The Stearman 4 is an American commercial biplane that was manufactured in the 1920s by Stearman Aircraft. They were marketed at the time as fast and luxurious executive transports and mail planes for about US$16,000.
Development
Stearman Aircraft developed the Model 4 from the C3, adding a deeper fuselage and offering a range of more powerful engines. These features enabled the Model 4 to carry heavier cargo loads. Being larger than the C3, but smaller than the M-2 and LT-1 models, it filled a gap in the Stearman product line. Designer Lloyd Stearman said that it was the best airplane he ever designed. Heaters were provided for both cockpits.
Operational history
Stearman sold the Model 4 to commercial operators in the United States, building 41 before ending production. Users of the type included Varney Air Lines and American Airways. Standard Oil operated three Junior Speedmails for product promotion. The aircraft was produced in Wichita, Kansas from September 1929 to August 1930. In Canada, Trans-Canada Air Lines bought three Stearman for pilot training and surveying new routes and were used from 1937 to 1939. One of them was sold in March 1939. 1930s socialite aviator Aline Rhonie flew NC796H out of Long Island, New York, before later joining the British war effort with the Air Transport Auxiliary. The aircraft's rugged construction helped it survive heavy handling and loads, and thirteen remained on the U.S. Civil Register in 1965. Several were operated as crop dusters, with their forward mail compartment converted into a hopper. Many later passed to private owners of veteran planes and are airworthy or in museums.
Variants
The first letter of the designation refers to the engine while an M indicates that it was intended as a mailplane, with the forward compartment covered. Minor modifications were made to the design which were reflected in the use of -1 after the designation. Reference: Simpson ;4-C/C-4/C-4A Junior Speedmail ;4-CM Senior Speedmail ;4-D Junior Speedmail ;4-DX Junior Speedmail ;4-DM Senior Speedmail ;4-E/C4W Junior Speedmail ;4-EX Senior Speedmail ;4-EM Senior Speedmail ;4-RM Special ;Model 80 Sportster ;Model 81
c/n 4007 4-E Junior Speedmail NC667K - delivered in 1929 to the Richfield Oil Company as the "Jimmie Allen Flying Club" flagship and used until 1937. Following a 2007 restoration, it flies on the North Americanair show circuit and in 2013 won the Sun 'n FunGrand Champion - Antique award.
