Thursday, October 8, 2009

Bristol Britannia

Bristol Britannia



Type 175 Britannia

Royal Air Force Bristol Britannia Spica in 1964.
Role
Airliner
Manufacturer
Bristol Aeroplane Company
First flight
16 August 1952
Introduced
1957
Retired
1975
Primary users
British Overseas Airways Corporation

Royal Air Force
Number built
85
Variants
Canadair Argus

Canadair CL-44
The Bristol Type 175 Britannia was a British medium/long-range airliner built by the Bristol Aeroplane Company in 1952 to fly across the British Empire. Soon after production the turboprop engines proved susceptible to inlet icing and two prototypes were lost while solutions were found. By the time it was cleared, jets from France, UK and the US were about to enter service and only 85 Britannias were built before production ended in 1960. Nevertheless, the Britannia is considered the high point in turboprop design and was popular with passengers, earning itself the title of "The Whispering Giant" for its quiet and smooth flying.

 

In 1942, during the Second world War, the US and UK agreed to split aircraft construction; the US concentrating on transport aircraft, and the UK on heavy bombers. This left the UK with little experience in transport construction at the end of the war, so in 1943, a committee under Lord Brabazon of Tara, investigated the future of the British civilian airliner market. The Brabazon Committee called for four main types of aircraft.

Bristol won the Type I and Type III contracts, delivering their Type I design, the Bristol Brabazon in 1949. The initial requirement for the Type III, Specification C.2/47, was issued by the Minister of Supply for an aircraft capable of carrying 48 passengers and powered with Bristol Centaurus radial engines. Turboprop and compound engines were also considered, but they were so new that Bristol could not guarantee the performance specifications. After wrangling between the Ministry of Supply and British Overseas Airways Corporation (BOAC) over costs, the go-ahead was given in July 1948 for three prototypes, although the second and third were to be convertible to Bristol Proteus turboprops.

In October, with work already underway, BOAC decided that only a Proteus-engined aircraft was worth working on, and the project was redrawn to allow both turboprop and piston aircraft. BOAC purchased options for 25 aircraft on 28 July 1949, to be powered initially with the Centaurus engine but to be re-fitted with the Proteus when available. The design was now aimed at long-haul Empire and trans-Atlantic routes rather than the medium haul Empire routes originaly planned and had grown to accomodate 83 passengers.

By the time the first prototype, registered G-ALBO, first flew on 16 August 1952 at Filton, BOAC and Bristol had dropped the Centaurus because the turboprop Proteus had shown such promise. The Britannia was now a 90-seater and BOAC ordered 15 of these Series 100s. In 1953 and 54, three de Havilland Comets disappeared without explanation, and the Air Ministry demanded the Britannia undergo lengthy tests. Further, delays were caused by engine problems, mostly related to icing and the loss of the second prototype G-ALRX in an accident caused by a failed engine in December 1953. This delayed the in-service date until February 1957, when BOAC put their first Britannia 102s into service on the London to South Africa route, with Australia following a month later.

Bristol then upgraded the design as a larger transatlantic airliner for BOAC, resulting in the Series 200 and 300. The new version had a fuselage stretch of 10 ft 3 in (3.12 m) and upgraded Proteus engines, and was offered as the all-cargo Series 200, the cargo/passenger (combi) Series 250, and the all-passenger Series 300.

The first public service was operated on the 1 February 1957 with a BOAC flight between London and Johannesburg. By August 1957 the first 15 Series 102 aircraft had been delivered to BOAC.  The last ten aircraft of the order were built as Series 300 aircraft for transatlantic operations.

The first 301 flew on 31 July 1956. BOAC ordered seven Model 302s but never took delivery - instead they were taken on by airlines including Aeronaves de México and Ghana Airways. The main long-range series were the 310s, of which BOAC took 18 and, after deliveries began in September 1957, put them into service between London and New York. The 310 series (318) also saw transatlantic service with Cubana de Aviación starting in 1958. In total 45 Series 300s were built, the first jet-powered, albeit in turboprop form, airliner to enter regular non-stop transatlantic service in both directions.

A further 23 Model 252 and 253 aircraft were purchased by the RAF, as the Britannia C.2 and C.1 respectively. Those in RAF service were allocated the names of stars, "Arcturus", "Sirius", "Vega" etc. The last retired in 1975, and were used by civil operators in Africa, Europe and the Middle East into the late 1990s.

Most aircraft were built by Bristol at Filton Aerodrome but 15 were built at Belfast by Short Brothers and Harland.

A licence was also issued to Canadair to build a maritime reconnaissance aircraft , the Canadair Argus and long-range transport, the Canadair Yukon. Unlike the Britannia, the Argus was built for endurance, not speed, and used four Wright R-3350-32W Turbo-Compound engines which use less fuel at low altitude. The unpressurized interior was left with almost no room to move, packed with sensors and weapons. Canadair also built 37 turboprop Rolls Royce Tyne-powered CL-44 variants for the civil market similar those built for the RCAF in CC-106 Yukon guise, most of which were used as freighters. Four were built as CL-44-Js had their fuselages lengthened, making them the highest capacity passenger aircraft of the day, for service with the Icelandic budget airline Loftleiðir. One, a modified Guppy version, remains airworthy, but not flying. Several were built with swing-tails to allow straight-in cargo loading.

General characteristics
  • Crew: 4-7
  • Capacity: 139 passengers (coach class)
  • Length: 124 ft 3 in (37.88 m)
  • Wingspan: 142 ft 3 in (43.36 m)
  • Height: 37 ft 6 in (11.43 m)
  • Wing area: 2,075 ft² (192.8 m²)
  • Empty weight: 86,400 lb   (38,500 kg)
  • Max takeoff weight: 185,000 lb (84,000 kg)
  • Powerplant: 4× Bristol Proteus 765 turboprops, 4,450 ehp (3,320 kW) each
Performance
  • Maximum speed: 397 mph (345 knots, 639 km/h)
  • Cruise speed: 357 mph (310 kn, 575 km/h) at 22,000 ft (6,700 m)
  • Range: 4,430 mi (3,852 nmi, 7,129 km)
  • Service ceiling: 24,000 ft ] (7,300 m)

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