[Avro 504K (E.3349) on display at the Militärhistorisches Museum Flugplatz Berlin-Gatow, Germany on 10/21/2008 (John Shupek photos copyright © 2008 Skytamer Images)]
[Avro 504K (E449) on display at c.1994 at the Royal Air Force Museum, RAF Hendon, London (John Shupek photo copyright © 1994)]
[Avro 504K (E449) on display on 9/7/2002 at the Royal Air Force Museum, RAF Hendon, London (John Shupek photos copyright © 2002 Skytamer Images)]
[Avro 504K (G-CYFG) on display (9/17/2003) at the Canada Aviation Museum, Ottawa, Ontario, Canada (John Shupek photos copyright © 2003 Skytamer Images)]
[Avro 504K (M-MABE, A-28) on display (10/6/20003) at the Museo de Aeronáutica y Astronáutica, Madrid, España (John Shupek photos copyright © 2000 Skytamer Images)]
[Avro 504K (N4929) on display 1998 at the Old Rhinebeck Aerodrome, Rhinebeck, New York, USA (John Shupek photos copyright © 1998)]
[Avro 504K (N4929) on display 9/18/2003 at the Old Rhinebeck Aerodrome, Rhinebeck, New York, USA (John Shupek photo copyright © 2003 Skytamer Images)]
[Avro 504K (E3404), Airplane card: 1977 “The Golden Age of Flying”, Doncella Cigars, UK (The Skytamer Archive)]
Overview of Avro 504 Series 
The Avro 504 was a World War I biplane series of aircraft made by the A.V. Roe and Company Ltd. and under license by others. Production during the War totalled 8,970 aircraft and continued for almost twenty 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 aircraft were built from 1913 to the time production ended in 1932.
Design and Development 
First flown in July 1913, powered by a 80-hp Gnôme Lambda seven-cylinder rotary engine, engine, the Avro 504 was a development of the earlier Avro 500, designed for training and private flying. it was a two-bay all-wood and biplane with the square-section fuselage.
Operational History 
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 pilot was 2nd Lt. Vincent Waterfall and his navigator Lt Charles George Gordon Bayly (both of 5 Sqn RFC). The RNAS used four Avro 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 the destruction of the hydrogen generating plant.
Soon obsolete as a front-line 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 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) Gnôme or 110-hp (80 kW) Le Rhône engines. 274 converted Avro 504Js and 504Ks 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 Avro 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-4s and Standard J-1s); civil Avro 504s continued flying in large numbers until well into the 1930s.
The embryonic air service of the Soviet Union formed just after World War I 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 with Russian-made copies of the Gnôme Monosoupape rotary engine. This Russian version of the Avro 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 in Soviet service in the late 1920s.
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, Thailand and South Africa, with licensed production taking place in Denmark, Belgium, Canada and Japan.
The RAF's Avro 504Ns were finally replaced in 1933 by the Avro 621 “Tutor”, with small numbers continuing in civilian use until 1940, when seven were impressed into RAF service, where they were used for target-towing and glider-towing.
The Avro 504 was the first aeroplane to strafe troops on the ground as well as the first to make a bombing raid over Germany. It was also the first Allied aeroplane to be downed by enemy anti-aircraft fire and was Billy Bishop's first army aircraft.
The Avro 504 is easily recognizable because of the single skid between the wheels, referred to as the “tooth pick” in the RAF.
Survivors and Flyable Reproductions 
A small number of static display, and airworthy examples of the Avro 504 exist, more than 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 a flyable Avro 504K reproduction aircraft, powered by an original 110-hp (82 kW) Le Rhône 9J rotary engine, flying since 1971, and a newly founded company (Blue Swallow Aircraft) in Virginia is starting to produce reproduction Avro 504 examples.
The Military Aviation Museum of Pungo, Virginia, USA also has a flyable reconstruction aircraft in its collection. The Avro (A. V. Roe) 504K “H5991” is presented in Royal Flying Corps colors.
Avro 504 Series Operators 
The Avro Standard Training Biplane 
By a process of detailed improvement, which has led to increased strength and greater simplicity, and by the adoption of standardized methods of manufacture, the 80-hp machine of 1913 has evolved into the Type 504K, a machine admirably adapted for the methods of quantity production.
This machine is especially suitable for the purpose of training pilots, and has been adopted as the Standard Training Machine by the Royal Air Force.
In the 504K Type the nose of the machine has been altered and engine mounted overhung from the bearers. The machine will now take any of the existing rotary engines up to 150-hp. This has been accomplished by suitably designing the engine mounting and fitting adapters to take the different engines. It will be seen that this is a great advantage from the engine supply point of view.
The machine retains its characteristics of simplicity, strength and controllability, and one of its chief advantages is the ease of which it can be repaired at School Workshops where interchangeable spares can be obtained readily.
Avro 504K Specifications 
The following tables give the main features of the Avro 504K machine.
Estimated speed with full load and with all fittings in position.
Maximum speed for the above hp and revolutions:
Duration at this speed:
Estimated climb with full load and with all fittings in position.
Details of Weights and Loadings
Main Lift Structure
Weight of Machine in Flying Trim
Total weight of machine in flying trim: 1,829 lbs
Areas: Wings and Ailerons
Factor of Safety
Center of Pressure
Avro 504K Production: Wartime Deliveries
Avro 504K Production: Post War Deliveries
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