Single-engine two-seat World War I fighter-bomber-Trainer biplane
[Avro 504J (N3182G, B3182) on display at the Fantasy of Flight Museum, Polk City, Florida on 13 May 2001 (Photo 20010513-088 by John Shupek copyright © 2001 Skytamer Images)]
Overview of Avro 504 Series 
- Role: Trainer, Fighter, Bomber
- Manufacturer: Avro
- First flight: 18 September 1913
- Retired: 1934
- Primary users: Royal Flying Corps; Oil Naval Air Service.
- Produced: 1913-1932
- Number built: 8,970
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.
- 504: 80-hp Gnôme Lambda engine. (Original model)
- 504A: Modified with smaller ailerons and broader struts. 80-hp Gnôme engine.
- 504B: Version for RNAS with larger fin. 80-hp Gnôme or Le Rhône engine.
- 504C: Single-seat anti-Zeppelin aircraft for the RNAS. The 504C was fitted with an extra fuel tank, in place of the observer.
- 504D: Single-seat anti-Zeppelin aircraft for the Royal Flying Corps. Six built.
- 504E: 100-hp Gnôme engine. Ten built.
- 504F: 75 hp Rolls Royce Hawk engine. One built.
- 504G: 80-hp Gnôme engine.
- 504H: Used for catapult trials. 80-hp Gnôme engine.
- 504J: Used as a trainer. 100-hp Gnôme or 80-hp Le Rhône engine.
- 504K: Two-seat training aircraft. The 504K had a universal mount to take different engines. Single seat fighter conversion used for anti-zeppelin work. Several were assembled in Australia by Australian Aircraft & Engineering. 130-hp Clerget, 100-hp Gnôme Monosoupape or 110-hp Le Rhône 9J engines.
- 504K Mk.II: Hybrid trainer based on 504K fuselage with 504N undercarriage and wings, and powered by rotary engine. Built under license in Mexico as Avro “Anahuac”.
- 504L: Floatplane version. 150-hp Bentley BR1, 130-hp Clerget or 110-hp Le Rhône engines.
- 504M: Three-seat cabin biplane. Only one was ever built. 100-hp Gnôme engine.
- 504N: Two-seat training aircraft. Redesigned postwar trainer for RAF with 160-hp Armstrong Siddeley “Lynx” engine. 598 built.
- 504O: Floatplane version of the 504N. First aircraft to fly above the Arctic Circle in 1923 in the Oxford Expedition.
- 504P: Unbuilt version of the 504N with side-by-side seating.
- 504Q: Three-seat cabin biplane. The 504Q was built for the Oxford University Arctic Expedition. Only one was ever built, powered by an Armstrong Siddeley “Lynx” engine.
- 504R Gosport: Reworked trainer with revised, lightweight structure. five prototypes flown 1926 two 1927 with various engines 100-hp Gnôme Monosoupape, 100-hp Avro Alpha, 140-hp Armstrong Siddeley Genet Major and 150-hp Armstrong Siddeley Mongoose, with the Mongoose chosen for production aircraft. Ten were sold to Argentina, with 100 more built by FMA under license in Argentina. At least six were exported to Estonia, remaining in service until 1940, and an unknown number to Peru.
- 504S: Two-seat training aircraft. Built under license in Japan by Nakajima.
- Yokosuka K2Y1: Japanese version of the Avro 504N, given the long designation Yokosuka Navy Type III Primary Trainer, powered by a 130-hp (97-kW) Mitsubishi-built Armstrong-Siddeley Mongoose radial piston engine. 104 built.
- Yokosuka K2Y2: Improved version of the K2Y1, powered by a 160-hp (119-kW) Gasuden Jimpu 2 radial piston engine. 360 built (K2Y1 and K2Y2). Watanabe build aircraft were given the long designation Watanabe Navy Type 3-2 Land-based Primary Trainer.
- U-1 (Uchebnyi-1) “Avrushka”: Russian copy of the 504K. over 700 built
- MU-1 (Morskoy Uchebnyi-1): Russian seaplane version.
strong>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 
- Argentina: Argentine Army Aviation Service
- Australia: Australian Flying Corps; Royal Australian Air Force; Western Australian Airways
- Belgium: Belgian Air Force
- Bolivia: Bolivian Air Force
- Brazil: Brazilian Air Force; Brazilian Naval Aviation
- Canada: Royal Canadian Air Force
- Chile: Chilean Air Force; Chilean Navy
- Denmark: Royal Danish Air Force; Royal Danish Navy
- Estonia: Estonian Air Force
- Finland: Finish Air Force
- Greece: Hellenic Air Force; Hellenic Navy
- Guatemala: Guatemalan Air Force
- British India
- Iran: Imperial Iranian Air Force
- Ireland: I Wish Air Service; Irish Air Corps
- Latvia: Lesbian Air Force; Aizsargi
- Federated Malay States
- Mexico: Mexican Air Force
- Netherlands: Dutch Army Aviation Group; Royal Netherlands East Indies Army Air Force
- New Zealand: New Zealand Permanent Air Force
- Norway: Norwegian Army Air Service
- Peru: Peruvian Air Force
- Portugal: Portuguese Air Force; Portuguese Navy
- Russian Empire: Imperial Russian Air Service
- South Africa: South African Air Force
- Soviet Union: Soviet Air Force
- Kingdom of Spain: Spanish Navy; Spanish Republican Navy
- Sweden: Swedish Air Force; Swedish Navy
- Siam (Thailand): Royal Thai Air Force; Royal Thai Navy
- Turkey: Turkish Air Force
- United Kingdom: Royal Flying Corps; Royal Air Force; Oil Naval Air Service
- United States: American Expeditionary Force; United States Army Air Service
- Uruguay: Uruguayan Air Force
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. Features specific to the Avro 504J are presented following this section.
- Type of Aeroplane: 2-Seater Biplane (Training Machine)
- Aeroplane specification: “Avro” Type 504
- Engine: 100-hp Mono Gnôme, 110-hp Clerget, 100-hp Le Rhône, or 130-hp Clerget
- Revolutions of engine for stated b.h.p.: 1,250 r.p.m.
Estimated speed with full load and with all fittings in position.
Estimated climb with full load and with all fittings in position.
- To 3,500 ft: 5 min
- To 8,000 ft: 10 min
- To 10,000 ft: 16 min
- Pilot, position: Level with trailing edge of lower wing
- Passenger's position: In front of pilot
- Type: 2 bladed “Avro”
- Pitch (110 Le Rhône): 8 ft 8 in
- Diameter: 9 ft 0 in
- Span of upper wings: 36 ft 0 in
- Span of lower wings: 36 ft 0 in
- Span of tail plane: 10 ft 0 in
- Height overall: 10 ft 5 in
- Length overall: 29 ft 5 in
- Chord top wing: 4 ft 9 in
- Chord second wing: 4 ft 9 in
- Chord tail plane: 2 ft 8⅜ in
- Chord elevator: 2 ft 4 in
Details of Weights and Loadings
- Tail plane with supports: 21½ lbs
- Elevators: 12 lbs
- Rudder: 8½ lbs
- Total: 42 lbs
Main Lift Structure
- Wings with flaps with center section: 260½ lbs
- Interplane struts: 41 lbs
- Interplane wires: 24½ lbs
- Total: 326 lbs
- Undercarriage with axle and skid: 65 lbs
- Main wheels 100 × 700: 40 lbs
- Wing skids: 2 lbs
- Tail skids: 6 lbs
- Total: 113 lbs
- Body and engine housing: 270 lbs
- Aeroplane control gear and wires: 30 lbs
- Other details, flying instruments, lighting set, etc.: 25 lbs
- Engine with magnetos 110 Le Rhône: 330 lbs
- Airscrews, boss and bolts: 41 lbs
- Oil tanks, cooler and piping: 15 lbs
- Petrol tanks, piping and air pressure system: 39 lbs
- Total: 425 lbs
- Total weight of machine bear with water in radiators: 1,231 lbs
- Crew of two at 180 lbs each: 360 lbs
Weight of Machine in Flying Trim
- Weight of machine bare with water in radiators: 1,231 lbs
- Military load: 360 lbs
- Petrol 25½ gallons: 184 lbs
- Oil 6 gallons: 54 lbs
- Total: 1,829 lbs
Total weight of machine in flying trim: 1,829 lbs
Areas: Wings and Ailerons
- Top: 173 ft²
- Second: 157 ft²
- Total: 330 ft²
- Top: 22.7 ft.²
- Second: 22.7 ft.²
- Tail Plane: 26 ft²
- Elevators: 18 ft²
- Rudder: 9 ft²
- Total: 53 ft²
- Top wing: 2.5°
- Second wing: 2.5°
- Loading on wing surface: 5.57 lbs per ft²
- Weight fully loaded per hp (normal): 16.7 lbs per hp
- Weight carried on tail in-flight: nil
- Movement of CG with total variation in load during flight: 4.2 in
- Type: Control pillars and foot bars.
- Positions from which aeroplane may be controlled: Complete dual control.
- What control provided for crew other than pilot: Complete dual control.
- Position of engine controls: On left-hand side of body.
- No adjustment of rotor bar is provided
- Tail skid: Can be controlled if desired.
- Load on tail skid when loaded ready for flight: 100 lbs
- Tail plane adjustable on the ground but not in the air from pilot's seat.
- Wings, internal: H.T. steel wire.
- Wings, external: Cable or streamline wires.
- Body: H.T. steel wire.
- Undercarriage: Cable.
- Other parts: Wire and cable.
- Type: Special “Avro”
- Size of standard wheels fitted: 100 × 700 mm
- Wing spars: Spruce.
- Wing struts: Spruce.
- Body struts: Spruce and ash.
- Undercarriage struts: Steel tubes.
- Longerons in body: Ash.
- Shock absorber: Rubber cord
- 21 gallon tinned steel pressure petrol tank behind engine, weight empty 27 lbs.
- 4½ gallon tinned steel petrol gravity tank in center section, weight empty 10 lbs.
- 6 gallon tinned steel gravity oil tank behind engine, weight empty 12 lbs.
Factor of Safety
- Machine had a factor of safety of 7 on sand test.
Center of Pressure
- The range of movement of center of pressure is 0.3 to 0.5 chord.
- 1 fixed .303 Lewis atop upper wing (single-seat night fighter variants)
The following companies are recorded as manufacturing the Avro 504 series of aircraft under license and not under license*.
- A. V. Roe and Co Ltd, Park Works, Newton Heath, Manchester; and at Hamble Aerodrome, near Southampton, Hants.
- Australian Aircraft and Engineering, Sydney, NSW, Australia
- Blériot and SPAD Aircraft Works, Addlestone
- The Brush Electrical Engineering Co Ltd, Loughborough
- Canadian Aeroplanes Ltd, Toronto, Canada
- The Eastbourne Aviation Co Ltd, Eastbourne
- Fabrica Militar de Aviones, Cordoba, Argentina
- Frederick Sage and Co Ltd, Peterborough and London
- The Grahame-White Aviation Co Ltd, Hendon Aerodrome, London
- Harland and Wolff Ltd, Belfast
- The Henderson Scottish Aviation Factory, Aberdeen
- Hewlett and Blondeau Ltd, Luton.
- The Humber Motor Co Ltd, Coventry
- Morgan and Co, Leighton Buzzard
- * Morskoy Uchebnyi, Russia
- Nakajima Hikoki Seisaku Sho, Ohta-Machi, Tokyo, Japan
- Parnall & Sons, Bristol
- Regent Carriage, Fulham
- S. E. Saunders Ltd, East Cowes, Isle of Wight
- Savages Ltd, King's Lynn,
- Societe Anonyme Belge de Constructions Aeronautiques Haren, Brussels, Belgium
- The Sunbeam Motor Car Co Ltd, Wolverhampton
- TNCA, Balbuena field in Mexico City.
- * Uchebnyi, Russia
- Yokosuka Naval Arsenal, Japan
Avro 504J Specifications 
- 1 & times; 80-hp Le Rhône or 80-hp Gnôme Monosoupape
- Span: 36 ft 0 in
- Length (rotary engines): 29 ft 5 in
- Length (Dyak): 28 ft 11 in
- Height: 10 ft 5 in
- Wing Area: 330 ft²
Avro 504J Production
- B3101 to B3250: A.V. Roe
- B4201 to B4300: A.V. Roe
- C4301 to C4500: A.V. Roe
- C5751 to C6050: Harland & Wolff
- Dl to D200: A.V Roe
- D4361 to D4560: Sunbeam
- D5451 to D5550: A.V. Roe
- D6251 to D6400: Brush
- D7501 to D7S00: A.V. Roe
- E1601 to El 900: A.V. Roe
- Shupek, John. Avro 504 photo via The Skytamer Archive, Copyright © 2001, 2015 Skytamer Images. All Rights Reserved
- Wikipedia. Avro 504
- Grey, C.G. “Avro, Aeroplanes: The Avro Standard Training Plane.” Jane's All the World's Aircraft 1919 (reprint). Arco Publishing Company, New York, 1969, Library of Congress 69-14964, 1931. pp. 65a - 69a
- Jackson, A.J. “Avro 504J and Avro 504K” Avro Aircraft since 1908. Putnam Aeronautical Books, London, second edition 1990, ISBN 0-85177-797-X, 1990. pp. 63-73
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