H.King Armament of British Aircraft (Putnam)
Osprey. In addition to two synchronised Vickers guns on the fuselage decking forward of the cockpit, and having ejection chutes in the fuselage sides, the single-seat Osprey (1917-18) had provision, as had competitive fighters, for a Lewis gun with a limited arc of movement. The aircraft being a triplane, this was mounted on the rear spar of the 'centre centresection'. The actual installation was in dummy form only (land-service type, with 'single' drum).
P.Lewis The British Fighter since 1912 (Putnam)
During 1917 the Austin Motor Co. decided to design a single-seat fighter to Specification A.1A but, rather surprisingly in view of the generally-conceded superiority by then of the well-developed biplane, their tender appeared at the beginning of 1918 as a triplane - the A.F.T.3 Osprey. The machine was fairly small and, as was to be expected with the power of the 230 h.p. Bentley B.R.2, the overall performance was quite creditable. The standard armament scheduled for the Osprey was a pair of fuselage-mounted Vickers but X15, the sole prototype, carried temporarily a Lewis gun in addition. However, against the new biplanes then appearing the Osprey stood relatively little chance of adoption and went the way of so many hopefully-created prototypes.
F.Mason The British Fighter since 1912 (Putnam)
Austin A.F.T.3 Osprey
It has been shown that, in 1917, the Austin Motor Company was already making positive efforts to contribute aircraft of its own origination, even though the Austin-Ball A.F.B.1 was not strictly the company’s own design. The issue that year by the War Office of an official Specification, A.1A, for a successor to the Sopwith Camel was an added spur to perseverance.
Before John North left Austin to join Boulton & Paul, he had schemed up the design of a small triplane fighter, much on the lines of the Sopwith Clerget Triplane, but intended for the new Bentley B.R.2 rotary engine. John Kenworthy now left the Royal Aircraft Factory - where he had been engaged in the design of the S.E.5 - to join Austin as chief designer, and took over responsibility for the new triplane, termed the A.F.T.3 (and later named the Osprey).
Despite it being officially notified as a contender to meet an Air Board requirement, Kenworthy discovered that Austin was required to obtain a licence to build prototypes under the new Regulations, and this may conceivably reflect the Air Board’s belief that the triplane configuration would no longer be adequate to meet the new operational requirement. Such prejudice may have been justifiable, having regard to the relatively high performance already being demonstrated by conventional biplanes, but certainly suggests that the Austin aeroplane was compromised from the start.
Nevertheless, Licence No 17 was issued for the manufacture of three prototypes, X15-X17. The Osprey was an attractive little aircraft, being flown early in 1918 and submitted for evaluation in March (by which time the Sopwith Snipe had already been adjudged the successful contender under Specification A.1A). Built very much on the lines of the Sopwith Clerget Triplane, with wooden box-girder fuselage, the Austin was a smaller aircraft, although its wing gaps were deeper and the wing chord greater. Considerable thought had been given to simplicity of construction and ease of maintenance, all six ailerons being interchangeable, as were the interplane struts. An interesting undercarriage feature (obviously ‘borrowed’ from Austin cars) was the attachment of a leaf-spring to the centre of the spreader bar, extending outwards to the bottom of the V-struts and attached to the half-axles at its extremities, which were bound with elastic chord.
The rudder was a small angular, balanced surface, but no fixed fin was fitted, and the tailplane was adjustable in flight. The armament comprised twin synchronized Vickers guns on the nose decking and, as originally called for in Specification A.1A, provision had been made to mount a Lewis gun on the steel tubular carry-through members of the centre wing.
After the announcement of the Sopwith Snipe’s success, Austin stopped work on the Osprey, and the other two prototypes remained unbuilt after the withdrawal of the Licence.
Type: Single-engine, single-seat, two-bay triplane fighter.
Manufacturer: The Austin Motor Co (1914) Ltd, Birmingham.
Powerplant: One 230hp Bentley B.R.2 rotary engine driving two-blade propeller. Dimensions: Span, 23ft 0in; length, 17ft 7in; height, 10ft 8in; wing area, 233 sq ft.
Weights: Tare, 1,106lb; all-up, 1,888lb.
Performance: Max speed, 118.5 mph at 10,000ft; climb to 10,000ft, 10 min 20 sec; service ceiling, 19,000ft.
Armament: Two synchronized 0.303in Vickers machine guns on fuselage decking forward of cockpit; provision originally made for one Lewis gun on centre wing carry-through structure.
Prototypes: Three ordered, X15-X17, under Licence No 17; X16 and X17 not completed.
W.Green, G.Swanborough The Complete Book of Fighters
AUSTIN A.F.T.3 OSPREY
A private venture intended to compete with the Sopwith Snipe, the Osprey was of wooden construction with fabric skinning and was powered by a 230 hp Bentley B.R.2 nine-cylinder rotary engine. Armament comprised two fixed and synchronised 0.303-in (7,7-mm) Vickers machine guns and one semi-free Lewis gun of similar calibre on the rear spanwise member of the middle-wing centre section. The Osprey was flown for the first time in February 1918, but performance proved to be inferior to that of the Snipe, and construction of second and third prototypes was abandoned.
Max speed, 118mph (190 km/h) at 10,000ft (3 050 m), 110 mph (177 km/h) at 15,000 ft (4 570 m).
Time to 10,000 ft (3 050 m), 10.35 min.
Endurance, 3 hrs. Empty weight, 1,106 lb (502 kg).
Loaded weight, 1,888 lb (856 kg).
Span, 23 ft 0 in (7,01m).
Length, 17 ft 7 in (5,36 m).
Height, 10 ft 8 in (3,25 m).
Wing area, 233 sq ft (21,64 m2).