General Discussion => Historical Spaceflight => Topic started by: catdlr on 11/30/2017 09:23 PM

Title: Navaho Missile: Project MX-770
Post by: catdlr on 11/30/2017 09:23 PM
Navaho Missile:
Project MX-770 Report July 1951 USAF;
Supersonic Intercontinental Cruise Missile

Jeff Quitney
Published on Nov 30, 2017


Contractor's progress report on the development of the Navaho missile: preliminary analysis, aerodynamics, airframe, guidance, and propulsion. Shots of classic hardware include an RTV-A-3 NATIV ballistic missile launch, XLR-43 engine firing, and a Reeves Electronic Analog Computer (REAC).

The North American SM-64 Navaho was a supersonic intercontinental cruise missile project built by North American Aviation. The program ran from 1946 to 1958 when it was canceled in favor of intercontinental ballistic missiles. The missile is named after the Navajo Nation and is in keeping with North American Aviation's habit of naming projects with code names starting with the letters "NA".


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 cruise missile that could deliver a nuclear (fission) warhead over a distance of 500 miles (800 km). This was more than double the range of the German V-1 rocket as well as having a larger payload. Design studies showed the promise of still greater ranges... to finally a 3,000-mile (4,800 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 5,500-mile (8,900 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, 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 taking off and landing. It was capable of speeds up to Mach 2 and could fly almost 500 miles (800 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 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... canceled before the first example was completed. The advanced rocket booster technology went on to be used in other missiles including the Atlas intercontinental ballistic missile 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.


Originally a public domain film, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.
The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).