Does the Folding Wing Make It Weaker?
folding wing modifications for the Mustang II do not change the main wing spar.
Ultimate G loading is therefore not changed. The only structural difference is the wing rear spar
attachment. From a design
standpoint the folding wing version is stronger than the standard fixed wing
airplane. This is because a 4130
steel bracket is used on the center section rear spar to attach the outer wing
rear spar. The wing has an extra
rear spar attach fitting added to sandwich a rod end bearing threaded into the
center section steel fitting.
The folding wing is a mechanical device and is therefore more vulnerable to user-induced damage. Because of this, the manual says no aerobatics with the folding wing. The problem is if the wing is damaged while being folded and not repaired before being put through the rigors of aerobatics. We cannot control a circumstance where someone drops the wing while folding it or trailers it improperly and then without completing a proper inspection subjects the aircraft to high inflight loads. The rear spar absorbs the wing's drag load, which is highest during high angles of attack and high airspeeds. There has, however, never been a problem with our folding wing design over the many years it has been used.