Avro Bison
The Avro 555 Bison was a single-engined biplane of the British manufacturer Avro, which was designed for use as a deck landing capable maritime surveillance.
Development of the Avro Bison
The machine is designed according to the tender 3/21 for a carrier-based reconnaissance and artillery observation. Since the machine was supposed to land on carrier decks, the pilot cockpit was mounted for better visibility in deck landings in front of the wing leading edge; so that the 555 offered a peculiar appearance. By default, the Avro 555 was equipped with air bags in the event of ditching.
The first prototype took off on its maiden flight in 1921 with a water-cooled 450 hp (336 kW/456 hp) payable Napier Lion engine. In this machine, the wing was immediately mounted on the hull; besides, she had a sprung tail skid.
It was not until over a year later led Avro Chief Test Pilot Bert Hinkler on 12 December 1922 in Hamble the second prototype before. In this machine, the upper wing was aufgestielt, she was now about 40 inches above the hull.
On June 30, 1923, the first flight of the third prototype, the same run of the first machine, but was equipped with elevator and rudders in the execution of the second prototype was made. This aircraft was initially stationed at the Wireless And Photographic Flight Farnborough and from 1924 in Gosport.
The British authorities issued a construction contract for the Avro machine but also for the design competition Blackburn Blackburn. The Avro 555 Bison was a zweistieliger biplane. The fuselage consisted of a steel tubular frame, which was mainly covered with fabric. The cabin area was sperrholzbeplankt. The chassis consisted of a rigid, two-wheeled, öldruckgefedertem main landing gear and a sprung tail skid.
The first series of twelve machine ( N9591 - N9602 ), designated Avro 555 Bison designated I, was identical to the first prototype. Eleven aircraft were delivered to the Engine Research Flight, one was rebuilt at Avro to an amphibious aircraft with a combined wheel - float chassis and called Avro 555B Bison I. However, this single piece showed unacceptable flying qualities. The first Bison machines were set up in late 1922 when the squadron of the RAF No.3, without whose main features Westland Walrus to replace. The squadron No.3 completed since September 1921 to April 1923 for a short time tasks in collaboration with the Royal Navy and was then dissolved in the Fleet Spotter Flights 421 and 422.
The second series, called Avro 555 A Bison IA, corresponded to the second prototype, with slight modifications - especially in the area of the wing geometry - and was delivered in four separate lots in the period December 1924 to February 1927 to the armed forces.
Service history
Although originally intended for use on aircraft carriers, the bison was first used as a reconnaissance in the coastal area and replaced as part of the Westland Walrus. The first unit with Avro Bison Mk.I was then the newly formed on November 21, 1923 Fleet Spotter Flight 423, but until July 1924 also had Westland Walrus. 423 was used by the HMS Argus. In April 1925, the unit was converted to Avro Bison Mk.II and allocated in February 1926, the HMS Eagle for their use in the Mediterranean. Mid- 1926 on the HMS Hermes, which practiced station with the Mediterranean fleet on its way to China, seconded, the unit returned early 1927 back to the Eagle, where she remained until the conversion to Fairey IIIF in March 1929. As a second application unit received the Fleet Spotter Flight 421 on HMS Furious in the Home Fleet May 1925 Avro Bison Mk.I in part by the above-mentioned unit as a replacement for the use then Westland Walrus. The Mk.I were replaced by new Avro Bison Mk.II in August. Early 1927, the unit divided into an A - and B -Flight, the latter also to June 1928, to the Eagle. The Fleet Spotter Flight 421 began then from January 1929 its conversion to Fairey IIIF. In March 1929, all Avro 555 Bison were withdrawn from use -Flights. The two now equipped only with Fairey III F Flight was renamed on 26 April 1929 in the "Fleet Spotter reconnaissance flight" s 447 and 448.
An Avro Bison still served for about a year at the Engine Research Flight at Farnborough as a test bed for engine and radiator tests.