 This resulted in several changes including the addition of a tailcone, sharpening the radar nose profile, thinning the intake lips, and reducing the cross-sectional area of the fuselage below the canopy.The construction of the airframe was fairly conventional, with a semi-monocoque frame and multi-spar wing.The aircraft used a measure of magnesium and titanium in the fuselage, the latter limited largely to the area around the engines and to fasteners.