Why do the Corsair's wings join the fuselage at a right angle?

To accommodate a folding wing, the designers considered retracting the main gear rearward, but with the chosen wing chord it was difficult to make the struts long enough to clear the large propeller, and the solution was the inverted gull wing, which considerably shortened the required strut length. With the chosen chord it was hard for the legs to give the propeller enough clearance, and the inverted gull wing greatly shortened the main gear legs. To keep the huge blades clear of the deck without a stilt-legged gear, Beisel bent the wing: it dropped sharply from the fuselage and rose again toward the tips, the famous inverted gull. Thus propeller clearance was solved by placing the main gear at the lowest point of the V formed by each wing, with a short, sturdy leg.

The negative dihedral of the inner wing section also allowed the wing and fuselage to meet at the optimal angle to minimize drag, without resorting to root fairings. The inverted gull design made the most of structural strength through the angle at which the wing joined the fuselage, while minimizing aerodynamic drag.

Vought's V-166B already featured wing stubs emerging from the fuselage dropping at an angle, with the outer panels climbing back up, giving the aircraft its characteristic inverted gull appearance. The bent wing, however, was heavier and harder to build, which offset those advantages.