It was the second American aircraft to feature cabin pressurization. It was initially described as a 'supercharged cabin' by the Army. The distinction of the world's first pressurized aircraft goes to the Engineering Division USD-9A which first flew in the United States in 1921.[1] The XC-35 was a development of the Lockheed Model 10 Electra that was designed per a 1935 request by the United States Army Air Corps for an aircraft with a pressurized cabin.[2]