[4] The Cubaroo, with a mainly steel tube metal structure, had an 11 ft (3.4 m) deep fuselage to accommodate the pilot who sat, with a navigator beside him, sitting over the engine.

The rear of the fuselage had a triangle cross section to improve the gunner's fields of fire from hatches located near each lower wing root which permitted them to cover the underside of the tail.

[5] Due to the change of British Air Ministry policy favouring twin-engine designs for the role, a new specification, 16/22 was drawn up, and the type was not ordered into service.

[6] The first prototype (with serial N166) flew in secrecy in the summer of 1924, proving to have good handling characteristics, with the engine not causing problems, as the Napier Cub had already been test flown in an Avro Aldershot.

[2] It was then fitted with a metal, three-blade adjustable-pitch propeller and was delivered for testing at RAF Martlesham Heath but was written off after its undercarriage collapsed on 2 February 1925.