It's been a while since we kept you folks posted on the Starwind 860 project. Don't worry, it hasn't died – we've just been busy!
The crossbeam webs are laminated from two layers of 12 mm marine ply. The inner layer includes this cutout...
...which is used to align the strut block in the crossbeam. The final alignment of the strut bearings should, with this arrangement, be accurate to 2-3 mm in 3D space.
A couple of plywood bulkheads set the web-to-web spacing at the ends of the crossbeam. We've used short chopped glass fibre, instead of the more common silica colloids, for the epoxy fillet.
When gluing all this up, it helps to pre-cut all the required fibreglass and lay the bits in convenient spots. The stuff's a pain in the arse to cut once your gloves are wet with epoxy, and pre-cutting it saves precious working time.
This last bit of tabbing will never take much of a load, but it's important for keeping everything rigidly aligned while we finish assembling the crossbeam.