The British Aircraft Corporation One-Eleven, also known as the BAC 1-11, or the BAC-111, was a British short-range jet airliner of the 1960s and 1970s. Conceived by Hunting Aircraft, it was developed and produced by the British Aircraft Corporation when Hunting merged into BAC along with other British aircraft makers in 1960.
The One-Eleven was designed to replace the Vickers Viscount. It was the second short-haul jet airliner to enter service, the first being the French Sud Aviation Caravelle. Due to its later service entry, the One-Eleven took advantage of more efficient engines and airline experience of jets. This made it popular, with over half of the sales at its launch being in the largest and most lucrative market, the United States. The One-Eleven was one of the most successful British airliner designs, and served until its widespread retirement in the 1990s due to noise restrictions.

In 1967 a larger 119-seat version was introduced as the One-Eleven 500 (also known as Super One-Eleven). This "stretched" version was delayed for at least a year while its launch customer BEA assessed its requirements. This gave competing US aircraft (the DC-9 and Boeing 737) the chance to make up for the One-Eleven's early penetration of their domestic market. The British aircraft's initial one-year advantage now turned into a one-year delay and the 500 failed to sell in the USA. Compared with earlier versions, the One-Eleven 500 was longer by 8ft 4in (2.54 m) ahead of the wing and 5ft 2in (1.57 m) behind it. The wing span was increased by 5 ft (1.5 m), 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 (denoted 1-11 510ED) varied significantly from other 1-11s, 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 HS.121 Trident, for better commonality with the type (which at the time was the BEA/BA shorthaul workhorse). Their additional equipment included a more sophisticated autoflight system, which allowed CAT II autolandings and included an autothrottle (autoland functionality was removed from most aircraft later in their careers). 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, despite the fact that aside from the flight deck it was basically identical to all other 500 series aircraft.

Having faced competition "from above" with the aforementioned US aircraft by 1966, by 1970 the One-Eleven also faced competition "from below." The new competitor was the Fokker F28. Available as a four-member "family," it was lighter, less complex, and cheaper. The One-Eleven 475 of 1970 was launched to compete with the F.28. It combined the 400 fuselage with the higher power and larger wing of the 500 and was intended for hot and high operations. Only ten of the One-Eleven Mk 475 were sold. In 1977, the One-Eleven 670, a quiet and updated 475, was offered to the Japanese domestic market, failing to sell. Total deliveries for 1966 stood at 46 aircraft, and another 120 were delivered by 1971. At this point orders slowed to a trickle. British production continued until 1982. There were two reasons why the production line was kept open for just 35 aircraft delivered over 11 years: first, BAC hoped that Rolls-Royce would develop a quieter and more powerful version of the Spey engine, making possible further One-Eleven developments; second, throughout the early part of the period Romania was negotiating to buy the entire One-Eleven programme and transfer production of the type to Bucharest.

Specifications

Crew: 2 pilots and 3 flight attendants
Capacity: 89 passengers in charter layout
Length: 92 ft 6 in (28.2 m)
Wingspan: 88 ft 6 in (26.9 m)
Height: 23 ft 9 in (7.2 m)
Wing area: 1,003 ft² (93.2 m²)
Empty weight: 46,405 lb (21,049 kg)
Max takeoff weight: 74,500 lb (33,800 kg)
Powerplant: 2× Rolls-Royce RB.163 Spey Mk. 506 turbofans, 10,600 lbf (47 kN) each.

Performance

Maximum speed: 470 knots (540 mph, 870 km/h)
Cruise speed: 430 knots (495 mph, 795 km/h)
Range: 1,250 nm (1,440 mi, 2,320 km)
Service ceiling: 35,000 ft (10,700 m)

Source : Wikipedia