I've reviewed a few A-Plane build logs and some builders try to save weight by replacing the 2x2 upper and lower tubes with 1x2 and atching the gussets with 3/16" stainless pull rivets only to find out they are nose heavy and end up with a chunk of lead bolted to the tailpost!This is a very good idea, and would bring the A-plane concept much closer to having some "real airplane" panache, gaining efficiency, and shedding weight like Billski is always haranguing us about.
If the ‘caps’ (for lack of a better term) of the channels were the same width on every component you could have a depth stop on your brake; push the pre-cut sheet in until it hits the stop then bend 90°, assuming the parts were milled/lasered/waterjetted with a good bit of accuracy then the web of the channels will stay compatible with each other. Really just adds to how it begs to be kitted. I don’t think there’s enough taper in the top and bottom keels to have to think about the diagonals being bent to anything other than right angles, they should torture into shape easily enough when riveting them together.all the diagonals will be different widths with flanges other than 90 degrees and if the top and bottom channels are not identical the diagonals will have to taper as well.
You’re right, it would need a mighty big brake. Some sheet metal shops could probably help out but admittedly it’s probably best as a kit that gets cut, drilled, and bent at the manufacturer.Bend plates have one problem. Having the bend tool that is long enough. Most tool are not longer than 1m. Mine is only 0,6m.
I was intrigued by the use of "thermoformed polystyrene" used for wing ribs on the production models. I can see certain advantages in the forming of flanges for stiffness and simplified attachment to tube spars. The sheet material could possibly be used for a formed leading edge and bonded to the ribs with adhesive. Hard to beat a light gauge aluminum formed rib for strength to weight but it appears polystyrene is viable in a light aircraft construction. Once you have the form you could knock out dozens of ribs is a short time inexpencively with thermoforming.The Butterfly was a Belgian kit (started as a hangglider but evolved into a very ultralight motorized airplane) which could be assembled with rivets in two weekends.
Pou-Guide - Un ultra-léger très ultra-léger: le BUTTERFLY