Thumper wrote:
Don't forget the added stiffness that the U shaped aluminum track give.
TooBusy wrote:
Just a little bit of engineering here.
Assuming
2x3 .125 wall box section steel tube
144 inch single beam length
1500 pound load ( a little heavy for a typical Locost)
A single 2x3 box beam would support a Locost with a maximum deflection of 2.2 inches and a maximum stress of a tad over 55kpsi, well below it's yield.
A similar 2x3 with only .065 wall would deflect a little less than 3 1/2 inches at a max stress a tad over 87kpsi, still well below it's yield
That's 1 steel beam supporting a car with reasonable deflection over a 12 foot span.
Now consider 2 side beams plus a center backbone. Yes, the trailer will flex a bit, about 1 inch, but the max stress drops to 29kpsi. This ultralight would handle a lifetime of hauling one of our cars without a fatigue failure.
Add a top rail or low triangle like horizenjob mentions and you've got a simple truss than deflects < 1/4 inch.
Yep, the C channel adds stiffness as well. I left it out of my rough estimate because of the 120 angle instead of a true "C" and I didn't know how you had it attached.
Your design is more than adequate for our little cars. Nice job sir!
oh, and thanks for the plans. This is on my to do list.