Hawker Siddeley HS.121 Trident
The Trident was designed by the De Havilland company to meet a 1956 British European Airways (BEA) specification for a high speed, short-haul jet airliner. The initial concept was powered by Rolls-Royce Medway engines and featured a two-class layout with seating for 111 passengers and a gross weight of up to 150,000 lbs. BEA’s intended order for 24 was delayed by the British Government, which favoured an alternative design by Hawker Siddeley. The onset of a recession in the airline industry led BEA to request De Havilland scale down its design. The company agreed and BEA finally signed a contract in August 1959.
By this time De Havilland had set up Airco with Hunting Aircraft and Fairey Aviation to manufacture and market the Trident, and the company actively looked at the possibility of a tie-up with Boeing, at the time relatively inexperienced in the commercial sector. These initiatives were undermined by late 1959 by the British Ministry of Supply which, concerned at over-capacity within the aircraft industry, forced De Havilland into a merger with Hawker Siddeley, and the break-up of the Airco partnership: Hunting was taken into the newly-formed British Aircraft Corporation, and Fairey partially into Westland.
The Trident was designed from the outset with advanced avionics, at the heart of which was a fully automatic blind landing system, and the Trident remained the only airliner so-equipped until the Tristar in the mid-1970s. The avionics bay was housed beneath the flightdeck, resulting in the Trident’s unique nosewheel arrangement, offset from the centreline with sideways retraction. Later development of the Trident was linked closely to BEA’s needs, perhaps overly so as the only substantial overseas sale came from China, where it became the first western-built jet airliner to enter service.
The last operational Tridents were retired in the late 1990s. For its part, Boeing went on to build 1,832 of its own three-engine design, the 727, the initial version of which was built to a specification almost identical to De Havilland’s original concept. Survivor numbers have steadied.
First flight: 9 Jan 62 (c/n 2101, G-ARPA)
Production: 117, at Hatfield, UK
First delivery: 9 Sep 64, to BEA (c/n 2103, G-ARPC)
Last delivery: 26 Sep 75, to Civil Aviation Administration of China (c/n 2328, B-270)
Variants: Trident 1C - initial production version for BEA, powered by 3 Rolls-Royce Spey 510 turbofans, and with a gross weight of 115,000 lbs and seating for up to 103 passengers (24 built);
Trident 1E - developed version, largely for export, with increased wing area, leading-edge slats, higher gross weight and high-density seating for up to 139 passengers; powered by Spey 511s (15 built; first flight 2 Nov 64);
Trident 2E - extended range version of Trident 1E powered by Spey 512s, featuring a 2.8m fuselage stretch, increased wing span, increased weights and seating for 114 passengers (50 built, first flight 27 Jul 67);
Trident 3B - increased gross weight version of Trident 2E with a further 5m fuselage stretch, seating for up to 180 passengers and reduced range; powered by 3 Rolls-Royce Spey 512s and a single, tail-mounted Rolls-Royce RB162 turbojet booster for improved ‘hot and high’ performance (26 built, first flight 11 Dec 69);
Super Trident 3B - Trident 3B with additional fuel capacity (2 built).