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.
Read more about this topic: Boulton Paul Balliol
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