Avro 504

For Production Tables of Military 504 variants see here.
For Production Tables of Civil 504K variants see here.

Contents

Type Description

• Type 504
• Two seat fighting/training tractor biplane with staggered, two bay wings, developed from the Type 500 basic trainer. Very lightly constructed, it featured a rectangular section, wire braced, box-girder fuselage built from four ash longerons channelled for lightness and strengthened by flanges. Cross struts were of spruce. For maximum view the pilot sat in the rear, the passenger occupying the front cockpit, from the corners of which four ash struts supported the centre section. Equal span, two bay wings were rigged with 2 ft. stagger and braced by streamline section, hollow spruce interplane struts pin-jointed to the spars. Each wing panel consisted of five main ribs with spanwise stringers supporting a number of contour-forming strips of wood anchored to leading and trailing edges. Lateral control was by inversely tapered ailerons rigidly fixed at the inner end, the widened outer ends of which were warped by means of cables.  Although similar to that of the Avro 500, the undercarriage was a much improved and simplified unit. An ash skid was anchored to the fuselage by steel Vee struts as before, but the axle was no longer bolted to it and was no longer a laminated spring. Instead, a simple steel tube axle was used in conjunction with two main undercarriage legs having built-in rubber shock absorbers in streamlined cases. The tailplane was steel framed, with a rectangular fixed stabiliser and elevator and a 'comma' style rudder with no fixed fin.The tail skid was attached to the bottom of the rudder. The prototype was initially powered by a 80 h.p. Gnome installed in a square section cowling bulged on top and sides.
  After testing, early changes to the design involved the adoption of a more streamlined cowling and conventional ailerons. The prototype featured horizontal top longerons, but on all further aircraft the top longerons sloped downwards aft of the cockpits to make the fuselage symmetrical in side elevation. Production aircraft featured restressing of the wings to comply with RFC strength requirements which included doubling the depth and width of the rear spar.

• Type 504A
• Strengthened version of Type 504 for the RFC, with wide chord interplane struts and ailerons of reduced span. The lower wing roots were sometimes stripped of fabric to improve the downward view. One 80 h.p. Gnome, Le Rhône or Clerget powerplant.

• Type 504B
• Strengthened version of Type 504 for the RNAS. It reverted to long span ailerons and featured a large, unbalanced rudder hinged to a considerable dorsal fin. The top longerons were recessed to provide curved cut-outs in the sides of the rear cockpit. A stout ash tail skid, sprung with rubber cord and hinged to a pylon under the rear fuselage, became standard fitment on this and all subsequent 504 variants. One 80 h.p. Gnome or Le Rhône powerplant.

• Type 504C
• Single-seat anti-zeppelin variant of Type 504B for the RNAS, it had a large cylindrical fuel tank in place of the front cockpit and a gap in the top centre section through which a Lewis gun could fire incendiary ammunition upward at an angle of 45 degrees. One 80 h.p. Gnome powerplant.

• Type 504D
• Single-seat anti-zeppelin variant of Type 504A for the RFC, retained the balanced comma-type rudder and short span ailerons, but had the recessed longerons and wing root modifications of the Avro 504C. One 80 h.p. Gnome powerplant.

• Type 504E
• Higher powered version of Type 504B for the RNAS, built using the fuselages of unfinished Type 521's, including the repositioned observers cockpit, straight upper longerons and splayed centre section struts, married to standard Type 504B wings, undercarriage (including tail skid) and tailplane. The main fuel tank was relocated to the space between the cockpits, the change of C.G. position caused by this being counteracted by reducing the wing stagger from 24 to 9 in. One 100 h.p. Gnome Monosoupape powerplant.

• Type 504F
• One Type 504C fitted with one 75 h.p. Rolls Royce Hawk powerplant. An order for 30 was cancelled and replaced by 504Bs.

• Type 504G
• All purpose training aeroplane for the RNAS. Conversions of the Type 504B having synchronised forward firing Vickers gun, bomb racks for practice bombs and a Lewis gun mounted on a Scarff ring for the rear cockpit.

• Type 504H
• Strengthened conversion of Type 504C fitted with catapult pick up points and used for catapult trials.

• Type 504J
• Two-seat training aircraft for the RFC, based on the Type 504A. One 100 h.p. Gnome Monosoupape or 80 h.p. Le Rhône powerplant. Externally identical with the earlier type, large numbers ordered as 504As were completed as 504Js.

• Type 504J Mk.II
• Original designation of 504R

• Type 504K
• Two-seat training aircraft. As the 504J with a universal mount to take different powerplants, most notably the 100 h.p. Gnome Monosoupape 9B-2, 80 h.p. Le Rhône 9C, 110 h.p. Le Rhône 9J or 130 h.p. Clerget 9B. In the older machines the engine mount was of the two bearer type, the front bearer being in the form of a ball race supported on four tubular arms forming extensions to the fuselage longerons. This 'spider' was now replaced by an overhung mounting which consisted of two bearer plates which would accept any suitable engine and allow the use of a smooth open fronted cowling. Irrespective of the type of engine fitted, aircraft built with this mounting were known as the Avro 504K, even though many had been ordered as 504Js or even 504As. The fuselage was strengthened by the addition of further spacers. In addition to the shortening of the bracing bays that these permitted, the longerons were further strengthened by the application of bow-shaped lengths of plywood between the upright spacers. Behind the engine cowling, improved flank fairings enhanced the lines of the forward fuselage. The mounting of the tailplane at the sternpost was revised to enable the surface‘s angle of incidence to be adjusted (as an on-ground rigging operation) to suit the type of engine fitted. Upper and lower mainplane panels and ailerons were re-designed to be interchangeable.
  A small number were pressed into service as Home Defence single-seat fighters, armed with a single Lewis gun on a Foster mounting above the centre section, and powered by the 110 h.p. Le Rhône.
  Postwar aircraft reconditioning was undertaken to Specfication 17/23 and the final production batch was built to Specification 15/26.

• Type 504K Mk.II
• Two-seat training aircraft featuring Type 504K fuselage with Type 504N wings and undercarriage. One 100 h.p. Gnome or 130 h.p. Clerget powerplant.

• Type 504KL
• Initially designed as a two-seat training seaplane version of Type 504K, the aircraft was mostly used as three seater for joy riding. The prototype used two wooden, pontoon-type, single step main floats, each attached to the fuselage by two steel struts, as well as a tail float bolted directly to the main structure. A large curved fin was fitted to compensate for the extra keel surface forward and the fairing of the fuselage sides was improved to conform more closely to the shape of the cowling. To give a reasonable take-off performance the higher powered 130 h.p. Clerget was fitted along with a four bladed airscrew. On production aircraft the main undercarriage was strengthened by means of an additional strut to the rear of each float, and the powerplant replaced by the 150 h.p. Bentley BR1.

• Type 504M
• Type 504K modified above the top longerons to produce a three-seat cabin biplane.  A curved plywood roof with two glazed portholes in each side was hinged along the port longeron. After it was opened the pilot entered by raising a further section of roofing, and once in, viewed the landscape through five vertical Triplex panels mounted round the edge of the cockpit. A light fabric covered structure faired the cabin smoothly into the tail and additional side area was compensated by the addition of a 504L-type dorsal fin. Despite the considerable weight penalty, improved streamlining made it faster than the standard 504K. One 100 h.p. Gnome powerplant.

• Type 504N
• Two-seat training aircraft to meet Specifications 32/24 and 3/27 for an ab-initio trainer, based on the Type 504K with radial rather than rotary powerplant and featuring several modifications: replacement of the skid plus elastic shock absorber undercarriage with a semi-oleo type, cutaway centre sections and wing roots to improve visibilty, fuel tanks located under the upper wing, adjustable tailplane and additional stringers to round out the fuselage sides. One 180 h.p. Armstrong Siddeley Lynx II, 200 h.p.Lynx III or 215 h.p. Lynx IVC powerplant.
  Early versions had a wooden fuselage and tapered ailerons, but later production to Specification 6/30 featured a welded steel tube fuselage and rectangular Frise-type ailerons.

• Type 504NS
• Canadian designation of float equiped Type 504N. Equivalent to Type 504O.

• Type 504O
• Floatplane version of 504N (early build), featuring twin floats and a dorsal fin similar to the Type 504L. One 215 h.p. Armstrong Siddeley Lynx IVC powerplant.

• Type 504Q
• Three-seat cabin seaplane, similar to the Type 504O but featuring a new, wider, fuselage with open cockpit ahead of a glazed cabin, designed to support the Oxford University Arctic Expedition. One 215 h.p. Armstrong Siddeley Lynx IVC powerplant.

• Type 504R Gosport
• Initially referred to as the Type 504J Mk.II, this was a reworked and reduced weight variant of the Type 504J, featuring tapered ailerons and cutaway wing roots to improve visibilty. Development aircraft featured the 100 h.p. Gnome Monosoupape rotary powerplant, but production aicraft utilised the more modern radial powerplant, either 140 h.p. Armstrong Siddeley Genet Major or 150 h.p. Armstrong Siddeley Mongoose.

• Type 504S
• Designation of Type 504L with Japanese Naval Air Service.

Foreign Derivatives

• K2Y
• Two-seat training aircraft for the Japanese Navy, similar to the Type 504N but with rounded wingtips and an all new undercarriage and tailplane. Built by Yokosuka, Kawanishi, Watanabe, Mitsubishi, Nippi and Showa. Designated Type 3 Land-based Trainer Kai-1 (K2Y1) with a 150 h.p. Mitsubishi-built Armstrong-Siddeley Mongoose powerplant and Type 3-2 Land-based Trainer (K2Y2) with a 160 h.p. Gasuden Jimpu 2 powerplant.

• U-1
• Utschebny (Учебный)-1 Avrushka (Little Avro), also known as the Duks U-1 (Дукс У-1 ), the original Duks factories having become a State Aircraft Plants in 1918. An unauthorised version of the Type 504K. Developed by S.V. Ilyushin, and fitted with a 120 h.p. M.2 powerplant. The VVS designation U-3 was originally assigned in 1925, but this was changed to U-1 in 1926. I was employed in Russia during from 1921 to 1932, when it was replaced by the U-2, although the U-1 continued to serve as a taxying trainer and in aeroclubs until 1935.

• MU-1
• (Morskoy Uchebnyi-1) - a seaplane version of the U-1. The construction of the floats in Russia was simplified, without any harm to their quality. They were made of .5 mm plywood, and pine board covering was retained only at the sides and the bottom but only as high as the waterline. Weight of the Russian floats went down to 375 lb.from the original weight of 465 lb. The MU-1 was used until 1934.

Production Summary Index

Total Avro 504 Production By Type
Total Wartime Avro 504 Production By Mark and Manufacturer
Total Post War Production Built New, By Mark, Manufacturer and Country
Exports, Including Imperial Gifts
UK Contracts
Foreign Derivatives

Total Avro 504 Production By Type (See Note 2)

Total Pre War and Wartime Type 504 Production By Mark and Manufacturer

Total Post War Type 504 Production Built New, By Mark, Manufacturer and Country

Exports of British Built or Converted Aircraft, Including Imperial Gifts

War Office, Air Board and Admiralty Contracts Associated With Avro 504 Production

Foreign Derivatives

Notes

1. Although the breakdown between 504A, J and K can no longer be precisely defined as aircraft build type changed on the production line (see Type 504A/K page), the sum of the three variants built can be considered fairly accurate.
2. With the availablity of a great number airframes that had gone directly to store or simply remained as spares, it is difficult to determine with accuracy how many of the post war aircraft were entirely new build or which used existing/spare airframes.
3. Export Type 504Ns and 504Os were either supplied in mixed batches or as 504Ns with optional floats, hence for this site this author will use the term Type 504N/O.

Production References

1. Air Britain RAF Aircraft Register Series, Various Volumes (Air-Britain Publications)
2. Avro Aircraft Since 1908, A.J. Jackson (Putnam, 1965 and 1990)
3. British Aeroplanes 1914-18, J.M. Bruce (Putnam, 1957)
4. Royal Navy Aircraft Serials and Units, 1911-1919, Ray Sturtivant and Gordon Page (Air-Britain Publications, 1992)
5. Berkshire Aviation Co. Ltd., Air Pictorial, Sept. 1977
6. Japanese Aircraft 1910-1941, Robert Mikesh and Shorzoe Abe (Putnam, 1990)
7. Canadian Aircraft since 1909, K.M. Molson and H.A. Taylor (Putnam, 1982)
8. Parnall Aircraft since 1914, K.E. Wixey (Putnam, 1990)
9. Plane to Plane - The Story of Frederick Sage and Co. Ltd, Martyn Chorlton (Old Forge Publishing, 2004)
10. Eastbourne Aviation Company, A History of the, 1911-1924, L. McMahon and M. Partridge (Eastbourne Local History Society, 2000)
11. British Military Aircraft Serial, 1878 - 1987, Bruce Robertson (Midland Counties Publishing, 1987)
12. 85 Years Of South African Air Force, Winston Brent (Freeworld Publications, 2005)
13. Australian 504s, Air Enthusiast 44
14. Complete Civil Register of New Zealand, Air Britain Archive, 1981/1 (Air-Britain Publications)
15. Japanese Civil Register 1919-1945, Air Britain Archive 1995/4 through 2003/3 (Air-Britain Publications)
16. Air Britain Digest, 1989/1 (Air-Britain Publications)
17. Air Britain Digest, 1989/3 (Air-Britain Publications)
18. Air Britain Digest, 1990/3 (Air-Britain Publications)
19. Latin American Military Aviation, John M. Andrade (Midland Counties Publications, 1982)
20. Avro 504 in Australian and New Zealand service at http://adf-serials.com.au/CMS/home
21. Encyclopedia of U.S. Military Aircraft Part II: The World War I Production Program, Volume 1 - Avro 504 to Bristol Scout, Robert B. Casari (Robert B. Casari, 1972)
22. http://www.joebaugher.com/usaf_serials/1908-1920.html
23. US Army Aviation: Serial Numbers and Orders, 1908-1923, Robert B. Casari (Military Aircraft Publications, 1995)
24. Avro 504K, Windsock Datafile 28, J.M. Bruce (Albatros Productions, 1991)
25. https://applications.icao.int/postalhistory/botswana_1984_40th_anniversary_of_icao.htm
26. http://www.airhistory.org.uk/rfc/aircraft.html
27. http://www.airhistory.org.uk/gy/index.html
28. https://documents.techno-science.ca/documents/CASM-Aircrafthistories-Avro504K.pdf
29. Canadian Military Aircraft Serial Numbers at CASPIR (Canadian Aircraft Serials Personnel Information Resource) at the Canadian Warplane Heritage Museum
30. https://www.avro504.org
31. Avro 504 in Portuguese service at https://ex-ogma.blogspot.com/2009/02/avioes-da-am-avro-504-k.html
32. http://www.edcoatescollection.com/
33. https://www.belgian-wings.be/
34. http://latvianaviation.com/Avro_504K.html
35. Irish Air Corps Aircraft 1922-2007 at https://studylib.net/doc/7859875/aircraft-of-the-irish-air-service--irish
36. Avro 504 in Chile at http://ivansiminic.blogspot.com/search?q=avro+504
37. Avro 504 in Argentina at http://www.amilarg.com.ar/avro-504.html
38. Aviation in Thailand via http://www.earlyaviators.com/ethai1.htm
39. Svenskt Flyghistoriskt Forum • Visa kategori - Sk 3, Avro Fb (flyghistoria.org)
40. Avro An Aircraft Album, E.A. Harlin and G.A. Jenks (Ian Allen, 1973)
41. Avro 504 in Swedish service at http://www.avrosys.nu/aircraft/MFV/064-Avro-504K/064-Avro504K.htm
42. The History Of Danish Military Aircraft Volume 1, Ole Nikolajsen at https://www.ole-nikolajsen.com/history%20acft%20dk.pdf
43. Los AVRO 504 en Argentina y el método Gosport (The Avro 504 in Argentina and the Gosport Method) at https://www.histarmar.com.ar/AVIACION/EloyMartin/EO20c/E020c.pdf
44. Avro 504K with Brazilian Naval Aviation at http://www.naval.com.br/anb/ANB-aeronaves/Avro_504_K/Avro_504_K.htm
45. Avro 504K with Brazilian Naval Aviation at http://www.armasnacionais.com/2017/10/avro-504k-na-aviacao-naval.html
46. Air Forces Of The Baltic States1918-2001 (Blue Rider Publishing, 2001)
47. Insignia No.11 (Blue Rider Publishing)
48. Insignia No.12 (Blue Rider Publishing)
49. Those Fabulous Flying Years, Colin Cruddas (Air Britain (Historians) Ltd, 2003)
50. Avro 504 in Taiwan (China) at http://www.daya.org.tw/hot-news-1/10003ju-ya-bao/dayadiyiweifeixingyuanzhangkuncan-1
51. Avro 504 in Dutch service at https://kw.jonkerweb.net/index.php?option=com_content&view=article&id=735:avro-504-uk&catid=82&lang=en&Itemid=544&showall=1&limitstart=#Registratie-KLu
52. Aeromilitaria, 1995/4 (Air-Britain Publications)
53. Flight 10 Apr 1924
54. Aerial Age 13 Dec 1920
55. The British Civil Aircraft Registers 1919-1928, Compiled and Edited by Peter W. Moss (Air-Britain, 1969)
56. The British Civil Aircraft Registers G-AAAA-'AAZZ (1928-1930, Compiled and Edited by Peter W. Moss (Air-Britain, 1971)
57. British Isles Civil Aircraft Registers 1919-2011 (LAAS International, 2011)
58. Soviet Aircraft and Aviation 1917-1941, Lennart Andersson (Putnam, 1994)
59. British Combat Aircraft in Latin America, Santiago Rivas (Hikoki, 2019)
60. History of Aircraft Design in the USSR Before 1938 (Istorii︠a︡ konstrukt︠s︡iĭ samoletov v SSSR do 1938), V. B. Shavrov ((Moscow: Mashinostroenie, 1986), translated by W. H. Schoonmaker, available from the Smithsonian/National Air and Space Museum)