In need for transport for their Atomic Bomb, the French Air Force brought out specifications in 1954 for a very fast long distance bomber.
Dassault was leading a consortium that (at first) was monitoring the development of the Sud-Ouest S.O. 4050 Vautour, but their interest was focused in 1956 on the possibilities of re-developing earlier studies of Dassault for a two-engine night fighter.
These studies led to the design of the Mirage IV, in fact an enlarged Mirage III with two engines and possibilities to transport a 60 kiloton AN22 Glider bomb.
The prototype flew for the first time in June 1959 thanks to the propulsion of two SNECMA Atar 9 turbojets (59,53 kN). It proved that it could keep up speeds of Mach 2 at high altitude.
Three pre-production aircraft were build with over the whole slightly lager measurements and two Atar 9C turbojets (63,50 kN). The first of those three flew in October 1961 and represented the Mirage IV A production model with a round radar dome under de fuselage for the antenna of the bomb-aiming radar.
The last of the three pre-production models was fitted with Atar 9K engines, the possibility of midair refueling and the latest navigation- and attack-systems.
The Mirage IV A production counted a total of 62 aircraft, twelve of those were later converted to Mirage IV R strategic reconnaissance-aircraft with the CT52 'Mission package' in the former bomb-bay. In the middle of the eighties another 18 Mirage IV's were upgraded to Mirage IV P 'Missile Carriers' They got new navigation and attack systems and improved electronic defense systems. The Mirage IV P is designed for penetrating enemy airspace on low altitudes as Launchers of the ASMP missiles with nuclear warheads.
Developed in the wake of the Suez crisis (1956), the Mirage IV is a two-seater, twin-engine supersonic bomber having an effective range of up to 4,500 km with in-flight refueling. The exterior similarity between this strategic bomber and the Mirage III is noteworthy, in particular the wing design, which is of the delta-type in the Mirage tradition. In June 1996, the Mirage IVP were retired. It was the linchpin of France's strategic nuclear strike force. Dassault was the prime contractor for the complete weapon system: aircraft, navigation and attack management system, as well as casing and release system for the nuclear device.
The Mirage IV 01 made its maiden flight 17th June 1959 at Melun-Villaroche (the Seine-et-Marne region of France), piloted by Roland Glavany. The first Mirage IV-A was delivered to the Air Force in February 1964. At the time of its delivery, the Mirage IV was the only plane in the world able to fly at Mach 2 during more than one half an hour. The 50 Mirage IV-A ordered in March 1959 were all finally delivered between 1964 and 1966; dispersed on nine air bases, organized into three mixed squadrons of bombardment, composed each of three squadrons of bombardment and a squadron for in-flight refueling. In June 1964, it was decided to order 12 additional Mirage IV-A having in addition the strategic capacity; this was explained by the fact that the force Mirage IV was to remain in service at least until 1975, and that had consequently to be compensated for attrition. Thus, in less than 2 years, the first component of the nuclear forces strong of 36 Mirage IV-A and 12 C 135 became operational. The production aircraft equipped French strategic nuclear forces between 1964 and 1996 (62 planes).
The most significant modification in the 1970s related to the flight profile of flight of the system. To respond to the increasing effectiveness of air defenses, the system focused on penetration low altitude in order to face the increasingly large effectiveness of the ground-to-air missiles in the Eastern European countries. Some modifications of the structure of the plane were necessary to face the constraints of the flight imposed by low altitude. Internal countermeasures were added, and the the model AN 22 nuclear weapon was modified to be releasable at low altitude.
The Mirage IV-P/ASMP program was made possible only by the control of very modern techniques and the judicious choices of the selected options. In addition, the Air Force had to adapt the men and the structures to the integration of the Mirage IV-P and the ASMP. Between 1986 and the end of the lifetime of Mirage IV-P [envisaged in 1996], the deployed component included the 91鑝e Escadre of bombardment with two squadrons, the Center of Instruction of the strategic air Forces and the 93鑝e Escadre of in-flight refueling with three squadrons.
Mirage IVA Original model carrying one AN22 60 kT free-fall nuclear bomb; 62 built
Upgraded bomber carrying 30 kT ASMP missile, upgraded avionics and computer displays rebuilt from 'A' models; 19 converted