Boulton Paul Balliol
|Balliol T.2 in 1955|
|Manufacturer||Boulton Paul Aircraft|
|Designer||John Dudley North|
|First flight||30 May 1947|
|Primary users|| Royal Air Force|
Royal Navy Fleet Air Arm
Royal Ceylon Air Force
The Boulton Paul Balliol and Sea Balliol were monoplane military advanced trainer aircraft built for the Royal Air Force (RAF) and the Royal Navy Fleet Air Arm (FAA) by Boulton Paul Aircraft. Developed in the late 1940s the Balliol was designed to replace the North American Harvard trainer and used the Rolls-Royce Merlin engine, with the Sea Balliol a naval version for deck landing training.
Design and development
The Balliol was developed to meet Air Ministry Specification T.7/45 for a three-seat advanced trainer powered by a turboprop engine, competing against the Avro Athena. It was a conventional low-wing monoplane with a retractable main undercarriage and a fixed tailwheel. Pilot and instructor sat side by side ahead of the observer. The first prototype first flew on 30 May 1947, being temporarily powered by an 820 hp (611 kW) Bristol Mercury 30 radial engine. The second prototype, powered by the intended Armstrong Siddeley Mamba turboprop, first flew on 17 May 1948, the world's first single-engined turboprop aircraft to fly. The Air Ministry had second thoughts about its training requirements, and issued a new specification, T.14/47, requiring a two-seat trainer, powered by a Rolls-Royce Merlin piston engine.
The Merlin powered Balliol, designated Balliol T.2, first flew on 10 July 1948, and after extensive evaluation, it was chosen over the Athena, with large orders being placed to replace some of the Harvards in RAF service. The observer's seat of the Mk 1 was removed, the side-by-side seats remaining.
The Sea Balliol T.21 had folding wings and arrestor hook for deck landings.
By 1951, however, the Air Ministry changed its mind about its training requirements yet again and decided to introduce a jet-powered advanced trainer, the de Havilland Vampire T.Mk11.
Pre-production Balliols were delivered to the RAF's Central Flying School in 1950, but with the change in air-training policy, the Balliol was only delivered to one Flying Training School, - No. 7 at RAF Cottesmore, replacing their Harvards. The Balliol later served at the RAF College, Cranwell until replaced there by the de Havilland Vampire T.Mk 11 in 1956. The Balliol also saw limited squadron service from 1953 with No. 288 Squadron RAF based at RAF Middle Wallop. Operations continued until the squadron was disbanded in September 1957.
- P.108 Balliol T.Mk 1
- Prototypes, 3 built, powered by the Armstrong Siddeley Mamba turboprop engine
- Balliol T.Mk 2
- Two-seat advanced training aircraft for the RAF; 196 built, (166 built by Boulton Paul, and 30 built by Blackburn Aircraft).
- Sea Balliol T.Mk 21
- Two-seat advanced training aircraft for FAA. A total of 30 built by Boulton Paul.
- Aeroplane and Armament Experimental Establishment
- Empire Test Pilot's School
- Royal Air Force
- Royal Navy, Fleet Air Arm
- On display
- Stored or under restoration
- On display
- Sea Balliol T21 WL732 former Royal Navy and A&AEE aircraft on display in Hangar 1 as part of the transport and training collection at the Royal Air Force Museum Cosford.
- Stored or under restoration
- Balliol T2 WN149 under restoration to display standard by the Boulton Paul Association at Wolverhampton, West Midlands.
- Crew: 2
- Length: 35 ft 1½ in (10.71 m)
- Wingspan: 39 ft 4 in (11.99 m)
- Height: 12 ft 6 in (3.81 m)
- Wing area: 250 ft² (24.2 m²)
- Empty weight: 6,730 lb (3,059 kg)
- Loaded weight: 8,410 lb (3,823 kg)
- Powerplant: 1 × Rolls-Royce Merlin 35 V-12 piston, 1,245 hp (929 kW)
- Maximum speed: 250 kn (288 mph, 464 km/h) at 9,000 ft
- Range: 574 nmi (660 mi, 1,063 km)
- Service ceiling: 32,500 ft (9,909 m)
- Rate of climb: 1,790 ft/min (9.1 m/s)
- Wing loading: 33.6 lb/ft² (158 kg/m²)
- Power/mass: 0.148 hp/lb (0.243 kW/kg)
- Endurance 3 hours at 220 mph (355 km/h)
- Climb to 10,000 ft 6 minutes
- Rockets: Provision for 4 × "60-lb" rockets.
- Aircraft of comparable role, configuration and era
- Related lists
- Thetford 1957, pp. 94–95.
- Donald 1997
- Jefford 2001, p. 85.
- "Boulton Paul Balliol T. 21." Archived 10 August 2009 at the Wayback Machine. RAF Museum. Retrieved: 10 August 2009.
- Brew, Boulton Paul Aircraft
- "Individual History - Boulton Paul P.108 Sea Balliol T Mk 21 WL732." Archived 5 June 2011 at the Wayback Machine. Royal Air Force Museum, 2007. Retrieved: 10 October 2009.
- Ellis 2008, p. 176.
- Ellis 2008, p. 155.
- Donald, David, ed. The Encyclopedia of World Aircraft. London: Aerospace Publishing, 1997. ISBN 1-85605-375-X.
- Ellis, Ken. Wrecks & Relics, 21st edition. Manchester, UK: Crécy Publishing, 2008. ISBN 978-0-85979-134-2.
- Jefford, Wing Commander C.G., MBE, BA, RAF (Retd). RAF Squadrons, a Comprehensive Record of the Movement and Equipment of all RAF Squadrons and their Antecedents since 1912. Shrewsbury, Shropshire, UK: Airlife Publishing, 2001. ISBN 1-84037-141-2.
- Thetford, Owen. Aircraft of the Royal Air Force 1918-57. London: Putnam, First Edition 1957.
- Thetford, Owen. British Naval Aircraft since 1912, Fourth Edition. London: Putnam, 1994. ISBN 0-85177-861-5.
|Wikimedia Commons has media related to Boulton Paul Balliol.|
- Balliol at British Aircraft Directory
- Sea Balliol entry at RAF Museum
- P.108 In The Air - a 1948 Flight article on flying the Balliol Mercury-engined prototype