I’m assuming the first topic was closed as I can’t find it, but I’m now done with the full article!
Exams are finally over for me, let’s get back into the swing of things with another PoTP! Today we will be focusing on the first T-tailed 3 holer, the Hawker Siddeley Trident or the HS 121!
Credits: Hawker Siddeley HS-121 Trident 2E - British Airways | Aviation Photo #1502478 | Airliners.net
Specifications:
3 Crew Cockpit
Capacity ranged from 101 pax (Trident 1/1C) to 108 (1E) then 115 (2E) then 180 in the Trident 3.
Tridents 1-2E were 34.98m long while the Trident 3 was 39.98m long.
The Tridents 1 to 1C had a wingspan of 27.38m while the 1E had a 29m wing and the 2E and 3B had a 30m wing.
All wings were swept back at 35 degrees.
The Tridents 1 to 2E cruised at M0.86 while the more weighty 3B cruised at M0.84.
All planes had a service ceiling of 35000 feet.
All planes had 3 Rolls Royce Spey engines, save for the Trident 3B which had an additional RR RB162 booster engine to get itself off the ground.
History:
BEA or British European Airways issued a requirement for a jet after seeing the success of the Sud Aviation Caravelle, which was matched by Hawker Siddeley and their Trident. As the jet was designed for BEA, the original prototype with Rolls-Royce Medway engines was determined to be too big as BEA wanted a smaller aircraft. This was scrapped and the plane was then shortened to create the Trident 1, with smaller Rolls-Royce Spey engines. This was to come back and bite Hawker Siddeley in the arse later when BEA realised that they indeed needed the larger aircraft as the original design had.
So what did HS do? They stretched the Trident. This was to be the new Trident 1E and 2E, with the 2E having more powerful Speys and a larger wing as well as more range. However, it was still not enough for BEA and definitely not big enough to compete with the other Trijet in the market, the Boeing 727. By the time that HS got around to the Trident 3, which was closest to the original HS 121 specification, the 727 had already taken the market away from HS.
Hawker Siddeley HS-121 Trident 3B - BEA - British European Airways | Aviation Photo #1785507 | Airliners.net
The Trident 3, being a much longer stretch of the original Trident, could not get into the air with the underpowered Speys, even with water injection. Thus, an addditional engine, a RB162 originally designed by RR to power VTOL aircraft was slotted in above the number 2 engine to get the heavy plane off the ground. Due to fuel consumption reasons, it was shut down once the plane had gotten to cruise height. This gave the plane a 15% thrust advantage over older planes with only a 5% weight penalty.
http://www.flightstory.net/20140802/bea-trident-unusual-70s-seat-layout
An interesting fact about the Tridents is that the first few rows of Economy would be facing backwards. Why? Some say it is due to the fact that in a plane crash, people sitting backwards are more likely to survive. Go figure…
Hawker Siddeley HS-121 Trident 2E - CAAC | Aviation Photo #0544404 | Airliners.net
The Tridents had the landing gear offset to the left of the plane. This was to make way for the equipment bay, which allowed this plane to land in CATIII conditions with a triplex autopilot system which had autoland. This was a lifesaver for BEA as many of their destinations in the 60s and 70s to the mid 80s had bad weather conditions at times, making lesser jets like the 737 without this capability being forced to divert while the Trident could land easily. Later when designing the L-1011, Lockheed hired many of the engineers that designed the Smiths autoland system to do the one on the TriStar, giving it the first CATIIIb/c capability.
Due to the rear mounted nature of the engines, they were very quiet on the inside but they were extremely loud on the outside.
It was also said that the earlier versions of the Trident were the fastest jets of the time. As said by a passenger, “I remember on one flight that a PIA 707 left FCO twenty minutes before the Trident. There was an assortment of aircraft waiting for their take off runs but our Trident went to the front of the queue and before turning the Speys were accelerated to full power and we did a remarkable take off – long run, great noise – just like a fighter waiting to get airborne. We arrived at LHR 20 minutes ahead of schedule and nearly half an hour before the PIA 707 that left FCO before us.”
However due to the fact that the wing was optimised for high speed cruise, it was described that the plane only got airborne due to the curvature of the earth!
Hawker Siddeley HS.121 Trident 3B Photos | Airplane-Pictures.net
The cockpit of G-AWZJ, a British Airways Trident 3B. Of note is the Doppler moving map system in the centre.
Who operated the aircraft?
The Trident was most known for being operated by BEA and later British Airways but the plane was also operated by the following airlines- CAAC (Civil Aviation Administration of China), Air Ceylon, China United Airlines, Iraqi Airways, Cyprus Airways, Kuwait Airways, Pakistan International Airlines as well as the Air Charter Service of Zaire.
Final Note:
This aircraft may not be the most well known, but it is arguably one of the best to learn from. Ever since then, with maybe the exception of the 747 and Pan Am, no other plane has been produced with such a huge influence from a single airline. It can be argued that if HS had gone ahead with the original HS121 proposal, we would be talking about how Tridents were everywhere instead of the 727. In fact, a team from Boeing was invited over to HS to take a look at the Trident, which later ended up with them building the 727-100. Take this as a warning, all aircraft manufacturers!
I hope you’ve enjoyed reading this PoTP! As usual, constructive criticism is always welcome. Until PoTP 6, ta-ra!
