The North American SM-64 Navaho was a supersonic intercontinental cruise missile project. The program ran from 1946 to 1958 when it was cancelled in favor of intercontinental ballistic missiles.
the Navaho program was broken up into three guided missile efforts. The first of these missiles was the North American X-10, a flying subrange vehicle to prove the general aerodynamics, guidance, and control technologies.
Step two, the G-26, was a nearly full-size Navaho nuclear vehicle. Launched vertically by a liquid-fuel rocket booster, the G-26 would rocket upward until it had reached a speed of approximately Mach 3 and an altitude of 50,000 ft (15,000 m). At this point the booster would be expended and the vehicle's ramjets ignited to power the vehicle to its target. The G-26 made a total of 10 launches from Launch Complex 9 (LC-9) at Cape Canaveral Air Force Station (CCAFS) between 1956 and 1957.
The final operational version, the G-38 or XSM-64A, was the same basic design as the G-26 only larger. None were ever flown, the program being cancelled before the first example was completed.
Officially, the program was canceled on July 13 1957 after the first four launches ended in failure. In reality the program was obsolete by mid-1957 as the first Atlas ICBM began flight tests in June and the Jupiter and Thor IRBMs were showing great promise.
The Navaho program is the least known, yet the most important of the United States early missile programs. In rocket technology alone, the Navaho made possible Thor, Jupiter and Redstone missiles. It also allowed construction of the Atlas ICBMs, and in the years to come this engine would power the Apollo moon rocket and our present-day space shuttle.