Armstrong Whitworth F.K.9 and F.K.10

Two seat heavily staggered single bay fighter equal span quadruplane, with one wing passing through the centre of the fuselage, one wing below on struts and two above. The third wing had no centre section and the pilot was located between the leading edge of the port and starboard planes. Single plank type struts supported the outer wings and ailerons were fitted to each mainplane. The tailplane featured a rudder with a very large horn balance with no fin above the fuselage, but a small fin below. The unusual undercarriage was wire braced fore and aft with only a single leg per side. One 110 h.p Clerget 9Z powerplant.

F.K.9 Specification
Span	Length	Height	Wing Area	Empty Wt	Max AUW	Cruise Speed	Maximum Speed	Endurance	Service Ceiling
27 ft 9 in	25 ft 10 in	11 ft 4 in	355 sq ft	1226 lb	2038 lb		100 mph/ 87 kn	3 hr	13000 ft
8.46 m	7.87 m	3.45 m	32.98 m2	556 kg	924 kg		161 km/h		3962 m

Production version of F.K.9 with deeper fuselage and increased span with rounded wing tips. The redesigned tail unit had a smaller rudder plus a small fin above the fuselage, but dispensed with the fixed horizontal tailplane. Armament was one fixed Vickers gun for the pilot and a Lewis gun on a pillar mounting for the observer. One 130 h.p. Clerget 9B or Le Rhône 9J powerplant. One 130 h.p. Clerget 9B or Le Rhône 9J powerplant.

F.K.10 (130 h.p. Clerget) Specification
Span	Length	Height	Wing Area	Empty Wt	Max AUW	Cruise Speed	Maximum Speed	Endurance	Service Ceiling
28 ft 3 in	25 ft 6 in	11 ft 6 in	361 sq ft	1236 lb	2019 lb		95 mph/ 83 kn	2-1/2 hr	10000 ft
8.61 m	7.77 m	3.51 m	33.54 m2	561 kg	916 kg		153 km/h		3048 m