BAC One-Eleven
The BAC One-Eleven is a retired early jet airliner produced by the British Aircraft Corporation.
Conceived by Hunting Aircraft as a 30-seat jet, before its merger into BAC in 1960, it was launched as an 80-seat airliner with a British United Airways order on 9 May 1961.
The prototype conducted its maiden flight on 20 August 1963, and it was first delivered to BUA on 22 January 1965.
The 119-seat, stretched 500 series was introduced in 1967.
Total production amounted to 244 until 1982 in the United Kingdom including 1982 to 1989 in Romania where nine Rombac One-Elevens were licence-built by Romaero.
The short haul, narrowbody aircraft was powered by aft-mounted Rolls-Royce Spey low-bypass turbofans, a configuration similar to the earlier Sud Aviation Caravelle and later Douglas DC-9.
It competed with early Boeing 737 models and was used by British, US, and European airlines, including Romanian operators.
It was replaced by the newer Airbus A320 and later 737 variants, as well as by the Bombardier CRJ200 regional jet.
Noise restrictions accelerated its transition to African carriers in the 1990s, and the last BAC One-Eleven was retired in 2019.
Development
Early development
In the 1950s, although the pioneering de Havilland Comet had suffered disasters in service, strong passenger demand had been demonstrated for jet propulsion. Several manufacturers raced to release passenger jets, including those aimed at the short-haul market, such as the Sud Aviation Caravelle. In July 1956, British European Airways published a paper calling for a "second generation" jet airliner to operate beside their existing turboprop designs. This led to a variety of designs from the British aerospace industry. Hunting Aircraft started design studies on a jet-powered replacement for the successful Vickers Viscount, developing the 30-seat Hunting 107. Around the same time, Vickers started a similar development of a 140-seat derivative of its VC10 project, the VC11. Many other aviation firms also produced designs.In 1960 Hunting, under British government pressure, merged with Vickers-Armstrongs, Bristol, and English Electric to form British Aircraft Corporation. The new BAC decided that the Hunting project had merit, but that there would be little market for a 30-seat jet airliner. The design was reworked into the BAC 107, a 59-seat airliner powered by two Bristol Siddeley BS75 turbofan engines. BAC also continued development of the larger, 140-seat VC-11 development of the Vickers VC10 which it had inherited. Other competing internal projects, such as the Bristol Type 200, were quickly abandoned following absorption of Hunting into BAC.
File:RR Spey.jpg|thumb|The selected Rolls-Royce Spey low-bypass turbofan
Market research showed the 59-seat BAC 107 was too small, and the design was reworked in 1961, with passenger capacity growing to 80 seats, and BS75s being discarded in favour of Rolls-Royce Speys. The revised design was redesignated the BAC 111, with BAC abandoning the VC11 project to concentrate on the more promising One-Eleven. Unlike contemporary British airliners such as the Hawker Siddeley Trident, the One-Eleven was not designed specifically to meet the needs of the state-owned British European Airways or British Overseas Airways Corporation, but on the needs of airlines around the world, and BAC expected orders for as many as 400.
On 9 May 1961 the One-Eleven was publicly launched when British United Airways placed the first order for ten One-Eleven 200s. On 20 October Braniff International Airways in the United States ordered six. Mohawk Airlines sent representatives to Europe seeking out a new aircraft to bring them into the jet era, and on 24 July 1962 concluded an agreement for four One-Elevens. Orders followed from Kuwait Airways for three, and Central African Airways for two. Braniff subsequently doubled their order to 12, while Ireland's Aer Lingus ordered four. Western Airlines ordered ten but later cancelled. Bonanza Air Lines also ordered three in 1962 but was stopped by the US Civil Aeronautics Board, which claimed that subsidies would be needed to operate a jet on Bonanza's routes, an action claimed by some at the time to be protectionism. The CAB also stopped Frontier Airlines and Ozark Air Lines from ordering One-Elevens, although allowing Ozark to order the similar Douglas DC-9 and Frontier to order Boeing 727-100s. The CAB had also unsuccessfully tried to block Mohawk's orders.
In May 1963, BAC announced the One-Eleven 300 and 400. The new versions used the Mk. 511 version of the Spey with increased power, allowing more fuel upload and hence longer range. The difference between the 300 and 400 lay in the equipment and avionics, the 400 intended for sales in the United States and thus equipped with US instruments. On 17 July 1963, American Airlines ordered 15 aircraft, bringing the total to 60, plus options for 15. American Airlines eventually bought 30 of the 400-series, making the airline the largest customer of One-Elevens.
Prototypes
The prototype rolled out of Hurn assembly hall on 28 July 1963, at which point BAC had received orders for the type from a number of operators. On 20 August 1963, the prototype conducted its first flight, painted in BUA livery. The first flight had taken place almost a year before the Douglas DC-9, a rival American jetliner; BAC considered the One-Eleven to hold a technological edge. The One-Eleven's lead was of significant importance commercially, since, as shown by the Bonanza Air Lines case, US authorities could refuse to approve sales of foreign aircraft to domestic airlines where an American alternative existed. Test flying was conducted by Squadron Leader Dave Glaser.The One-Eleven prototype, flown by test pilot Mike Lithgow, crashed on 22 October 1963 during stall testing, with the loss of all on board. The investigation led to the discovery of what became known as deep stall or superstall, a phenomenon caused by reduced airflow to the tailplane caused by the combined blanking effects of the wing and the aft-mounted engine nacelles at high angles of attack, which prevents recovery of normal flight. To prevent such stalls, BAC designed and added devices known as stick shakers and stick pushers to the One-Eleven's control system. It also redesigned the wing's leading edge to smooth airflow into the engines and over the tailplane. The specially modified aircraft used for testing this problem is now preserved at Brooklands Museum.
Despite the crash, testing continued and customer confidence remained high. American Airlines and Braniff took up their optional orders and placed more in February 1964. Further orders came from Mohawk, Philippine Airlines and German businessman Helmut Horten, who ordered the first executive modification of the aircraft. By the end of 1964, 13 aircraft had rolled off the production line. The One-Eleven was certified and the first handover, of G-ASJI to BUA, was on 22 January 1965. After several weeks of route-proving flights, the first revenue service flew on 9 April from Gatwick to Genoa. Braniff took delivery of its first aircraft on 11 March, while Mohawk received its first on 15 May. Deliveries continued, and by the end of 1965 airlines had received 34 aircraft. Demand remained buoyant, with a second production line set up at Weybridgeproducing thirteen 1-11s between 1966 and 1970.
The One-Eleven 500, 510ED and 475
In 1967 a larger 119-seat version was introduced as the One-Eleven 500. This "stretched" version was delayed for at least a year while its launch customer BEA assessed its requirements. This gave competing US aircraft the opportunity to compensate for the One-Eleven's early penetration of the US domestic market. The British aircraft's initial one-year advantage now turned into a one-year delay, and the stretched series 500 failed to sell in the US. The type saw service with Cayman Airways and Leeward Islands Air Transport in the Caribbean with Cayman Airways operating the series 500 on scheduled services to Houston, Texas and Miami, Florida, and LIAT flying its series 500s into San Juan, Puerto Rico. Bahamasair also operated the stretched 500 model with service between Nassau and Miami among other routes while Guatemalan carrier Aviateca operated its series 500 aircraft into both Miami and New Orleans, Louisiana. Costa Rican airline LACSA operated the series 500 as well on its services to Miami. Another air carrier which operated the series 500 into Miami was Belize Airways Ltd.Compared with earlier versions, the One-Eleven 500 was longer by 8 ft 4in ahead of the wing and 5 ft 2in behind it. The wing span was increased by 5 ft, and the latest Mk. 512 version of the Spey was used. The new version sold reasonably well across the world, particularly to European charter airlines. In 1971 it received an incremental upgrade to reduce drag and reduce runway requirements.
BEA/British Airways 500 series aircraft varied significantly from other One-Elevens, at BEA's request. The One-Eleven 510ED had a modified cockpit which incorporated instrumentation and avionics from or similar to that of the Hawker Siddeley Trident, for better commonality with the type. Their additional equipment included a more sophisticated autopilot, which allowed autoland in CAT II and included an autothrottle. The modifications went as far as reversing the "on" position of most switches to match that of the Trident; indeed, the 510ED was so different from other One-Elevens and 500 series aircraft that a different type rating was required to fly it.
Having faced competition from US aircraft by 1966, by 1970 the One-Eleven also faced competition from newer, smaller aircraft such as the Fokker F28 Fellowship. The F28 was lighter, less complex, and cheaper. The One-Eleven 475 of 1970 was launched to compete with the F28. It combined the 400 fuselage with the higher power and larger wing of the 500 and was intended for hot and high as well as rough airfield operations; however only ten One-Eleven Mk 475s were sold with one airline being Faucett Peru which operated its series 475 aircraft on scheduled domestic services into several airports with unpaved gravel runways in Peru. In 1977, the One-Eleven 670, a quiet and updated 475, was offered to the Japanese domestic market, also failing to sell.