In place of the curtailed B-57A, a more refined bomber variant, the "B-57B", was developed. Having a more lengthy development time, this model incorporated the structural and system changes that had been recommended by WADC, which resulted in the aircraft being more adaptable than its B-57A predecessor. Of the external changes, the most significant was the adoption of a fighter-style canopy accompanied by a flat-panel windshield and a tandem seating arrangement, providing for greater transparency and an improved view for both the pilot and navigator, as well as allowing for a gunsight to be equipped. The corresponding glazed bombing nose of the B-57A was deleted along with the starboard crew entrance to the cockpit.