The basic design of the later KC-97 started out as a transport version of the B-29 Superfortress. Using the B-29’s tail section, wing, and lower fuselage, the Boeing company added a larger diameter upper fuselage section and the U.S. military promptly ordered several examples. They were used as general transports and even as airborne hospitals. The design was being produced shortly after the War when the military started pursuing the art of airborne refueling. Thus, the C-97 was modified into a new version called the KC-97. This airplane was very successful in this role, and by far the majority of the production run of this series was devoted to the inflight refueler models. There was also a civilian airliner version of this basic design, which could carry up to 117 people, but it was very expensive to operate and was not one of Boeing’s more successful airliners. There have been several post-military applications of this Boeing design, but the most common seems to be as an aerial fire fighter.