The Lockheed Model 49-46-10 Constellation prototype NX25600. It made its first flight on January 9, 1943.

Another flying shot of the prototype Constellation.

The Lockheed Model 49-46-10 Constellation prototype NX25600. It made its first flight on January 9, 1943.

“Old 1961“and one of its Pratt & Whitney R-2800 engines.

After the war Lockheed’s assembly lines rushed the first commercial versions of the Constellation to awaiting airlines - some of them are pictured here in November 1945.

Lockheed’s chief research engineer Clarence L. "Kelly" Johnson, left, and Milo Burcham, chief test pilot, in front of the prototype Constellation.

A rather pensive Howard Hughes sitting in the left-hand seat of a TWA Constellation. In addition to being a major shareholder in the airliner, he was no mean pilot himself.

A 1947 photograph of a Constellation flight deck during a training flight. Just below the nose is the Empire State Building in Manhattan which, presumably, the pilots have already spotted!

A design study of Constellation’s forerunner. The L-44 Excalibur project was revealed in April 1939 and resembled a scaled-up four-engined Model 10A Electra.

An artist’s impression of the Constellation as it was first conceived in 1939. Note the reverse-flow engine cowlings and completely faired nose, with no windscreen step.