Avro bison

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Avro 555 bison
Avro bison in flight
Type: Reconnaissance aircraft , carrier aircraft
Design country:

United KingdomUnited Kingdom United Kingdom

Manufacturer:

Avro

First flight:

1921

Commissioning:

1922

Production time:

1921 to 1927

Number of pieces:

55

The Avro 555 Bison was a single-engine biplane made by the British manufacturer Avro , which was designed for use as a deck-landing sea reconnaissance aircraft.

Development of the Avro Bison

The machine was developed according to tender 3/21 for a carrier-based reconnaissance and artillery observation aircraft . Since the machine was supposed to land on carrier decks, the pilot's cockpit was installed in front of the leading edge of the wing for better visibility during deck landings; this gave the 555 a peculiar appearance. As standard, the Avro 555 was equipped with air bags in the event of a ditching.

The first prototype made its maiden flight in 1921 with a water-cooled 450 hp (336 kW / 456 hp) Napier Lion engine. In this machine, the wing was attached directly to the fuselage; it also had a sprung tail spur.

It was only over a year later that Avro chief test pilot Bert Hinkler demonstrated the second prototype on December 12, 1922 in Hamble . On this machine, the upper wing was stalked, it was now about 40 centimeters above the fuselage.

On June 30, 1923, the first flight of the third prototype took place, which was designed like the first machine, but was equipped with elevators and rudders in the design of the second prototype. This aircraft was initially stationed at the Wireless And Photographic Flight in Farnborough and from 1924 in Gosport .

The
Blackburn also ordered Blackburn

The British authorities issued a construction contract for the Avro machine but also for the competitor Blackburn Blackburn . The Avro 555 Bison was a two-handled biplane. The fuselage consisted of a tubular steel frame, which was mainly covered with fabric. The cabin area was paneled with plywood. The landing gear consisted of a rigid, two-wheeled, oil pressure sprung main landing gear and a sprung tail spur.

The first series of twelve machines ( N9591-N9602 ), designated as Avro 555 Bison I , was identical to the first prototype. Eleven planes were delivered to the Engine Research Flight, one was converted in Avro to an amphibian with a combined wheel chassis and float as Avro 555B Bison I referred to. However, this one-off showed unacceptable flight characteristics. The first Bison machines were also used in Season No. 3 used by the RAF without replacing their main equipment Westland Walrus . Season No. 3 carried out brief tasks in cooperation with the Royal Navy from September 1921 to April 1923 and was then dissolved into 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 to the armed forces in four separate lots between December 1924 and February 1927.

Mission history

Although originally intended for use on aircraft carriers, the Bison was initially used as a reconnaissance aircraft in the coastal area, partially replacing the Westland Walrus .
The first unit with Avro Bison Mk.I was then the newly formed Fleet Spotter Flight 423 on November 21, 1923 , but which also had Westland Walrus until July 1924 . 423 was used by the HMS Argus . In April 1925 the unit was converted to Avro Bison Mk.II and in February 1926 the HMS Eagle was assigned for its use in the Mediterranean. Seconded to HMS Hermes in mid-1926 , which was practicing with the
Mediterranean fleet on the way to the China Station , the unit returned to the Eagle in early 1927 , where it remained until it was converted to Fairey IIIF in March 1929. As a second operational unit, the Fleet Spotter Flight 421 on the HMS Furious at Home Fleet received Avro Bison Mk.I in May 1925, partly from the aforementioned unit as a replacement for the Westland Walrus, which had been used up until then . The Mk.I were replaced by the new Avro Bison Mk.II in August . At the beginning of 1927, the unit split into an A and B flight , the latter also joining the Eagle until June 1928 . The Fleet Spotter Flight 421 then began its conversion to Fairey IIIF in January 1929 . In March 1929 all Avro 555 bison were withdrawn from the mission flights. The two flights, now only equipped with Fairey III F , were renamed on April 26, 1929 as the "Fleet Spotter reconnaissance Flight" s 447 and 448 .

An Avro Bison served for about a year at the Engine Research Flight in Farnborough as a test vehicle for engine and radiator tests.

Technical specifications

Parameter Avro 555 Bison I Blackburn Blackburn Mk.I
length 10.97 m 11.02 m
height 4.11 m 3.81 m
Wingspan (upper wing) 14.02 m 13.84 m
Wing area 57.62 m² 60.4 m²
Empty mass 1887 kg 1786 kg
Max. Flight weight with a full tank 2631 kg 2710 kg
drive a water-cooled Napier Lion II Lion IIB
power 358 kW (487 hp) 450 hp
Top speed 177 km / h 157 km / h
Marching speed 145 km / h
Summit height 4270 m 3950 m
Rate of climb 183 m / min 210 m / min
Range / flight time approx. 550 km 4h 15´
crew 3 men (pilot, rear gunner, observer) 3 men
Armament a pivoting 7.7 mm Lewis MG one swiveling and one fixed machine gun

See also

literature

  • Eric J. Harlin: The Sea-Going Bison. In: Air Enthusiast (August 22-November 1983) pp. 40-51.
  • AJ Jackson: Avro Aircraft since 1908. Putnam, London 1990, ISBN 0-85177-834-8 .
  • Ray Sturtivant: The Squadrons of the Fleet Air Arm , Air-Britain Tonbridge, 1984, ISBN 0-85130-120-7
  • Owen Thetford: Aircraft of the Royal Navy since 1912 , Putnam London, 4th edition 1978, ISBN 0-370-30021-1
  • Owen Thetford: British Naval Aircraft since 1912. (Fourth ed.) Putnam, London 1978, ISBN 0-370-30021-1 .
  • The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985). Orbis Publishing.

Web links

Commons : Avro Bison  - Collection of images, videos and audio files

Individual evidence

  1. a b Jackson: Avro Aircraft , pp. 204f.
  2. ^ A b Thetford: Aircraft of the RAF , p. 573
  3. a b c Sturtivant: The Squadrons of the Fleet Air Arm , p. 467