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.[1][2]
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. Heaters were provided for both cockpits.[3]
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 (later American Airlines). Standard Oil operated three Junior Speedmails for product promotion. The aircraft was produced in Wichita, Kansas from September 1929 to August 1930.[4]
In Canada, Trans-Canada Air Lines (later Air Canada) 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.[5]
The aircraft's rugged construction helped it survive heavy handling and loads, and thirteen remained on the U.S. Civil Register in 1965.[7] 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.[8]
Variants
[edit]Stearman 4-C Junior Speedmail CF-CCH showing characteristic front manifold exhaust of the Wright J6 radial.Stearman Model 81 photo from L'Aerophile July 1933
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[9]
1933 one-off custom two-seater with dual controls and an enclosed canopy for the rear cockpit, with a 420 hp (313 kW) Pratt & Whitney Wasp Junior T3A engine.[20]
One built as a trainer variant of the 80 with enclosed canopy over both cockpits.[13] Sold to the Mexican government after a tour of South America while on floats.[13]
Operators
[edit]Northern Airways Stearman 4-EM CF-ASF with crop dusting attachment under the fuselage
[edit]Stearman 4-E NC667K at 2013 SUN 'n FUN fly-in
c/n 4005 4-E Junior Speedmail N663K - privately owned, in National Air Tour markings.[26]
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 American air show circuit[2] and in 2013 won the Sun 'n Fun Grand Champion - Antique award.[27]
Bowers, Peter M. (1998). Wings of Stearman: The Story of Lloyd Stearman and the Classic Stearman Biplanes (Historic Aircraft Series). Flying Books. ISBN978-0911139280.
Cupido, Joe (Spring 1994). "Return of the Bull: Stearman 4E Junior Speedmail". Air Enthusiast. No. 53. pp. 20–21. ISSN0143-5450.
Davies, R.E.G. (1998). Airlines of the United States since 1914. Smithsonian Institution Press. ISBN1-888962-08-9.
Green, William (1965). The Aircraft of the World. Macdonald & Co. (Publishers) Ltd. OCLC2641875.
Juptner, Joseph P. (1966). US Civil Aircraft: Vol. 3 (ATC 201 - 300). Fallbrook, CA: Aero Publishers. pp. 261–263. LCCN62-15967.
Juptner, Joseph P. (1993). US Civil Aircraft: Vol. 4 (ATC 301 - 400). Blue Ridge Summit, PA: Tab Aero. pp. 19–24, 80–82, 89–94. LCCN62-15967.
Juptner, Joseph P. (1974). US Civil Aircraft: Vol. 6 (ATC 501 - 600). Aero Publishers, Inc. pp. 20–22. ISBN0-8168-9170-2.
Ogden, Bob (2007). Aviation Museums and Collections of North America. Air-Britain (Historians) Ltd. ISBN978-0-85130-385-7.
Phillips, Edward H. (2006). Stearman Aircraft: A Detailed History. Specialty Press. ISBN978-1580070874.
Simpson, Rod (2001). Airlife's World Aircraft. Airlife Publishing Ltd. ISBN1-84037-115-3.
