Bristol Britannia

Design and development

Origins

In 1942, during the Second World War, Allied aircraft construction saw the British, of necessity, concentrating on heavy bombers, leaving the production of transport aircraft to the USA. This would have left Britain with little experience in transport construction at the end of the war. In 1943, a committee under Lord Brabazon of Tara investigated the future British civilian airliner market. The Brabazon Committee called for several aircraft to be developed to its specifications for Britain's civilian aviation needs.

Bristol won the Type I and Type III contracts, delivering their Type I design, the Bristol Brabazon in 1949. The requirement for the 1946 British Overseas Airways Corporation (BOAC) Medium Range Empire (MRE) Requirements coincided with the Type III, Specification C.2/47, issued in April 1947 by the Minister of Supply. The specifications called for an airliner capable of carrying 48 passengers and powered with Bristol Centaurus radial engines or Napier Nomad turbo-compound Diesel engine. Turboprop options were also considered, but they were so new that Bristol could not guarantee their performance.

Although company Proposals "X" for conversions of Lockheed Constellations to Centaurus 662 powerplants or "Y" for licence production of the Constellation were considered in late 1946, BOAC decided that a new design was preferred. After wrangling, the Ministry of Supply and BOAC agreed costs and the project went ahead being assigned the company designation Model 175 in July 1948. Three prototypes were ordered with the first being Mk 1 (Centaurus 662) and the second and third prototypes called Mk 2 (to be convertible to Bristol Proteus turboprops, then under development).

In October 1947, with work underway, Bristol had settled on a Centaurus-powered design with a gross weight of 103,000 lb (47,000 kg) and a payload of 13,300 lb (6,000 kg). The anticipated Karachi–Cairo run necessitated a 48-seat limit including sufficient fuel for the lengthy stage. On 5 July 1949, the Ministry of Supply ordered five prototypes with the understanding that BOAC would contract for 25 production aircraft. BOAC purchased options for 25 aircraft on 28 July powered by the Bristol Centaurus, but to be re-fitted with the Bristol Proteus when available.

Redefinition and prototypes

In November 1948, the Type 175 was revised again to accommodate 74 passengers and a longer wingspan in a contemplated long-range version aimed at long-haul Empire and transatlantic routes, rather than the medium-haul Empire routes originally planned. On reflection, BOAC decided that only the Proteus engine was viable, necessitating a further redesign eliminating the Centaurus option. Senior figures within BOAC such as the Deputy Chairman Whitney Straight considered the Proteus engine to be "an obsolete contraption". Despite BOAC's desire to have a turboprop engine, the Type 175 project was contingent on the Proteus passing a 150-hour type test.

During April 1950, the airliner's name, Britannia, was selected. The name Britannia 101 was applied to first pair of prototypes, which were powered by the early Proteus 625, the successor to the 600 series engine that had already completed type trials. The first prototype, registered G-ALBO, with Bristol Chief Test Pilot A.J. "Bill" Pegg at the controls, first flew on 16 August 1952 at Filton Aerodrome. During the maiden flight, the over-sensitive flying controls led to wild pitching before Pegg restored control. During the landing approach, smoke filled the cockpit and the main undercarriage bogie temporarily stuck, only fully deploying seconds before landing. The snags were resolved and by September, the prototype was cleared to perform at the 1952 SBAC Display at Farnborough where spectators commented on the "quietness" of the giant airliner. In November 1952, Popular Science reported that by 1954 BOAC would have 25 of these aircraft on routes such as London-to-Tokyo over the Arctic and North Pole.

Delays

After three de Havilland Comets crashed without explanation in 1953 and 1954, the Air Ministry demanded that the Britannia undergo lengthy tests. Further delays were attributed to teething problems with the engine resulting in the loss in February 1954 of the second prototype, G-ALRX, caused by a failed reduction gear that led to an engine fire and the aircraft landing on the mudflats of the Severn Estuary. Finally, time was lost in resolving inlet icing issues (by selecting a different cruising height) that were discovered as the first aircraft were being delivered to BOAC. These were exaggerated by BOAC, devastated future sales and delayed the Britannia's introduction by two years.

The first prototype G-ALBO was modified to more closely approximate a production standard, but was retained by the company to undergo engine testing and development. Bristol revised the design into a larger transatlantic airliner for BOAC, resulting in the Series 200 and 300; the Britannia 300LR (Long-Range) was viewed as being "eminently suitable" for BOAC's services between London and Sydney.