Geometrical, flight, computational fluid dynamics (CFD), and wind-tunnel studies for the F-16XL-1 airplane are summarized over a wide range of test conditions. Details are as follows: (1) For geometry, the upper surface of the airplane and the numerical surface description compare reasonably well. (2) For flight, CFD, and wind-tunnel surface pressures, the comparisons are generally good at low angles of attack at both subsonic and transonic speeds; however, local differences are present. In addition, the shock location at transonic speeds from wind-tunnel presure contours is near the aileron hinge line and generally is in correlative agreement with flight results.
Geometrical, flight, computational fluid dynamics (CFD), and wind-tunnel studies for the F-16XL-1 airplane are summarized over a wide range of test conditions. Details are as follows: (1) For geometry, the upper surface of the airplane and the numerical surface description compare reasonably well. (2) For flight, CFD, and wind-tunnel surface pressures, the comparisons are generally good at low angles of attack at both subsonic and transonic speeds, however, local differences are present. In addition, the shock location at transonic speeds from wind-tunnel pressure contours is near the aileron hinge line and generally is in correlative agreement with flight results. (3) For boundary layers, flight profiles were predicted reasonably well for attached flow and underneath the primary vortex but not for the secondary vortex. Flight data indicate the presence of an interaction of the secondary vortex system and the boundary layer and the boundary-layer measurements show the secondary vortex located more outboard than predicted. (4) Predicted and measured skin friction distributions showed qualitative agreement for a two vortex system. (5) Web-based data-extraction and computational-graphical tools have proven useful in expediting the preceding comparisons. (6) Data fusion has produced insightful results for a variety of visualization-based data sets. Lamar, John E. and Obara, Clifford J. and Fisher, Bruce D. and Fisher, David F. Armstrong Flight Research Center; Langley Research Center RTOP 522-31-31-03
The X-31 Enhanced Fighter Maneuverability Demonstrator was unique among experimental aircraft. A joint effort of the United States and Germany, the X-31 was the only X-plane to be designed, manufactured, and flight tested as an international collaboration. It was also the only X-plane to support two separate test programs conducted years apart, one administered largely by NASA and the other by the U.S. Navy, as well as the first X-plane ever to perform at the Paris Air Show. Flying Beyond the Stall begins by describing the government agencies and private-sector industries involved in the X-31 program, the genesis of the supermaneuverability concept and its initial design breakthroughs, design and fabrication of two test airframes, preparation for the X-31's first flight, and the first flights of Ship #1 and Ship #2. Subsequent chapters discuss envelope expansion, handling qualities (especially at high angles of attack), and flight with vectored thrust. The book then turns to the program's move to NASA's Dryden Flight Research Center and actual flight test data. Additional tasking, such as helmet-mounted display evaluations, handling quality studies, aerodynamic parameter estimation, and a "tailless" study are also discussed.The book describes how, in the aftermath of a disastrous accident with Ship #1 in 1995, Ship #2 was prepared for its outstanding participation in the Paris Air Show. The aircraft was then shipped back to Edwards AFB and put into storage until the late 1990s, when it was refurbished for participation in the U. S. Navy's VECTOR program. The book ends with a comprehensive discussion of lessons learned and includes an Appendix containing detailed information.
