This is a 1:24 scale model of the Navaho, a U.S. Air Force intercontinental surface-to-surface missile designed to carry a nuclear warhead. In contrast to ballistic missiles that fly part of their route outside the atmosphere, the Navaho flew entirely within it like a cruise missile. The booster's liquid-fuel engines lifted the Navaho to about 18 kilometers (11 miles) then fell away. The missile leveled off, and its two ramjet engines propelled it the rest of the way to the target. Nine flight tests took place, beginning in 1956. However, the project was canceled in 1957 due to major problems with some components and excessive costs. Despite this, the Navaho contributed greatly to the nation's rocket and missile programs. David Gianakos made this model and donated it to the National Air and Space Museum in 2002.