AN INNOVATIVE APPROACH TO NON-OBTRUSIVE QUANTITATIVE MEASUREMENTS OF VORTEX FLOWS

MODERN FIGHTER AIRCRAFT ARE OPERATING IN A FLIGHT REGIME WITH INCREASING DEMANDS FOR MANEUVERABILITY AND CONTROLLABILITY TO BE EFFECTIVE IN THE COMBAT ARENA. ONE OF THE LIMITATIONS TO THAT EFFECTIVENESS IS THE INABILITY TO ACCURATELY TRACK TARGETS FOR GUN OR MISSILE SHOTS DUE TO THE DEGRADING CHARACTERISTICS OF WING ROCK. WING ROCK IS A SELF-INDUCED, LIMIT-CYCLE OSCILLATION IN ROLL, SOMETIMES ACCOMPANIED BY COUPLED OSCILLATIONS IN YAW, THAT OCCURS NEAR THE STALL ANGLE OF ATTACK. THE PURPOSE OF THIS STUDY IS TO THOROUGHLYINVESTIGATE THE WING-ROCK CHARACTERISTICS OF ONE MODERN FIGHTER. THE RESEARCH PLAN WILL ANALYZE AND CORRELATE FLIGHT TIME HISTORIES, THE CORRESPONDING AERODYNAMIC DATA BASE, RESULTS FROM BASIC FLUID MECHANICS EXPERIMENTS INCLUDING WATER-TUNNEL FLOW VISUALIZATION STUDIES OF A MODEL PERFORMING A WING-ROCK MOTION, AND A 6-DOF STUDY TO ASSESS THE IMPORTANCE OF SPECIFIC AERODYNAMIC PARAMETERS. SUCCESS IN THE ANALYSIS OF ONE AIRCRAFT WILL PROVIDE THE OPPORTUNITY TO EVALUATE OTHER MODERN AIRCRAFT AND, ALONG WITH ONGOING BASIC RESEARCH IN WING-ROCK FLOW PHENOMENA, WILL PROVIDE THE METHODOLOGY FOR PREDICTING AND AVOIDING WING ROCK IN THE DESIGN PHASES OF NEW AIRCRAFT OR IMPROVING EXISTING AIRCRAFT, EITHER THROUGH AERODYNAMIC MEANS OR IMPROVED CONTROL SYSTEMS. THE SELECTED CANDIDATE FOR THE PHASE I STUDY IS THE F-18 AIRCRAFT. AIRCRAFT TO FOLLOW MIGHT INCLUDE THE F-4, F-14,F-15, AND F-16.