Blackburn Perth

The Blackburn Perth was a British flying boat in service during the interwar period. It was an upgraded Blackburn Iris, 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. 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.

Four Perths were ordered for service for the RAF.