....

Personally, I don't think aluminum is the best material for a trailer frame. Under normal road vibration, it will work harden and crack. If the arguments were in its favour as a structural material, we would see commercial trailers built with aluminum frames because, over millions of road miles, the initially higher cost would still pay for itself in increased payload and fuel savings. As it is, we do see aluminum used in more passive roles: most dump and trailer bodies are aluminum for that very reason....but the frames are still steel.

Secondly, I think there is value in having a significant portion of a trailer's weight down low. The first is simply to keep the CG's moment arm short - imagine pulling a foamie with a roof mounted a/c unit, especially a standie built on a narrow frame (as mine is designed). Whenever the wind blew or you took a corner at speed, the trailer's tracking would be out to lunch...or worse.
I'm planning on the additional weight of two deep cycle batteries and ~25 gallons of water over each end of the axle to balance the trailer's tendency to act like a sail in a crosswind and to keep that inside/windward tire stuck to the road.

BTW dog, good job posting the West link. I've been getting the (free) Epoxyworks magazine for a long time - good stuff....and no sweepstakes/junk mail because of it !

[linuxmanxxx]

I agree WW because for aluminum to work it would have to be one of the very very expensive alloys and that high a cost just can't be reckoned with raising the overall cost of a product vs using just standard much cheaper heavier steel. Building most of the frame structure from wood would be lighter but then you bring the rot aspect into the long term picture at the most perilous point of the towed vehicle.

The axle and springs are usually the heaviest part of a trailer structure unless it's just seriously over built steel wise in the framing and then the decking is the next heaviest thing.

The one I built wound up overall 1440 with all sandwich 3/4" walls and floors and 1 1/2" sandwich roof and the actual cabin weight is right around 650 pounds as the trailer was 730 empty when we started and at least 200 of that was the 2x6 flooring inside it which we left there. So dropping 200 from the wood and another 150 from axle and springs would take it down to around 480 using torsion axles. My cabin is 6x9 in size so there can be variations in size to reduce it further as well as this was an exterior of aluminum siding and luan which would further drop the weight if changed to a different exterior shell. So honestly if you massage things a lot a sandwich build can come in around 800 to 900 lbs and still have decent space inside the camper. In my 2 builds so far a lot of weight comes in the final skinning of the camper and mine have been both luan and one topped with FRP and the other with .30 aluminum skin and are a large portion of my overall weight of the cabin.

2 quickest reductions are torsion axles and changing the skin configuration.

[mezmo]

Thanks Dog!

Bookmarked that site - good info and inspiration material.

Cheers,
Norm/mezmo

[loaderman]

OK so I use steel for the angle.