the wing tube looks a bit short. i have 2 aircraft w/wing tubes, proportionatly, i would think that the tube in this aircraft should go thru two rib bays each side. i haven't seen the plans yet, but guessing, the length you used may be the same length as a plywood joiner to join the spars. also, did you use a 1/4x20 blind nut in the rh wing panel to thread the nylon bolt into?
jon b