Thanks for the feedback on the brackets.
Not shown is the massive steel walls of the luggage bay that wrap around the frame rails, so throwing something around the top of the frame rail would be desirable but pretty impractical.
The cross braces huck bolted to the frame web are located within a few inches of the spans for the brackets, and since the farthest fiber of the bracket spans are touching the webbing, the load will get distributed pretty well on that bottom flange.
Approximate max static load of the webbing, per side:
aft (3 tank end) 300 lbs
mid (between) 280 lbs
front (front tank end) 260 lbs
total of 1680 lbs
Double that for some sort of safety factor, and it's still within the realm of probably not going to break.
What I'd like to do is duct tape my phone to the floor and drive over some speed bumps at different speeds - that should give me some measure of vertical acceleration over time, and give me an idea of what sort of dynamic acceleration I'd be expecting of the tank bracket system.
The floor of the cradle is constructed with 1.5"x3" thick wall channel, and the angled bracing is 2"x.5" flat bar. Only some of the floor components will be welded together, most of the components will be grade 8 bolts through members.
Your call out on the lower frame lip gives me an idea - it would be pretty trivial to lay a second cross-channel on the top of the frame, and hang the verticals from both sets of cross-channels. That would distribute the load significantly, and provide a safety factor that would make sense.
Remember too, the general plan is to drive anywhere with only half the tanks full. The worst case solution is all 4 tanks full for some reason. (two are waste, two are fresh)
Originally Posted by joeblack5
Nice drawing of the tank holders. All the weight is supported by the lower lip of the frame. It looks like with your design you are able to weld it all up and then angle it in between the frame rails. That is a great feature.
I would like the outer support brackets brackets to be a little steeper. For that an additional pipe could go above the frame rails. So in that case the potholes that will increase the forces by a factor of 2??.. just a guess... are not all concentrated on the lower lip of the frame.
You can pull your lower bearing member and my upper member together with all thread.