The Osprey is a folding-wing navalised version of Hart to Air Ministry Specification O.22/26.
The Hart prototype (J9052) was used for development of the Osprey (from 1927). Development of the Osprey also included adaptations for catapult launching and for seaplane operations.
The float undercarriage was designed to be interchangeable with the normal wheeled undercarriage, using the same four attachment points thus allowing for both carrier-borne and conventional operation.
The modifications to the prototype, known as the Naval Hart against Specification O.22/26, resulted in the drafting of a new Specification 19/30 against which the production Osprey aircraft were procured.
Two production prototypes were ordered (S1667 and S1678) flying during 1931 and being tested in both landplane and seaplane form.
An initial production contract for 20 Osprey followed with Type I floats, using the Kestrel II MS engine (S1679 to S1698). The next batch of 17 aircraft (K2774 to K2790) were fitted with a larger fin and rudder.
The Osprey entered service with the Fleet Air Arm in 1936 and continued into World War II where it was utilised as a Trainer for FAA Pilots.
A production contract was for 14 aircraft were built as Osprey II with Type II floats although these were later modified to Osprey III standard. One Hart aircraft (K3594) was also converted to Osprey configuration.
Three trials aircraft (Osprey III stainless steel construction) were ordered for trials (S1699 to S1701). The first was tested on twin floats, whereas the last two were fitted with a single central float and wing-tip stabilising floats.
These were followed by production quantities of the Osprey III to Specification 10/33 with a Fairey Reed metal airscrew, dinghy (stowed in the starboard upper wing) and other modifications. Contracts were placed for 3 (further trials aircraft), 39, 7 and 14 aircraft, for a total of 66 production Osprey III.
By 1936 Ospreys had been deployed to 701 Squadron at RAF Kalafrana, acting in an anti-submarine and anti-piracy role. Over its life the Osprey saw service with Portugese, Spanish, Swedish and UK military forces.
The final version for the Royal Navy was the Osprey IV, fitted with a Kestrel V engine. A total of 26 were ordered to Specification 26/35. These aircraft (K5742 to K5767) were later used as trainers and for target towing.
Variants & Numbers
In summary, UK production comprised:
- Naval Hart (J9052) two Osprey I prototypes
- 37 Osprey I production
- 14 Osprey II,
- 67 Osprey III
- 26 Osprey IV.
- Naval Hart plus 146 Osprey.
Export aircraft comprised: Four aircraft to Sweden (2401-2404) powered by a Swedish-built Bristol Pegasus engine. The first flight (2401) took place on 8th September 1934. Two Osprey II were supplied to Portugal (71 & 72). The first was in landplane configuration with the second as a seaplane. These aircraft were powered by the Kestrel II MS engine.
A single Osprey was supplied to Spain: This aircraft (EA-KAJ / ex-G-AEBD). This was in fact a company demonstrator fitted with a Kestrel V engine that was later changed to Hispano-Suiza 12X brs engine prior to delivery to Spain.
131 RN plus 7 export (138) plus at least two aircraft built locally in Sweden. Sweden are reported as using a total of six Osprey aircraft with serials 2401 to 2406, the first four of these having been built in the UK.
By the outbreak of the Second World War, the Osprey had largely been withdrawn from service. Those remaining continued in limited use as trainers and target tugs until early 1943.
|Naval Hart||Hart prototype (J9052) used as naval development aircraft with folding wings and seaplane undercarriage|
|Prototypes||Two aircraft: S1667, S1678|
|Osprey I||37 production aircraft, last 17 with larger fin and rudder. Fitted with Type I floats|
|Osprey II||14 aircraft and one Hart conversion with Type II floats. Later converted to Osprey III|
|Osprey IV||26 aircraft fitted with 640 hp Rolls-Royce Kestrel V engine|
|Swedish Osprey||Six aircraft 2401 – 2406 (first four built by Hawker)|
|Portuguese Osprey||Two aircraft, as Osprey III|
|Spanish Osprey||One aircraft (EA-KAJ) with Hispano-Suiza 12X brs engine|
|Powerplant||One 630hp Rolls-Royce Kestrel II MS|
|Span||37 ft 0 in|
|Maximum Weight||4,950 lb||5,570 lb|
|Capacity and armament||Two crew, One Vickers forward-firing machine gun, one self- defence Lewis gun fired from the rear cockpit. Bomb load up to four 112 lb bombs.|
|Maximum Speed||168 mph at 6,000 ft||146 mph at 4,700 ft|