model40

Modified Model 40.

This is a (relatively rare) photo of the original Boeing Model 40 powered by a (by 1925, heavy and inefficient) Liberty Engine - as specified by the US government, which had hundreds of surplus Liberty L-12 engines from World War I production. The aircraft was designed and built to compete for US Post Office Air Mail service contract for 50 aircraft. Ultimately, the Douglas M-2 would get the contract. However, an improved Boeing Model 40, the Boeing Model 40A, would provide the impetus for the development and production of the Pratt & Whitney Wasp radial engine, as well as representing Boeing's start in building airliners. See: www.avsim.com/pages/0809/GAS/B40.htm en.wikipedia.org/wiki/Boeing_Model_40

Modified Model 40.

This is the first Boeing Model 40 as originally powered by the (US Government-specified) Liberty L-12 engine.

Boeing Model 40-Y NC381 c/n 1095 The sole 40-Y was a custom conversion of a 40-B airframe built for the Standard Oil Company of California. It had a cabin for two passengers and two open cockpits with dual controls. Powerplant was a 525 hp Pratt & Whitney Hornet radial engine, it had a balanced rudder and a tail-wheel. NC381 was turned over to the customer on December 9, 1928, and made its first flight the following day.