Emerging as a rival to Boeing's 247, the rigorously tested twin-engine DC3 would eventually radicalise the aviation industry in 1934.

This double-decked monster was designed to carry 800 passengers and revolutionise the highways of the sky, so why did it take 17 years to lift off?

Lockheed were tasked with creating a plane invisible to Russian radar, capable of reaching an altitude of 80,000 ft and speeds of Mach 3.2.