The unpiloted X-40 was built to 85 percent scale to test aerodynamics and navigation of the X-37 Future-X Reusable Launch Vehicle project.
After the first drop test in August 1998 the vehicle was transferred to NASA, which modified it. Between April 4 and May 19, 2001 the vehicle successfully conducted seven free flights. In 2001 it successfully demonstrated the glide capabilities of the X-37's fat-bodied, short-winged design and validated the proposed guidance system.
The first X-40 drop test occurred at Holloman AFB, New Mexico on August 11, 1998 at 06:59. This was a joint Air Force/Boeing project known as Space Maneuver Vehicle. It was released from an altitude of approximately 9,200 feet (2,800 m) and 2.5 miles (4.0 km) away from the end of Runway 04 by a UH-60 Black Hawkhelicopter (later tests used the CH-47 Chinook helicopter). The vehicle dove to the runway in an approach similar to the space shuttle's, flared, and landed left of the runway centerline. Its drag chutes successfully deployed, and the vehicle tracked to within seven feet of the centerline and stopped at a distance of slightly more than 7,000 feet (2,100 m).