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The Avro 504J was a two seat trainer powered by a 100hp Gnome Monosoupape engine and that replaced the Avro 504A as the RFC’s main trainer.
Work on the 504J began in the autumn of 1916. It was externally identical to the Avro 504A (with the balanced comma shaped rudder and short span ailerons), apart from the unusual lobed cowling needed for the more powerful engine.
One of the first units to get the 504J was the School of Special Flying, which had been founded at Gosport in July 1917 by Major R.R. Smith-Barry. He introduced a new training system in which the instructor was able to communicate verbally with the pupil using ‘Gosport’ speaking tubes. This allowed the instructor to give demonstrations of what he wanted the pupil to do, while explaining it, or to give clear instructions in the air without having to stall the engine first. This system of training became part of the RAF’s Flying Training School syllabus for over 40 years, while Gosport tubes remained in widespread use into the 1950s. During the First World War this training system was also used at Shoreham, Lilbourne, Redcar, Ayr and the Curragh.
Production of the Avro 504J was split between Avro, Harland and Wolff, Sunbeam and Brush. Avro themselves built the components in Manchester and assembled the aircraft at Hamble. Eight batches of serial numbers were allocated, for a total of 1,750 aircraft, although some aircraft from five of these were completed as either the Avro 504K or Avro 504N.
Amongst the many people to learn to fly in the 504J was H.R.H. Prince Albert, who later became King George VI.
By the end of 1917 the supply of Monosoupape engines was beginning to run short, so production switched to the Avro 504K, which had a universal mount capable of taking a wide range of engines.
Very little experimental work was done with the 504J. One aircraft, B4264 (from a batch ordered as the 504A but built as a 504J), was given short span single bay wings and a curved fin at Gosport in January 1918. The same aircraft was later given standard 36ft wings but with the wing gap reduced from 5ft 6in to 5ft 1.25in.
In March 1918 these same wings were tested on B3144. This was a two-seater with a shortened fuselage and armed with a Lewis gun. By May 1918 it had been converted into a single seater, with a fuel tank in the front cockpit. This aircraft was followed by a number of single seat 504Ks which were used for high altitude work by Home Defence Squadrons in the north of England.
Aircraft Ordered as Avro 504J
Serial Numbers |
Manufacture |
Number of aircraft |
C4301-C4500 |
A.V.Roe |
200 |
C5751-C6050 |
Harland & Wolff |
300* |
D1-D200 |
A.V.Roe |
200 |
D4361-D4560 |
Sunbeam |
200 |
D5451-D5550 |
A.R.Roe |
100* |
D6251-D6400 |
Brush |
150* |
D7501-D7800 |
A.V.Roe |
300* |
E1601-E1900 |
A.V.Roe |
300* |
* some completed as 504K or 504N
Engine: Le Rhone or Gnome Monosoupape
Power: 80hp to 100hp
Crew: 2
Span: 36ft 0in
Length: 29ft 5in
Height: 10ft 5in