Avro 504B

The Avro 504B was constructed for the RNAS and retained the long ailerons of the original Avro 504. (The RFC and RNAS insisted on different specifications for their 504s, forcing Avro into the wasteful practice of creating special aircraft for each.) It was the first 504 to deploy the landing skid that would become common on future models. While a few 504Bs were used in service from Dunkirk, most were used for training.