Armstrong Whitworth F.K.2

Armstrong Whitworth Aircraft
Industry	Aerospace
Founded	1914
Founder	Frederick Koolhoven
Headquarters	United Kingdom
Products	Aircraft, including the Armstrong Whitworth F.K.3

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File:Armstrong-Whitworth FK3.jpg

A British aviator, possibly 2nd Lt. A.C. Stopher of No. 47 Squadron RAF, Thessalonika, pictured with an FK.3

File:Armstrong-Whitworth-bulgarian.jpg

Officers and personnel of the Bulgarian Air Force gathered around a seized FK.3 in 1917

File:Armstrong Whitworth F.K.3 5519.jpg

Armstrong Whitworth F.K.3 dating from 1915

The Armstrong Whitworth F.K.3 was a British two-seat biplane designed for general-purpose roles, constructed by Armstrong Whitworth Aircraft during the First World War. By the war’s conclusion, it was regarded as outdated for frontline combat duties.

History

In 1914, Dutch aircraft engineer Frederick Koolhoven joined Armstrong Whitworth and developed a series of planes bearing his initials in their designations. The F.K.3 was based on the fundamental design of the Royal Aircraft Factory B.E.2c, which Armstrong Whitworth produced under contract for the Royal Flying Corps. Its design aimed to enhance simplicity and ease of manufacture compared to its predecessor. The prototype, piloted by Norman Spratt on its maiden flight, was equipped with a 70 hp (52 kW) air-cooled Renault 70 hp V-8 engine.^[1] Unlike the B.E.2, this model eliminated welded joints and avoided intricate metal parts in its framework, while increasing the dihedral angle on the upper wing. The cockpit arrangement mirrored that of the B.E.2, featuring separate open cockpits for the pilot and observer, with the observer seated forward. An initial series of seven aircraft built to this specification—sometimes designated as the F.K.2—were produced.^[2]

This early batch showed minimal advancement over the BE.2 and was not accepted for deployment in France.^[3] Subsequent units were manufactured according to an updated design featuring a redesigned fin and rudder with a straight leading edge, eliminating the earlier comma-shaped horn balance, and powered by a more potent Renault-derived 90 hp (67 kW) RAF 1a engine.^[1] Both crew members were positioned within a single elongated cockpit, with the pilot seated at the front,^[1] providing the observer with an improved field of fire; however, only a limited number of F.K.3s were actually armed. Performance tests conducted at Upavon in May 1916 indicated that while the F.K.3 outperformed the B.E.2c in certain aspects, it carried a reduced useful load. Armstrong Whitworth received an order for 150 units, with an additional 350 manufactured by Hewlett & Blondeau Limited at Luton. Some early examples featured twin high exhaust pipes extending above the upper wing similar to the B.E.2 design but were later modified to use rams' horn-style forward exhaust stubs.Cite error: The opening <ref> tag is malformed or has a bad name

During production, a shortage of RAF engines led to twelve aircraft being fitted with heavier and longer 120 hp (90 kW) six-cylinder inline water-cooled Beardmore 120 hp engines. To accommodate this increased weight, wingspan was extended by 2 ft (610 mm). Although this upgrade improved climb performance, maximum speed remained nearly unchanged, and these planes were eventually reverted to RAF engines once supplies normalized.^[1]

Operational Service

The F.K.3 did not see deployment with frontline RFC squadrons in France, as the more advanced F.K.8 and R.E.8 models were already planned for introduction. Overseas, the only squadron equipped with the F.K.3 was 47 Squadron stationed at Salonika, while the remainder of the fleet remained within the United Kingdom. The majority of these aircraft served primarily in a training capacity until they were eventually superseded by the Avro 504.