The North American F-10

The North American X-10, much like the X-9 Shrike, was an unmanned technology demonstrator for advanced missile technologies.

Development

To facilitate development of the long-range Navaho surface-to-surface missile, North American Aviation developed the RTV-A-5, or X-10 in 1951. This vehicle was to prove out critical flight technology for the design of the cruise vehicle of the Navaho missile design. These included proving the basic aerodynamics out to Mach 2, flight testing the inertial guidance unit and flight control avionics to the same speed, and finally validate the recovery system for the next phase in the Navaho program. Preliminary design of the X-10 was completed in February of 1951 and the first vehicle was delivered to Edwards AFB in May of 1953. The first flight occurred on October 14 1953.^[1]^[2]

The X-10 was powered by two Westinghouse J-40 turbojet engines with afterburners, and equipped with landing gear for conventional take off and landing. The combination of a delta wing with an all-moving canards gave it extremely good aerodynamics in the trans-sonic and supersonic environments. It also made the vehicle unstable requiring active computer flight control in the form of an autopilot. Thus, the X-10 is similar to modern military fighters which are flown by the onboard computer and not directly by the pilot. In this same regard, though the X-10 was receiving directional commands from a radio-command guidance system, these commands were sent through the on-board computer which in turn implemented the commands. Later X-10s included an N-6 inertial navigation system which completely controlled the vehicle through the cruise portion of the flight.

The ultimate derivative of the X-10 was the short-lived SM-64 Navaho cruise missile.

Service history

At the time it came into service, the X-10 was one of the fastest turbojet-powered aircraft flown. From 1953 to 1955 a total of five X-10s flew 15 flights at Edwards AFB. There it reached a maximum flight speed of Mach 1.84, flew a distance of 400 miles, and reached an altitude of 41,000 feet. These were performance levels superior to nearly all manned turbojet aircraft (the exception being the YF-104 starfighter). In 1955 the program moved to Cape Canaveral Florida to complete the test program. Here a new set of six X-10 vehicles would complete the testing of the N-6 inertial navigation system out to supersonic speeds, reach 49,000 feet altitude, a total flight distance of 627 miles and a peak speed of Mach 2.05.

Of all the X-10s built, only one survived the test program. This is vehicle 19307, the first X-10 to ever fly. Of the other four aircraft that flew at Edwards AFB, one blew-up on take-off, one was lost in flight and the remaining two were destroyed in landing accidents. As for the vehicles flown at Cape Canaveral, three were expended in planned dive-in flights against Grand Bahamas Island, and two were lost in landing accidents.

In 1958 the remaining three Cape Canaveral X-10s were selected for use as high speed targets for the BOMARC surface-to-air missile. The plan was to recover and reuse the X-10, not to have them shot down by the Bomarc. Unfortunately, none of these vehicles would complete their target flight: two were lost on landing and the third suffered a mechanical problem forcing it to be flown into the Atlantic.

In 1946, North American began the development of a long-range supersonic surface-to-surface cruise missile. This development effort eventually led to the SM-64 Navaho (q.v. for further details) design, and included a test vehicle to verify the basic aerodynamic and systems design of the Navaho. The test vehicle was ordered as RTV-A-5 in 1950, but was redesignated as X-10 in 1951. The first flight of an X-10 occurred in October 1953.

The X-10 was powered by two Westinghouse XJ40 (later J40) turbojet engines, and took off and landed on a conventional runway. Its all-moving canard and delta-wing configuration was that of the planned SM-64 Navaho cruise stage. The X-10 was equipped with an autopilot for automatic stable flight, and controlled by a radio-command guidance system with an AN/ARW-56 on-board receiver and an AN/ARW-55 transmitter in the ground control station. An AN/APW-11 radar transponder was carried for tracking of the vehicle by the ground control radar. Later X-10 vehicles were also equipped with an N-6 inertial navigation system, which was planned for use by the forthcoming SM-64. The X-10 was a very high performance aircraft, and was for a short time actually the fastest turbojet-powered aircraft flown, reaching Mach 2.05.

The X-10 flight test program was very successful, and continued through November 1956, when the (significantly less successful) tests of the XSM-64 Navaho began. After the X-10 program was moved from Edwards AFB to Cape Canaveral in 1955, several X-10s were lost in landing accidents, when the vehicle either veered off the landing strip, did not properly extend the prarabrake, or failed to engage the landing barrier. Between September 1958 and January 1959, three surplus X-10s were launched as high-speed, high-altitude target drones, but all these flights ended with the unplanned loss of the vehicle. In the end, of the thirteen X-10s built only a single one survived the whole program.

In October 1945, the Army Technical Services Command asked aeronautical corporations in the United States to design a guided missile. Consolidated Vultee proposed the MX-774, which would become the Atlas Intercontinental Ballistic Missile. North American Aviation proposed the MX-770, the Navaho -- a 500-mile-range missile with greater accuracy than the German-built V-2.

Although the Air Force canceled the Navaho program in 1957, in its 10 years of existence, the Navaho made many key technological breakthroughs. The X-10 Navaho test drone was the first turbojet-powered vehicle to reach Mach 2 and the first aircraft to fly a complete mission under inertial (computerized) guidance. Its booster engine set a record by producing 405,000 pounds of thrust. The X-10 was the only missile to be classified as an "X" plane and completed more than 20 flights. Data from these flights led to the development of the SM-64 Navaho ground-to-ground missile system.

Phase two of the nuclear Navaho development program was the G-26 drone missile, which would prove the vertical launch system. The G-26 required the development of the largest ramjet engines built, an auxiliary power unit to power the missile's electronics and hydraulics, and a more effective autonavigator unit, the N-6 or NAVAN (North American Vehicle Auto Navigation), built by North American's Autonetics Division.

The Navaho program was canceled in July 1957 when, after extensive testing at Cape Canaveral, Fla., the Atlas ICBM was chosen over winged missile designs. On July 13, 1998, exactly 41 years from the day when the Navaho was canceled, and after two years restoring the X-10, the Air Force Space and Missile Museum rolled out the only Navaho missile in existence and placed it on display.

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