"Avro" was short for A.V. Roe & Co., Ltd., of Manchester and Hamble. A. V. Roe's planes may have only played a small direct part in the history of WWI air combat, but the 504 played a larger part as a trainer, and of course (unlike many of its contemporaries) the Avro firm had a history lasting long after World War One. 8340 504s were produced during the war.
Aircraft from the Great War or shortly thereafter include:
- Ten 504Es were built and used as trainers.
- The 504F was an experimental version with a 75hp Rolls-Royce Hawk engine. Production was not undertaken, as it was underpowered.
- The 504G was a gunnery trainer version of the 504B.
- The 504H was a converted 504C used in RNAS experimentation with catapult launches from ships.
- The 504J was a widely-used trainer which appeared in the autumn of 1916. Many were converted to 504Ks.
- Bruce, p.36
- Bruce, p.53.
- Bruce, pp.39-55.