Stearman Senior Speedmail
The Stearman Model 4 was a commercial biplane built by the Stearman Aircraft Company at Wichita, Kansas, first flown in 1929. Its two-seat versions were Junior Speedmails and its single-seat mailplanes Senior Speedmails; fast and strongly built, the type served airlines and oil-company fleets, and only forty were built. Survivors still fly in private hands, and several are preserved in museums.
Why It Mattered
The Stearman Model 4 was a commercial biplane built at Wichita, Kansas, by the Stearman Aircraft Company, and it first flew on 4 September 1929. Its single-seat mailplane versions were the Senior Speedmails, the name this record carries; the two-seat versions were Junior Speedmails. In their heyday, the Canada Aviation and Space Museum records, Stearman 4s were the fastest aircraft in Canadian skies, faster even than the RCAF's Siskin fighters. Lloyd Stearman himself claimed the Model 4 was the best aircraft he ever designed. Only forty were built, but the type's speed, strength and adaptability gave it a working life far longer than its brief production run.
Design Notes
Stearman developed the Model 4 from its earlier C3 with a deeper fuselage and a choice of more powerful engines, which let it carry heavier cargo loads. The letters in each variant's designation denoted its engine, and an M marked a mailplane, with the forward compartment covered over. In mailplane form, as on the museum's 4EM, that forward compartment was a dedicated space for mail storage. The Model 4 was among the first production types to carry the NACA engine cowl, a streamlined ring around the radial engine that reduced drag. Engines ranged from the 300 hp Wright J6-9 of the 4-C to the 450 hp Pratt & Whitney Wasp of the 4-E; the 4EM's Wasp SC gave it a maximum speed of 158 mph. Both cockpits were provided with heaters.
Operational History
Production ran at Wichita from September 1929 to August 1930, and Stearman sold the Model 4 to commercial operators in the United States. The largest fleet belonged to American Airlines; its predecessor American Airways and Varney Air Lines were also among the type's users. Standard Oil operated three Junior Speedmails for product promotion. Canadian Airways flew four 4EM mailplanes on its eastern Canada routes in the early 1930s. Trans-Canada Air Lines bought three Stearmans in 1937 and used them for pilot training and surveying new routes until 1939. The Richfield Oil Company's 4E, delivered in 1929, served until 1937 as flagship of the Jimmie Allen Flying Club, the promotional tie-in for the company's sponsorship of a popular radio serial. Strong construction helped the type survive hard use, and thirteen were still on the U.S. Civil Register in 1965. Several ended their working lives as crop dusters, the forward mail compartment converted into a hopper.
Afterlife
Many Model 4s later passed to private owners of veteran aircraft, and examples are airworthy or in museums. The Canada Aviation and Space Museum's Senior Speedmail was built as a 4E in 1930, one of three supplied to the Standard Oil Company of California as corporate aircraft. Converted to a crop-duster in 1944, it was restored over four years as a Canadian Airways 4EM. In 1970 it flew from Fort William to Rockcliffe airport carrying commemorative mail, and on arrival on 25 September it was presented to the museum, where it has been displayed since. It now sits in the museum's conservation hangar, undergoing partial restoration. In Florida, a 4E built in 1929 returned to the air in 2013 after a five-year restoration by Jim Kimball Enterprises, and flies as the oldest airworthy example of the model. Other survivors include an airworthy 4-D at the Western Antique Aeroplane and Automobile Museum in Oregon and a 4-D displayed at the Kansas Aviation Museum in Wichita.