TECHNOLOGY FOR PRESSURE-INSTRUMENTED THIN AIRFOIL MODELS

PRESSURE INSTRUMENTED AIRFOIL MODELS FOR TESTING IN CRYOGENIC WIND TUNNELS DEMAND THE SIMULTANEOUS ACHIEVEMENT OF MANY FACTORS INCLUDING STRENGTH, TOUGHNESS, DIMENSIONAL STABILITY, MACHINABILITY, BONDABILITY, ACCURACY OF PROFILE AND SURFACE FINISH. MANY PREVIOUS MODELS HAVE FAILED TO REACH COMPLETION OR HAVE PERFORMED INADEQUATELY BECAUSE ACHIEVEMENT OF SOME FACTORS HAS CRITICALLY COMPROMISED OTHERS, PARTICULARLY SO FOR RELATIVELY THIN AIRFOLLS, I.E., THOSE WITH MAXIMUM THICKNESS LESS THAN ABOUT 6% OF CHORD. HOWEVER, THEIR IS A SOLID BASIS FOR BELIEVING THAT NECESSARY TECHNOLOGIES TO BUILD THIN AIRFOIL MODELS ARE ALREADY AVAILABLE, OR ARE IN ADVANCED STATE OF DEVELOPMENT, IN THE USA. THIS PROJECT AIMS TO PROVE THE VALIDITY OF THIS BELIEF BY IDENTIFYING THE REQUIRED MATERIALS AND FABRICATION TECHNOLOGIES AND TO DEVELOP A CO-ORDINATED AND PHASED PROGRAM CULMINATING IN THE FABRICATION OF AN ADEQUATELY PRESSURE INSTRUMENTED THIN AIRFOIL MODEL FOR TESTING. CAREFUL ATTENTION IS PAID TO ENSURING THE DIMENSIONAL STABILITY OF THE BASE MATERIAL, POSSIBLY BY USING STREE-FREE MACHINING TECHNIQUES, THE STRENGTH AND TOUGHNESS OF ANY BONDS AND THE DEFINITION OF THE ORIFICES AND PASSAGES NEEDED FOR PRESSURE INSTRUMENTATION. SPECIFICALLY INCLUDED WITHIN PROGRAM IS THE PROVISION OF PRESSURE ORIFICES IN THE THIN TRAILING EDGE AT LOCATIONS FROM 80 TO 100 PERRCENT OF CHORD.