|A Perth, flying with the MAEE in 1935|
|Manufacturer||Blackburn Aeroplane and Motor Company|
|Designer||John Douglas Rennie|
|First flight||11 October 1933|
|Primary user||Royal Air Force|
|Developed from||Blackburn Iris|
The Blackburn Perth was a British flying boat in service during the interwar period. It was essentially an upgraded 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).
Design and development
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.
The Perth entered service with the RAF in January 1934, when the second aircraft was delivered to No. 209 Squadron RAF at RAF Mount Batten Plymouth. Perths remained in service until 1937, being replaced by the Short Singapore and the Saro London. One aircraft was retained by the Marine Aircraft Experimental Establishment until 1938.
- Royal Air Force
- Marine Aircraft Experimental Establishment
Data from Aircraft of the Royal Air Force 1918–57
- Crew: 5
- Length: 70 ft 0 in (21.34 m)
- Wingspan: 97 ft 0 in (29.57 m)
- Height: 26 ft 5.5 in (8.065 m)
- Wing area: 2,461 sq ft (228.6 m2)
- Empty weight: 20,927 lb (9,492 kg)
- Gross weight: 32,500 lb (14,742 kg)
- Max takeoff weight: 38,000 lb (17,237 kg) 
- Powerplant: 3 × Rolls-Royce Buzzard II MS V-12 water-cooled piston engines, 825 hp (615 kW) each
- Propellers: 2-bladed fixed-pitch propellers
- Maximum speed: 132 mph (212 km/h, 115 kn)
- Cruise speed: 109 mph (175 km/h, 95 kn) 
- Range: 1,300 mi (2,100 km, 1,100 nmi)
- Service ceiling: 11,500 ft (3,500 m)
- Rate of climb: 800 ft/min (4.1 m/s)
- Wing loading: 13.2 lb/sq ft (64 kg/m2)
- Power/mass: 0.076 hp/lb (0.125 kW/kg)
- Up to 2,000 lb (907 kg) bombs
Aircraft of comparable role, configuration, and era
- Thetford, Owen (1957). Aircraft of the Royal Air Force 1918–57 (1st ed.). London: Putnam. pp. 76–77.
- "C.O.W. 37mm cannon fitted to Blackburn Perth flying boat", YouTube
- Donald, David (Editor) (1997). The Encyclopedia of World Aircraft. Aerospace Publishing. p. 134. ISBN 1-85605-375-X.CS1 maint: extra text: authors list (link)
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