kreb wrote:
Not to diss on the Goblin, which I respect, but I find it interesting that they could have tightened the clearances quite a bit without making it any harder to fit and weld.
I too brought my triangulation tubes in adjacent to the node, rather than fully into it, with the triangulations tubes offset to create a 0.5" gap on the tight angle side. My intention is to also go back and reinforce the gap with fully wrapped (3-sided) 'taco' gussets, made from the same square chassis tube with one side cut off. While my design has definitely allowed better welding access (and subsequently better welds) than than I otherwise would have been able to achieve if bringing the triangulation tube directly into the node, I can also tell you that the 0.5" gap is still too tight from a manufacturability standpoint. I would guess to continue seeing manufacturability improvements continuing easily through a 1" gap, and probably at least a bit beyond, but without further experimentation I can't really say how far out the 'sweet spot' might actually end up either. Like Kurt said, it's all a balancing act when designing and building for production.
I'd also clarify that the takeaway from FIA Appendix J is simply that the larger and heavier the tubing is, the larger the gap may be...Not that a nearly 4" gap is an acceptable general design practice throughout a spaceframe chassis. Which goes back to the first statement in my previous post though. Along with that, increasing stiffness is a game of diminishing returns, and there has to be a point where it becomes 'stiff enough'. And while I don't know how stiff their chassis is, but I wouldn't be surprised if it is in fact quite a bit stiffer than most book based Locost chassis...Which also still tend to perform more than adequately for most enthusiasts.
TLDR: From a technical standpoint, I agree with you completely. But from a manufacturability standpoint, I also agree with them...At least up to a point.