504D: Single seat fighter for the RFC.
504J: Gnome Monosoupape engine.
504K: Trainer version, able to be fitted with Monosupape, Le Rhone, or Clerget engines. A Fairly large number of 504Ks were refitted late in the war as single seaters, and emplyed to defend English airspace against Zeppelin raids.
504L: Eighty aircraft converted for service with the RNAS as single seat fighters.
504M: solitary aircraft with an enclosed two-seat cabin.
The 504 had a long career post 1918, and indeed development and production continued long after the end of the war. The pair of 504N prototypes converted from earlier uncompleted aircraft in 1925 had a new landing gear design and did away with the skid; powered by Bristol Lucifer and Armstrong Siddeley Lynx engines respectively, the led to the production Avro Lynx, most of which had a redesigned fuselage of welded tube construction. aside from new production aircraft, existing 504Ks were brought up to 504N standard in both the UK and Canada.
504Ns were built under license in Belgium, Denmark, Canada, and Japan. The Japanese built Yokosuka K1Y1 led to the Mongoose powered K2Y1, and to the K2Y2 Type with a Jimpu engine.
504Q: Single Lynx-engined aircraft (G-EBJD) fitted with an internal cabin and used to support Antarctic research by Oxford.
|504K on display in the Early Years Gallery at the National Museum of the US Air Force, Dayton|
A nice walkaround of another 504K preserved in Canada
Some detail photos of 504 replica G-ECKE
The Airfix 1/72 scale 504K model kit
Greek 504N for FSX
An RC 504 night fighter model project
Pictures of the Shuttleworth Collection's 504K
Photos (2): Avro 504K G-EBYB. Aeroplane Monthly December 1988 p.748