The Blackburn B-25 Roc was Second World War Fleet Air Arm fighter, closely related to the B-24 Skua from which it was derived and developed in parallel. The Roc, a two-seat, low wing cantilever monoplane, was designed against Specification O.30/35 and was broadly a naval equivalent to the Boulton Paul Defiant turret fighter for the Royal Air Force.
Compared with the Skua, a number of structural changes were incorporated, including an increase in the mid-fuselage width to accommodate the Boulton Paul power-driven gun turret with its four 0.303 Browning machine guns. Critically, like the Boulton Paul Defiant, there was no fixed forward-firing armament.
Power was supplied by a Bristol Perseus radial engine driving a 3-blade propeller whilst other changes included the introduction of dihedral on the outer wing panels which resulted in the deletion of the upturned wing tips used on the Blackburn Skua. Fittings were also provided as standard to allow for the aircraft to be operated as a seaplane, although relatively few aircraft were ever used in this manner.
The gun turret rotated through a full 360 degrees, with firing cut-offs being used to protect the propeller arc and the tail unit. A fuselage fairing aft of the turret was automatically retracted as the turret guns traversed the rear centreline.
A 250 lb bomb could be carried under the wing centre-section, with provision to carry four practice bombs under the wings and like the Skua, wing-mounted dive brakes / flaps were fitted.
A formation of five B-25 Roc II aircraft photographed on 9th August 1940.
A single production order for 136 aircraft was placed, this being sub-contracted to Boulton Paul at Wolverhampton due to Blackburn workload in respect of Skua and Botha production. There was no specific prototype and the first aircraft (L3057) was to fly on 23rd December 1938.
As the aircraft was also intended to operate as a twin-float seaplane, two aircraft (L3057 and L3059) were sent to Blackburn’s Dumbarton factory to be converted to float operation. The landplane wheel wells were provided with waterproof covers and water rudders were added to the rear of the two floats. These were controlled pneumatically from the aircraft’s standard differential braking system.
Blackburn B-25 Roc Seaplane L3059 at Helensburgh in November 1939.
Roc floatplane trials were conducted in November 1939 at MAEE Helensburgh, close to the Dumbarton factory and early trials showed that it was directionally unstable in this configuration, with L3059 crashing just after take-off on 3rd December 1939. L3057 was subsequently fitted with a larger fin beneath the tailplane whilst L3060 was also flown as a seaplane and in March 1942, L3174 was operating with floats and a target-towing winch in place of its gun turret.
The Roc entered service in early 1940 with the Fleet Air Arm with land-based squadrons (806 Sqn and 801 Sqn) but the type’s poor performance and lack of forward-firing armament meant that it was not effective in air fighting. Consequently, the Roc saw only a few months of operational service.
A late production Blackburn B-25 Roc photographed at Brough in October 1940.
The type was relegated to second-line duties, serving with such units as No2 Anti-Aircraft Cooperation Unit, Gosport, 759 Fighter School at Yeovilton, 760 Fighter Pool at Eastleigh, 769 Sqn at Donibristle, 792 Target Towing Unit at St Merryn and so on.
Although intended for shipboard operation, it was only ever operated from land bases and never actually made a deck landing.
Some aircraft were even used as airfield defence machine gun posts at No.2 Anti-Aircraft Co-operation Unit at Gosport with their gun turrets continuously manned.
By the summer of 1943, all Roc aircraft had been withdrawn from service.