The Blackburn Perth was a British flying boat which was in service during the interwar period. It was essentially an upgraded Iris, and hence the largest flying-boat to serve with the Royal Air Force at the time (and the largest biplane flying boat ever to serve with the RAF).
The Blackburn R.B.3A Perth was designed as a replacement for the earlier Iris to Air Ministry Specification 20/32. Developed from the Iris Mk. V, the Perth first flew in 1933.[1] It differed from the Iris by replacing the Rolls-Royce Condor engines of the Iris by more powerful Rolls-Royce Buzzards and having an enclosed cockpit for the pilots. Unusually, in addition to its normal armament, the Perth was fitted with a Coventry Ordnance Works C.O.W 37 mm (1.46 in) autocannon in its bows.[2]
Four Perths were ordered for service for the RAF.[3]
The Perth entered service with the RAF in January 1934,[3] when the second aircraft was delivered to No. 209 Squadron RAF at RAF Mount Batten Plymouth.[1] Perths remained in service until 1937,[1] being replaced by the Short Singapore and the Saro London. One aircraft was retained by the Marine Aircraft Experimental Establishment until 1938.