The Avro 504 was a World War I biplane aircraft made by the Avro aircraft company and under licence by others. Production during the War totalled 8,970 and continued for almost 20 years, making it the most-produced aircraft of any kind that served in World War I, in any military capacity, during that conflict. Over 10,000 would be built from 1913 to the time production ended in 1932.
Design and development
First flown on 18 September 1913, powered by an 80 hp (60 kW) Gnome Monosoupape engine, the Avro 504 was a development of the earlier Avro 500, designed for training and private flying. It was a two-bay biplane of all-wooden construction, with a square-section fuselage.
Small numbers of early aircraft were purchased both by the Royal Flying Corps (RFC) and the Royal Naval Air Service (RNAS) prior to the start of World War I, and were taken to France when the war started. One of the RFC aircraft was the first British aircraft to be shot down by the Germans, on 22 August 1914. The RNAS used four 504s to form a special flight in order to bomb the Zeppelin works at Friedrichshafen on the shores of Lake Constance. Three set out from Belfort in north-eastern France on 21 November 1914, carrying four 20 lb (9 kg) bombs each. While one aircraft was shot down, the raid was successful, with several direct hits on the airship sheds and destroying the hydrogen plant.
Soon obsolete as a front-line aircraft, it came into its own as a trainer, with thousands being built in the war, with major production types being the 504J and the mass production 504K, which was designed with modified engine bearers to accommodate a range of engines, in order to cope with engine shortages. 8,340 Avro 504s had been produced by the end of 1918.
In the winter of 1917-18, it was decided to use converted 504Js and 504Ks to equip Home Defence squadrons of the RFC, replacing ageing B.E.2cs, which had poor altitude performance. These aircraft were modified as single-seaters, armed with a Lewis gun above the wing on a Foster mounting, and powered by 100 hp (75 kW) Gnome or 110 hp (80 kW) Le Rhône engines. 274 converted Avro 504Js and Ks were issued to eight home defence squadrons in 1918, with 226 still being used as fighters at the end of World War I.
Following the end of the war, while the type continued in service as the standard trainer of the RAF, large numbers of surplus aircraft were available for sale, both for civil and military use. More than 300 504Ks were placed on the civil register in Britain. Being used for training, pleasure flying and banner towing, civil 504s continued flying in large numbers until well into the 1930s.
Although Avro 504s sold to China were training versions, they participated in battles among warlords by acting as bombers with pilot dropping hand grenades and modified mortar shells.
The improved, redesigned and radial engined 504N was produced by Avro in 1925. After evaluation of two prototypes powered by Bristol Lucifer and Armstrong-Siddeley Lynx engines respectively, the Lynx powered aircraft was selected by the RAF to replace the 504K. 592 were built between 1925 and 1932, equipping the RAF's five flying training schools, while also being used as communication aircraft. The 504N was also exported to the militaries of Belgium, Brazil, Chile, Denmark, Greece, Thailand and South Africa, with licenced production taking place in Denmark, Belgium, Canada and Japan.
The 504N was finally replaced in 1933 by the Avro Tutor in RAF service, with small numbers continuing in civilian use until 1940, when seven were impressed into RAF service, where they were used for target- and glider-towing.
The 504 was the first airplane to strafe troops on the ground as well as the first to make a bombing raid over Germany. It was also the first Allied airplane to be downed by enemy anti-aircraft fire and was Billy Bishop's first army aircraft.
The 504 is easily recognisable because of the single skid between the wheels.
Survivors and flyable reproductions
A small number of static display, and airworthy examples of the Avro 504 exist, almost a century after the first one flew, one of the airworthy examples being the Shuttleworth Collection's example -another flyable example exists in a Canadian aviation museum. An Avro 504K can also be found on static display in the Making of the Modern World Gallery at the London Science Museum.
The Old Rhinebeck Aerodrome has had a flyable Avro 504 reproduction aircraft, powered by an original 110 hp Le Rhône rotary engine, flying since 1971, and a newly founded company (Blue Swallow Aircraft) in Virginia is starting to produce reproduction Avro 504 examples.
Specifications (Avro 504K)
Data from The Encyclopedia of World Aircraft
The following companies are recorded as manufacturing the Avro 504 under licence.
Published in July 2009.
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