The Airliner Whose Engine Was Buried Inside The Tail

In 1965, a British airliner landed at Heathrow with nobody flying it. The autopilot took it down, flared, and put the wheels on the runway with passengers aboard — the first automatic landing on a scheduled commercial flight in history. The aircraft that did it had one of its three engines buried inside the base of the fin, invisible from outside. It flew more than a year before Boeing's version of the same idea. It was more advanced in almost every way that engineers care about. Boeing sold seventeen 727s for every Trident ever built. This is the story of why being first and being cleverer wasn't enough — how a design frozen around one airline's timetable ran out of room to grow, and why the stretched version needed a fourth engine bolted into the tail just to get off the ground.