10/31/2013. Remarks by Johan Visschedijk: "Late in 1916, France's leading fighter ace, Georges Guynemer, asked Louis Béchereau to design for him a fighter capable of mounting a 1.46 in (37 mm) shell-firing gun. Béchereau developed from the S.VII a generally similar aircraft powered by a 200 hp Hispano-Suiza BC engine and incorporating a 1.46 in (37 mm) Puteaux cannon firing through a hollow propeller shaft, an arrangement made possible by the engine's spur reduction gear. A supplementary 0.303 in (7.7 mm) Vickers gun was fitted, and the mainplanes, unlike those of the S.VII, had modest stagger.

The SFA designation of the aircraft was Spa.XII Ca1. Series aircraft were powered by the 220 hp Hispano-Suiza BCb engine, and, although 300 of the cannon-armed S.XII fighters were ordered, their operational use proved to be very limited. They could be flown with any hope of success only by pilots of considerable skill and experience. The cannon was a single-shot weapon, fumes filled the cockpit when it was fired and reloading in combat was tricky. Owing to the bulk of the gun, the S.XII used (at Guynemer's suggestion) Deperdussin-type flying controls (ie, a wheel on a rocking arch).

No escadrille was ever completely equipped with this fighter, which was allotted in small numbers and only to selected pilots. Guynemer made his first operational sortie on the S.XII on July 5, 1917, and fifteen months later, on October 1, 191B, there were only eight S.XIIs with operational escadrilles."

Span: 26 ft 3 in (8.00 m)
Length: 21 ft 0 in (6.40 m)
Height: 8 ft 4.5 in (2.55 m)
Wing area: 217.44 sq.ft (20.20 sq.m)
Empty weight: 1,295 lb (587 kg)
Loaded weight: 1,947 lb (803 kg)
Max speed: 126 mph (203 kmh) at 6,560 ft (2,000 m)
Climb: to 6,560 ft (2,000 m) 6 min 3 sec
Endurance: 1 hr 45 min min