Avro 504N F8833 from Avro 504K Hamble
FN8833 is Avro 504N converted from an Avro 504K and seen at Hamble.


First flown at Brooklands in 1913 and still in RAF service in 1944, the A.V. Roe & Company Avro 504 was a development of the Avro 500 and it produced in greater numbers than any other British aircraft during the First World War.
Built by at least 18 different contractors, the total number built during the First World War is unclear although there is general agreement that it is more than 8,000. 
Earlier models of the Avro 504 (Avro 504 to 504H) and (Avro 504J and 504K) are described elsewhere on this website and so we purely concentrate on later models: Avro 504L, M, N, O, Q & R.

Avro 504L

A training seaplane version of the Avro 504K and the first conversion (C4329), the Avro 504L was tested in February 1919, powered by a 130hp Clerget engine. Some 31 aircraft were built (6 new build and 25 conversions) with the production standard being a three-seater powered by the 150 hp Bentley BR1 rotary.

Avro 504M

A three-seat cabin version of the Avro 504K, known informally as the Avro Limousine. A single example was produced (K-134 / G-EACX) which was powered by a 100hp Gnome Monosoupape rotary. Registered on 13th May 1919, the aircraft was flying by 28th May.
However, its Certificate of Airworthiness was not renewed in 1920.
Avro 504N RAF K1812  air to air
An RAF Avro 504N K1812 showing the revised undercarriage of this type.

Avro 504N

Later models of the Avro 504 used radial engines including the Lynx and Mongoose, the most significant version being the Avro 504N and its seaplane variant, the Avro 504 O.
The Avro 504N was designed to meet Specifications 32/24, 3/27 and 6/30 for an ab-initio trainer and was powered by a 160 h.p. Armstrong Siddeley Lynx powerplant. It also featured a new undercarriage arrangement and other structural changes, including cutaway centre-section and wing roots to improve upward and downward visibility, and the adoption of tapered ailerons.
After a number of interim prototypes, the first true Avro 504N prototype (J733) which was Lucifer-powered and in effect, a conversion of an Avro 504K airframe whose contract had been cancelled at the end of the First World War. A second prototype (J750) was powered by the Armstrong Siddeley Lynx. These aircraft were flown in 1924.
In large scale production from 1927, some 561 Avro 504N aircraft were built in the UK with 17 conversions from Avro 504K. Overseas production (Canada, Denmark, Greece, Thailand and Belgium) comprised a further 121 new build and 27 conversions, for a total of 682 new build and 44 conversions.
Although retired as a training machine by 1939, seven ex-civilian Avro 504N aircraft were used during the Second World War as glider tugs. In this role, they supported the development and improvement of Britain’s radar detection system.
Their last known use was reported as late as October 1944. 12 aircraft also remained in Belgian service up to the German invasion of May 1940.
Avro 504O Greek Hamble
Greek Avro 504O seaplane being tested at Hamble.

Avro 504O

As highlighted earlier, the 5040 was a seaplane conversion of the Avro 504N. Seven were built, being exported to Brazil, Chile, Greece and Japan.
Similar Canadian float-equipped Avro 504Ns were designated as Avro 504NS.
Avro 504O Chilean Navy 19 land undercarriage
Avro 504O 19 of the Chilean Navy being tested on a temporary land undercarriage.

Avro 504Q

This was a single three-seat seaplane that was erected on the south coast at The Hamble in 1924, to support the Oxford University Arctic Expedition. It was powered by a 160hp Armstrong Siddeley Lynx engine and featured an open cockpit with an enclosed passenger cabin.
After being test flown in the UK, it was flown from Green Harbour, Spitzbergen on 15th July 1924, but it was forced down whilst at sea due to engine failure. After 18 hours on the open seas, it was recovered and taken to Liefde Bay. After further tribulations, the engine was removed before the expedition returned to England with the rest of the airframe being abandoned at Liefde Bay.

Avro 504R Gosport

The final iteration of the Avro 504 was the Avro 504R Gosport which was first flown in July 1926. This was a lighter-weight derivative using a 100hp Gnome Monosoupape engine and it was intended to have similar handling and performance to a standard Avro 504K fitted with a 130hp Clerget engine.
Six Avro 504R appeared on the British civil register, powered by either the Gnome rotary or Mongoose radial engine. The main sales were to the export market with the Avro 504R Gosport being used as a trainer in Argentina (10 supplied from UK, at least 34 built locally although a figure of 100 is also widely quoted), Estonia (at least 6) and Peru (6).


A final mention should be made of an Avro 504N derivative produced in Japan. The K2Y (360 built) was a Japanese version of the Avro 504N, built by Yokosuka, Kawanishi, Watanabe, Mitsubishi, Nippi and Showa. When powered by a 150 h.p. Mitsubishi-built Armstrong Siddeley Mongoose engine, it was designated K2Y1.
The designation changed to K2Y2 when a 160 h.p. Gasuden Jimpu 2 powerplant was fitted.


  Avro 504N Avro 504O Seaplane
Powerplant One 180hp AS Lynx I  One 215hp AS Lynx IVC
Span 36 ft 0 in
Maximum Weight 2,166 lb 2,663 lb
Capacity and armament 2 crew, normally unarmed
Maximum Speed 100 mph 96 mph
Cruising speed 85 mph 80 mph
Range 255 miles 240 miles


Variants & Numbers

Avro 504L                  Floatplane version of Avro 504K. 150hp Bentley BR1, 130hp Clerget or 110hp Le Rhône engines, Six new build and 25 conversions.
Avro 504M Three-seat cabin biplane. 100hp Gnome engine. One conversion,
Avro 504N Two-seat training aircraft to meet Specifications 32/24, 3/27 and 6/30 for an ab-initio trainer. 160hp Armstrong Siddeley Lynx engine. 682 new build and 44 conversions.
Avro 504NS Canadian designation of float equipped Type 504N. Equivalent to Type 504O.
Avro 504O Floatplane version of Avro 504N – 7 conversions.
Avro 504Q Three-seat cabin biplane. 160hp Armstrong Siddeley Lynx engine. One only.
Avro 504R Reworked and reduced weight variant of the Avro 504J. At least 62 aircraft.
Japan K2Y  Japanese version of the Avro 504N. Designated K2Y1 with a 150hp. Mitsubishi-built Mongoose engine and K2Y2 with a 160hp Gasuden Jimpu 2 engine. A total of 360 built.
Grand total Avro 504 Total production of all types of Avro 504: 10,057 aircraft, plus a total of 1,201 derivative aircraft built in Japan and Russia.



Avro 504N (LB1) 110  Danish Army Air Corps, Danmarks Flymuseum, Stauning



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