The Dassault MD.454 Mystère IV is a 1950s French fighter-bomber aircraft, the first transonic aircraft to enter service with the French Air Force.
It was used in large-scale combat in the Israeli Air Force during the 1967 Six Day War.
The Mystère IV was an evolutionary development of the Mystère II aircraft.
Although bearing an external resemblance to the earlier aircraft, the Mystère IV was in fact a new design with aerodynamic improvements for supersonic flight.
The prototype first flew on 28 September 1952, and the aircraft entered service in April 1953.
The first 50 Mystere IVA production aircraft were powered by British Rolls-Royce Tay turbojets, while the remainder had the French-built Hispano-Suiza Verdon 350 version of that engine.
Prototype powered by a Rolls-Royce Tay 250 engine
Production fighter-bomber, 421 built, first 50 with the Rolls-Royce Tay 250 the remaining 371 with a French derivative of the Tay, the Hispano-Suiza Verdon.
In addition to production Mystère IVA, Dassault developed an upgraded Mystère IVB with either Rolls-Royce Avon (first two prototypes) or SNECMA Atar 101 (third prototype) afterburning engine and a radar ranging gunsight.
Six pre-production aircraft were built but the project was abandoned in favour of the promising Super Mystère.
Dassault also proposed a two-seat all-weather interceptor version called Mystère IVN.
The aircraft was equipped with the AN/APG-33 radar in an arrangement similar to North American F-86D Sabre Dog, powered by a Rolls-Royce Avon turbojet, and armed with 55× 68 mm Matra rockets in a retractable belly tray.
The first prototype flew on 19 July 1954.
AdA eventually decided to purchase Sud Aviation Vautour and F-86K Sabre for the interceptor role but the Mystère IVN prototype continued to fly for several years as a testbed for radar equipment.