|Roc Mk.I L3154, 805 sqn., RNAS Donibristle, 1940|
|Designer||George Edward Petty|
|First flight||23 December 1938|
|Primary user||Fleet Air Arm|
The Blackburn B-25 Roc was a British Second World War-era Fleet Air Arm fighter aircraft designed by Blackburn Aircraft Ltd. It took its name from the mythical bird of the tales of the Arabian Nights, the Roc. Derived from Blackburn's Skua and developed in parallel, the Roc differed in its adoption of a turret for its armament. Operationally, the Roc came to be viewed as inferior to existing aircraft, such as the Skua, and the type was only had a brief frontline service.
Design and development
On 31 December 1935, the British Air Ministry issued Specification O.30/35 for a carrier-based turret-armed fighter. Blackburn proposed a derivative of their Skua dive bomber, of which two prototypes had been ordered for the Fleet Air Arm earlier that year, while Boulton Paul proposed the P.85, a redesigned version of its land-based Defiant P.82 turret fighter.
Like the Skua on which it was based, Blackburn's B-25 Roc was a two-seat low-wing cantilever monoplane of all metal construction. It was fitted with a retractable tailwheel undercarriage, while its wings folded for storage aboard aircraft carriers. It was powered by a single Bristol Perseus radial engine driving a three-bladed propeller. It used the same Boulton Paul power operated gun turret as the Defiant, with four .303 in (7.7 mm) Browning machine guns. It retained the wing mounted dive brakes of the Skua, with bomb racks under each wing allowing two 250 lb (110 kg) bombs and eight practice bombs to be carried.
On 28 April 1937, the Air Ministry placed an order for 136 Rocs. As Blackburn already had full order books for the Skua and the Botha torpedo bomber for the RAF, it was decided to sub-contract detailed design and production to Boulton Paul at Wolverhampton.
The first flight by a Roc was on 23 December 1938, While handling was acceptable, and better than that of the Skua, performance was poor, with a maximum speed of only 223 mph (194 kn; 359 km/h). It had been already realised by some that this performance was inadequate, with the Fifth Sea Lord (the Chief of Naval Air Services) Alexander Ramsay suggesting that the Roc be abandoned in October 1938. Production was allowed to continue, however, as cancellation would cause too much disruption for Boulton Paul, with work beginning on the aircraft's adaption to the target towing role.
As well as its primary role as a carrier-based fighter, the Roc was also required to be capable of operating as a floatplane, with a conversion kit being designed to allow a set of floats from a Blackburn Shark to be fitted. The first example to be converted proved to be unstable, and crashed when being tested at Helensburgh in December 1939. While the addition of an enlarged ventral fin solved the stability problems, the effects of the floats on the aircraft's performance was too great to be ignored, with maximum speed falling to only 193 mph (168 kn; 311 km/h) and plans to form a fighter squadron equipped with Roc floatplanes abandoned.
The Skua started to be issued to the Skua-equipped 800 and 803 Naval Air Squadrons late in 1939, with three or four Rocs supplementing the squadrons' Skuas. When 803 Squadron moved to Wick in northern Scotland in order top provide fighter cover to the Royal Navy's major base at Scapa Flow in the Orkney Islands, it took its Skuas with it, but they proved ineffective, being described as a 'constant hinderance' by the squadron's commanding officer, who requested that they be replaced by more Skuas. During the Allied campaign in Norway a small contingent of Rocs travelled with 800 and 801 Naval Air Squadrons squadrons onboard HMS Ark Royal (803 had abandoned its Rocs to become an all-Skua squadron). They were used to carry out combat air patrols over the fleet, and again were of little use, showing inadequate performance to intercept German aircraft.
Skuas and Rocs operated over the English Channel in the Summer of 1940, including providing support for Operation Dynamo, and Operation Ariel, the evacuation of Allied forces from Dunkirk and other French ports. What was probably the Roc's sole confirmed victory occurred on 28 May 1940 when a patrolling 806 Naval Air Squadron Roc flown by pilot Midshipman A. G. Day, together with two Blackburn Skuas, intercepted five Junkers Ju 88s which were attacking a convoy off Ostende in Belgium. Flying underneath the Junkers while the Skuas attacked from above, Midshipman Day's Roc destroyed one Ju 88 before returning safely to Detling. Rocs and Skuas of 801 Naval Air Squadron strafed and dive-bombed German E-boats in Boulogne harbour on 12 June, damaging several E-boats, while on 20 June Skuas and Rocs were used to bomb gun emplacements at Cap Gris Nez.
Finally, the Roc was relegated to Air Sea Rescue and target-towing roles until 1943, when the type was withdrawn from service. However, until late 1944, four non-airworthy Rocs were stationed at HMS Daedalus in Gosport, their turrets being used for anti-aircraft defence.
Data from British Naval Aircraft since 1912 
- Crew: 2
- Length: 35 ft 7 in (10.85 m)
- Wingspan: 46 ft (14.02 m)
- Height: 12 ft 1 in (3.68 m)
- Wing area: 310 ft² (28.8 m²)
- Empty weight: 6,121 lb (2,782 kg)
- Loaded weight: 7,950 lb (3,614 kg)
- Powerplant: 1 × Bristol Perseus XII radial engine, 890 hp (664 kW)
- Maximum speed: 194 kn (223 mph, 359 km/h) at 10,000 ft (3,050 m)
- Cruise speed: 117 knots (135 mph, 217 km/h) 
- Range: 704 nmi (810 mi, 1,304 km) with 70 imp gal (320 l; 84 US gal) long-range tank
- Service ceiling: 18,000 ft (5,500 m)
- Rate of climb: 1,500 ft/min (7.6 m/s)
- Wing loading: 25.6 lb/ft² (125 kg/m²)
- Power/mass: 0.11 hp/lb (0.18 kW/kg)
- Guns: 4 × 0.303 in (7.7 mm) Browning machine guns in power operated dorsal turret
- Bombs: 8 × 30 lb (14 kg) bombs
- Related development
- Aircraft of comparable role, configuration and era
- Related lists
- List of aircraft of the RAF
- List of aircraft of the Fleet Air Arm
- List of fighter aircraft
- List of aircraft of World War II
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