Boeing Model 42

The Boeing Model 42, also designated XCO-7 for Experimental Corps Observation Model 7, was an American biplane aircraft developed from the Airco DH.4 to take advantage of the large number of aircraft left over after the end of World War I. It was essentially an Airco DH-4M-1 fitted with new Boeing tailplanes, tapered wings and tripod landing gear. The first aircraft built, the XCO-7, was used as a static test bed and never flew. The second, the XCO-7A, used a standard DH-4M-1 fuselage and Liberty engine with the Boeing modifications, and the final one, the XCO-7B, added balanced elevators and an inverted Liberty engine. Both flyable aircraft were shipped to McCook Field, where the first flight took place on 6 February 1925. The performance of the new aircraft did not justify the cost of the conversion, and Boeing abandoned the project.