Hawker Siddeley
HS121 Trident

A unique 3 engine medium range jet airliner for fast inter-city travel.
Hawker Siddeley HS121 Trident 3 take off (viewed from above). Hawker Siddeley HS121 Trident 3 take off (viewed from above).
Originally designed under the designation DH121, the Trident was a revolutionary ‘Tri-liner’ design featuring three-engines and a T-tail, never seen before on a UK aircraft.
American Airlines were one of the first operators to show interest in the Trident concept and to fulfil their needs De Havilland designed the Trident 1A, combining the required long range capability with the powerful Rolls-Royce Medway engines and an appropriately increased fuel capacity. Eventually however, and to much disappointment at Hatfield, American Airlines selected the Boeing 727 which 'matched its requirement perfectly'. 
De Havilland immediately adapted its initial design and built an aircraft to directly reflect the specifications of domestic carrier British European Airways (BEA), complete with Rolls-Royce Spey engines which would feature on every variant thereafter..
The first full prototype (G-ARPA), designated DH121 Trident 1C (G-ARPA), flew for the first time at Hatfield on 9th January 1962.
Configured for air routes within Western Europe, the Trident was compromised by its strict BEA specification and according to most prospective customers it was 'lacking range and short field performance'.  This was particularly evident when compared with its US rival, the Boeing 727, which by now was beginning to dominate this emerging and valuable market.
The initial production run was of 24 Trident 1C’s for BEA who also took out an option on a further 12 aircraft. From the outset Trident was planned to incorporate the very latest in avionics and within a few years of operation it had pioneered the revolutionary Smiths Aircraft Industries 'Autoland' System (which allowed for continued operations in effectively zero visibility).  With this increasing its in-sevice reliability and winter reliability, the Trident served BEA well throughout the airlines relationship with the type.
Various BEA Tridents lined up on stands at Heathrow Airport Various BEA Tridents lined up on stands at Heathrow Airport
During the development cycle of the aircraft it was subject to the rationalisation of the British aircraft industry which saw De Havilland merged into the Hawker Siddeley Group and meant a change of designation to the Hawker Siddeley HS121.  The delays created by the re-organisation and upheaval saw Trident lose out to the Boeing 727 on more than one occasion, with a number of prospective buyers ruling delivery promises as 'commercially too risky'.
Hawker then introduced the Trident 1E which offered increased passenger capacity (115 - 139), a much increased fuel capacity with a higher take-off weight.  Many observers commented that the aircraft was now much closer in specification to the original Trident 1A configuration although in the end only 15 were built, operating with Kuwait Airways, Iraqi Airways and Pakistan International.  Other operators included Channel Airways, Northeast Airlines, Air Ceylon and Cyprus Airways (who chose a very cramped 7 across seat pattern).
By now the mood was changing within BEA who had started to investigate longer routes.  This caused another re-think at Hawker who responded with the Trident 1F.  However, as work started and various changes made to the Trident 1F package, it was soon concluded that it would be renamed Trident 2E (the E standing for ‘Extended Range’).
Hawker Siddeley Trident 2E (G-AVFI) BEA. Hawker Siddeley Trident 2E (G-AVFI) BEA.
The first Trident 2 flew on 27th July 1967 and featured an increase in fuel capacity, which, when combined with more powerful engines and increased take off weight, allowed the type to offer both an greater passenger capacity and longer range.
50 were built, serving with BEA (15 aircraft), China’s CAAC (33 aircraft) and Cyprus Airways (2 aircraft) and the BEA aircraft became the mainstay of the BEA operations and it wasn’t long before they were asking for an even bigger aircraft.  Initially, Hawker offered 2 designs: The HS132 (158 seater) and the HS134 (185 seater). Both aircraft departed from the Tri-Jet design concept by relocating the engines under the wings although this found little favour with the airlines.  BEA opted for the Boeing 727 and 737 to fill the previous roles met by its Tridents BAC1-11’s but its plans were vetoed by the British government. 
BEA were forced to return to Hawker Siddeley who responded with an even further stretched version of the basic Trident, known this time as the Trident 3. At some 5 metres longer that the Trident 2, the Trident 3B could carry up to 180 passengers and although the engines remained the same, the wings were cleverly reconfigured to handle the increased weight.  This was possibly the first real example of Britain's lead in the specialist design of wing technology which is now seen in Airbus aircraft around the world.
BEA initially rejected the Trident 3 design as being unable to perform in ‘Hot and high’ conditions and in response, and rather than replacing the 3 Spey engines, Hawker decided to add a ‘fourth engine’ into the tail with the placement the Rolls-Royce RB162, a tiny turbo-jet.  This gave the aircraft a 15% increase in take-off power needed to avert critisism and the first Trident 3B flew on 11th December 1969.
Twenty-six aircraft were built for BEA with 2 additional ‘Super 3B’ aircraft being delivered to CAAC with maximum weight raised to 158,000 lb.  China became a key export customer for the Trident and eventually some 35 aircraft went into service in the People’s Republic.  With its low by-pass engines, the Trident was undoubtedly noisy and the advent of more stringent ICAO noise regulations introduced in January 1986 contributed to its early withdrawal from airline service.  
By then BEA had been consumed by British Airways who concluded that it was not viable to convert their Trident fleet and embarked on a phased-retirement - Meanwhile CAAC were committed to the aircraft and continued to operate their fleet in China until the early 1990’s.  China became a key export customer for the Trident and eventually some 35 aircraft went into service in the People’s Republic and is still held in high regard as the 'best aircraft the west had ever produced'.


Trident 1C                       
24 built                  
Main production variant for British European Airways
Trident 1E
15 built
Increased passenger seating capacity with uprated engines and added wing leading edge slats
Trident 2E
50 built
Same as Trident 1E but with Smiths Industries Autoland system
Trident 3B
26 built
Short / medium range, high capacity variant of the Trident 2E - Stretched fuselage and RB162 Booster engine
Super Trident 3 B
2 built
Extended range variant.


Trident 1C
Trident 2E
Trident 3B
Three 9,850 lbst
Rolls-Royce Spey 505
Three 11,930 lbst
Rolls-Royce Spey 512
Three 11,960 lbst
Rolls-Royce Spey 512 and one 5,250 lb R-R RB162-86 booster jet
89 ft 10 in
98 ft 0 in
98 ft 0 in
Maximum Weight
117,300 lb
142,500 lb
150,000 lb
3 crew and up to 109 passengers
(normally 88)
3 crew and up to 150 passengers 
3 crew and up to 180 passengers
(typically 150)
Cruise Speed
589 mph
605 mph
581 mph
Range (max payload)
930 miles
2,430 miles
1,094 miles


Trident 1C
North East Aircraft Museum, Sunderland Airport, Sunderland, UK   
Trident 1E
Military Museum of the Chinese People's Revolution, Beijing, China
Trident 2E
Imperial War Museum, Duxford, Cambridgeshire, UK www.iwm.org.uk/visits/iwm-duxford
Trident 3B
Aviation Viewing Park, Manchester Ringway Airport, Manchester, UK
Trident 3B
Science Museum, Wroughton, Wiltshire, UK 

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