Northrop Alpha

Northrop's first aircraft for his new company was known as the Flying Wing but of more immediate consequence was the next design, the Northrop Alpha, an all-metal seven-seat single-engine low-wing monoplane. In 1929 Avion Corporation became the Northrop Aircraft Corporation, a division of United Aircraft and Transport Corporation of which Boeing was also a part. Trans Continental and Western Air Inc, (later to become Trans World Airlines) ordered five Alphas with 313kW Pratt & Whitney Wasp engines and began services on 20 April 1931 from San Francisco to New York, with 13 intermediate stops, the journey taking just over 23 hours. The Alphas were configured for three passengers and 211kg of mail and cargo, for mail flying was a plum contract at that time, but regularity and reliability was required. To achieve all-weather and night-flying capability, the Alphas had the most modern radio and navigation equipment, and for winter operations became the first commercial type to be fitted with Goodrich rubber de-icer boots on wing "and tail surface leading edges. Thirteen of the 17 Alphas built saw service with TWA, and three were supplied for evaluation to the US Army Air Corps where, had production orders been given, they would have been designated C-19.

Various configurations carried the designations Alpha 2, Alpha 3, Alpha 4 and Alpha 4-A, and a number of changes were made between individual aircraft as late modifications were made retrospectively to earlier aircraft, including fitting of streamlined 'trousers' over the original rather utilitarian landing gear. The last conversion was the Gamma 4-A, an all-cargo aircraft which could carry 567kg; the Gamma 4 and Gamma 4-A had a 336kW Wasp engine and most of the earlier aircraft were similarly retrofitted.

The last surviving Alpha, the third built, served with the US Assistant Secretary of Commerce for Aeronautics, the Ford Motor Company, National Air Transport (part of United Airlines) and TWA; it was re-acquired by the airline in 1975 and superbly restored before being placed in Washington's Smithsonian Institution National Air and Space Museum.