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I want to build an Ultra-Light Teardrop.

PostPosted: Tue Aug 29, 2006 11:39 am
by Gerdo
I'm starting to think about building a second TD. This time I'm thinking of an ultra-light. Who has built one? Who has pictures/designs? What does it weigh? What would you change?

PostPosted: Tue Aug 29, 2006 11:46 am
by Steve Frederick
Is #740 light enough?

Peg's is a 4-by-8, sandwich construction, light frame, torsion axle..

PostPosted: Tue Aug 29, 2006 12:22 pm
by mikeschn
I take it you've already checked out the Ultralight Design thread from top to bottom?

http://tnttt.com/viewto ... ultralight


Mike...

PostPosted: Tue Aug 29, 2006 1:15 pm
by Gerdo
Mike
I searched for an article like this but could not find it. Still reading. Thanks.
Chris

PostPosted: Tue Aug 29, 2006 1:49 pm
by rmcelroy
I was dissapointed-I took mine to get it weighed and it came in at 560 lbs. I had hoped for about 400 to 450. But it still pulls pretty well.

It will be awhile but I may consider a second effort in the future.

Left out things like

12v battery pack
3/4" plywood galley cabinets
Propane tanks
Excessive frame work

Included

Aluminum frame
1/4" luan interior cabinet work

I will be trading my full torsen axle for a pair of shorties-which should get me down about 45-50 lbs.

I didn't have the cofidence to go really radical with hollow core door floor and cabin frame with 1/8" luan skin w/o aluminum, or all wood frame construction. There are some really creative folks here.

Mc

PostPosted: Tue Aug 29, 2006 2:23 pm
by Gerdo
Mike
I just finished reading the 15 pages on Ultralights. How is yours coming. Did you go with a straight tongue or an A frame? Did origimaly think of incorporating the HF frame into the floor (use the metalframe instead if wood sandwich)?

too light

PostPosted: Tue Aug 29, 2006 3:28 pm
by jay
don't confuse "creative" with, err, "not practical"

PostPosted: Tue Aug 29, 2006 4:07 pm
by mikeschn
Gerdo wrote:Mike
I just finished reading the 15 pages on Ultralights. How is yours coming. Did you go with a straight tongue or an A frame? Did origimaly think of incorporating the HF frame into the floor (use the metalframe instead if wood sandwich)?


Gerdo,

It's still on the bench in the basement. I had designed it to be 4' wide, andhalfway thru the build I decided I really want it to be 5' wide. I'm not sure the design is capable of 5'.

So it's sitting down there, as a future project.

Meanwhile, I've built the Escape Hatch/Winter Warrior which I designed a couple summers ago, and now my thoughts are turning to a more fully featured Winter Warrior. Meanwhile I want to do up a set of plans on ebay to increase the traffic here, plus I have a whole lot of CAD work I want to do.

But I have to agree with Jay. Creative is not always safe. I would definitely bounce any ideas off of Andrew before taking an untested concept on the road.

Mike...

PostPosted: Tue Aug 29, 2006 7:23 pm
by apratt
Mike, I can't see where there be any problem in making the ultralite into a 5 foot wide trailer?

PostPosted: Tue Aug 29, 2006 8:09 pm
by mikeschn
apratt wrote:Mike, I can't see where there be any problem in making the ultralite into a 5 foot wide trailer?


Arthur,

A couple problems come to mind, not all of which are design related...

1) The HF axle is set up for a 4' wide trailer

2) The sides are made out of 5mm luan. Is that strong enough for a torsion box, or do I need to have 1/4" baltic birch, with it's many layers?

I imagine if the torsion box is strong enough, and the axle is wide enough, and the floor is stiff enough, then it shouldn't be a problem.

Andrew, go ahead and take my theory and smash it to pieces! :BE

Mike...

PostPosted: Tue Aug 29, 2006 8:56 pm
by apratt
Sorry Mike, in my mind I changed a few things....
1) not use H/F axle, buy an axle kit to the width I need.
2) go with 1" frame and 1/8 panel for the walls.
3) use the A frame set that Andrew showed.

PostPosted: Thu Aug 31, 2006 1:33 am
by Roly Nelson
Gerdo, use a 40" x 48" HF frame, (150 Lbs) and build the 6 foot wooden teardrop using a 1 3/8" hollow core door for the floor, 1/4" sidewalls and 1/8" roof. All of this wood, with basic shelves and cabinets in the galley will only weigh 95 lb. I know, I did it and the TD only weighs 245 lbs.

Roly :thumbsup:

what an i missing?

PostPosted: Thu Aug 31, 2006 4:54 am
by jay
i understand "light" - but what is the purpose of "ultra-"?

tow by bike or human powered craft?

PostPosted: Thu Aug 31, 2006 9:07 am
by angib
apratt wrote:Mike, I can't see where there be any problem in making the ultralite into a 5 foot wide trailer?

I can't either. The only things that the extra width affects are the roof spars and the floor.

As I remember the Ultralight has a single skin roof, so the strength of the roof spars is quite important. On a 5ft span, even close-spaced 1x2s (with the 2 vertical) sounds a bit weak to me, but 1x3s sounds over the top, so maybe it's 1x3s cut down to 3/4"x2" actual.

As the floor is a sandwich panel, I don't think the 5ft span is any problem - Mike drew 1/4" ply top and bottom which I think is probably overkill! My only concern would be the point load on the front of the floor if a single tongue is used - using a piece of oak (of the same size) instead of softwood would address that.

I can't see any problem with the axle on a 5ft wide - except that you can't use a HF trailer kit. Either torsion or leaf spring would do, though I would have a preference for torsion as it provides a strong cross-member for free.

On the subject of the axle, I have now seen a couple of places where it clearly shows that in full-beam torsion axles, the rubber goes nowhere near the middle, so Mike's original idea of welding a single tongue to the middle should work fine - though as I mentioned before, I guess you can kiss goodbye any warranty on the axle. I still prefer an A-frame for the lower load it puts on the body.

Andrew

PostPosted: Fri Sep 01, 2006 9:31 am
by Gerdo
Roly
Can you post any build descriptions and pictures so I can see how you kept the weight down. I don't want to over build but I also don't want to under build it and have it flimsy. I would hate to see it blow apart on the highway.