Avro 504


The Avro 504 is a single-engine biplane bomber made by the Avro aircraft company and under licence by others. Production during World War I totalled 8,970 and continued for almost 20 years, making it the most-produced aircraft of any kind that served in any military capacity during the First World War. More than 10,000 were built from 1913 until production ended in 1932.

Design and development

First flown from Brooklands by Fred "Freddie" Raynham on 18 September 1913, powered by an Gnome Lambda seven-cylinder rotary engine, the Avro 504 was a development of the earlier Avro 500, designed for training and private flying. It was a two-bay all-wooden biplane with a square-section fuselage.

Manufacturers

The following companies are recorded as manufacturing the Avro 504 under licence.
Small numbers of early aircraft were purchased by the Royal Flying Corps and the Royal Naval Air Service 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 2nd Lt. Vincent Waterfall and his navigator Lt Charles George Gordon Bayly 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 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.
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.
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 Gnome or 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.
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 ; civil 504s continued flying in large numbers until well into the 1930s.
The embryonic air service of the Soviet Union, formed just after the First World War, used both original Avro 504s and their own Avrushka 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 warlords by acting as bombers with the pilot dropping hand grenades and modified mortar shells.
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 as well as the first British aircraft to make a bombing raid over Germany. 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.

Variants

  • 504: Gnome Lambda engine.
  • 504A:
  • 504B
  • 504C
  • 504D
  • 504E
  • 504F
  • 504G
  • 504H
  • 504J
  • 504K
File:Avro Dyack used by QANTAS ca. 1921.jpg|thumb|Qantas 504K Dyak
  • 504K Mk.II
  • 504L
  • 504M
  • 504N
  • 504O
  • 504P
  • 504Q
  • 504R Gosport
  • 504S
  • 540
  • 582
  • 585
  • 598 Warregull
  • 599 Warregull II
  • Yokosuka K2Y1
  • Yokosuka K2Y2
  • U-1 Avrushka
  • MU-1
  • Orlogsværftet Flyvemaskineværksted LB.I – Danish production at the Royal Naval Dockyard
  • I1A
  • I2A
  • '''B.F.4'''

    Operators

  • Afghan Air Force
  • Argentine Army Aviation Service – purchased 10 directly from Avro, with a further 34 license-built by FMA from 1928 to 1937. In service until 1938.
  • Australian Flying Corps
  • *No. 5 Squadron in the United Kingdom
  • *No. 6 Squadron in the United Kingdom
  • *No. 7 Squadron in the United Kingdom
  • *No. 8 Squadron in the United Kingdom
  • *Central Flying School AFC at Point Cook, Victoria
  • Royal Australian Air Force
  • *No. 1 Flying Training School RAAF at Point Cook
  • Western Australian Airways
  • Qantas
  • Belgian Air Force purchased 50 British-built 504Ks from 1920 to 1922, with a further 27 being built under license by SABCA These were replaced by the 504N, 17 being built by Avro in 1929–31, and 31 being built under license.
  • Bolivian Air Force 11 Avro 504R Gosport
  • Brazilian Air Force
  • Brazilian Naval Aviation
  • Royal Canadian Air Force
  • Chilean Air Force
  • Chilean Navy
; Republic of China
  • Chinese Nationalist Air Force
; China-Puppet
; British India
  • Imperial Iranian Air Force
  • Irish Air Service
  • Irish Air Corps
  • Imperial Japanese Navy Air Service
  • Latvian Air Force
  • Aizsargi
  • Mexican Air Force
  • *Models made in Mexico were called "Avro Anáhuac"
  • Mongolian People's Army Air Corps
  • Dutch Army Aviation Group –
  • Royal Netherlands East Indies Army Air Force
  • New Zealand Permanent Air Force
  • Norwegian Army Air Service
  • Peruvian Air Force
  • Polish Air Force – 1 Avro 504K.
  • Portuguese Air Force
  • Portuguese Navy
  • Imperial Russian Air Service
  • South African Air Force
  • Soviet Air Force – With original British-built examples, and Soviet built U-1 Avrushka copy.
; Kingdom of Spain
  • Spanish Navy
  • Spanish Republican Navy
  • Swedish Air Force
  • Swedish Navy
  • Swiss Air Force
;
  • Royal Siamese Air Force – 40 Avro 504N.
  • Royal Thai Navy
  • Turkish Air Force – Two aircraft
  • Royal Flying Corps
  • Royal Air Force
  • Royal Naval Air Service
  • American Expeditionary Force
  • United States Army Air Service
  • Uruguayan Air Force

    Surviving aircraft and replicas

;Australia
File:Qantas Replica Mascot Airport.JPG|thumb|Qantas Avro 504K replica with Sunbeam engine displayed at Qantas Domestic Terminal
  • A3-4 – 504K on static display at the Australian War Memorial in Campbell, Australian Capital Territory. It was initially given the serial number H2174 before being sent to Australia in 1918–19. It was donated to the memorial in August 1929. It was loaned to Qantas in 1965 and restored to resemble the first Qantas aircraft. It was restored to original condition and returned to the Australian War Memorial in 1987.
  • Replica – 504K on static display at the Qantas Founders Outback Museum in Longreach, Queensland. Built in 1988, it is marked as G-AUBG and represents the first Qantas Avro 504K.
  • Replica – 504K on static display at the Sydney Airport in Sydney. Built in 1988, it is marked as G-AUBG and represents the first Qantas Avro 504K.
  • Replica – 504K on static display at the RAAF Museum in Point Cook, Victoria. It uses an original engine, fittings, and instruments and is marked as E3747.
;Canada
;Finland
;New Zealand
;Norway
  • Unknown – 504K on static display at the Norwegian Aviation Museum in Bodø, Nordland. It was in service from July 1921 to 1928 and has been on display at the museum since 1995. It is painted with the registration number 103, which belonged to 504A that crashed in 1919.
;Russia
;United Kingdom
  • BK892 – 504K airworthy at the Shuttleworth Collection in Old Warden, Bedfordshire. It was originally given the serial number H5199, but was converted to a 504N and sold into civilian ownership. However, it was later impressed into RAF service during World War II as a glider tug, at which point it was given a new serial number. Again returned to civilian use after the war, it was used in the filming of Reach for the Sky.
  • D7560 – 504K on static display at the Science Museum in London.
  • H2311 – 504K on static display at the Museum of Science and Industry in Manchester.
  • Composite – 504K on static display at the Royal Air Force Museum London in London. It is made up of the fuselage of G-EBJE and the wings of G-EBKN.
  • Replica – 504K on static display at the Brooklands Museum in Weybridge, Surrey. Marked as G-AACA, it was originally built as a taxiable replica for the 1970s BBC TV series 'Wings'; later acquired by the RAF Museum, Hendon and stored at RAF Henlow then loaned to Brooklands Museum c.1987. Later donated to Brooklands Museum, fitted with an original rotary engine and restored to represent one of two 504s used by the Brooklands School of Flying in the late 1920s and early 1930s.
  • Replica – 504J on static display at Solent Sky in Southampton, Hampshire. It is marked as C4451 and was built by ADJ, BAPC No 210.
  • Replica-504K built by Pursang in Argentina in 2010, bought by Eric Vernon-Roe, grandson of Alliot Vernon-Roe, founder of Avro, and then to the UK. Registered as G-EROE, it displays with the Great War Display Team.
;United States