The Boeing Model 40 was a mail plane. It was made in the 1920s. The Boeing Model 40 was a biplane with one engine. It was used a lot to deliver mail in the 1920s and 1930s. It was the first plane made by Boeing which carried passengers.
In 1925, the US Post Office asked for a mail plane to replace the DH-4s that it was using then. The new plane would need to use the same engine as the DH-4. A lot of these could be bought.[1] The Boeing Model 40 could carry up to 1,000lb (450kg) of mail. The mail was stored in two places at the front of the plane. The wings were made of wood. The Model 40 had landing gear that did not move.[1][2]
The Model 40 flew for the first time on July 7, 1925. The US Post Office bought the prototype of the Model 40, but it decided to use the Douglas M-2 instead.[1][3]
Later, Boeing made the Model 40A. The Model 40A had a new engine, which was 200lb (91kg) lighter than the old one. A cabin was also made, which could carry passengers.1,200lb (540kg) of mail. The US Post Office let Boeing carry mail from San Francisco to Chicago in January 1927. Boeing built 24 Model 40As to do this.[4][3][5]
The next type of Model 40 was the Model 40C. It had a bigger cabin so that four passengers could be carried. Model 40As had their engines changed to even lighter ones. Model 40As with this new engine were called the Model 40B-2.[6] The Model 40B-4 was another model which had the cabin of the Model 40C and the engine of the Model 40B-2.[7] Boeing Model 40s were made until February 1932.[8]
As of February 17, 2008, a Model 40 called Boeing 40C S/N 1043 is the only Model 40 which can still fly. It is the oldest Boeing plane which can still fly. In 1928, the aircraft was damaged after a crash. It was rebuilt by Pemberton and Sons Aviation[13] in Spokane, Washington. On May 8, 2010, this plane flew with Boeing's newest plane, the Boeing 787 Dreamliner.[14]
Model 40C Pilot's panel with some modern features added for safe operationModel 40C front seat of rear passenger cabin showing the fold-down writing desk/table