Boulton Paul Balliol

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.

Operational history

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.

The Sea Balliols served with 781 squadron at Lee-on-Solent and 1843 Squadron RNVR at Abbotsinch. The last one was delivered in December 1954. Some remained active at Abbotsinch until September 1963.

Two Balliols were used for the testing of radar absorbing coatings.

The only Balliols exported were 12 Mk.2s to the Royal Ceylon Air Force, 7 from RAF cancelled contracts and five from RAF stocks, which were replaced by a further five production aircraft.

Variants

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.

Operators

 Ceylon

Royal Ceylon Air Force

 United Kingdom

Aeroplane and Armament Experimental Establishment

Empire Test Pilot's School

Royal Air Force

No. 288 Squadron RAF at Middle Wallop

No. 238 Operational Conversion Unit at RAF Colerne

No. 7 Flying Training School at RAF Cottesmore

No. 3 Civilian Anti-aircraft Cooperation Unit at Exeter Airport

Central Flying School

RAF College Cranwell

Royal Navy, Fleet Air Arm

702 Naval Air Squadron

750 Naval Air Squadron

781 Naval Air Squadron

1843 Naval Air Squadron (Royal Naval Volunteer Reserve)

Sri Lanka

On display

Balliol T2 CA310 on display on the parade ground at SLAF Ground Combat Training Unit at Diyatalawa.

Stored or under restoration

Balliol T2 CA303 stored by the Sri Lankan Air Force Museum, Ratmalana Air Base.

United Kingdom

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.

Specifications (T.2)

Data from Aircraft of the Royal Air Force

General characteristics

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)

Performance

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

Armament

Rockets: Provision for 4 × "60-lb" rockets.