The Hawker Hotspur was a Hawker Henley redesigned to take a Boulton-Paul semi-powered four gun turret. It was designed in response to Air Ministry Specification F.9/35, which required a powered turret as the main armament to replace the Hawker Demon.
In the same fashion as the Henley, the Hotspur used standard Hurricane outer wing panels. One prototype aircraft, K8309, was built in 1937, fitted with armament of four 7.7 mm Browning machine guns in a Boulton Paul dorsal turret plus one 7.7 mm Vickers machine gun mounted in the front fuselage.
The completion of the prototype was delayed until 1938, by which time the rival Boulton Paul Defiant had already flown. The Hotspur first flew on 14 June 1938 with only a wooden mock-up of the turret and with ballast equivalent to the weight of armament.
Crew: Two, pilot & gunner
Length: 10.02 m
Wingspan: 12.34 m
Height: 4.22 m
Wing area: 31.8 m²
Empty weight: 2,630 kg
Max. takeoff weight: 3,470 kg
Powerplant: Rolls-Royce Merlin II hp V-12 inline piston engine, 1,030 hp / 768 kW
Maximum speed: 510 km/h
Service ceiling: 8,500 m
Armament: 4 × 7.7 mm Browning machine guns in a Boulton-Paul turret.
1 × 7.7 mm Vickers machine gun in nose
As Hawker was committed to the production of Hurricanes and Gloster to Henley production, there was insufficient capacity to introduce another type and production was abandoned. The mock-up turret was removed and a cockpit fairing installed. Planned production by Avro to Specification 17/36 was abandoned and the prototype, with turret removed, served at the RAE Farnborough on miscellaneous test programmes of flap and dive brake configurations until 1942.