The Boeing Model 200 Monomail
was an American mail plane
of the early 1930s.
Design and development
The aircraft marked a departure from the traditional biplane
configuration for a transport aircraft, instead featuring a single, low set, all metal cantilever
wing. Retractable landing gear and a streamlined fuselage
added to the aerodynamic efficiency of the aircraft. A single example was constructed for evaluation by both Boeing and the US Army (under the designation Y1C-18
) but no mass production ensued, and the aircraft eventually joined Boeing's fleet on the San Francisco
air mail route from July 1931.
A second version was developed as the Model 221
, with a fuselage stretched by 8 inches (20 cm) that sacrificed some of its cargo capacity to carry six passengers in an enclosed cabin; however the single pilot sat in an open cockpit
. This version first flew on 18 August 1930. Both the Model 200
and the Model 221
were eventually modified for transcontinental service as the Model 221A
, with slight fuselage stretches to give both a cabin for eight passengers. These aircraft were flown on United Air Lines
The advanced design of the Monomail was hampered by the lack of suitable engine
technology. By the time variable pitch propellers
and more powerful engines were available, the design had been surpassed by multi engined aircraft, including Boeing's own 247
- Model 200
- mailplane (1 built)
- Model 221
- mailplane with capacity......