Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Martin B-33 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. 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 and the two prototypes ordered by the USAAF were not built.