The Blackburn Aircraft Company R.B.3A Perth was a large, three-engine flying boat, developed against Air Ministry Specification 20/32 which called for a replacement for the Blackburn RB1 Iris which it replaced it in RAF service.
The three-bay biplane featured wings of 97 ft span and was of all metal construction with a fabric covering. It was and still is RAF’s largest biplane flying boat to see service.
Power was provided by three 825hp Rolls-Royce Buzzard II engines, with the outer unitss mounted on the inner inter-plane struts, with a central pylon supporting the middle engine. Each engine was fed by its own 575 gallon fuel tank, these having been streamlined into the wing leading edge above each engine.
The all-metal hull was skinned in Alclad (corrosion-resistant aluminium) and incorporated two steps in its bottom surface. Accommodation was provided for up to five crew plus a wide range of internal equipment including an auxiliary power supply (APU) for electrical services, an air compressor, a fuelling pump, life belts and dinghy plus galley, radio and navigation equipment. Finally and most importantly it included a toilet and sleeping berths.
The five crew roles were Captain, Second pilot / Navigator, Bow-gunner / Bomb-aimer, Midships gunner / Wireless operator and Rear-gunner / Engineer. The two pilots sat side-by-side, in an enclosed cockpit.
A 37 mm Coventry Ordnance Works (COW) automatic cannon was fitted in the Bow-gunner’s position, which was supplemented by three machine guns in bow, dorsal and tail positions. The 37 mm cannon was intended for anti-ship use, firing 1.5 lb shells at 100 rounds per minute whilst a maximum bomb payload of 2,000 lb could be carried.
Patrol endurance was around 4.5 hours and the aircraft had a maximum still air range of around 1,500 miles. Fuel supplies could be cross-fed from any tank, to any engine via fuel pumps, piping and control cocks which were mounted external to the hull.
A total of four Blackburn R.B.3A Perth aircraft were built, the first aircraft (K3580) being flown for the first time on 11th October 1933, before being delivered to Marine Aircraft Experimental Establishment (MAEE) at Felixstowe for trials on 10th November.
The second Blackburn R.B.3A Perth (K3581) flew on 5th January 1934, being handed over at once to the RAF and flown non-stop to 209 Sqn’s Mount Batten base, at Plymouth. The third aircraft (K3582) was delivered a month later.
The first aircraft (K3580) was lost in an accident off Stornoway in September 1935 whilst the other two aircraft were struck off charge during 1936.
The Blackburn R.B.3A Perth’s were used by 209 Sqn for patrols over the Irish Sea, operating from either Plymouth, or from an outstation at Stranraer.
A fourth aircraft (K4011) was flown on 16th April 1934, and had two (rather than three) fuel tanks. This aircraft spent its service career at the Marine Aircraft Experimental Establishment (MAEE) at Felixstowe, until it was struck off charge on 2nd February 1938.
Variants & Number Built
|RB3A Perth||Three aircraft (K3580 - K3582 used) by 209 Sqn RAF. One aircraft K4011 used by Marine Aircraft Experimental Establishment, Felixstowe|
|Total production||Four aircraft|
|Powerplant||Three 825 hp Rolls-Royce Buzzard IIMS engines|
|Span||97 ft 0 in|
|Maximum Weight||32,500 lb (overload weight 38,000 lb)|
|Capacity & Armament||Five crew; one forward-firing 37 mm COW automatic cannon, three defensive Lewis guns, up to 2,000 lb bomb load.|
|Maximum Speed||132 mph sea level, 126 mph at 5,000 ft|
|Econ cruise speed||109 mph|
|Range||Normal 898 miles, maximum 1,500 miles|