STRESS TEST -- A test section of a wing being developed for the Apex high-altitude research project is being subjected to simulated air loads similar to what it will encounter in flight during tests at Dryden's Flight Loads Laboratory. The current tests on a fiberglass test wing are developing test methods to be used during future ultimate loads tests that will apply loads of 150 percent or greater on another test section until it fails. That section is being built from the actual materials to be used in the Apex flight wing, an all-composite structure which features a stiff, lightweight boron fiber skin covering a foam and graphite cloth core. It is designed for flight loads of 5 Gs (five times the force of gravity) positive and 3 Gs negative. The Apex project, part of NASA's Revolutionary Concepts (RevCon) effort, will use a highly-modified commercial sailplane design to acquire data on the aerodynamics of flight in the previously unexplored regime of 70,000 to 100,000 feet altitude and subsonic speeds of about Mach 0.65. The Apex High-Altitude Flight Experiment is expected to explore the aerodynamics of controlled flight at very high altitudes near 100,000 feet. The Apex will be hoisted aloft tail-first from Dryden by a large high-altitude balloon and released at about 110,000-feet altitude. As it gradually descends, its instrumentation will collect aerodynamic data. The remotely-piloted, semi-autonomous Apex will combine a modified ASC sailplane fuselage design with a new wing designed at the Massachusetts Institute of Technology. The wing will have a special airfoil designed for high subsonic speeds at extreme altitudes. A device extending behind the right wing is a "wake rake," which will measure aerodynamic drag behind a test section of the wing, while a rocket pack mounted beneath the fuselage will assist the Apex in transitioning to horizontal flight. Research flights were expected to begin in mid-1998, but a series of technical problems delayed them. In the spring of 1999, Apex entered mothball status. This continued for a year, and in the spring of 2000 NASA selected Apex as part of phase 1 of the Revolutionary Concepts effort.
