Why does the Corsair have inverted gull wings?

The F4U was designed to operate from carriers, so the wing had to fold, and that requirement shaped the landing gear solution from the start. The designers considered retracting the main gear rearward, but with the chosen wing chord it was difficult to give the struts enough length for the huge propeller to keep sufficient clearance from the ground. Mounting the fighter on long, spindly legs was not a solution either: it would have made the aircraft heavy, fragile, and unstable on a moving deck.

The solution was an inverted gull wing. Beisel made the wing drop sharply from the fuselage and rise again toward the tips, so the wing reached its lowest point exactly where the landing gear was anchored. The legs could then be short and sturdy, and the required length of the struts was shortened considerably. The blades cleared the deck without needing stilts.

The negative dihedral of the inner wing section also brought a clean advantage: it allowed the wing and fuselage to meet at the optimal angle - an efficient right angle - to minimize drag, and it did so without resorting to wing-root fairings, the usual solution for smoothing that junction. The price was paid on the shop floor: the broken wing was heavier and harder to build, which offset some of those benefits. In exchange, the plane's zigzag outline gave the Corsair a silhouette unlike any other.