AN OPTICAL ANGLE OF ATTACK SENSOR

A MAJOR SOURCE OF TRANSONIC AND SUPERSONIC WIND TUNNEL TEST DATA UNCERTAINTY IS DUE TO ANGLE OF ATTACK MEASUREMENT ERRORCAUSED BY UNKNOWN STING AND BALANCE DEFLECTIONS UNDER LOAD. SINCE DYNAMIC LOADS IN THE UNITARY PLANFACILITIES GENERALLY EXCEED THOSE IN CONVENTIONAL LOW SPEED ATMOSPHERIC WIND TUN-NELS THE NEED TO ACCOUNT FOR THESE DISTORTIONS DURING MODEL TESTING IS EVEN MORE ACUTE. TO MEET THIS CHALLENGE A NOVEL LASER-BASED INSTRUMENT FOR THE IN-SITU MEASUREMENT OF WIND TUNNEL MODEL ANGLE OF ATTACK IN PROPOSEDTHE SENSOR WILL ENABLE CONTINUOUS TIME-DEPENDENTS MEASURE- MENTS TO BE MADE WITHOUT SIGNAL DROPOUT. IN PHASE I SUCCESSPROOF OF CONCEPT EXPERIMENTS WERE CO- PROOF OF CONCEPT EXPERIMENTS WERE CONDUCTED TO DETRMINE THE RELIABLE RANGE SENSITIVITY AND LONG TERM STABILITY OF THE INSTRUMENT. THESE NEW TEST RESULTS SHOW THAT 0.001 DESEN-SITIVITY CAN BE ACHIEVED AND THAT OPTICAL AND DETECTOR PACK-AGING REQUIREMENTS CAN BE REDUCED TO LESS THAN THOSE REQUIRED FOR CURRENT TILT SENSOR MODEL INSTALLATION. THE PHASE II OBJECTIVES WILL BE TO EXTEND SENSOR RANGE AND SEN- SITIVITY AND TO DESIGN AND BUILD A REAL-TIME MEASUREMENT SYSTEM FOR USE IN UNITARY PLAN FACILITIES. RESULTS OBTAINEDIN THE 11-FT PRESSURE WIND TUNNEL WILL ALSO PROVIDE AN IN- DEPENDENT ASSESSMENT OF OBSERVED DIFFERENCES BETWEEN CURRENTCURRENT ANGLE OF ATTACK MEASUREMENT TECHNIQUES.