Avro 555 Bison • wp.archivoaereo.com

The “Avro” company entered naval aviation with the Avro 555 Bison series deck aircraft, designed in accordance with specification 3/21 for the creation of a spotter and reconnaissance aircraft for the fleet. The first Bison Mk I prototype took to the air in 1921, followed by a second machine, built according to the revised specification 33/22, which featured many improvements.

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Development and Design Evolution

The most important of these modifications was the upper wing, raised approximately 40 cm above the fuselage on struts. A third prototype appeared in 1923, followed by a batch of 12 machines. The design of the production aircraft, built to specification 16/23, was based on the second prototype.

In the fleet, these aircraft were designated as Bison Mk IA, with more than 35 such aircraft built. Further orders followed for another 35 aircraft of the 555A series, which were designated as Bison Mk.II. Production of these aircraft concluded in April 1927.

Operational History and Deployment

Despite the aircraft being initially created as a naval type, the Bison Mk IA first entered service with the 3rd Squadron of the British RAF, where it replaced the Westland Walrus for coastal reconnaissance. The 423rd Naval Spotter Flight became the first Naval Aviation unit to receive the Bison.

Later, these aircraft were taken aboard the aircraft carriers “Eagle” and “Furious.” On land, the Bison was operated by the 448th Flight, stationed in Hal Far, Malta. In 1929, all listed flights were re-equipped with the Fairey III.

Initial Configuration Challenges

The first production Bisons were equipped with one central and two underwing floats, plus retractable wheels like those of the 555B series. However, tests showed that this configuration was unsatisfactory.

Technical Specifications

Modification	Bison Mk.IА
Wingspan, m	14.02
Length, m	10.97
Height, m	4.22
Wing area, m2	57.60
Empty weight	1887
Normal takeoff weight	2631
Engine type	1 Piston engine Napier Lion II
Power, hp	1 x 450
Maximum speed, km/h	177
Cruising speed, km/h	151
Practical range, km	550
Practical ceiling, m	4250
Crew, crew members	3-4
Armament	one 7.7-mm Lewis machine gun