The world of aviation in the mid-20th century saw the arrival of the Hawker Siddeley Trident, a British trijet airliner that made its first flight in 1962 and began its commercial service journey in 1964. This aircraft was birthed by de Havilland Aircraft Company, as an advanced replacement to the much-loved Comet, and its production was later undertaken by Hawker Siddeley Aviation.
The Hawker Siddeley HS-121 Trident, initially known as the de Havilland DH.121 and briefly as the Airco DH.121, is a British airliner manufactured by Hawker Siddeley. The DH.121 trijet design was initially proposed by de Havilland in 1957 in response to a request from British European Airways (BEA). By 1960, de Havilland was acquired by Hawker Siddeley, who carried forward the development of the aircraft. The Trident took its first flight on January 9, 1962, and was officially introduced into service on April 1, 1964, trailing its main competitor, the Boeing 727, by just two months. By the time the production ceased in 1978, a total of 117 Tridents were produced. The Trident aircraft was finally retired from service in 1995.
The airliner is equipped with three Rolls-Royce Spey low-bypass turbofans mounted at the rear. It features a low swept wing and a T-tail configuration. Thanks to its advanced avionics, the Trident was the first airliner to achieve a blind landing in revenue service in 1965. The initial Trident 1/2 models were designed to seat between 101 and 115 passengers and could cover a range of up to 2,350 nautical miles (4,350 kilometers). The later Trident 3 variant was elongated by 5 meters (16 feet) to accommodate 180 passengers and had a range of 1,940 nautical miles (3,590 kilometers; 2,230 miles). It was also fitted with an additional RB.162 booster engine in the tail.
Versions and Advances
The Trident was offered in three primary variants, the Trident 1, 2, and 3, each one building upon the strengths of its predecessor and featuring technological improvements and greater passenger capacity. All variants had a standout flight control system complete with an automatic landing system and a digital flight data recorder.
The initial variant, the Trident 1, boasted three Rolls-Royce RB.163 Spey turbofan engines that gave a maximum thrust of 11,400 lbf each. With a passenger capacity of up to 119, this model could reach a maximum range of 1,800 nautical miles.
The upgraded Trident 2, had more powerful engines that provided a thrust of 12,550 lbf each. It offered a flight range of 2,400 nautical miles and could comfortably accommodate 115 passengers.
The Trident 3, the final variant, was equipped with the most powerful RB.167 turbofan engines that provided a maximum thrust of 20,000 lbf each. The airplane could cover a distance of 2,700 nautical miles and had a passenger capacity of up to 180.
| Variant | Trident 1/1C | Trident 1E | Trident 2E | Trident 3B |
|---|---|---|---|---|
| Cockpit crew | Three (Captain, First Officer, and Flight Engineer) | Three (Captain, First Officer, and Flight Engineer) | Three (Captain, First Officer, and Flight Engineer) | Three (Captain, First Officer, and Flight Engineer) |
| Typical seats | 101 seats | 108 seats | 115 seats | 180 seats |
| Length | 114 ft 9 in (34.98 m) | 114 ft 9 in (34.98 m) | 131 ft 2 in (39.98 m) | 131 ft 2 in (39.98 m) |
| Wingspan | 89 ft 10 in (27.38 m) | 95 ft (29 m) | 98 ft (30 m) | 98 ft (30 m) |
| Wing area | 1,358 sq ft (126.2 m2) | 1,415 sq ft (131.5 m2) | 1,462 sq ft (135.8 m2) | 1,462 sq ft (135.8 m2) |
| Wingsweep | 35 degrees | 35 degrees | 35 degrees | 35 degrees |
| Height | 27 ft 0 in (8.23 m) | 27 ft 0 in (8.23 m) | 28 ft 3 in (8.61 m) | 28 ft 3 in (8.61 m) |
| Max. cabin width | 11 ft 3.5 in (3.442 m) | 11 ft 3.5 in (3.442 m) | 11 ft 3.5 in (3.442 m) | 11 ft 3.5 in (3.442 m) |
| Typical OEW | 66,700 lb (30.3 t) 1C: 67,200 lb (30.5 t) | 70,000 lb (31.8 t) | 73,200 lb (33.2 t) | 83,000 lb (37.6 t) |
| MTOW | 107,000 lb (48.5 t) 1C: 115,000 lb (52.2 t) | 128,000 lb (58.1 t) | 142,500 lb (64.6 t) | 150,000 lb (68.0 t) |
| Fuel capacity | 3,840 imperial gallons (17,500 L) 1C: 4,840 imp gal (22,000 L) | 5,440 imp gal (24,700 L) | 5,774 imp gal (26,250 L) | 5,440 imp gal (24,700 L) |
| Engines | 3 x Spey RB163-1 Mk505-5 | 3 x Spey RB163-25 Mk511-5 | 3 x Spey RB.163-25 Mk512-5 | 3 x Spey RB.163-25 Mk512-5 +RB.162-86 |
| Thrust | 3 x 10,400 lbf (46 kN) | 3 x 11,400 lbf (51 kN) | 3 x 11,960 lbf (53.2 kN) | 3 x 11,960 lbf (53.2 kN) +5,250 lbf (23.4 kN) |
| FL300 cruise | Mach 0.86 – 506 kn (937 km/h) | Mach 0.84 – 495 kn (917 km/h) | Mach 0.84 – 495 kn (917 km/h) | Mach 0.84 – 495 kn (917 km/h) |
| Ceiling | 35,000 ft (11,000 m) | 35,000 ft (11,000 m) | 35,000 ft (11,000 m) | 35,000 ft (11,000 m) |
| Range | 1,170 nmi; 2,170 km 1C: 1,760 nmi; 3,260 km | 1,910 nmi; 3,540 km | 2,350 nmi; 4,350 km | 1,940 nmi; 3,600 km |
The Distinctive Design Features
A key feature that set the Hawker Siddeley Trident apart was its unique nose landing gear design. Rather than being centered, the wheel was situated to the left side of the fuselage and retracted to the right, providing additional hold space and accommodating a sizable electronics bay under the flight deck. The nose wheel was also positioned further back for the same reason.
The final model, the Trident 3B, incorporated a fourth Rolls Royce RB162 booster engine delivering 23 kN of thrust. While it increased the aircraft weight by 5%, it offered an extra 15% thrust on take-off and was used as required.
Innovation and Passenger Comfort
Technological advancements and passenger comfort were at the heart of the Trident design. It was the first commercial airliner to introduce an automatic landing system for low visibility conditions and one of the earliest to feature a digital flight deck. Its sleek three-engine configuration was designed to minimize noise and vibration, enhancing passenger comfort.
The cabin layout prioritized passenger comfort and convenience, with wider seats equipped with adjustable headrests, footrests, and lumbar support. To keep passengers entertained during their journey, the aircraft featured a variety of music genres and the latest movies. The advanced lighting and temperature control systems ensured a relaxed and soothing environment for the passengers.
The Journey of Trident’s Development
The Trident’s roots date back to the 1950s when British European Airways (BEA) initiated the search for a replacement for their Vickers Viscount turboprop aircraft. The goal was to find a quicker, more efficient aircraft that would enhance passenger comfort and reliability. The de Havilland’s DH121 Trident design emerged from this vision. Significant design changes followed, notably the introduction of Rolls-Royce’s groundbreaking Spey turbofan engine in 1957.
The Hawker Siddeley Trident made its service debut with BEA in April 1964 and soon became known for its speed, dependability, and comfort. Over the subsequent years, the Trident flew for several airlines globally. However, despite its numerous innovations, the Trident eventually succumbed to the advent of advanced aircraft such as the Boeing 737 and Airbus A300. Production ceased in 1978, but the Trident’s legacy of speed, reliability, comfort, and advanced design lived on, influencing the development of several successful aircraft, including the Airbus A300 and Boeing 757.
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