[1] Designed by René Leduc in 1938, it was built at the Breguet Aviation factory after a protracted, semi-secret construction phase kept at arm's length from German occupation authorities, and was finally completed in 1947.

[1] It could not take off unassisted (ramjets cannot produce thrust at zero airspeed and thus cannot move an aircraft from a standstill) and was therefore intended to be carried aloft by a parasite aircraft mother ship, such as the four-engined AAS 01A & -B German-origin designs[2] or the French-designed Sud-Est Languedoc four-engined airliners, and released at altitude.

Released in a shallow dive at an altitude of 3,050 m (10,010 ft), the engine was tested at half power for twelve minutes, propelling the aircraft to 680 km/h (420 mph).

[1] In subsequent tests, the 0.10 reached a top speed of Mach 0.85 and demonstrated the viability of the ramjet as an aviation powerplant, with a rate of climb of 40 m/s (7,900 ft/min) to 11,000 metres (36,000 ft), exceeding that of the best jet fighters of the time.

This first flew on 8 February 1951, but was converted back to 0.10 standards (and thereafter referred to as Leduc 010 n°03)[3] a few months later after problems occurred, including misting of the pilot's windows, powerplant synchronization, and wing deflection caused by the turbojets.