Need frame help

[dh]

I'm building my TD 9' long, and 64" wide. I'm building the frame 62" wide, and a few inches shy of 9' long with the walls and a front and back wood plate bringing everything up to final dimensions. I will have a 2"x2"x.25"x4' tongue, and plan to build the frame perimiter and first X member out of 2"x2"x.120" tube. I'm not building a sub floor, and the floor will rest directly on the X members, so I'm using 4 crossmembers evenly spaced to support the floor. My question is, is the .120" tubing heavy enough, and what is the minimum material I can get away with for the remaining 3 X members?

OH, I'm using a torsion axle too, here are a few othr specs,

In Gally,

Microwave
Cooler
AC
Stove
Maybe 80lbs supplies and foodstuff

On Tongue,

Tongue Box (Folding chairs, power cord, water hose, jack handle)
Battery
Propane Tank

[angib]

The 2"x2"x.25" tongue (single tongue, right?) 4 feet long passes the Aussie utility trailer tongue strength rule for a 1050lb trailer - I've suggested before that a teardrop trailer, subject to much less abuse, can double that weight, so you're good to around 2000lb.

I'm assuming the front and second cross-member are 30" apart - any less than that and the figures below do not apply.

Now that tongue, at its maximum loading, puts just a little too much force on the front cross-member for 2"x2"x11g (.120") - to match the tongue strength the front cross-member would need to be 2"x2"x3/16". However if the front wall of the teardrop is landing on that front cross-member, it will carry quite a lot of load itself, so I think in reality the 2"x2"x11g is enough.

For the second cross-member, 2"x2"x11g is enough and 2"x2"x14g (0.083") is nearly enough - but this cross-member can be the weak link, so I'd use the 11g.

For the rest of the frame, cross-members and main rails, 2"x2"x14g is enough, but you have to have (or be) a good enough welder to weld 14g properly - if in doubt, 11g is a safer bet for easy welding.

And, to throw a spanner in the works, I wouldn't say 2"x2"x0.25" is a very sensible choice - it's heavy and expensive, but not that strong. 2.5"x2.5"x11g would be a bit cheaper and lighter but just as strong, while 3"x3"x11g would be about the same price and weight but 20% stronger.

The bigger dimension tubes are also stiffer than smaller but thicker tube and with a fairly long single tongue, stiffer is good.

Andrew

[bobhenry]

My barn has a single tube 2 x 2 x 3/16 and it simply was not up to the task. While it did not fail it flexed enough to mash the front wall of the barn. I did run it all the way from front to rear with about 4' extending in front of the trailer. By extending it to the rear I was able to shim and drill it for a rear class 2 reciever tube for a 1 1/4 ball mount.

If you will look hard in the picture you will see we had to truss the tube to stiffen it with a front support an some 1/8 " x 1 1/2 flat strap. I am still experencing some side to side flex but the vertical flex has been eliminated. The vertical stub is placed at the front of the 8 foot trailers frame the barn cantilivers 2" forward that is why the support piece is 2' back.



many of the forum members expressed concern over the long expanse of the 2x2 tongue that this picture clearly shows and guess what they were right .....

[dh]

So, Andrew, what about stepping up to 2x2x3/16 tube instead of 2x2x.120, could I get away with 1x2x.125 channel or 2x2x.125 angle for the rest of the Xmembers?

I guess I'm not really concerned about about the tongue, I forgot to mention that I will have an "A" structure for mounting the box, propane tank, etc, this shoud give me pleanty of strength.

Edit:

I really don't want to go bigger than 2" on the frame, I need more head room!!!, thats why I'm doing away with the sub-floor.

[angib]

If you mean you're going to have an A-frame tongue, as shown below, then you can forget everything I wrote as it only applies to a single tongue design:



With a single tongue, the front two cross-members matter a lot. With an A-frame tongue only the front cross-member matters, and then a little bit, but not a whole lot. All the other cross-members aren't needed to tow the teardrop down the road, they're just to stop you falling out the bottom when you go to sleep*. Many teardrops appear to be designed to allow a barn dance to take place on the floor. Presumably the fiddle player stands outside? So I'd say the 2x2 angle is fine for all non-structural cross-members.

*Actually I'll add the proviso that leaf spring axles do need a cross-member near each spring perch, or maybe one cross-member between them.

Andrew

[dh]

Thanks for the help Andrew