Société de Production des Aéroplanes Deperdussin
SPAD S.XIII 

Variants

The SPAD S.XIII was a single-engine biplane fighter aircraft. In terms of its construction, it shared a similar configuration and layout to the earlier S.VII, featuring a mainly wooden structure complete with a fabric covering; however, it was generally larger and heavier than its predecessor. Other changes included the tapered chord of its ailerons, the rounded tips of the tailplanes, bulkier cowling accommodating the gear-drive Hispano-Suiza 8B engine choice, and enlarged fin and rudder. The S.XIII was armed with a pair of forward-mounted Vickers machine guns with 400 rounds per gun, which took the place of the single gun that had been used on the earlier aircraft.

The S.XIII featured relatively conventional construction, that being a wire-braced biplane with a box-shaped fuselage and a front-mounted engine, except for its interposed wing struts located half-way along the wing span, which gave the fighter the deceptive appearance of being a double-bay aircraft instead of a single bay. This change prevented the landing brace wires from whipping and chafing during flight, and was attributed by Andrews as a key factor for the aircraft's high rate of climb. Otherwise, it had an orthodox structure, comprising wooden members attached to metal joint fixtures. The fuselage consisted of four square-section longerons, complete with wooden struts and cross-members while braced with heavy-gauge piano wire; wire cable was instead used for the flying and landing wires.