Aerospace Technology Development

The X-34's First Captive Test Flight

A TEST VERSION OF AN X-34 DEMONSTRATOR vehicle recently made its first captive-carry test flight. The vehicle is designed to test new technologies and methods of operations needed to develop low-cost reusable space vehicles.

The first of several captive-carry flights between the X-34 technology testbed demonstrator and its L-1011 carrier aircraft was conducted in June at NASA's Dryden Flight Research Center at Edwards, California. The purpose of this test was to verify the safety of the combined vehicles for Federal Aviation Administration (FAA) certification purposes because of modifications to the L-1011 carrier vehicle.

Initial data indicate that no major problems occurred in the 1 hour, 50 minute flight. Additional flights will be required, however, to examine the entire flight profile for the X-34 and its carrier before subsequent air-launched and unpowered approach and landing flights later in the year.

Several planned test objectives were accomplished during the flight. The operational program is designed to demonstrate that reusable launch vehicles can be more reliable, fly more often and fly in worse conditions than current vehicles using a smaller operations team. The performance of the aircraft was evaluated during several scheduled maneuvers at various speeds and altitudes. The L-1011 crew conducted a simulated rocket engine propellant release from the X-34 using fluorescent dye. The electronic connections among the mated aircraft, data collection systems and the video camera system on the L-1011 were also checked.

When a commercial airplane such as the L-1011 is altered, the FAA must certify that the changes have not adversely affected the plane's safe operation. The planned 2.5-hour test was shortened after a safety observer aboard a NASA F-18 chase plane noticed a fuselage panel on the L-1011 seemed to be vibrating. The panel was located on the bottom aft fuselage of the carrier aircraft behind the X-34. Based on video from the chase plane, test officials decided to end the flight. No further details were available pending a close inspection of the aircraft and extensive flight test data.

Eventually, the X-34 will perform high-speed suborbital free flights to demonstrate such technologies as an advanced thermal protection system, composite structural components and autonomous landing. The unpiloted X-34 is a single-engine rocket plane that will fly itself with onboard computers. It will be powered by the new Fastrac engine, designed by NASA's Marshall Space Flight Center in Huntsville, Alabama, which also manages the X-34 program for NASA. Dryden is supporting the captive-carry part of the program with flight testing and ground vibration tests.

In 1996, NASA awarded Orbital Sciences Corporation of Dulles, Virginia, a contract to design, build and test-fly the X-34. The contract includes a structural test vehicle for vibration and captive-carry flights and two flight vehicles. Orbital Sciences owns the L-1011, which also launches the company's Pegasus launch vehicle. X-34 engineers are in the process of strengthening the L-1011 panel and support structure for the second flight, which is scheduled sometime in August.

For more information, contact Leslie Mathews at Dryden Flight Research Center.
Call: 661/258-3458, E-mail: leslie.mathews@mail.dfrc.nasa.gov Please mention you read about it in Innovation.