SO.9000 Trident I, II and III

In 1993, Jean Lacroze, the undisputed expert on propulsion, discussed with the editors of "Trait d'Union" the idea of ​​an article on an aircraft absolutely unique in the entire history of French and—perhaps—world aeronautics: two turbojet engines and three rocket engines, enough to shatter many climb records. It quickly became apparent that the wealth of information available on the Trident I justified a special issue, now out of print. Two years later, Jean Lacroze returned with a special issue of "Trait d'Union" twice as long and entirely devoted to versions II and III of the same Trident program.

At the request of the French Air Force, which was interested in a supersonic interceptor, SNCASO studied in 1951 the concept of an aircraft whose main propulsion system was a rocket engine, coupled with one or more auxiliary jet engines, used primarily for takeoff to conserve rocket engine fuel. To obtain sufficient thrust, several combustion chambers had to be placed side-by-side, which could be ignited separately or all at once. To avoid any asymmetry in thrust, this propulsion unit had to be located along the centerline, therefore within the fuselage. Most of the fuselage was occupied by kerosene tanks for the jet engines or propellant tanks for the rocket engines. As there was no room for these tanks, the jet engines were placed at the wingtips.

The Trident set several world altitude records (the highest at 28,000 m) and climb rates (18,000 m in 3 minutes 17 seconds after brake release). Despite these successes, the program was discontinued in 1958 due to budgetary reasons. Given the aircraft's cost and its specialization as an interceptor, the series was not continued.