[2] The undercarriage used oleo shock absorbers and the observer was equipped with a Scarff ring mounting for a .303 in (7.7 mm) Lewis machine gun.

[2] Because its rival, the Royal Aircraft Factory R.E.8 was an unknown quantity, it was decided that fifty of the Armstrong Whitworth design, renamed the F.K.8., would be ordered for the RFC.

[2] The production aircraft were identical in most respects to A411, with the addition of a forward-firing .303 in (7.7 mm) Vickers machine gun to port of and slightly behind the engine.

The Armstrong Whitworth gun synchronising mechanism was incomplete at the time the first example A2636 arrived in France and some early production F.K.8s may have used the Arsiad interrupter gear instead.

[5] The type had several teething troubles: the oleo undercarriage was unable to withstand rough use on the front line airfields, tail skids frequently broke and the original radiators blocked up quickly.

In service the F.K.8 (nicknamed the "Big Ack") proved to be effective and dependable, being used for reconnaissance, artillery spotting, ground-attack, contact-patrol and day and night bombing.

[1] It was reputedly easier to fly than the R.E.8 and was sturdier but its performance was even more pedestrian and it shared the inherent stability of the Royal Aircraft Factory types.

The type eventually served with several squadrons on operations in France, Macedonia, Palestine and for home defence, proving more popular in service than its better known contemporary the R.E.8.

[13] Western Front:[16] Home Defence:[16] Macedonia:[16] Palestine:[16] Training:[1] Data from Armstrong Whitworth Aircraft since 1913[17]General characteristics Performance Armament