The Avro Type 557 Ava was a British twin-engined biplane torpedo bomber of the 1920s. It was developed by Avro to meet a requirement for a heavy torpedo bomber for the Royal Air Force but was unsuccessful, only two prototypes being built.
The British Air Ministry produced Specification 16/22 in 1922 for a long-range land-based torpedo bomber. The specification required that the aircraft be capable of carrying a 21 in (533 mm) torpedo or an equivalent weight of bombs and produced responses both from Blackburn Aircraft (the Cubaroo) and Avro.[1] Roy Chadwick, chief designer of Avro, initially produced a single-engined design, the Avro 556 powered by a Napier Cub engine, similar to the Cubaroo. This was rejected in favour of a twin-engined aircraft using two Rolls-Royce Condor engines, the Avro Type 557 Ava and winning an order for two prototypes from the Air Ministry.[1] Completed in secret (owing to its armament of a 21 in (533 mm) torpedo, thought to be able to sink the largest warships), the first prototype Ava (serial number N171) flew in mid-1924.[1]
The Ava was a three-bay biplane of wooden construction, with the un-cowled engines between the wings. It had a biplane tail, initially fitted with triple rudders, of which the centre rudder was soon removed.[2] The fuselage accommodated two pilots in an open cockpit, with nose and dorsal gun positions and a retractable ventral "dustbin" gun position that could be manned by the navigator/bomb aimer, who otherwise occupied a large enclosed cabin. The 2,000 lb (910 kg) torpedo or equivalent bomb load were carried on external racks under the fuselage.[1]
The Air Ministry dropped its plans to use the 21 in (533 mm) torpedo but Avro continued with construction of the second prototype, which was of all-metal construction but was otherwise similar to the first prototype, flying on 22 April 1927.[2] While a modified version of the Ava was proposed to meet Specification B19/27 for a heavy bomber, it was unsuccessful, no further aircraft being built.[1]