BAC One-Eleven

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 (BAC). 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 7,000 pounds-force (31 kN) 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.

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 (later known as the One-Eleven), 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 (CAB), 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 (G-ASHG) 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 (Bonanza ended up ordering and operating the DC-9). 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 (nose-down) flight.