5/07/1937: XC-35's First Successful Pressurized Airplane Cabin

DALLAS — Today, in 1937, the first successful pressurized airplane cabin, tested in the Lockheed XC-35, revolutionized high-altitude flight.

The Lockheed XC-35 emerged from a 1935 U.S. Army Air Corps initiative to develop an aircraft capable of sustained high-altitude operations. Modified from the Lockheed Model 10 Electra, the XC-35 featured a circular fuselage cross-section reinforced to withstand pressure differentials up to 10 psi, alongside smaller windows to prevent blowouts.

The Lockheed XC-35: Pioneering Pressurized Flight

Engineers Major Carl Greene and John Younger collaborated with Lockheed to integrate a groundbreaking pressurization system. This system bled air from the engines’ turbo-superchargers to maintain a cabin altitude of 12,000 feet (3,658 meters) even at 30,000 feet (9,144 meters). 

This innovation allowed crews and passengers to avoid the hypoxia and extreme cold typical of unpressurized flight, enabling longer-duration missions and laying the groundwork for modern commercial aviation. The XC-35’s first flight validated its design, earning the Army Air Corps the 1937 Collier Trophy for aeronautical achievement.

Later repurposed by the National Advisory Committee for Aeronautics (NACA) for thunderstorm research, the aircraft demonstrated the practicality of pressurization, influencing subsequent designs like the Boeing 307 Stratoliner and the iconic post-war de Havilland Comet. 

Today, the XC-35 resides at the Smithsonian Institution’s National Air and Space Museum, a testament to its historical significance.

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