North American XB28

In 1939, the USAAF issued requirement for a new medium bomber which could operate at high-altitude to avoid attack from ground fire. Martin and North American responded with the requirement, Martin submitted the Model 182 which was redesigned from the B-26 Marauder, and North American proposed NA-63 which was based from the B-25 Mitchell. In 1940, North American's design was chosen to entry the development, and was received contract for two prototypes that designated XB-28. The first prototype made its first flight on April 1942, and was proved an excellent design, with significantly better performance than the B-25. However, USAAF changed the requirement and rejected the XB-28 project as it was to be found that high-altitude bombing was too susceptible to errors caused by wind, cloud cover. The second prototype was completed as the XB-28A reconnaissance version. At the same time, most medium bombing during the war was done successfully from low altitudes, and it was decided not to interrupt Mitchell production for an untried type, the XB-28 project was cancelled.