Espadon History:The flying sub program "Exocet" found its origin in the final months of WW2 and America's planned invasion of Japan. Because the War's end failed to decrease international tensions, the project was allowed to continue. However, to hide the project's existance from former allies, the British changed its codename to "Swordfish". A lot of input from captured German aircraft engineers resulted in modifications to the machine's appearance. The lozenge wings of the Zitterrochen missile were adopted and, in a concern for the high mach speeds the craft was expected to reach, it was decided that some of the prototypes would test the prone pilot arrangement that had been found on the captured DFS 228 D-IBFQ (examined by the RAF Farnborough).

At this time there was considerable discussion regarding the best seating arrangement for supersonic aircraft. Other configurations, like a highly reclined seat or even the "submerged" cockpit proposed by the Horten brothers, were planned for future prototypes. However, the first five machines were to be built with conventional seating since it was believed to offer the best exterior visibility considering the high taper of the aircraft's nose.

Propulsion was also a hot topic of debate between proponents of a simple rocket engine and those who wished to use the new atomic engine that was then in development. The first tests of the atomic powerplant aboard a Boeing "Golden Rocket" bomber convinced the skeptics, and atomic propulsion was selected for the Òswordfish mk-1.

The first prototype was built in 1947-48 at the "Scawfell" secret factory (this spurious name was a cover for one the "shadow factories" built by Lord Beaverbrook at the height of the Battle of Britain). However this first machine was never completed : it was voluntarily destroyed with all the factory during the surprise attack by Basam-Badus forces in mid-1948.

Construction of the first prototypes was then transferred to a British base near the Ormuz Straits. The first machine, which had inherited the destroyed prototype's SX-1 designation, flew about 6 months later, but was soon destroyed by the enemy forces. However SX-2 had, in the meantime, proved the value of the concept by destroying part of the "Yellow" (Tibetan) navy.. Production of a pre-series was therefore rushed and the planned manufacturer testing (originally estimated at a very optimistic two months) was reduced to static runs of the engine and a few underwater tests.

A few weeks later, all the machines available (SX-2 to SX-9) were mustered for an attack on the Tibetan capital, Lhassa. Most of the city, including the famous Potala temple, was destroyed by A-bombs launched by the British squadron. The dictator emperor Basam-Badu was killed in the attack, thus ending the war.

Production of the SX-series was apparently abandoned after that, possibly because all efforts were now directed toward rebuilding the economy.