Dassault started work on vertical take-off and landing (VTOL) at the beginning of the 1960s and elected to modify the original Mirage III-001 prototype for VTOL research. This used the cockpit, wings and vertical tail of the Mirage III married to a similar but new fuselage containing a 4850-lb (2200-kg) thrust Bristol Orpheus turbojet for forward propulsion and eight 2160-lb (980-kg) thrust Rolls-Royce RB.108 turbojets mounted vertically for direct lift. These were installed in four groups of two on each side of the centreline fore and aft of the centre of gravity. These lift engines featured retractable intake grilles and the exhausts were covered by fairing doors during normal forward flight.
After tethered hovering trials, the Balzac - as it was renamed - made its first free hovering flight on October 13, 1962 and its first transition on March 18, 1963.
Its career was interrupted by a crash landing on January 10, 1964 but it was subsequently repaired and flew again. The Balzac provided Dassault with a great deal of information on stabilization in hovering flight and led to the Mirage III-V.
The Balzac was capable of Mach 2 flight.