Travel Air 4000
The Travel Air 4000 was a three-seat, open-cockpit biplane built by the Travel Air Manufacturing Company of Wichita, Kansas. It was the radial-engined member of the biplane family that began with the Model A, sharing the welded-steel-tube airframe of the OX-5-powered Model 2000 but fitted first with Wright Whirlwinds and later with a wide range of other air-cooled radials. Around 100 were built from 1927 under the 4000 name, in many lettered variants for sporting flying, mail carrying and training. Travel Airs worked as barnstormers and crop dusters across the United States, and the 4000 has had an unusually long afterlife: examples are held by museums across North America and a few still fly.
Why It Mattered
The Travel Air 4000 brought modern radial engines to the open-cockpit biplane on which the Travel Air Manufacturing Company had built its name. The biplane line was the first success of the company's founders, Lloyd Stearman, Walter Beech and Clyde Cessna, who established Travel Air at Wichita in 1925. The firm delivered more than 400 aircraft in 1928, and Smithsonian Magazine records that the following year it became the world's largest manufacturer of commercial monoplanes and biplanes. More than 1,200 of the open-cockpit biplanes were built between 1925 and 1930, and the 4000, popular for its better performance and versatility, was the version that kept the basic design current.
Design Notes
Like the rest of the family, the 4000 was an unequal-span, single-bay biplane with staggered wings, tandem open cockpits, a conventional tail and a fixed tailskid undercarriage. Its fuselage was welded steel tube — a construction Stearman and Beech had lobbied for at the Swallow company, against a wood framework — while the wings were built of wood. Two passengers sat side by side in the wide front cockpit, the model's major feature in EAA's account, ahead of the pilot's single cockpit. Travel Air's model numbers mainly recorded a change of engine: the 4000 began with Wright J-4 and J-5 Whirlwind radials, and from late 1928 the name covered aircraft with a wide variety of other air-cooled radials. Changes of wing and powerplant, and details such as the "outrigger" undercarriage, split the type into a long list of lettered variants. The radial power transformed the aeroplane: where the OX-5 models had 90 hp, the 220 hp J-5 gave a 4000 a top speed of about 130 mph.
Operational History
Fourteen Model 4000s were built in 1927, the design's first year, and ATC-32 certification followed in April 1928. The E-4000 became the most widely produced member of the family, its Wright J-6 Whirlwind giving 165 hp; EAA describes the model as designed to compete with inexpensive war-surplus Standards and Jennies. In everyday work the biplanes served around the country as crop dusters and barnstormers, and as private aeroplanes for the sportsman pilot. A dedicated mailplane, the BM-4000, replaced the front cockpit with a mail compartment, and Parks Air College used Model 4000s to train transport pilots. The type performed in public, too: Louise Thaden flew a D-4000 to win the first Women's Air Derby at the 1929 National Air Races, and D-4000s represented First World War Nieuport fighters in The Dawn Patrol, Hell's Angels and Young Eagles, all released in 1930. The performance had a price — a new J-5-powered 4000 cost $9,100 in 1928. Travel Air merged with Curtiss-Wright in 1929, some later variants were built by Curtiss, and the Travel Air division did not survive the Depression, closing in September 1932.
Afterlife
The type has lasted unusually well. EAA's 1929 E-4000 is among the last flying examples: restored by the association's staff and many volunteers, it remains in regular flight service at Pioneer Airport in Oshkosh. The National Air and Space Museum's D4D, the Pepsi Skywriter, performed skywriting for Pepsi-Cola from 1931 to 1953 and returned to air show and advertising duty from 1973 until its retirement in 2000; the museum displays it at the Steven F. Udvar-Hazy Center. Other survivors are held by museums across North America, among them the Reynolds Museum at Wetaskiwin in Canada and, on loan, the Kansas Aviation Museum in Wichita, the type's home city. And the type still works: as of 2022, one 4000 was reported to be the oldest aircraft regularly tracked by Flightradar24.