Hawker Siddeley Trident 3B and its fourth "booster" engine
Hi all,
I recently read about the interesting powerplant configuration of the Hawker Siddeley Trident 3B.
For those who don't know, the Hawker-Siddeley Trident, HS-121, was a British trijet of the 1960s similar in overall configuration to the Boeing 727. The aircraft was equipped with three Rolls-Royce Spey RB163 turbofan engines, each of around 46 to 53 kN of rated thrust (depending on variant). Its last variant, the Trident 3B, featured a fourth RB162 booster engine of 23 kN of thrust which added 5% extra weight to the aircraft but provided an extra 15% thrust on take-off. It was used on demand when needed.
Since there's very little information available on this interesting and odd powerplant configuration, I'd love to hear from anyone who knows more of the Trident 3B. I'm particularly interested in the actual operation of the fourth engine. Was it used only for take-off and then shut down? If so, when exactly was it shut-down? Would it be left on for the whole flight? What about shutting it down during cruise but later relighting to comply with potential go-around climb gradient requirements? What were the normal procedures and limitations? How was the fourth engine controlled in the cockpit: did it have its own lever? was the lever the same as the other three? was it rather more like an "on/off" control? Did the pilots or the flight engineer control it? Was it operated in a similar way to those water injection systems on older turbofans like on the 707 and 747?
Any sort of insight into this feature of the Trident 3B beyond what's available on Wikipedia would be greatly appreciated.