O.Thetford, P.Gray German Aircraft of the First World War (Putnam)
Ago S I
Two of these single-seat aircraft were built, but were not completed before the war ended. They were designed for low-level attack, and probably had some degree of protective armour. Armament was given as two Spandau machine-guns and one 2 cm. cannon, although how the cannon was installed is not known. The photograph is the only one known to exist and, although poor, it does show well the split undercarriage chassis, which was considerably ahead of its time. Engine: 260 h.p. Basse und Selve BuS III.