Editing Avro 504 (section)

== Operational history ==
[[File:Foster Mount Avro504.jpg|thumb|[[Foster mounting|Foster-mounted]] [[Lewis gun]] on [[night fighter]] Avro 504K]]
[[File:StateLibQld 1 111320 Flight Commander Smith flies for the Peace Loan, 1919.jpg|thumb|"[[Francis Smith (RAAF officer)|Flight Commander Smith]] flies for the Peace Loan" ''Queenslander Pictorial'' (1919)<ref>{{Cite web |date=2017-09-18 |title=Peace Loan Aeroplane crashes in Gympie (1919) {{!}} State Library Of Queensland |url=https://www.slq.qld.gov.au/blog/peace-loan-aeroplane-crashes-gympie-1919 |access-date=2022-11-17 |website=www.slq.qld.gov.au |language=en}}</ref>]]
Small numbers of early aircraft were purchased by the [[Royal Flying Corps]] (RFC) and the [[Royal Naval Air Service]] (RNAS) prior to the start of the First World War, 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 pilot was [[Second Lieutenant|2nd Lt.]] Vincent Waterfall and his navigator [[Lieutenant|Lt]] Charles George Gordon Bayly (both of [[No. 5 Squadron RFC|5 Sqn RFC]])<ref>"[http://www.cwgc.org/find-war-dead/casualty/478797 Casualty Details:Vincent Waterfall]". ''Commonwealth War Graves Commission''. Retrieved 10 January 2010.</ref><ref name="Jackson Avro p56">Jackson 1990, p.56.</ref> The RNAS used four 504s to form a special flight 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 {{cvt|20|lb|0}} bombs each. While one aircraft was shot down, the raid was successful, with several direct hits on the airship sheds and the destruction of the hydrogen generating plant.<ref name="Mason Bomber p21">Mason 1994, p.21.</ref>

Soon obsolete as a frontline aircraft, it came into its own as a trainer, with thousands being built during the war, with the major production types being the 504J and the mass production 504K, designed with modified engine bearers to accommodate a range of engines to cope with engine shortages. 8,340 Avro 504s had been produced by the end of 1918.<ref name="Bruce ptII p87">Bruce 16 July 1954, p.87.</ref>

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 [[Royal Aircraft Factory B.E.2|B.E.2c]]s, 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 {{cvt|100|hp}} Gnome or {{cvt|110|hp}} 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 the First World War.<ref name="Mason Fighter">Mason 1992, p.127.</ref>

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. Used for training, pleasure flying, banner towing and even [[barnstorming]] exhibitions (as was ongoing in North America following World War I with the similar-role, surplus [[Curtiss JN-4]]s and [[Standard J]]-1s); civil 504s continued flying in large numbers until well into the 1930s.

The embryonic [[Soviet Air Forces|air service of the Soviet Union]], formed just after the First World War, used both original Avro 504s and their own ''Avrushka'' (" Little Avro") copy of it for primary training as the '''U-1''' in the early 1920s, usually powered by Russian-made copies of the [[Gnome Monosoupape]] rotary engine.  This Russian version of the 504 was replaced by what would become the most produced biplane in all of aviation history, the [[Polikarpov Po-2]], first known as the '''U-2'''; the type remained in Soviet service till the late 1920s, and much later elsewhere.

Although Avro 504s sold to China were training versions, they participated in battles among [[Warlord era|warlords]] by acting as bombers with the pilot dropping hand grenades and modified mortar shells {{Citation needed|date=July 2007}}.

The improved, redesigned and radial-engined 504N with a new undercarriage was produced by Avro in 1925. After evaluation of two prototypes, one powered by the [[Bristol Lucifer]] and the other by the [[Armstrong-Siddeley Lynx]], 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 armed forces of Belgium, Brazil, Chile, Denmark, Greece, Siam and South Africa, with licensed production taking place in Denmark, Belgium, Canada, Siam and Japan.

The RAF's 504Ns were finally replaced in 1933 by the [[Avro Tutor]], 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 British aeroplane to strafe troops on the ground<ref name ="Bruce pt I p43">Bruce 9 July 1954, p.43.</ref> as well as the first British aircraft to make a bombing raid over Germany.<ref name="Holmes"/><ref>{{Cite book |last=Lindqvist |first=Sven |url=https://www.worldcat.org/oclc/44794868 |title=A history of bombing |date=2001 |publisher=New Press |isbn=1-56584-625-7 |location=New York |oclc=44794868}}</ref> It was also the first Allied aeroplane to be downed by enemy [[anti-aircraft]] fire and was the first aircraft flown by many future aces, including [[Billy Bishop]].

The 504 is easily recognisable because of the single skid between the wheels, referred to as the "toothpick" in the RAF.{{Citation needed|date=November 2022}}