The light bombers of the time were deemed unsatisfactory and new specifications were considered. Shortly after the crew exited the plane, she broke into flames and was completely destroyed.īy 1938, the threatening situation in Europe had grabbed the attention of the United States Army Air Corps. On April 11, 1939, during single engine testing, the aircraft lost altitude and crashed. The improvements were completely successful and testing continued. ![]() She was given the civil registration of X14221. The NA-40 airframe was re-designated as the NA-40B. They were, however, not available at that time. The Hamilton propellers were capable of full feathering faster than the Curtiss electric propellers. The Curtiss electric propellers were kept, although the intention was to replace them with Hamilton Standard Hydromatic propellers. The Pratt & Whitney engines were replaced by Wright engines. Between February 28, and March 1, 1939, the NA-40 underwent a design overhaul. The initial test flights proved to North American that the aircraft needed bigger power plants and more streamlined aerodynamics. As a result, she only flew fourteen test flights for a total of five hours and twenty minutes. On initial test flights, the NA-40 proved unstable. 30 caliber guns were designed into each wing, but these were not initially fitted. 30 caliber flexible guns with 500 rounds each. The NA-40 was powered by two Pratt & Whitney engines with three blade Curtiss electric propellers. ![]() The wings were shoulder mounted, constant dihedral with fully underhung nacelles. This arrangement allowed for a maximum fuselage width of 45 inches. A greenhouse nose was fitted for the bombardier/navigator and the radio operator and gunner were seated aft. The pilot and co-pilot were seated in tandem. This would include: a pilot, co-pilot, bombardier/navigator, radio operator/gunner, and gunner. The NA-40 design was based on a crew of 5. The engineering design team headed by Howard Evans had produced an excellent aircraft. All of these problems were overcome with eventual design changes. ![]() Early on, the aircraft was plagued with problems. Although North American lost the competition for this contract, the testing of the NA-40 proved an impressive proof of concept. The NA-40 was North American Aviation's entry in the twin engine attack bomber competition of 1938. You may be wondering why I have included the history of the NA-40 here on a B-25 website. The B-25 bomber had no prototype as it was developed as it was built. The NA-40 was indeed a totally separate aircraft. It was also not the prototype for the B-25. Before I get too deep in the history of the NA-40, it is important to note that the NA-40 was not a B-25.
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