Hawker Siddeley Trident

Hawker Siddeley Trident

Discussion
Ask a question about 'Hawker Siddeley Trident'
Start a new discussion about 'Hawker Siddeley Trident'
Answer questions from other users
Full Discussion Forum
 
Encyclopedia


The Hawker Siddeley HS 121 Trident (alternatively the D.H.121) was a British short/medium-range three-engined
Trijet
A Trijet is an aircraft powered by three jet engines. Early twin-jet designs were limited by the FAA's "60-minute rule", whereby the flight path of twin-engined jetliners was restricted to within 60 minutes' flying time from a suitable airport, in case of engine failure. In 1964 this rule was...

 jet airliner
Jet airliner
A jet airliner is an airliner that is powered by jet engines. This term is sometimes contracted to jetliner or jet.In contrast to today's relatively fuel-efficient, turbofan-powered air travel, first generation jet airliner travel was noisy and fuel inefficient...

 designed by de Havilland
De Havilland
The de Havilland Aircraft Company was a British aviation manufacturer founded in 1920 when Airco, of which Geoffrey de Havilland had been chief designer, was sold to BSA by the owner George Holt Thomas. De Havilland then set up a company under his name in September of that year at Stag Lane...

 and built by Hawker Siddeley in the 1960s and 1970s. The Trident is notable for its pioneering avionics
Avionics
Avionics are electronic systems used on aircraft, artificial satellites and spacecraft.Avionic systems include communications, navigation, the display and management of multiple systems and the hundreds of systems that are fitted to aircraft to meet individual roles...

 which enabled it to become the first airliner to make a fully automatic approach and landing in revenue service in 1965 and to be the sole airliner capable of automatic landings in regular service from 1966 until versions of the Lockheed TriStar were also cleared to perform them in the mid-1970s.

Designed very tightly around a British European Airways
British European Airways
British European Airways or British European Airways Corporation was a British airline which existed from 1946 until 1974. The airline operated European and North African routes from airports around the United Kingdom...

 (BEA) specification, the Trident had modest sales, with 117 produced. The political and industrial aspects of its emergence, development, production, operation, and marketing were highly controversial in the 1960s and 1970s. Commentators have felt that the sales prospects and commercial usefulness of the type were gravely compromised because undue attention was paid to the needs of its launch customer who first insisted that it should be made much smaller than originally envisaged and who then insisted that it should be enlarged practically beyond the limits of its airframe
Airframe
The airframe of an aircraft is its mechanical structure. It is typically considered to include fuselage, wings and undercarriage and exclude the propulsion system...

 and powerplant
PowerPlant
PowerPlant is an object-oriented GUI toolkit, application framework and set of class libraries for Mac OS, created by Metrowerks. The framework was fairly popular at the height of the Classic Mac OS era, and was primarily used with CodeWarrior...

.

BEA's successor, British Airways
British Airways
British Airways is the flag carrier airline of the United Kingdom, based in Waterside, near its main hub at London Heathrow Airport. British Airways is the largest airline in the UK based on fleet size, international flights and international destinations...

 retired the type in the early-mid 1980s. In China the Trident remained active in Air China
Air China
Air China is the flag carrier and one of the major airlines of the People's Republic of China. Based in Beijing Capital International Airport, Air China is the world's 10th largest airline by fleet size. The airline ranked behind its main competitors China Southern Airlines and China Eastern...

 service until the 1990s.

Development



Original specification


In April 1956, BEA's chief executive Anthony Milward stated that the Corporation "would rather do without [jet airliners]". Nevertheless, in July 1956, BEA announced what it called "outline requirements" for a short-haul "second generation jet airliner". The new type would work alongside BEA's turboprop airliners, carry a payload of some 20,000 lb (9,000 kg) or some 70 passengers over up to 1,000 miles (1,600 km), weigh about 100,000 lb (46,000 kg), use 6,000 ft (1,800 m) runways, cruise at the very high speed of 610 to 620 mph (975 to 990 km/h) and have "more than two engines". While not an express requirement, commentators ever since have taken these figures to constitute a definite call to industry.

Four companies prepared projects to match the BEA views. Bristol
Bristol Aeroplane Company
The Bristol Aeroplane Company, originally the British and Colonial Aeroplane Company, was both one of the first and one of the most important British aviation companies, designing and manufacturing both airframes and aero engines...

 proposed the four-engined (but ultimately three-engined) Bristol Type 200
Bristol Type 200
-External links:*...

. Avro
Avro
Avro was a British aircraft manufacturer, with numerous landmark designs such as the Avro 504 trainer in the First World War, the Avro Lancaster, one of the pre-eminent bombers of the Second World War, and the delta wing Avro Vulcan, a stalwart of the Cold War.-Early history:One of the world's...

 also proposed the four-engined Avro 740 which later became a three-engined design; the company eventually shelved its proposal and joined forces with Bristol and Hawker Siddeley (Hawker Siddeley was Avro's parent company). Vickers proposed a four-engined aircraft closely related to the future VC10
Vickers VC10
The Vickers VC10 is a long-range British airliner designed and built by Vickers-Armstrongs Ltd, and first flown in 1962. The airliner was designed to operate on long-distance routes with a high subsonic speed and also be capable of hot and high operations from African airports...

 and designated the VC11.

The de Havilland company considered three possible contenders for the specification. Two were four-engined developments of the Comet
De Havilland Comet
The de Havilland DH 106 Comet was the world's first commercial jet airliner to reach production. Developed and manufactured by de Havilland at the Hatfield, Hertfordshire, United Kingdom headquarters, it first flew in 1949 and was a landmark in aeronautical design...

: the D.H.119 and the D.H.120, the latter also intended for offer to BOAC
British Overseas Airways Corporation
The British Overseas Airways Corporation was the British state airline from 1939 until 1946 and the long-haul British state airline from 1946 to 1974. The company started life with a merger between Imperial Airways Ltd. and British Airways Ltd...

. The third, the D.H.121, was announced in May 1957, had three engines, and was the contender which eventually proceeded to bid for BEA's attention.

In February 1958, BEA announced that the D.H.121 had come closest to its requirements and that it would order 24 with options on 12 more. It took a further six months for the British government to approve a formal BEA order for the D.H.121; the government had favoured the Hawker Siddeley Bristol 200 for industrial policy reasons.

The D.H.121 was to be the world's first trijet
Trijet
A Trijet is an aircraft powered by three jet engines. Early twin-jet designs were limited by the FAA's "60-minute rule", whereby the flight path of twin-engined jetliners was restricted to within 60 minutes' flying time from a suitable airport, in case of engine failure. In 1964 this rule was...

 airliner. Its designers felt this configuration offered a trade-off between cruising economy and take-off safety in case of an engine failure; moreover, the BEA specification had called for "more than two engines." Each of the three engines would drive its own hydraulic system, offering triple redundancy in case of any of the other two systems (or both of them) failing. The engines were to be 13,790 lbf (61.34 kN) Rolls-Royce Medway
Rolls-Royce Medway
|-See also:-Bibliography:* Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9-External links:*...

s. The D.H.121 was to have a gross weight of 123,000 lb (55,900 kg) or optionally, up to 150,000 lb or 63,000 kg), a range of 2,070 miles (3330 km), and seating for 111 in a two-class layout (or for over 140 in a high-density single-class layout as typical from the 1960s onwards on inclusive-tour charter flights).

The design initially included a cruciform
Cruciform
Cruciform means having the shape of a cross or Christian cross.- Cruciform architectural plan :This is a common description of Christian churches. In Early Christian, Byzantine and other Eastern Orthodox forms of church architecture this is more likely to mean a tetraconch plan, a Greek cross,...

 tail layout similar to that of the Sud Aviation Caravelle
Sud Aviation Caravelle
The Sud Aviation SE 210 Caravelle was the first short/medium-range jet airliner produced by the French Sud Aviation firm starting in 1955 . The Caravelle was one of the more successful European first generation jetliners, selling throughout Europe and even penetrating the United States market, with...

. The engines were clustered at the rear, with the centre engine situated in the extreme rear of the fuselage fed by air ducted through a large oval intake at the front of the fin, a configuration similar to the later Boeing 727
Boeing 727
The Boeing 727 is a mid-size, narrow-body, three-engine, T-tailed commercial jet airliner, manufactured by Boeing. The Boeing 727 first flew in 1963, and for over a decade more were built per year than any other jet airliner. When production ended in 1984 a total of 1,832 aircraft had been produced...

 design. In time, the design settled on a variable-incidence T-tail with the centre engine situated in the tailcone, beneath the fin.

From the outset, the D.H.121 was planned to employ avionics
Avionics
Avionics are electronic systems used on aircraft, artificial satellites and spacecraft.Avionic systems include communications, navigation, the display and management of multiple systems and the hundreds of systems that are fitted to aircraft to meet individual roles...

 which were very advanced for the period. They were intended to offer the capability of automatic approaches and landings within a year or two of the airliner's service entry. The avionics were also to have triplicated components for reliability, and also to allow "majority 2:1 voting" in guiding the aircraft during automatic approaches and landings. The bulky size of the period's avionics required them to be housed in a large hold beneath the flightdeck floor; its size dictated a distinctive nose undercarriage
Undercarriage
The undercarriage or landing gear in aviation, is the structure that supports an aircraft on the ground and allows it to taxi, takeoff and land...

 design: offset by 2 ft (60 cm) to the port side and retracting sideways to stow across the D.H.121's longitudinal axis beneath the forward passenger vestibule.

Revised specification


Through 1958, BEA management increasingly felt that the D.H.121's payload and range capacity would be too great and pleaded with de Havilland to reduce the design to fit its revised requirements. BEA's concern was due to three factors: a short-lived airline recession in the late 1950s; the imminent arrival into service of the turboprop Vickers Vanguard
Vickers Vanguard
The Vickers Type 950 Vanguard was a British short/medium-range turboprop airliner introduced in 1959 by Vickers-Armstrongs, a development of their successful Viscount design with considerably more internal room. The Vanguard was introduced just before the first of the large jet-powered airliners,...

 which duplicated the D.H.121's general payload and range area, and the growing trend to higher-density seating. At the time, many reputable airlines were reducing their short/medium range seat pitches from the then-customary minimum of 36 in (90 cm) to 34 in (87 cm) or even less, while emergent inclusive-tour charter airlines installed their seat rows at yet shorter pitches.

Although de Havilland stated that they generally concurred with these BEA views, upper management also stated that they had worked "under terms more onerous than anything D.H. had previously undertaken". Industry observers at the time felt that the British aircraft industry had again stumbled "into the pitfall of having designed exclusively for one customer an aeroplane that has potentially a much wider scope": a sentiment which would be echoed throughout the Trident's subsequent progress. It was, however, noted that de Havilland had not yet secured a formal and final BEA order and that its competitor Bristol was actively promoting their 200 project, which was significantly smaller than the D.H.121. At the time Boeing
Boeing
The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...

 and Douglas
Douglas Aircraft Company
The Douglas Aircraft Company was an American aerospace manufacturer, based in Long Beach, California. It was founded in 1921 by Donald Wills Douglas, Sr. and later merged with McDonnell Aircraft in 1967 to form McDonnell Douglas...

 were also downsizing their DC-9
McDonnell Douglas DC-9
The McDonnell Douglas DC-9 is a twin-engine, single-aisle jet airliner. It was first manufactured in 1965 with its maiden flight later that year. The DC-9 was designed for frequent, short flights. The final DC-9 was delivered in October 1982.The DC-9 was followed in subsequent modified forms by...

 and 727
Boeing 727
The Boeing 727 is a mid-size, narrow-body, three-engine, T-tailed commercial jet airliner, manufactured by Boeing. The Boeing 727 first flew in 1963, and for over a decade more were built per year than any other jet airliner. When production ended in 1984 a total of 1,832 aircraft had been produced...

 projects and it was felt that the original large D.H.121 would have to compete against the Convair 880
Convair 880
The Convair 880 was a narrow-body jet airliner produced by the Convair division of General Dynamics. It was designed to compete with the Boeing 707 and Douglas DC-8 by being smaller and faster, a niche that failed to create demand...

 and Boeing 720
Boeing 707
The Boeing 707 is a four-engine narrow-body commercial passenger jet airliner developed by Boeing in the early 1950s. Its name is most commonly pronounced as "Seven Oh Seven". The first airline to operate the 707 was Pan American World Airways, inaugurating the type's first commercial flight on...

 some four years after their entry into service, whereas a cut-back design would be more competitive against the then-projected 75–100 seat, two-engined DC-9.

The result of BEA's and de Havillands' concerns that the D.H.121 "had been allowed to grow too large" was a wholesale downsizing. Significantly, this involved changing the powerplant from the initial Medway engine to the 40 percent less powerful 9,850 lbf (43.8 kN) Rolls-Royce Spey 505. The gross weight was cut by about a third to 105,000 pounds (48,000 kilograms), range was cut by more than half to 930 miles (1500 kilometres), and mixed-class seating was cut by about a quarter to 75 or 80 (97 in a single-class layout). Wing span was reduced by approximately 17 ft (5 m), wing area by 30 percent and overall length by 13 ft (3,9 m). The revised design retained some features of the original larger one, notably the fuselage
Fuselage
The fuselage is an aircraft's main body section that holds crew and passengers or cargo. In single-engine aircraft it will usually contain an engine, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage which in turn is used as a floating hull...

 diameter. It had a smaller flightdeck and single-axis, two-wheel, four-tyre main undercarriage legs in place of the four-wheel bogies of its larger predecessor. Fuller details, including particulars of the pioneering avionics fit, were announced to the public in early 1960.

It was this aircraft which BEA ultimately ordered on 24 August 1959, initially in 24 examples with 12 options. The future airliner's name, Trident, was announced at the Farnborough Airshow in September 1960, reflecting its then-unique three-jet, triple-hydraulic layout.

British aircraft industry consolidation


While the D.H.121 emerged in the late 1950s, British government policy on the aircraft and aeroengine industries posed a requirement that the then-many companies should merge to form a few large groups. De Havilland had accordingly consorted with Hunting Aircraft
Hunting Aircraft
Hunting Aircraft was a British aircraft manufacturer, that produced light training aircraft and initially designed the BAC 1-11 jet airliner. The company, based in Luton, merged with other companies to form the British Aircraft Corporation in 1959.-History:...

 and Fairey Aviation
Fairey Aviation
The Fairey Aviation Company Limited was a British aircraft manufacturer of the first half of the 20th century based in Hayes in Greater London and Heaton Chapel and RAF Ringway in Greater Manchester...

 to manufacture and market the D.H.121 under the corporate name of Airco
Airco
The Aircraft Manufacturing Company Limited was established in 1912 by George Holt Thomas at The Hyde in Hendon, north London, England.-Geoffrey de Havilland:...

, after Geoffrey de Havilland
Geoffrey de Havilland
Captain Sir Geoffrey de Havilland, OM, CBE, AFC, RDI, FRAeS, was a British aviation pioneer and aircraft engineer...

's defunct pre-First World War employer.

The Minister of Supply, however, stated of the Airco consortium that "this is not quite what [he] had in mind". By late 1959, he had forced de Havilland to merge into the Hawker Siddeley group which until recently had promoted its competing Hawker Siddeley Bristol 200 project and publicly deprecated the D.H.121 project.

The complex merger was completed by April 1960. Until its very eve, Airco executives intensively explored alternatives to the merger, such as the possibility that Boeing may drop its 727 project and instead manufacture Airco D.H.121s in the USA. This involved two Airco visits to Boeing and a return visit by Boeing executives and engineers. British commentators have tended to interpret this episode as involving the acquisition of sensitive proprietary data on the D.H.121 by a direct competitor.

After the de Havilland takeover by Hawker Siddeley, Airco was disbanded. Hunting was marshalled into the competing newly-formed British Aircraft Corporation
British Aircraft Corporation
The British Aircraft Corporation was a British aircraft manufacturer formed from the government-pressured merger of English Electric Aviation Ltd., Vickers-Armstrongs , the Bristol Aeroplane Company and Hunting Aircraft in 1960. Bristol, English Electric and Vickers became "parents" of BAC with...

 (BAC
BAC
- Arts and entertainment :* Batman: Arkham City, a 2011 video game* Battersea Arts Centre, London, England, United Kingdom* Benedicta Arts Center, St...

). Their departure removed any putative possibility of the Hunting 107 (later the BAC One-Eleven
BAC One-Eleven
The British Aircraft Corporation One-Eleven, also known as the BAC-111, BAC-1-11 or BAC 1-11, was a British short-range jet airliner of the 1960s and 1970s...

) being marketed alongside the D.H.121 as a complementary, smaller member of the same airliner family. Fairey Aviation, partially incorporated into Westland Aircraft
Westland Aircraft
Westland Aircraft was a British aircraft manufacturer located in Yeovil in Somerset. Formed as a separate company by separation from Petters Ltd just before the start of the Second World War, Westland had been building aircraft since 1915...

, also left the D.H.121 project. With the move to Hawker Siddeley Aviation, the designation eventually changed to the HS 121.

By 1960, the cumulative delays to the D.H.121 programme from changes to BEA's requirements and British aircraft industry mergers had amounted to between two and three years. Nevertheless, for a year the D.H.121 was the first and only firm contender in a market segment so far unoccupied by an American or other product: that for a short/medium range, medium capacity jet airliner.

Overview


The Trident was a jet airliner
Jet airliner
A jet airliner is an airliner that is powered by jet engines. This term is sometimes contracted to jetliner or jet.In contrast to today's relatively fuel-efficient, turbofan-powered air travel, first generation jet airliner travel was noisy and fuel inefficient...

 of all-metal construction with a T-tail
T-tail
thumb|right|Grob motor gliderA T-tail is an aircraft tail stabilizer configuration in which the horizontal surfaces are mounted to the top of the vertical stabilizer. Traditionally, the horizontal control surfaces are mounted to the fuselage at the base of the vertical stabilizer...

 and a low-mounted wing
Swept wing
A swept wing is a wing planform favored for high subsonic jet speeds first investigated by Germany during the Second World War. Since the introduction of the MiG-15 and North American F-86 which demonstrated a decisive superiority over the slower first generation of straight-wing jet fighters...

 with a quarter-chord sweepback of 35 degrees. It had three rear-mounted engines: two in side-fuselage pods, and the third in the fuselage tailcone, aspirating through an S-shaped duct
S-duct
An S-duct is a unique type of jet engine intake duct, used in several types of trijet aircraft. In this configuration, the intake is in the upper rear center of the aircraft, just below the stabilizer, while the exhaust is at the rear of the aircraft. The S-duct is located in the tail, or...

. One version had a fourth "boost" engine aspirated through a separate intake duct above the main S-duct. All versions were powered by versions of the Rolls-Royce Spey, while the boost engine was also by Rolls-Royce: the RB.162
Rolls-Royce RB162
|-See also:-Bibliography:*Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9*Swanborough, Gordon. Air Enthusiast, Volume One. London: Pilot Press, 1971. ISBN 0-385-08171-5....

, originally intended as a lift engine for VTOL
VTOL
A vertical take-off and landing aircraft is one that can hover, take off and land vertically. This classification includes fixed-wing aircraft as well as helicopters and other aircraft with powered rotors, such as cyclogyros/cyclocopters and tiltrotors...

 applications.

The Trident was one of the fastest subsonic commercial airliners, regularly cruising at over 610 mph (965 km/h). At introduction into service its standard cruise Mach Number was 0.88/ 380kts IAS, probably the highest of any of its contemporaries. Designed for high speed, the wing produced relatively limited lift at lower speeds. This, and the aircraft's low power-to-weight ratio, called for prolonged takeoff runs. Nevertheless, the Trident fulfilled BEA's 6,000 ft (1,800 m) field length criterion and its relatively staid airfield performance was deemed adequate before the arrival into service of the Boeing 727 and later jet airliners built to 4500 ft (1360 m) field length criteria.

The Trident was routinely able to descend at rates of up to 4500 fpm (23 m/sec) in regular service. In emergency descents it was permissible to use reverse thrust of up to 10,000 rpm. Below 280 kt IAS, it was also possible to extend the main landing gear for use as an emergency airbrake. The Trident's first version, Trident 1C, had the unusual capability of using reverse thrust prior to touchdown. The throttles could be closed in the flare and reverse idle set to open the reverser buckets. At pilot discretion, up to full reverse thrust could then be used prior to touchdown. This was helpful to reduce hydroplaning and give a very short landing run on wet or slippery runways, while preserving wheel brake efficiency and keeping wheel brake temperatures low.

Avionics


The Trident had a complex, sophisticated and comprehensive avionics fit which was successful in service. This comprised a completely automatic blind landing system
Autoland
In aviation, autoland describes a system that fully automates the landing phase of an aircraft's flight, with the human crew merely supervising the process.-Description:...

 developed by Hawker Siddeley and Smiths Aircraft Instruments
Smiths Group
Smiths Group plc is a global engineering company headquartered in London, United Kingdom. It has operations in over 50 countries and employs around 23,550 staff....

. It was capable of guiding the aircraft automatically during airfield approach, flare, touchdown and even roll-out from the landing runway. The system was intended to offer autoland by 1970. In the event, it enabled the Trident to perform the first automatic landing by a civil airliner in scheduled passenger service as early as 10 June 1965 and the first genuinely "blind" landing in scheduled passenger service as early as 4 November 1966.

The ability to land in fog solved a major problem at London Heathrow and other British airports. Delays were commonplace when Category 1 (Cat 1 = 200 ft (61 m) decision height and 600 metre runway visual range RVR) instrument landing system
Instrument Landing System
An instrument landing system is a ground-based instrument approach system that provides precision guidance to an aircraft approaching and landing on a runway, using a combination of radio signals and, in many cases, high-intensity lighting arrays to enable a safe landing during instrument...

 (ILS) was in use. The Trident with its autoland system pioneered the use of lower landing minima starting with Cat 2 (100 ft decision height and 400 metres RVR) and going on to "zero-zero" (Cat 3B) operations. Because the Trident fleet could operate safely to airfields equipped with suitable ILS installations, it could operate as scheduled irrespective of weather, while other aircraft were forced to divert.

The Trident's advanced avionics displayed the aircraft's momentary position relative to the ground on a moving map display on the centre instrument panel. This electro-mechanical device also recorded the aircraft's track using a stylus plotting on a motor-driven paper map. Positional information was derived from a doppler
Doppler
-Doppler effect and its applications:* Doppler effect* Doppler beaming* Doppler broadening* Doppler cooling** Doppler cooling limit* Doppler echocardiography** Doppler ultrasound, also called Doppler sonography** Transcranial doppler* Doppler fetal monitor...

 navigation system which read groundspeed and drift data which, alongside heading data, drove the stylus.

The Trident was the first airliner fitted with a quick access flight data recorder. This sampled 13 variables, converted them into a digital format and stored them on magnetic tape for ground analysis.

Introduction


Hawker Siddeley Aviation, by this time, the parent of de Havilland, needed additional customers for the Trident, so entered into discussions with American Airlines
American Airlines
American Airlines, Inc. is the world's fourth-largest airline in passenger miles transported and operating revenues. American Airlines is a subsidiary of the AMR Corporation and is headquartered in Fort Worth, Texas adjacent to its largest hub at Dallas/Fort Worth International Airport...

 (AA) in 1960. They demanded an aircraft with a longer range, which meant that the original DH121 design would have fulfilled American's requirements almost perfectly. To fill AA's needs, design began on a new Trident 1A, powered with uprated Rolls-Royce Spey 510s of 10,700 lbf (47.6 kN) thrust
Thrust
Thrust is a reaction force described quantitatively by Newton's second and third laws. When a system expels or accelerates mass in one direction the accelerated mass will cause a force of equal magnitude but opposite direction on that system....

, and a larger wing with more fuel, raising gross weight
Mass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...

 to 120,000 lb (54,000 kg) and range to 1,800 miles (2900 km). American Airlines eventually declined the aircraft in favour of the Boeing 727, an aircraft which filled the original DH121 specifications almost exactly.

Some of these changes were nevertheless added into the original prototype, and it was renamed the Trident 1C. The main difference was a larger fuel tank in the centre section of the wing, raising weights to 115,000 lb (52,000 kg) and range to 1,400 miles (2250 km). The first Trident 1, G-ARPA, made its maiden flight on 9 January 1962 from Hatfield Aerodrome
Hatfield Aerodrome
Hatfield Aerodrome, formerly , was an airfield and aircraft factory located in the town of Hatfield, Hertfordshire from 1930 until its closure and redevelopment in the 1990s.-Early history:...

, and entered service on 1 April 1964. By 1965, there were 15 Tridents in BEA's fleet and by March 1966, the fleet had increased to 21.

Hawker Siddeley then proposed an improved 1C, the Trident 1E. This would use 11,400 lbf (50.7 kN) Spey 511s, have a gross weight of 128,000 lb (58,000 kg), an increased wing area by extending the chord
Chord (aircraft)
In aeronautics, chord refers to the imaginary straight line joining the trailing edge and the center of curvature of the leading edge of the cross-section of an airfoil...

, and the same fuselage but with up to 140 seats in a six-abreast configuration. This specification took the 1C closer to the larger concept of the original DH121, but powered with 7,000 lbf (31 kN) less thrust. There were only a few sales of the new design: three each for Kuwait Airways
Kuwait Airways
Kuwait Airways is the national airline of Kuwait, with its head office on the grounds of Kuwait International Airport, Al Farwaniyah Governorate. It operates scheduled international services throughout the Middle East, to the Indian subcontinent, Europe, Southeast Asia and North America, from its...

 and Iraqi Airways
Iraqi Airways
Iraqi Airways Company, operating as Iraqi Airways , is the national carrier of Iraq, headquartered on the grounds of Baghdad International Airport in Baghdad. One of the oldest airlines in the Middle East, Iraqi Airways operates domestic and regional service...

, four for PIA
Pakistan International Airlines
Pakistan International Airlines Corporation commonly known as PIA, is the flag carrier airline of Pakistan. The airline has its head office on the grounds of Jinnah International Airport in Karachi. and operates scheduled services to 24 domestic destinations and 38 international destinations in 27...

 (later sold to CAAC), two each for Channel Airways
Channel Airways
Channel Airways was a private airline formed in the United Kingdom in 1946 as East Anglian Flying Services.The newly formed airline initially operated aerial joy rides with a single, three-seater aircraft from an airstrip on the Kent coast...

 and Northeast Airlines
Northeast Airlines
Northeast Airlines was an American airline based in Boston, Massachusetts. They began as Boston-Maine Airways, which was founded as a Pan Am contract carrier on July 20, 1931, by the Boston and Maine Railroad and Maine Central Railroad offering service from Boston to Bangor via Portland...

, and one for Air Ceylon
Air Ceylon
Air Ceylon was the flag carrier airline of Sri Lanka from 1947 until 1978, when it was replaced by Air Lanka.- History :...

.

Trident 2E


At this point, BEA decided that the Trident was now too short-legged for its ever-expanding routes, and that an even longer-ranged version was needed. Hawker-Siddeley responded with another upgrade as the Trident 1F. It would have the Spey 511 engines, a 2.8 m fuselage stretch, a gross weight of 132,000 lb (60,000 kg) and up to 128 seats in the original five-abreast configuration. BEA planned to buy 10 1Fs, plus an option
Option (aircraft purchasing)
An option, when purchasing aircraft, allows an airline to purchase additional aircraft in the future at an agreed price and date.When placing orders for new aircraft, airlines commonly obtain options from the aircraft manufacturer, for example Airbus or Boeing...

 for 14 further aircraft. As work continued on the 1F the changes became so widespread that it was renamed the Trident 2E, E for Extended Range. Now powered by newer Spey 512s with 11,930 lbf (53.1 kN) thrust, it also replaced wing leading-edge droops with slats, and extended the span with Küchemann
Dietrich Küchemann
Dietrich Küchemann CBE FRS FRAeS was a German aerodynamicist who made several important contributions to the advancement of high-speed flight...

-style tips. It had a gross weight of 142,400 lb (65,000 kg) and a 2,000 mile (3200 km) range. BEA bought 15, two were bought by Cyprus Airways
Cyprus Airways
Cyprus Airways is the national airline of Cyprus, a public limited company with its head offices located in the capital of the island, Nicosia. It operates scheduled services to 41 destinations in Europe, the Middle East and the Gulf. It flies from both airports of the island, Larnaca and Paphos,...

 and 33 by CAAC, the Chinese national airline. The first flight of this version was made on 27 July 1967 and it entered service with BEA in April 1968.

Trident 3B



Subsequently, the Trident was becoming the backbone of the BEA fleet and BEA wanted an even larger aircraft. Hawker-Siddeley offered two new designs in 1965, a larger 158-seat two-engine aircraft otherwise similar to the Trident known as the HS132, and the 185-seat HS134, which moved the engines under the wings and led to a modern-looking design very similar to the Boeing 757
Boeing 757
The Boeing 757 is a mid-size, narrow-body twin-engine jet airliner manufactured by Boeing Commercial Airplanes. Passenger versions of the twinjet have a capacity of 186 to 289 persons and a maximum range of , depending on variant and cabin configuration...

. Both were to be powered by a new high-bypass engine under development at the time, the Rolls-Royce RB178. BEA instead opted for Boeing 727s and 737s to fill the role of both the BAC 1–11 and Trident, but this plan was later vetoed by the British government (the owners of BEA).

BEA returned to Hawker Siddeley and instead chose a stretched version of the basic Trident, the Trident 3. This included a fuselage stretch of 5 m for up to 180 passengers, raised the gross weight to 143,000 lb (65,000 kg), and made modifications to the wing to increase its chord. The engines remained the same, and BEA rejected the design as being unable to get off the ground in "hot and high
Hot and high
In aviation, hot and high is a condition of low air density due to high ambient temperature and high airport elevation. Air density decreases with increasing temperature and altitude. Lower air density reduces the amount of lift generated by the wings or the rotors of an aircraft, which may hamper...

" conditions, given that the 2E was having so many problems already. Since the Spey 512 was the last of the Spey line, extra power would be difficult to add. Instead of attempting to fit a new engine, which would be difficult given that one was buried in the tail, Hawker-Siddeley decided to add a fourth engine in the tail, the tiny RB162
Rolls-Royce RB162
|-See also:-Bibliography:*Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9*Swanborough, Gordon. Air Enthusiast, Volume One. London: Pilot Press, 1971. ISBN 0-385-08171-5....

 turbojet, fed from its own intake behind a pair of movable doors. The engine added 15% more thrust for takeoff, while adding only 5% more weight, and would only be used when needed. BEA accepted this as the Trident 3B, and ordered 26. In some configurations, BEA
British European Airways
British European Airways or British European Airways Corporation was a British airline which existed from 1946 until 1974. The airline operated European and North African routes from airports around the United Kingdom...

 (later British Airways
British Airways
British Airways is the flag carrier airline of the United Kingdom, based in Waterside, near its main hub at London Heathrow Airport. British Airways is the largest airline in the UK based on fleet size, international flights and international destinations...

) Trident aircraft had a number of rearward-facing passenger seats, an uncommon seating arrangement for civil aircraft. The first flight was on 11 December 1969 and the aircraft entered service on 1 April 1971. Addition of extra fuel capacity resulted in the Super Trident 3B, two of which were sold to CAAC.

In 1977, fatigue cracks were discovered in the wings of the British Airways Trident fleet. The aircraft were ferried back to the manufacturer, and repaired, then returned to service.

In total, 117 Tridents were produced, while the Boeing 727, built to the original airline specification for the Trident, sold over 1,700.

Variants


Trident 1C: Production version for British European Airways, 24 built
Trident 1E: Increased seating capacity
Seating capacity
Seating capacity refers to the number of people who can be seated in a specific space, both in terms of the physical space available, and in terms of limitations set by law. Seating capacity can be used in the description of anything ranging from an automobile that seats two to a stadium that seats...

 uprated engines and addition of leading edge slats, 15 built
Trident 2E: As Trident 1E version with triplex autoland system, 50 built
Trident 3B: High-capacity short-medium range version of the 2E with a 16 ft 5 in (5m) stretch, 1 RB.162
Rolls-Royce RB162
|-See also:-Bibliography:*Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9*Swanborough, Gordon. Air Enthusiast, Volume One. London: Pilot Press, 1971. ISBN 0-385-08171-5....

 booster engine in the tail; 26 built
Super Trident 3B: Extended range by 692 (430) miles, two built

Civil operators


(Ceylon):
  • Air Ceylon
    Air Ceylon
    Air Ceylon was the flag carrier airline of Sri Lanka from 1947 until 1978, when it was replaced by Air Lanka.- History :...


:
  • Civil Aviation Administration of China
    Civil Aviation Administration of China
    The Civil Aviation Administration of China , formerly the General Administration of Civil Aviation of China , is the aviation authority under the Ministry of Transport of the People's Republic of China. It oversees civil aviation and investigates aviation accidents and incidents...

     (CAAC)
  • China United Airlines
    China United Airlines
    China United Airlines Co., Ltd. is an airline based in Beijing, People's Republic of China, operating scheduled flights and charter services in co-operation with local enterprises out of Beijing Nanyuan Airport, making it the only commercial airline using this airport.-History and Development:China...


:
  • Cyprus Airways
    Cyprus Airways
    Cyprus Airways is the national airline of Cyprus, a public limited company with its head offices located in the capital of the island, Nicosia. It operates scheduled services to 41 destinations in Europe, the Middle East and the Gulf. It flies from both airports of the island, Larnaca and Paphos,...


:
  • Iraqi Airways
    Iraqi Airways
    Iraqi Airways Company, operating as Iraqi Airways , is the national carrier of Iraq, headquartered on the grounds of Baghdad International Airport in Baghdad. One of the oldest airlines in the Middle East, Iraqi Airways operates domestic and regional service...


:
  • Kuwait Airways
    Kuwait Airways
    Kuwait Airways is the national airline of Kuwait, with its head office on the grounds of Kuwait International Airport, Al Farwaniyah Governorate. It operates scheduled international services throughout the Middle East, to the Indian subcontinent, Europe, Southeast Asia and North America, from its...


:
  • Pakistan International Airlines
    Pakistan International Airlines
    Pakistan International Airlines Corporation commonly known as PIA, is the flag carrier airline of Pakistan. The airline has its head office on the grounds of Jinnah International Airport in Karachi. and operates scheduled services to 24 domestic destinations and 38 international destinations in 27...


:
  • BKS/Northeast Airlines (UK)
    Northeast Airlines (UK)
    Northeast Airlines - formerly BKS Air Transport - was an airline based in the United Kingdom that operated as BKS from 1951 until 1970. NEA's operations and fleet were merged into British Airways in 1976.-BKS:...

  • British Airways
    British Airways
    British Airways is the flag carrier airline of the United Kingdom, based in Waterside, near its main hub at London Heathrow Airport. British Airways is the largest airline in the UK based on fleet size, international flights and international destinations...

  • British European Airways
    British European Airways
    British European Airways or British European Airways Corporation was a British airline which existed from 1946 until 1974. The airline operated European and North African routes from airports around the United Kingdom...

  • Channel Airways
    Channel Airways
    Channel Airways was a private airline formed in the United Kingdom in 1946 as East Anglian Flying Services.The newly formed airline initially operated aerial joy rides with a single, three-seater aircraft from an airstrip on the Kent coast...


:
  • Air Charter Service of Zaire

Military operators


  • People's Liberation Army Air Force
    People's Liberation Army Air Force
    The People's Liberation Army Air Force is the aviation branch of the People's Liberation Army, the military of the People's Republic of China...


  • Pakistan Air Force
    Pakistan Air Force
    The Pakistan Air Force is the leading air arm of the Pakistan Armed Forces and is primarily tasked with the aerial defence of Pakistan with a secondary role of providing air support to the Pakistan Army and the Pakistan Navy. The PAF also has a tertiary role of providing strategic air transport...


Aircraft on display


Four complete aircraft are preserved in the United Kingdom:
  • Trident 1C G-ARPO Save the Trident Group at North East Aircraft Museum
    North East Aircraft Museum
    The North East Aircraft Museum is a volunteer-run aviation museum situated on the site of the former RAF Usworth/Sunderland Airport, between Washington and Sunderland, England. The museum has the largest aviation collection between Yorkshire and Scotland and houses over 30 aircraft and a wide...

    .
  • Trident 2E G-AVFB at Duxford
    Duxford
    Duxford is a village in Cambridgeshire, England, some ten miles south of Cambridge.-History:The village formed on the banks of the River Cam, a little below its emergence from the hills of north Essex...

     near Cambridge.
  • Trident 3B G-AWZM at Science Museum
    Science Museum (London)
    The Science Museum is one of the three major museums on Exhibition Road, South Kensington, London in the Royal Borough of Kensington and Chelsea. It is part of the National Museum of Science and Industry. The museum is a major London tourist attraction....

    's exhibit store at Wroughton in Wiltshire
    Wiltshire
    Wiltshire is a ceremonial county in South West England. It is landlocked and borders the counties of Dorset, Somerset, Hampshire, Gloucestershire, Oxfordshire and Berkshire. It contains the unitary authority of Swindon and covers...

    .
  • Trident 3B G-AWZK in Aviation Viewing Park at Manchester Airport, moved from Heathrow in September 2005 (clipped wings).


Various other Tridents survive as static exhibits in China.

Survivors

  • Trident 2E 5B-DAB at Nicosia International Airport
    Nicosia International Airport
    Nicosia International Airport is a largely disused airport located to the west of the Cypriot capital city of Nicosia. It was originally the main airport for the island, but commercial activity ceased following the Turkish invasion of Cyprus in 1974...

     (derelict). As of June 2009, the aircraft was still in existence, having stood for 35 years.
  • Trident 3B G-AWZS at International fire training centre Teesside Airport (complete).


Several aircraft or sections in use as fire service training aids and aircraft either preserved or in storage at various locations in China (three airframes, one with a broken back, can be seen at the Beijing Aeroplane Museum at Datangshan
Datangshan
Datangshan is the name of a hill in the Changping District of Beijing, China. It is the site of China's largest aviation museum, the China Aviation Museum....

, north of Beijing). In 2008, the personal aircraft of Mao Zedong
Mao Zedong
Mao Zedong, also transliterated as Mao Tse-tung , and commonly referred to as Chairman Mao , was a Chinese Communist revolutionary, guerrilla warfare strategist, Marxist political philosopher, and leader of the Chinese Revolution...

 was offered for sale after a decision by merchants at a market in Zhuhai
Zhuhai
Zhuhai is a prefecture-level city on the southern coast of Guangdong province in the People's Republic of China. Located in the Pearl River Delta, Zhuhai borders Jiangmen to the northwest, Zhongshan to the north, and Macau to the south. Zhuhai was one of the original Special Economic Zones...

 that the Trident, formerly a tourist attraction
Tourist attraction
A tourist attraction is a place of interest where tourists visit, typically for its inherent or exhibited cultural value, historical significance, natural or built beauty, or amusement opportunities....

, was limiting business.

Accidents

  • On 3 June 1966, Trident 1C G-ARPY entered into a deep stall whilst on a test flight and crashed
    1966 Felthorpe Trident crash
    The Felthorpe Trident crash occurred on 3 July 1966 when Hawker Siddeley Trident 1C G-ARPY entered a deep stall from which the crew were unable to recover. The aircraft crashed at Felthorpe, Norfolk killing all four crew. This was the first loss of a Trident aircraft.-Accident Flight:The flight was...

     at Felthorpe
    Felthorpe
    Felthorpe is a civil parish in the English county of Norfolk.It covers an area of and had a population of 710 in 287 households as of the 2001 census.For the purposes of local government, it falls within the district of Broadland....

    , Norfolk, killing all four crew.
  • On 3 July 1968, Trident 1s G-ARPI and G-ARPT were struck by Airspeed Ambassador
    Airspeed Ambassador
    The Airspeed AS.57 Ambassador was a British twin piston engined airliner that first flew on 10 July 1947 and served in small numbers through the 1950s and 1960s.-Design and development:...

     G-AMAD, which crashed
    1968 BKS Air Transport Heathrow crash
    On 3 July 1968 an Airspeed Ambassador of BKS Air Transport, registration G-AMAD, crashed at London Heathrow Airport, damaging two parked Trident airliners as it cartwheeled into the uncompleted London Heathrow Terminal 1, then under construction...

     at London Heathrow Airport
    London Heathrow Airport
    London Heathrow Airport or Heathrow , in the London Borough of Hillingdon, is the busiest airport in the United Kingdom and the third busiest airport in the world in terms of total passenger traffic, handling more international passengers than any other airport around the globe...

     due to the failure of a flap operating rod. G-ARPI was severely damaged, but repaired and returned to service, whereas G-ARPT was written off.
  • On 13 September 1971, a People's Liberation Army Air Force
    People's Liberation Army Air Force
    The People's Liberation Army Air Force is the aviation branch of the People's Liberation Army, the military of the People's Republic of China...

     Trident 1E crashed in Mongolia
    Mongolia
    Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...

     under mysterious circumstances during an attempt by Lin Biao
    Lin Biao
    Lin Biao was a major Chinese Communist military leader who was pivotal in the communist victory in the Chinese Civil War, especially in Northeastern China...

     and his family to defect to the Soviet Union
    Soviet Union
    The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

    . Official PRC
    People's Republic of China
    China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

     accounts claim that the Trident ran out of fuel.
  • On 18 June 1972, British European Airways Flight 548
    British European Airways Flight 548
    British European Airways Flight 548 was a Hawker Siddeley Trident 1C airliner, registration G-ARPI, operating as a British European Airways scheduled commercial passenger flight from London Heathrow Airport to Brussels, Belgium...

    , a Trident 1, G-ARPI, stalled due to pilot error and crashed at Staines
    Staines
    Staines is a Thames-side town in the Spelthorne borough of Surrey and Greater London Urban Area, as well as the London Commuter Belt of South East England. It is a suburban development within the western bounds of the M25 motorway and located 17 miles west south-west of Charing Cross in...

     shortly after takeoff from Heathrow Airport. All 118 on board were killed. As of 2010, it is still the worst aviation accident to have occurred on British soil (Pan Am Flight 103
    Pan Am Flight 103
    Pan Am Flight 103 was Pan American World Airways' third daily scheduled transatlantic flight from London Heathrow Airport to New York's John F. Kennedy International Airport...

     was a terrorist incident).
  • On 10 September 1976, a British Airways
    British Airways
    British Airways is the flag carrier airline of the United Kingdom, based in Waterside, near its main hub at London Heathrow Airport. British Airways is the largest airline in the UK based on fleet size, international flights and international destinations...

     Trident 3B, G-AWZT, collided in midair with an Inex Adria McDonnell-Douglas DC-9, YU-AJR, over Yugoslavia, killing everyone on both aircraft. The 1976 Zagreb midair collision
    1976 Zagreb mid-air collision
    The 1976 Zagreb mid-air collision occurred on 10 September 1976 over Vrbovec, Yugoslavia when British Airways Flight 476, a Hawker Siddeley Trident 3B en route from London Heathrow Airport to Yeşilköy International Airport, Istanbul, collided in mid-air with Inex-Adria Aviopromet Flight 550, a...

     was attributed to an air traffic control
    Air traffic control
    Air traffic control is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is to separate aircraft to prevent collisions, to organize and expedite the flow of traffic, and to provide information and other...

     error.
  • On 14 March 1979, a CAAC
    Civil Aviation Administration of China
    The Civil Aviation Administration of China , formerly the General Administration of Civil Aviation of China , is the aviation authority under the Ministry of Transport of the People's Republic of China. It oversees civil aviation and investigates aviation accidents and incidents...

     Trident 2E, B-274, crashed into a factory near Beijing, injuring at least 200. The crash was caused by an unqualified pilot who stole and flew the airliner. Total fatalities were all 12 crew, 32 ground, and no passengers.
  • On 26 April 1982, CAAC Flight 3303
    CAAC Flight 3303
    On the 27 April 1982 CAAC Flight 3303 was on a flight from Guangzhou Baiyun International Airport to Guilin Qifeng Airport in China. There were 104 passengers and 8 crewmembers on board the Hawker Siddeley Trident with the Registration B-266. Then at 16:45 as Flight 3303 was on approach to the...

     Trident 2E, B-266 crashed near Yangsuo, China killing all 112 passengers and crew.
  • On 31 August 1988, the right outboard flap of a CAAC
    Civil Aviation Administration of China
    The Civil Aviation Administration of China , formerly the General Administration of Civil Aviation of China , is the aviation authority under the Ministry of Transport of the People's Republic of China. It oversees civil aviation and investigates aviation accidents and incidents...

     Trident 2B hit approach lights of runway 31 of Hong Kong's Kai Tak Airport
    Kai Tak Airport
    Kai Tak Airport was the international airport of Hong Kong from 1925 until 1998. It was officially known as the Hong Kong International Airport from 1954 to 6 July 1998, when it was closed and replaced by the new Hong Kong International Airport at Chek Lap Kok, 30 km to the west...

     while landing in rain and fog. The right main landing gear then struck a lip and collapsed, causing the aircraft to run off the runway and slip into the harbour. Seven people were killed.

Specifications (Trident 2E)



Variant comparison

Trident 2E Trident 3B
Capacity 115 Passengers 180 Passengers
Length 35 m (114 ft 9 in) 40 m (131 ft 2 in)
Wingspan 28.9 m (98 ft)
Height 8.3 m (27 ft) 8.6 m (28 ft 2.5 in)
Max Takeoff Weight 143,500 lb (65,000 kg) 155,000 lb (70,300 kg)
Cruise Speed 604 MPH (972 km/h) 582 MPH (936 km/h)
Range 2,400 mi (3,860 km) 1,800 mi (3,060 km)

See also



External links