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Which Lockheed project was the cover for the Constellation?
Short answer
The L-044 Excalibur, a pressurized four-engine airliner Lockheed had been studying since 1937. According to Lockheed engineer Willis Hawkins, that program actually served to cover up the development of the Constellation, born from a 1939 TWA order that far exceeded the Excalibur's scope.

The Excalibur, an earlier project
Lockheed had been working since 1937 on the L-044 Excalibur, a four-engine commercial airliner with a pressurized cabin derived from the twin-engine Lockheed 14. It was an ambitious project for its time, but in 1939 came an order that made it look small. Trans World Airlines, then under the influence of Howard Hughes, its majority shareholder, asked Lockheed for a transcontinental aircraft capable of crossing the United States coast to coast with 40 passengers and a range of 5,630 kilometers, requirements that far exceeded those of the Excalibur.
A screen for the Constellation
From those TWA requirements came the L-049 Constellation, designed by a team of Lockheed engineers that included Kelly Johnson and Hall Hibbard. Another company engineer, Willis Hawkins, claimed years later that the true purpose of the Excalibur program had been to cover up the development of the Constellation. Discretion made sense in a market where several manufacturers competed for orders from the major airlines, and where TWA wanted an edge over its rivals with a faster, longer-range aircraft.
A design with ideas of its own
The Constellation borrowed solutions from other Lockheed aircraft: its wing closely resembled that of the P-38 Lightning fighter and differed mainly in size. It also adopted a tricycle landing gear, unusual for large aircraft of the era, and a triple tail chosen to reduce overall height. The Excalibur never entered series production, while 856 Constellations were built between 1943 and 1958 at the Burbank plant in California.
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