The rest of the main construction of the bottom wings was fairly straightforward. The hinges are pinned, again using model railway track pins, to the rear spar, glued with epoxy (see early photo) and finally given a few wraps with carbon fibre tows. The rear section of the bottom wings is hinged using commercial flat plate hinges and is held in place by 2 small magnets, the theory being that the air flow will keep them in position once the airspeed has built up and this has proved to be the case.
The photo below shows the mechanism for locking the wings in place. There is very little tension in the springs when locked, they’re just there to stop any movement caused by vibration. They lock into slots cut into free-floating tongues that pass right through the top centre section and fuselage.
The tongues were originally made from 1.5mm paxolin circuit board but having given it some thought I came to the conclusion that the model would have better flight characteristics if the wings stayed in the non-folded position during flight, so I replaced the tongues with ones made from carbon fibre sheet!
If you haven’t used carbon fibre tows before I can highly recommend them where some extra strength is needed without adding too much weight. Just a few strands glued using epoxy, the best but a bit messy, or cyano, watch out for the fumes, will greatly increase the strength. I also moulded the tailskid from carbon fibre tows and epoxy; it has produced a very strong, light and flexible job.