An artist's concept of the X-33 reusable launch vehicle demonstrator. Photo: NASA

Using NASA's high-altitude ER-2 airplane equipped with X-33 avionics, engineers at NASA's Dryden Flight Research Center and the Air Force Flight Test Center, both from Edwards, Calif., have completed operational tests of a diverse network of range facilities and ground stations that make up the X-33 extended test range.

The test flights took place over three states (California, Nevada and Utah) and included three Air Force ranges. The objective of the range test was to validate Dryden's portion of the X-33 range systems.

Dryden's Airborne Science ER-2 aircraft, with X-33 flight communication equipment aboard, flew the flight path designated for the X-33 to the Army's Dugway Proving Ground, Utah. The X-33 communication equipment flown on the ER-2 was thoroughly flight qualified.

The unpiloted X-33 is a half-scale technology demonstrator of a full-scale, commercially developed reusable launch vehicle, which Lockheed Martin has named VentureStar, planned for development within the decade.

The X-33 will take off vertically like a rocket, reaching an altitude of up to 60 miles and speeds faster than Mach 13 and will land horizontally like an airplane. Although suborbital, the X-33 will fly high enough and fast enough to encounter conditions similar to those experienced on an orbital flight path to fully prove its systems and performance.

NASA's ER-2 high-altitude aircraft during takeoff from Dryden. Photo: NASA

The ER-2, flying at 65,000-70,000 feet, completed two flight paths between the launch facility at Edwards Air Force Base, Calif., and the landing site at Michael Army Airfield at Dugway Proving Ground, as part of the range test.

In the first flight, the ER-2 was used to help engineers demonstrate continuous radio frequency communication between the range and the aircraft over the X-33 ground track.

The second path was used to verify range operation in case of system failures during the X-33 research flights. The ability to operate with failures present validated the redundant systems of the range.

Though similar to the Air Force U-2, the ER-2, has been adapted to carry scientific instruments in support of NASA's Earth Science Enterprise. The ER-2 has a range beyond 3,000 miles, is capable of long flight duration and can operate at altitudes above 70,000 feet. On a single flight, the ER-2 can carry over one ton of instruments to altitudes above 65,000 feet and outside 95 percent of the Earth's atmosphere making it an excellent fill-in for the X-33.

The X-33 Program is managed for NASA by the Marshall Space Flight Center in Huntsville, Ala.

VentureStar is a registered trademark of the Lockheed Martin Skunk Works, Palmdale, Calif.