M.Goodall, A.Tagg British Aircraft before the Great War (Schiffer)
Deleted by request of (c)Schiffer Publishing
O.Tapper Armstrong Whitworth Aircraft since 1913 (Putnam)
The first Armstrong Whitworth aeroplane to be designed by Koolhoven was a small single-seater. This aeroplane was known, probably correctly, as the F.K.I; the qualification arises because there is considerable uncertainty about the true sequence of the F.K. numbers. Koolhoven himself seems to have applied, in retrospect, F.K. numbers to all the designs with which he had been in any way concerned, and in one Dutch publication the F.K.I appears as the F.K.14. The uncertainty about the F.K. numbers is made worse by the secrecy concerning its experimental types which Armstrong Whitworth maintained even after the war.
The F.K.I, originally planned as a monoplane, was altered in the design stage to a biplane. It was a simple, straightforward, single-seat aircraft with single-bay wings, no stagger and a large gap. The fuselage terminated in a horizontal knife-edge, and there were divided elevators but no fixed tailplane. When first flown, by Koolhoven himself, the F.K.I proved to be seriously underpowered, having been fitted with a Gnome engine of 50 hp in place of the intended 80 hp version. Later, the aircraft was given larger ailerons and a fixed tailplane and in this form was flown by B. C. Hucks and some naval pilots; but there was clearly no future for the type and its development was abandoned.
P.Lewis The British Fighter since 1912 (Putnam)
Yet another tractor scout had appeared within a month of the outbreak of war. This was the F.K.1, built by Sir W. G. Armstrong Whitworth and Co., and designed for them by a Dutch designer, Frederick Koolhoven, whose name was to be perpetuated by a prolific series of aircraft to appear under his signature for many years ahead. Before drafting the F.K.1, his first design for Armstrong Whitworth, Koolhoven had accumulated considerable experience through the successful Deperdussin monoplanes.
In the new scout the monoplane formula was disregarded, despite its inherent quality of speed, and the F.K.1 made its debut in September, 1914. A relatively simple biplane in every way, it showed evidence of French practice in the horizontal knife-edge termination of the rear fuselage and in the omission of a fixed tailplane. The upper wings were taken over the fuselage at a considerable gap on inverted-V centre-section struts and this feature, combined with undercarriage legs spread wide apart fore and aft, gave the whole machine a rather gawky appearance. The 80 h.p. Gnome, around which the F.K.1 had been designed, was not obtainable so it flew instead with a 50 h.p. Gnome.
The machine was modified after early tests and was given a normal fixed tailplane and larger, inversely-tapered ailerons. The F.K.1’s top speed of 75 m.p.h. on its low power reduced any chances that it might have had of competing with its counterparts from Bristol, Martin-Handasyde and Sopwith for orders and the design was abandoned.
F.Mason The British Fighter since 1912 (Putnam)
Armstrong Whitworth F.K.1
The Aeroplane Department of the heavy engineering enterprise, Sir W G Armstrong, Whitworth & Co Ltd, came into being at the beginning of 1914, its first works manager and aircraft designer being the Dutch-born Frederick Koolhoven. A qualified pilot himself, who had already acquired design experience working on Deperdussin monoplanes, Koolhoven’s first aircraft for Armstrong Whitworth was a small single-bay unstaggered biplane designated the F.K.1.
Of exceptional simplicity in the interests of possible future production orders as a military scout, the F.K.1 was intended to be powered by an 80hp Gnome rotary; however, as this engine was not immediately available, recourse was made to the 50hp version, with the result that the aircraft was substantially underpowered. Although the tail unit included a fixed fin forward of the rudder hinge-post, there was initially no tailplane, a balanced elevator being fitted.
The F.K.1 was first flown by Koolhoven himself in September 1914. He was clearly dissatisfied with the longitudinal and lateral control, and the ailerons were replaced by much enlarged surfaces with inverse taper, and a fixed tailplane was added.
Although no reliable design and performance figures appear to have survived, the aircraft was obviously inferior to such contemporary aircraft as the Sopwith Tabloid and Bristol Scout, and its development was not pursued.
Type: Single-engine, single-seat, single-bay tractor biplane.
Manufacturer: Sir W G Armstrong, Whitworth & Co Ltd, Newcastle-upon-Tyne.
Powerplant: One 50hp Gnome rotary engine driving two-blade propeller.
Structure: Steel and wood composite construction; square-section box-girder fuselage, fabric covered. Twin-wheel, single-skid undercarriage.
Performance: Max speed, 75 mph at sea level; landing speed, 30 mph.
Prototype: One (first flown by Frederick Koolhoven in September 1914). No production.