The B-58 was developed during the 1950s for the United States Air Force (USAF) Strategic Air Command (SAC). To achieve the high speeds desired, Convair adapted the delta wing used by contemporary fighters such as the Convair F-102. The bomber was powered by four General Electric J79 engines in underwing pods. It had no bomb bay: it carried a single nuclear weapon plus fuel in a combination bomb/fuel pod underneath the fuselage. Later, four external hardpoints were added, enabling it to carry up to five weapons. The B-58 was designed to fly at high altitudes and supersonic speeds to avoid Soviet interceptors. But with the Soviet introduction of high-altitude surface-to-air missiles, the B-58 was forced to adopt a low-level-penetration role that severely limited its range and strategic value. It was never used to deliver conventional bombs. The B-58 was substantially more expensive to operate than other bombers, such as the Boeing B-52 Stratofortress, and required more frequent aerial refueling. The B-58 also suffered from a high rate of accidental losses. These factors resulted in a relatively brief operational career of ten years. The B-58 was succeeded in its role by the smaller, swing-wing FB-111A. The B-58 was operated by a crew of three: pilot, bombardier/navigator, and defensive systems operator. They were seated in separated tandem cockpits. The pilot's cockpit, which was provided with very deep windows, was considered to be mostly conventional for a large multi-engine aircraft.[23][22] The defensive systems operator was provisioned with a complex arrangement of different systems, which Gunston and Gilchrist describe as being the most complicated of any aircraft of the era. The space allocated to the crew, despite being roughly half of the fuselage's internal volume, was typically considered to be cramped and claustrophobic. Number built 116 For more details of development, design and operational history, click here.