The D.I incorporated a relatively unconventional innovation in the form of an unusual aerofoil section. Specifically, the upper camber of the wing had a pronounced reflex curvature towards its trailing edge, while the maximum depth was further aft than was standard amongst contemporary fighter aircraft. To enable this unusual construction, the rear-portion of the ribs were somewhat thin and flexible, resulting the wing "giving" under sudden forces such as gusts of wind, but without losing equilibrium. According to Haddow, these features of the wing were attributable for the D.I's high level of stability, which allegedly did little to lessen or undermine its responsiveness to control inputs, as would normally be the case amongst typical aerodynamically stable fighters.