The North American SM-64 Navaho was a supersonic

Supersonic

Supersonic speed is a rate of travel of an object that exceeds the speed of sound . For objects traveling in dry air of a temperature of 20 °C this speed is approximately 343 m/s, 1,125 ft/s, 768 mph or 1,235 km/h. Speeds greater than five times the speed of sound are often...

 intercontinental cruise missile

Cruise missile

A cruise missile is a guided missile that carries an explosive payload and is propelled, usually by a jet engine, towards a land-based or sea-based target. Cruise missiles are designed to deliver a large warhead over long distances with high accuracy...

 project built by North American Aviation

North American Aviation

North American Aviation was a major US aerospace manufacturer, responsible for a number of historic aircraft, including the T-6 Texan trainer, the P-51 Mustang fighter, the B-25 Mitchell bomber, the F-86 Sabre jet fighter, the X-15 rocket plane, and the XB-70, as well as Apollo Command and Service...

. The program ran from 1946 to 1958 when it was cancelled in favor of intercontinental ballistic missile

Intercontinental ballistic missile

An intercontinental ballistic missile is a ballistic missile with a long range typically designed for nuclear weapons delivery...

s. The missile is named after the Navajo Nation

Navajo Nation

The Navajo Nation is a semi-autonomous Native American-governed territory covering , occupying all of northeastern Arizona, the southeastern portion of Utah, and northwestern New Mexico...

 and is in keeping with North American Aviation's habit of naming projects with code names starting with the letters "NA".

Development

The Navaho program began as part of a series of guided missile research efforts started in 1946. Designated MX-770, the original intent of the program was the development of a winged V-2 missile

V-2 rocket

The V-2 rocket , technical name Aggregat-4 , was a ballistic missile that was developed at the beginning of the Second World War in Germany, specifically targeted at London and later Antwerp. The liquid-propellant rocket was the world's first long-range combat-ballistic missile and first known...

 that could deliver a nuclear (fission) warhead over a distance of 500 miles (804.7 km). This was more than double the range of the V-2 as well as having a larger payload. Design studies showed the promise of still greater ranges and by 1950 the vehicle had evolved from a 500 miles (804.7 km) ground launched winged V-2, to a 1000 miles (1,609.3 km) range ramjet powered winged V-2, to a 1500 miles (2,414 km) air-launched, ramjet-powered, winged V-2 (actually designated XSSM-A-2), to finally a 3000 miles (4,828 km) plus rocket boosted ramjet powered cruise missile. The design evolution finally ended in July 1950 with the issuing by the Air Force of Weapon System 104-A. Under this new requirement the purpose of the program was the development of a 5500 miles (8,851.4 km) range nuclear missile.

Under the new requirements of WS-104A, the Navaho program was broken up into three guided missile efforts. The first of these missiles was the North American X-10

North American X-10

The North American X-10 was an unmanned technology demonstrator for advanced missile technologies during the 1950s. The X-10 was similar to the development of Bell's X-9 Shrike project.-Development:...

, a flying subrange vehicle to prove the general aerodynamics, guidance, and control technologies for vehicles two and three. The X-10 was essentially an unmanned high performance jet, powered by two afterburning J-40 turbojets and equipped with retractable landing gear for take off and landing. It was capable of speeds up to Mach 2 and could fly almost 500 miles (804.7 km). Its success at Edwards AFB and then at Cape Canaveral set the stage for the development of the second vehicle: XSSM-A-4, Navaho II, or G-26.

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 50000 ft (15,240 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. Launch Complex 10 (LC-10) was also assigned to the Navaho program, but no G-26's were ever launched from it (it was only used for ground tests of the planned portable launcher).

The final operational version, the G-38 or XSM-64A, was the same basic design as the G-26 only larger. It incorporated numerous new technologies: Titanium, gimballed rocket engines, Kerosene/Lox fuel combination, full solid-state

Solid state (electronics)

Solid-state electronics are those circuits or devices built entirely from solid materials and in which the electrons, or other charge carriers, are confined entirely within the solid material...

, etc. None were ever flown, the program being cancelled before the first example was completed. The advanced rocket booster technology went on to be used in other missiles including the Atlas

Atlas (missile)

The SM-65 Atlas was the first intercontinental ballistic missile developed and deployed by the United States. It was built for the U.S. Air Force by Convair Division of General Dynamics at the Kearny Mesa assembly plant north of San Diego, California...

  intercontinental ballistic missile

Intercontinental ballistic missile

An intercontinental ballistic missile is a ballistic missile with a long range typically designed for nuclear weapons delivery...

 and the inertial guidance system was later used as the guidance system on the first U.S. nuclear powered submarines.

Development of the first stage rocket engine for the Navaho began with two refurbished V-2 engines in 1947. That same year, the phase II engine was designed, the XLR-41-NA-1, a simplified version of the V-2 engine made from American parts. The phase III engine, XLR-43-NA-1 (also called 75K), adopted a cylindrical combustion chamber with the experimental German impinging-stream injector plate. Engineers at North American were able to solve the combustion stability problem, which had prevented it being used in the V-2, and the engine was successfully tested at full power in 1951. The Phase IV engine, XLR-43-NA-3 (120K), replaced the poorly cooled heavy German engine wall with a brazed tubular ("spaghetti") construction, which was becoming the new standard method for regenerative cooling in American engines. A dual-engine version of this, XLR-71-NA-1 (240K), was used in the G-26 Navaho. With improved cooling, a more powerful kerosene-burning version was developed for the triple-engine XLR-83-NA-1 (405K), used in the G-38 Navaho. With all the elements of a modern engine (except a bell-shaped nozzle), this led to designs for the Atlas, Thor and Titan engines.

The first launch attempt, in November 1956, failed after 26 seconds of flight. Ten failed launches followed, before another got off successfully, on 22 March 1957, for 4 minutes, 39 seconds of flight. An April 25 attempt exploded seconds after liftoff, while a 26 June flight lasted only 4 minutes, 29 seconds.

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. These ballistic missiles however would not have been possible without the liquid fuel rocket engine developments accomplished in the Navaho program. The launch of the Soviet Satellite Sputnik in October 1957 only finished Navaho as the Air Force shifted its research money into ICBMs. But the technologies developed for the Navaho were reused in 1957 for the development of the AGM-28 Hound Dog

AGM-28 Hound Dog

The North American Aviation Corporation AGM-28 Hound Dog was a supersonic, jet propelled, air-launched cruise missile. The Hound Dog missile was first given the designation B-77, then redesignated the GAM-77, and finally designated the AGM-28, permanently...

, a nuclear cruise missile which entered in production in 1959.

The Soviet Union had been working on parallel projects, The Myasishchev "Buran

Buran cruise missile

The Buran cruise missile, designation RSS-40, was a Soviet intercontinental cruise missile capable of carrying a 3,500 kg nuclear warhead. The project was canceled before flight tests began.-Development:...

" and Lavochkin "Burya

Burya

The Burya was a trisonic, intercontinental cruise missile developed by the Lavochkin design bureau , based on a request for proposal issued by the Soviet government in 1954. The purpose of the design competition was to develop a cruise missile capable of delivering a nuclear payload to the United...

" and a little later, the Tupolev Tu-123

Tupolev Tu-123

-References:This article contains material that originally came from the web article by Greg Goebel, which exists in the Public Domain....

. The first two types were also large rocket-boosted ramjets while the third was a turbojet-powered machine. With the cancellation of the Navaho and the promise of ICBMs in the strategic missile role, the first two were canceled as well, though the Lavochkin project, which had some successful test flights, was carried on for R&D purposes and the Tupolev was reworked as a big, fast reconnaissance drone.

Operators

: The United States Air Force

United States Air Force

The United States Air Force is the aerial warfare service branch of the United States Armed Forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on September 18, 1947 under the National Security Act of...

 canceled the program before accepting the Navaho into service.

Survivors

The only Navaho missile in existence is currently displayed outside the south entrance gate of the Cape Canaveral Air Force Station, Florida.

Specifications

See also

External links

• The Evolution of the Cruise Missile by Werrell, Kenneth P.
• Directory of U.S. Military Rockets and Missiles: North American SM-64 Navaho, by Andreas Parsch
• http://www.astronautix.com/lvs/navhog26.htm
• http://www.fas.org/nuke/guide/usa/icbm/n19980710_981014.html