This is the prototype of the Boeing B-17 Flying Fortress. The B-17 was smaller than the XB-15, though it shared some resemblence, particularly in the A, B, C, and D models of the B-17, due to the tailplane being largely the same design and the wings being roughly the same shape though perhaps with a differing amount of taper compared to the B-17. The XB-15 was used as a cargo plane and was renamed the XC-105 until it was scrapped. Note: THIS WAS A REAL AIRPLANE IN THE SECOND WORLD WAR ERA. More information can be found on WikipediaThis rather obscure airplane unltimately led to the developement of the reknowned Boeing B-17 Flying Fortress. The B-17 was smaller than the XB-15, though it shared some resemblence, particularly in the A, B, C, and D models of the B-17, due to the tailplane being largely the same design and the wings being roughly the same shape though perhaps with a differing amount of taper compared to the B-17. The XB-15 was used as a cargo plane and was renamed the XC-105 until it was scrapped. Note: THIS WAS A REAL AIRPLANE IN THE SECOND WORLD WAR ERA. More information can be found on Wikipedia