Variants

Trident 1C and 1E/1E-110/1E-140

Trident 1C, Photo: Steve Williams

The original Trident 1C for BEA had a lower capacity and range than later models.  BEA requested the DH121 design be downsized after a drop in passenger numbers which proved to be only temporary and later regretted this decision.  The original Trident design features a complex nose gear bay door arrangement, Krueger flaps and leading edge droops and the APU is mounted in a pod above the central engine.  The 1E and its derivatives were based on essentially the same airframe, but had a new leading edge slat arrangement, uprated engines, greater range and most importantly a higher capacity.  They were principally aimed at the export market, but were sold to UK airlines BKS (later Northeast) and Channel Airways.

The seating capacity of the 1C was typically 96, whereas the 1E with essentially the same internal space, could be configured to accommodate 149 passengers in seven abreast layout as shown above.  The original Trident wing featured Krueger flaps and a leading edge droop and short wing tips compared to the 1E and 2E.  Although the wing was low drag (permitting high cruise speeds), it was necessary to fly with the droop down at speeds below 225kts IAS below 300ft as the aircraft had a relatively high stall speed.  The 1E featured 3 foot wing tip extensions and the Krueger flap/droop arrangement being replaced by a more conventional leading edge slat arrangement.

Seven abreast seating in the Channel Airways Trident 1E,  Neil Lomax Collection

Trident 2E

Trident 2E, Photo: Steve Williams

The Trident 2E was developed as a higher capacity, longer ranged version of the original Trident and feature an enlarged wing with new high lift devices and uprated engines.  BEA and CAAC were the biggest customers, making the 2E the most built model.

The fuselage of the Trident 2E is virtually identical to that of the Trident 1.  It features a simplified nose gear door arrangement.  Accommodation is typically 103 (varied from 91 up to 149 high density, seven abreast) in six abreast seating configuration.  The wings of the 2E are larger (greater area and span), than those of the previous models (1C & 1E).  The leading edge droop was replaced by slats on the leading edge of the wing.  The increase in area of the 2E over the 1E is marginal and is due to the revised "Kuchemann" wingtips used.

The 2E was the first to feature the Mk 512 Spey engine - the final derivative to be used on an airliner.  This provided 560lb more thrust than the Mk 511 fitted to the 1E and kept the cruise speed the same despite the increase in weight of the 2E airframe over the series 1.

Cabin of the Trident 2E, Hawker Siddeley Aviation via Neil Lomax Collection

Trident 3B

Trident 3B, Photo: Johan Ljungdahl

The Trident 3B was developed for BEA after the HS132 and HS134 and were dropped, as a cheaper solution to the requirement for an enlarged capacity airliner.  The main features of this variant are the stretched fuselage and wings and the addition of the fourth engine.  A subtler modification was the increase in wing incidence angle.

The Trident was originally powered by 3 Spey Mk 505 engines.  Although they produced enough thrust for a high cruise speed, more power was required on takeoff, so the three Mk 512 engines used on the 2E were supplemented on the 3B with a single RB162-86, used only on takeoff.  The RB162 was a development of the RB108 vertical lift engine used in the previous to decade in experimental vertical takeoff aircraft.

Trident Super 3B

Two examples of this version were built for CAAC of China.  The main difference was additional fuel capacity (6,000 Imp. Gal as opposed to 5,620) which resulted in an additional range of 400 miles and an increased MTOW of 159,900 lbs.