Wooden teardrop (no steel frame)

[Arne]

I'm back on this topic during the winter dodrums. Has anyone else been thinking about this?

The walls get built first, with a cleat along the bottom of the wall to hold the floor. The walls give the floor it's anit-sag quality. There would be x-members under the floor.

It would use a torsion axle. The floor would be 3/4" ply, reinforced with a second 3/4" ply piece where the axle and tongue attached.

The tongue would be long enough under the tear to 'T' up to the axle. The front of the tongue, under the tear would have a plate welded to it, and another doubler of 3/4" ply would be put under the front of the tear.

The torsion and tongue plates would be mounted as close to the vertical edges as possible to take advantage of the rigidity of the wall area...

I'm still wondering about whether the cleat should be above or below the floor.....

Anyway, looking for comments..... there is a weight and $$ savings advantage. Also, no metal is needed till the tear is almost done...

I'm assuming a torsion axle can be built to a custom width with little or no additional cost..?? If not, the tear could be built to a std. width axle...

[DANL]

Hi Arne,

Let me preface this by saying that I am not an engineer nor do I have any qualifications to comment on this other than instinct.

First point: I recall back about two or three decades there was experimentation building Indy type racers with plywood unibody construction. Obviously, this never went far but the tests revealed a better than steel strength-to-weight ratio. Anyway...

Point two: As I look at the mounting brackets on my torsion axles I have to wonder how much strain is put on the attachment points. Just conjuring up a mental vision of the forces involved makes me think that I would use a piece of angle iron at least three feet long running along the bottom of the wall/floor joint to spread out the flexing loads.

I could be totally wrong on this. As I said, just a gut feeling.

Other than that, I think a totally wood tear would be totally cool.

Now, if we had a really huge pile of money, we could build a total carbon fiber tear and tow it with a kick scooter. Since it would be so light that it would float a few inches off the ground, wheels and suspension would not be required.

[Gus]

Some of the 1st tears built were of wood frames. I think they wouldn't pass the DMV now tho. Maybe I ought to check and see if it would pass! They proly wouldn't hold up at the speeds we now travel.

[Jiminsav]

well well well..it just so happens that i atempted to make a wooden frame for my tear, and I used a box frame configuation, and low and behold, the tongue was an issue that I couldn't resolve, and the torsion half shafts i used put way too much strain on the plywood and beam i used, so i scrapped that idea and put the metal frame i welded up for the first attemp back under the cabin i have now, so i'm actually working on teardrop 2.5 here.

[Arne]

Well, they built PT boats out of wood. Don't think they were fiberglassed. And they took a beating.

One thing would be how rigid the suspension was. If it was too rigid, a lot of road irregularities would be transmitted (the axle would have to be closely matched to the max weight)... I don't think torsion stubs could be used, it would have to be a full axle to spread the load..... extending the pads with angle iron is a good idea.

The 3/4" doubled up would be 1.5 inches of wood.... that would be pretty rugged... that floor wall attachment would be critical as the wall has to be a structural part of the package...... I'm still thinking...

[josephhanson]

My dad built a utility trailer out of wood. The toung was metal pipe. the floor and frame members were all wood. It is a 5 x 9 trailer that will haul as much weight as any metal framed trailer. Don't say that wood won't hold the weight. Have you ever been in a three story wood frame building? A metal frame is easier to build and will require less attention through the years, but the home craftsman can build a wood frame trailer that is safe and efficient.

[mikeschn]

What about something like this?



Mike...

[SteveH]

What about something like this?

Cool Mike. Aren't those called IGA's by the construction industry? Wonder what that means?

[mikeschn]

I've never heard of IGAs. I call them wooden structural beams!

Mike...

[Ken A Hood]

There's also the "SIPS" panels. They would be ideal for the walls if you could find a company to cut the profile out, windows, doors, electrical etc....

[Joseph]

If I had it to do over, I'd have built a wooden frame and used the money I spent on my HF frame for an axle, larger wheels and nicer fenders.

Live & learn, die & forget it all...

Joseph

[McTeardrops]

Arne

I used my axle in this configuration to haul home the steel for the chassis and the oak for the subframe. Towed like a dream with the oak at 80mph on I-30. With twentyfour foot lengths of tubing on rutted surface roads it still tracked straight, but the steel swayed side to side about a lane and a half! The doubler at the axle to tongue connection is a split section of
2 1/2" tube, 1/4" wall. See avatar. The sub-assemblys bolt together, and hang on the garage wall when the axle moves back under the TD

http://img.photobucket.com/albums/v378/ ... mber-4.jpg

[Arne]

Lenny, chop off the tongue tube right behind the axle, and that is what I'm talking about...!

Mike, disecting you drawing. First, the sides aren't needed because the walls would serve the same purpose, only better. After all, they vary from 12 inches at the back to 48 inches near the middle and front.

x-bars: not sure about this one. But, in some places on my tear, I use 2x3's turned sideways, 3/4" deck, and no springing. I think those beams are overkill unless you want them for storage.

If a tear were built with some thought, I think it would be just like a cardboard box, and lifted from the middle of the sides, would not sag.

The only downside I see is the gally hatch could not go to the floor. It would have to end at least 12" above the floor for a stable platform...

I wish I had your ability to mess around with some of this cad type stuff to develop some drawings, but I might try it on a piece of graph paper.

[Guy]

Dear Mike,

The wooden chassis you have there works with some revisions. First you are using "wood I-Joists" The flange must be some graded lumber or LVL . The web is either plywood or Advantech OSB.

What you are building is really nothing more than a torsion box, more familiar when used as a hollow core door, the top and bottom sheets provides the additional racking strength and surface glue strength. ( Especially if you do not put another I-joist down the middle. The two most important considerations are (the Chorus, "Here goes Guy again!!!!") first, the Glue used in the making of the i-joist. Ashland, which is the company better known for Valvoline oil make adhesives specifically for I-joist and other structurally important wood laminations. I think they are called, Isoset and Isogrip. Second, the connection to the axle must be significantly strengthened since, as you are well aware, bolts react differently than welds. A gusset of some form will probably suffice. Steve will know about dramatically increasing a bolts' strength when using wood and epoxy. It is something about drilling a hole wider than the bolt.

[mikeschn]

I'm really looking for someone like you who could take the concept and run with it... heck, it would be cool if you could improve on it.

But maybe I'm getting ahead of myself... first of all I should probably ask, is there a place on todays highways for a wooden frame? Or should we really be building wooden boxes with steel tongues?

Mike..