New stand-up tear design

[karch67]

I have been studying the forum for a couple of weeks now and came up with my first attempt at a design, would welcome comments and/or suggestions on it. I have posted a few pictures in my gallery at http://www.mikenchell.com/forums/album_personal.php?user_id=4459.
My main requirements are a full size bed, stand up height for a shower, toilet compartment, rear outside galley, and weight under 1500#. My T1 design would require a custom stepped frame and I am a little worried about the ground clearance of ~7" for the frame rails under the dropped floor. I am looking for suggestions on how to constuct the walls, was thinking of 1/8" interior skin, .75" plywood ribs/insulation, and aluminum skin on the outside. My question is do I need an outside wood skin to put the Aluminum on, and is the .75" thick framing sturdy enough for 6' high walls?

My main inspiration for the design was the Widget, many thanks to Andrew for all the excellent CAD work on all of his designs which are an invaluable reference.

[toypusher]

WOW! Seems like a pretty big tear to pull with an Element. I do like, though.

[karch67]

Yes, I think I may have to downsize it to keep it under the 1500# tow limit on the Element, I know from the Element forum there are a couple of people who pull Tab's with them so theoretically it is possible.

[bobhenry]

I have been studying the forum for a couple of weeks now and came up with my first attempt at a design, would welcome comments and/or suggestions on it. I have posted a few pictures in my gallery at http://www.mikenchell.com/forums/album_personal.php?user_id=4459.

My main requirements are a full size bed, stand up height for a shower, toilet compartment, rear outside galley, and weight under 1500#. My T1 design would require a custom stepped frame and I am a little worried about the ground clearance of ~7" for the frame rails under the dropped floor. I am looking for suggestions on how to constuct the walls, was thinking of 1/8" interior skin, .75" plywood ribs/insulation, and aluminum skin on the outside. My question is do I need an outside wood skin to put the Aluminum on, and is the .75" thick framing sturdy enough for 6' high walls?

My main inspiration for the design was the Widget, many thanks to Andrew for all the excellent CAD work on all of his designs which are an invaluable reference.

I would incorporate a skid plate at the front from frame to drop this way if you are unfortunate enough to encounter an obstacle the trailer would lift and ride over it rather than catching and bending the he%% out of the dropped frame. The shallower the angle the better !

[Miriam C.]

Looks good to me. Remember the side framing keeps it rigid. The stuff inside will keep the sides together. I added 1x2 framing because I wasn't putting much inside. Your shelving bed and bulk head wall will do a lot toward that goal.

[angib]

I don't see a problem with 7" under the frame - plenty of the fiberglass trailers have frames as low as, or lower than that. And occasionally touching the frame to the road isn't too harmful, though it sounds bad - you just need to make sure that nothing hangs below that.

Keeping under 1500lb seems very unlikely unless you are fanatical about weight control.

See the Glen-L photo build sequences for using only aluminium outer skin: trailer and truck camper. But I would point out the Brylcreem'd and combed quiff is not an essential part of the technique.......

Remember you need to keep the loaded weight under your Element's limit - so that means the trailer's empty weight must be 100-200lb less than that - more if you want a water tank.

Andrew

[karch67]

I did a quick wall design with some ribs and a quick weight estimate using the CAD software, the model shown below weighs 960# with all the major structure. I still need to add in cabinets, galley hardware, and seat bases but I think I may have a shot at bringing it in around 1300# dry.

[dhazard]

I like your rib design but… Can you get a sheet of ¾” that size? I would also add a connection from the door jam to window and the door jam to the forward rib.

[karch67]

I agree with you in attaching the door and window frames with cross braces, I haven't optimized the ribs yet, this was more to see where I am in regards to weight. 4x8 sheets would be used and spliced together to make the side panel frames.

[Rickxr2]

Edevans here on the forum has the drop floor you are
talking about. My first thought was ground clearance, he
said it wasn't a problem. The added height really makes
a difference inside.
http://www.mikenchell.com/forums/album_personal.php?user_id=2806

[bledsoe3]

Karch, That's one big tear. I like that you could have a table without it being part of the bed. Kind of reminds me of Steve's.

[Elumia]

Older travel trailers were build of 2x2's with Alum on the outside and 1/8" plywood insides skin. Many of them have lasted 20+ years and are very light weight. Easy to frame. Seems it would be less wasteful than cutting out all that plywood.

All trailers at some point will get leakage - or condensation in the walls. Would it be a concern to have your framing delaminating should it get wet?

Just some thoughts. I like the layout

Mark

[grant whipp]

Karch!

Nice design, well thought out, and it looks kind of familiar (Andrew, did you leak my drawings of the Campster12 ... ...?).

Depending on where you live, 5'x12'x3/4" plywood is available, though on the expen$$ive side. I think if you really want to be weight-conscious, you should look at the laminated framing methods used in the 1940's Streamline Midget and cut it down to the 3/4" wall thickness you are looking for, using 1x2s for the general verticle/horizontal wall ribs and something a little wider for the window surrounds and door hinge/jamb areas.

You can get away without outside wall sheathing if your exterior aluminum skin is an assembled RV-style rolled or "mesa'd" variety, usually in the .025" thickness (but also available in .019") ... the rolls or mesas give the thin aluminum ridigity. Nearly all travel trailers used this method for many, many years back in the '60s thru the late-'80s (some truck campers are still skinned that way), and with reasonable care have lasted a good long time.

You can get away from some nightmarish chassis framing (and some weight, too) if you build a traditional perimeter frame and then build a dropped foot well out of 16-guage sheetmetal and suspend it from the floor (the piece you cut from the floor becomes the floor of the footwell, the 16-guage is shaped in a sheetmetal break in a "Z" and forms the perimeter of the footwell).

I think you can achieve your goal of 1500#, especially if you pay real close attention to your framing methods and materials. If you look at how many wooden airplanes were framed, you'll discover some even more interesting possibilities.

Just some additional thoughts ... ...

Good Luck with the build! In the meantime ...

CHEERS!

Grant

[karch67]

Thanks for all the great suggestions! I agree using 1 x 2's as the studs and lapping the joints would give equal strength for a lower cost. Any idea how the trailer manufacturers attach the aluminum skin to the framing? I like the sheetmetal dropped floor idea as well.

Karch

[Elumia]

I am rehabbing an old travel trailer. The skin was held on by screws at the windows & doors, trim, seams in the skin and a few at the bottom an in the middle of long spans. There were some nails, but I beleive those wer used to hold the skin in place until the screws could be put in. seal them good.

Mark