Free-flights of Air Force X-40A test vehicle planned as part of NASA’s X-37 flight demonstrator program

The first of up to seven free-flight tests of the X-40A, an 85
percent scale version of NASA’s X-37 technology demonstrator, is planned
to begin this week at the Dryden Flight Research Center at Edwards, Calif.

NASA and its industry partner The Boeing Company are using the
X-40A, on loan from the U.S. Air Force, as part of its risk mitigation
activities for the X-37 program. It will help test the shape, guidance
and other systems for the X-37. Flight objectives include validation of
Computed Air Data Systems (CADS), which will be used in the flight control
system of the X-37.

Other test points are: in-flight performance evaluation of the
Honeywell SIGI Space Integrated Global Positioning System Inertial
Navigation System; test of control Room Operations; and flight test of
guidance, navigation and control software.

“These tests with the X-40A will provide us a great deal of valuable
data applicable to the X-37,” said Dick Cervisi, Boeing Phantom Works X-37
program manager. “Performing these tests will significantly reduce the
risk to be encountered in the X-37 flight program.”

The X-40A will be lifted by a U.S. Army Chinook helicopter to an
altitude of 15,000 feet above ground level and released to glide to a
runway landing, guided by on-board systems. The free-flight will take
approximately 75 seconds from release to landing. The vehicle will reach a
velocity of up to about 200 miles per hour (168 knots).

Six captive-carry flights — when a vehicle is tethered to an
aircraft but not released — of the X-40A by the Chinook helicopter have
been conducted at Dryden. Each flight averaged one hour and 40 minutes,
at an elevation of 15,000 feet (about 4.6 kilometers) and speed of 108
miles per hour (about 90 knots). Those flights validated the
functionality and performance of the X-40A’s guidance, navigation and
control systems, air-data and telemetry.

The X-40A test vehicle was built for the Air Force by The Boeing
Company at its Seal Beach, Calif., facility. It has a fuselage length of
22 feet (about 6.7 meters), a wing span of 12 feet (about 3.65 meters) and
weighs about 2,600 pounds (about 1179 kilograms). It was flight tested
once before, in August 1998 at Holloman Air Force Base in southern New
Mexico, for the Air Force’s Space Maneuver Vehicle program.

Although Boeing performed a number of modifications to the X-40A in
preparation for the current tests, including improved instrumentation and
telemetry, a new integrated inertial navigation system/global positioning
system (INS/GPS) payload, upgraded power systems and additional redundancy
for range safety, the flight control system remains single string.
Inherently, a single string system is not as reliable as the
fault-tolerant system planned for the X-37.

The X-37, managed for NASA by the Marshall Space Flight Center in
Huntsville, Ala., is designed to demonstrate technologies in the orbital
and reentry environments for next-generation reusable launch vehicles that
will increase both safety and reliability, while reducing launch costs
from $10,000 per pound to $1,000 per pound.

The X-37, carried into orbit by the Space Shuttle, is planned to fly
two orbital missions beginning in 2003.

The X-37 government team, led by the Marshall Center, includes
NASA’s Ames Research Center in Mountain View, Calif.; Johnson Space Flight
Center in Houston, Texas; Kennedy Space Center at Cape Canaveral, Fla.;
Goddard Space Flight Center in Greenbelt, Md.; Langley Research Center in
Hampton, Va.; Dryden Flight Research Center and the Air Force Flight Test
Center, both at Edwards Air Force Base in Edwards, Calif.; and the Space
and Missile Systems Center and the Air Force Research Laboratory in
Albuquerque, N.M. The X-37 industry team is led by Boeing at Seal Beach,
Calif.