Development SPAD S.XII

restored hs.8ca geared-output engine, similar 8cb used on spad s.xii

the gun chosen spad xii not old hotchkiss cannon new 37 mm semi automatique moteur canon (samc), built puteaux, 12 shots carried. hispano-suiza aviation engine had geared allow gun fire through propeller shaft. spad xii carried single 0.303 inch synchronized (7.7 mm) vickers machine gun mounted on starboard side of nose. in order carry heavy cannon airframe lengthened , wingspan , wing area increased. wingtips rounded rather squared off , wings given slight forward stagger. accommodate required geared output propshaft engine, allowed hollow propeller shaft cannon fire through, , power resultingly heavier airframe, 587 kg compared 500 kg of spad 7, 180 bhp hispano-suiza 8 direct-drive ab engine replaced geared 220 bhp model 8cb, , gave spad xii clockwise rotating propeller, seen nose-on view.

test flown guynemer, production models of spad xii highly successful after overcoming initial problems reduction gear between engine , propeller. other aces had success new model. however, deliveries slow, spad vii , later spad xiii having top priority, , modest total of 300 aircraft ordered not completed. best estimates 20 produced. average pilots found spad 12 difficult aircraft master, , cannon difficult aim , fire, while manual reloading difficult. cockpit filled fumes upon every firing. breech mechanism protruded cockpit , prevented use of conventional stick control aircraft, adding difficulties encountered ordinary pilots. control setup reverted split setup on either side of pilot, la deperdussin.