Just one Brabazon made it off the assembly line. The supersized airliner, with its 230-foot wingspan, rumbled over the British countryside in 1951, accompanied by a Bristol 170 Freighter.

Designed to redefine air travel, the Bristol Brabazon was a post-war marvel—stretching longer than a Boeing 747 and weighing in at 130 tons. Yet despite its grandeur and ambition, it never saw ...