The Avro 555 Bison was a British single-engined fleet spotter/

reconnaissance In military operations, reconnaissance or scouting is the exploration of an area by military forces to obtain information about enemy forces, terrain, and other activities. Examples of reconnaissance include patrolling by troops (skirmisher ...

aircraft built by

Avro AVRO, short for Algemene Vereniging Radio Omroep ("General Association of Radio Broadcasting"), was a Dutch public broadcasting association operating within the framework of the Nederlandse Publieke Omroep system. It was the first public broad ...

Development and design

The Bison was designed to meet British Specification 3/21 for a carrier-based fleet spotter and reconnaissance aircraft. An order for three prototypes was placed in October 1921, together with three of the competing design from

Blackburn Aircraft Blackburn () is an industrial town and the administrative centre of the Blackburn with Darwen borough in Lancashire, England. The town is north of the West Pennine Moors on the southern edge of the Ribble Valley, east of Preston and north- ...

, the

Blackburn Blackburn The Blackburn R-1 Blackburn was a 1920s British single-engine fleet spotter/ reconnaissance aircraft built by Blackburn Aircraft. History The Blackburn was developed to meet a naval requirement ( Specification 3/21) for a carrier-based recon ...

. Avro's design, the Type 555 Bison, was a two-bay biplane, powered, like the Blackburn, by a

Napier Lion The Napier Lion is a 12-cylinder, petrol-fueled 'broad arrow' W12 configuration aircraft engine built by D. Napier & Son from 1917 until the 1930s. A number of advanced features made it the most powerful engine of its day and kept it in produ ...

engine. The deep slab-sided fuselage was constructed of steel tube, with the pilot sitting in an open cockpit forward of the wings, and the engine cowling sloping steeply down ahead of the pilot. An enclosed cabin with large rectangular windows on each side housed the navigator and radio operator and all their equipment, with sufficient headroom to stand upright, while a cockpit for a gunner armed with a Lewis gun on a

Scarff ring The Scarff ring was a type of machine gun mounting developed during the First World War by Warrant Officer (Gunner) F. W. Scarff of the Admiralty Air Department for use on two-seater aircraft. The mount incorporated bungee cord suspension in eleva ...

was provided in the rear fuselage. The upper wings were mounted directly on the top of the fuselage. The first prototype flew in 1921, with an order for 12 Bison Is following. The aircraft had handling problems, however, caused by interference of the pilots cockpit with the airflow over the upper wing. This was resolved by revising the wing design of the second prototype, raising the centre section of the upper wing by 2 ft (0.6 m) and removing dihedral from the upper wings, flying in this form in April 1923. Further production orders followed with these modifications incorporated as the Bison II, while some Bison Is were modified to a similar standard, sometimes known as the Bison IA. A Bison I was fitted with floats and retractable wheels but tests proved the design was not suitable for seaborne use.

Operational history

Although designed for a naval requirement the first deliveries were to the

Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) and ...

in 1922 to replace the

Westland Walrus The Westland Walrus was a British spotter/reconnaissance aircraft built by Westland Aircraft. Design and development In 1919 the Royal Navy had an urgent need for a three-seat spotter/reconnaissance aircraft. To save money, the Airco DH.9A was ...

for coastal reconnaissance work with

No. 3 Squadron RAF Number 3 Squadron, also known as No. 3 (Fighter) Squadron, of the Royal Air Force operates the Eurofighter Typhoon FGR4 from RAF Coningsby, Lincolnshire, since reforming on 1 April 2006. It was first formed on 13 May 1912 as one of the first squ ...

. In April 1923, 3 Squadron was broken up to form a number of Fleet Spotter Flights of the

Fleet Air Arm The Fleet Air Arm (FAA) is one of the five fighting arms of the Royal Navy and is responsible for the delivery of naval air power both from land and at sea. The Fleet Air Arm operates the F-35 Lightning II for maritime strike, the AW159 Wil ...

. Naval aircraft served on , and and onshore at

Gosport Gosport ( ) is a town and non-metropolitan borough on the south coast of Hampshire, South East England. At the 2011 Census, its population was 82,662. Gosport is situated on a peninsula on the western side of Portsmouth Harbour, opposite t ...

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

and

Hal Far HAL may refer to: Aviation * Halali Airport (IATA airport code: HAL) Halali, Oshikoto, Namibia * Hawaiian Airlines (ICAO airline code: HAL) * HAL Airport, Bangalore, India * Hindustan Aeronautics Limited an Indian aerospace manufacturer of fight ...

Malta Malta ( , , ), officially the Republic of Malta ( mt, Repubblika ta' Malta ), is an island country in the Mediterranean Sea. It consists of an archipelago, between Italy and Libya, and is often considered a part of Southern Europe. It lies ...

. The aircraft were retired in 1929 when they were replaced by the

Fairey IIIF The Fairey Aviation Company Fairey III was a family of British reconnaissance biplanes that enjoyed a very long production and service history in both landplane and seaplane variants. First flying on 14 September 1917, examples were still in us ...

Operators

; *

** 421 Fleet Spotter Flight

** 423 Fleet Spotter Flight

Variants

;Avro 555 Bison :Three prototypes to Air Ministry specification 3/21. ;Avro 555 Bison I :Twelve Lion II powered production aircraft, survivors rebuilt as IAs ;Avro 555 Bison IA :Bison Is modified with a biplane gap and additional dorsal fin. ;Avro 555A Bison II :Improved variant with biplane gap modification, 23 built. ;Avro 555B Bison I :One Bison I converted to an amphibian to meet Air Ministry Specification 8/23, not ordered into production.

Specifications (Bison II)

Footnotes

References

* * * * {{Avro aircraft 1920s British military reconnaissance aircraft

Bison Bison are large bovines in the genus ''Bison'' (Greek: "wild ox" (bison)) within the tribe Bovini. Two extant and numerous extinct species are recognised. Of the two surviving species, the American bison, ''B. bison'', found only in North Ame ...

Single-engined tractor aircraft Biplanes Aircraft first flown in 1921