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).

J.Bruce British Aeroplanes 1914-1918 (Putnam)

Austin A.F.T.3, the Osprey

  THIS rather corpulent triplane was designed in 1917 to meet the requirements of the official specification A. 1A and was flown early in 1918. It was tested at Martlesham Heath in March of that year.
  In construction the Austin A.F.T.3 was typical of the period, and was almost wholly made of wood. The fuselage was a wire-braced wooden box-girder with a rounded top-decking and fairings behind the engine-cowling. Particular care was devoted to detail design with a view to simplification of production and ease of maintenance in the field: only two patterns of fittings for the fuselage spacers were used, and any longeron could be replaced without disturbing the cross-bracing. All mainplanes on each side were interchangeable, as also were the ailerons.
  The undercarriage was sprung in an unorthodox fashion. A special shock-absorber was mounted centrally under the spreader-bar, and from its sides cables ran to the apices of the undercarriage vees where they passed over pulleys and were connected to the ends of the axle. Thus any upward deflection of the axle extended the rubber cord within the shock-absorber.
  The rudder was a plain balanced surface, and it was braced to the rear spar of the tailplane by cables which ran from the top of its axis. The incidence of the tailplane could be adjusted in flight.
  It seems probable that the Austin Osprey was a competitor of the Sopwith Snipe. Its performance was quite good and it must have been manoeuvrable, but the triplane configuration imposed penalties of drag and made rigging rather more complicated. The Snipe was officially adopted, and the Austin triplane was not further developed. It was, however, flown well into the summer of 1918.


SPECIFICATION
  Manufacturers: The Austin Motor Co. (1914), Ltd., Northfield, Birmingham.
  Power: 230 h.p. Bentley B.R.2 rotary engine; engine No. E.X.3.
  Dimensions: Span: 23 ft. Length: 17 ft 7 in. Height: 10 ft 8 in. Chord: 3 ft 8 1/2 in. Gap: upper 3 ft 1 1/2 in., lower 3 ft 6 1/2 in. Stagger: 2 ft 2 in. Dihedral: 30. Incidence: 30. Span of tail: 8 ft 2 1/2 in.
  Areas: Wings: 233 sq ft. Ailerons: each 5-33 sq ft, total 32 sq ft. Tailplane: 23-4 sq ft. Elevators: 23-4 sq ft. Rudder: 5-5 sq ft.
  Weights: Empty: 1,106 lb. Military load: 291 lb. Pilot: 180 lb. Fuel and oil: 311 lb. Loaded: 1,888 lb. Performance: No. of Trial Report: M.189. Date of Trial Report: March, 1918. Type of airscrew used on trial: Lang 4040. Maximum speed at 10,000 ft: 118-5 m.p.h.; at 15,000 ft: 110-5 m.p.h. Climb to 6,500 ft: 5 min 30 sec; to 10,000 ft: 10 min 20 sec; to 15,000 ft: 21 min 20 sec. Service ceiling: 19,000 ft. Endurance: 3 hours at 15,000 ft.
  Tankage: Petrol: main (gravity) tank 26 gallons, service tank 14 gallons, total 40 gallons.
  Armament: There were two fixed and synchronised Vickers machine-guns mounted on top of the fuselage, firing forwards; and at one time a Lewis machine-gun was fitted on the steel tube spars of the middle centre section.
  Serial Number: X.15, built under Licence No. 17.

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).