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First, I’ve decided to use the well-respected NACA 23112 airfoil – as recommended by nearly all modern Flea designers.  It is a much thinner airfoil that the NACA 747a315 I had been considering, but it has a much higher max Cl (1.5 vs 1.35), which lowers the stall by 5 kts.

Second, I’ve been agonising over how to pivot wings which need to pass through the fuselage.  Why do they need to pass through the fuse?  Well, if they didn’t, I’d have to secure them to the airframe at three points (at the pivot point, and on the pivot line outboard just like other Fleas.  Three external tubes on each side.  And that would spoil the aesthetic completely.  So in order to make them clutter free, the main spar would need to pass though the fuselage like all other cantilevered wing airplanes.

If there were only one wing, I’d simply close in the D-tube, and that would provide the required stiffness and torsional rigidity.  But check out what would happen at thew rerar wing.  The D-tube would go right through the pilot’s bum.  Not a pleasant prospect.

My solution is to have a super-wide main spar (100mm in fact).  Closed in on both sides, this would form a very stiff replacement for the usual D-tube, and protect the pilot’s bum at the same time.  The main spar will be attached to a 25mm tube, which rotates in two bearings fixed to the bulkheads.  Secure, simple and effective.

The outer panels don’t require this oversized main spar, and will revert to the usual 20mmx20mm spar caps.