The British-originated Avro "Type 504" biplane series of aircraft would become the most-produced and influential aircraft designs of the World War 1 period, being fielded from 1913 into the early part of the 1930s. The design's service originally began as an armed reconnaissance biplane until, eventually, the outmoded series was relegated to the training role with the arrival of new and better-performing fighter aircraft seen in The Great War. However, it was in this new role that the Avro 504 would go on to make a name for itself with the British Royal Air Force (RAF) and others for decades to come.
The Avro Type 504 followed tried-and-true design and construction practices for its make-up and was centered around a single engine biplane (over-under) design. Depending on the production variant, the aircraft could seat one or two crewmen and machine gun armament was usually 1 x 7.7mm Lewis machine gun on a trainable, rear-facing mounting at the rear cockpit. Both cockpit positions were of the open-air variety. The aircraft could further be armed with conventional drop bombs at underwing hardpoints for ground-attack sorties. Early production models also contained a landing skid in addition to its fixed landing gears for additional support when landing, though this assembly was removed in future operational forms when found to add little.
Its single Gnome rotary-based engine developed 80 horsepower though, in practice, it was closer rated to 60 horsepower driving a two-bladed propeller unit at the nose. Performance figures (Type 504K) included a maximum speed of 95 miles-per-hour though cruising was closer to 75 mph. Range was out to 250 miles and its service ceiling reached 16,000 feet. Rate-of-climb was near 700 feet-per-minute.
The legacy of the Type 504 began when a further development of the Avro "Type 500" basic trainer biplane was drawn up. An order was then placed by the British Royal Navy and Army services and pushed the Type 504 in formal operational service during 1913, just prior to the events beginning the First World War. Early combat experience saw the Type 504 conduct limited strikes against enemy ground targets with the more-than-occasional Zeppelin-busting sortie mixed in. Though a relative success in these critical roles, the advancing technology of the war meant that the Type 504 was drawn back to airman training as soon as 1914 - the year the war began.
Despite this, the Type 504 proved to be a versatile performer as proven by the myriad of variants manufactured and operated and these would, in turn, produce minor structural revisions, new designations for specialized roles, and a plethora of engine fittings. The Type 504K model represented the two-seat version while the 504C was a specialized anti-Zeppelin gunnery platform. The addition of float components in place of the traditional undercarriage produced the Type 504L floatplane while the Type 504M was a transport-minded development. By the end of the war, the series was still in serial production, such was its importance to the British war effort, and would see nearly 600 more units added to the existing grand total of 10,000+ between the years of 1925 and 1932. Newer mounts were designated Type 504N and were of either new-build or conversion measures, the latter pulled form existing stocks of Type 504 aeroplanes. For the British, Type 504s would eventually be superceded by the Avro "Tutor" biplane series in the same training role.
In the end, the remarkable Type 504 series would become one of the most impressive and respected aircraft of its generation. Many-a-military pilot certainly "owed his wings" to having trained on the platform at one point or another and many more civilian pilots would join them throughout the post-war period. The Type 504 would become a mainstay of the famous "Barnstorming" touring groups of the 1920s-1930s as well as going on to become prized collector pieces for avid flyers able to afford the type.