Martin XB-33 Super Marauder
The Martin XB-33 Super Marauder was a proposed World War II American bomber aircraft. It was designed by the Glenn L. Martin Company as the Martin Model 190 and was a high-altitude derivative of the company's B-26 Marauder. Two different designs were developed, first as a twin-engined aircraft and then as a four-engined aircraft. The four-engined version was ordered by the United States Army Air Forces, but the program was cancelled before any aircraft were built. Design and development. XB-33. The first version of the B-33 design, the XB-33, was a  twin-tailed medium bomber with two Wright R-3350 engines and pressurised crew compartments; its design began in 1940. It would carry around 4,000 lb (1,814 kg) of bombs. Soon after design of the XB-33 began it became clear that a twin-engined aircraft would not achieve the performance requested by the army. The company moved on to developing a larger four-engined design, but the two prototypes ordered by the USAAF were not built. XB-33A. Following the abandonment of the original twin-engined design, the company continued to design a larger four-engined aircraft, and two prototypes were ordered by  the USAAF as the XB-33A; its bombload was to have been 12,000 lb (5,443 kg), as much as that of the B-24 Liberator, the heaviest US bomber flown in combat prior to the B-29. The original XB-33 design was to have been powered by the R-3350, the redesigned XB-33A was to have used Wright R-2600 engines. The main reason for this was the demand for R-3350s for the B-29, one of the most highly valued projects of the Army Air Forces. On January 17, 1942, the USAAF placed an order for 400 B-33As, to be built at the government-owned  plant in Omaha, Nebraska, operated by Martin. On November 25, 1942, the project was cancelled to allow the Omaha plant to concentrate on manufacturing B-29s.