Recession Curve Generation for Space Shuttle Solid Rocket Booster Thermal Protection System Coatings

Howard S. Kanner"C. kvln Stuc -key_Un_ited Space Alliance, LLC, Cape Canaveral, FL 32920Darrell W. Davis:NASA Marshall Space Flight Center, Huntsville. AL 35812Ablatable Thermal l_otoetion System (TPS) coatings are used on the Space Shutd_ Vehicle Solid Rocket Boostea's in order toprotect the aluminum structure from experiencing exccs_ivo Iomperature_. The methodology u_ed to characterize tile recession ofsuch materials k outlined, l_¢tails of the tests, indudlng the facility, t=st articles and test a_ti¢l¢ processing are also presented.The mccs.sion rates are collapsed into an empirical power.law relation. A design curve is defined usilag a 95-percentile smdent-tdistribution, based on the nominal results, hemal test results are presented for the current acreage TPS material used.L0 INTltODUCTIONThe following document summarizes the methodologyused to determine the design recession rate curves forthe United Space Alliance Solid Rocket Boosterdement (USASRB) Thermal Analysis and TestPrograms. Herein, we shall also include informationabout the test facilities typically used and the basicprocedures followed, as well as _;ome typical data.calibration plate (Figure 4, H2501-H2520). Thick'ne,_measuremcnts aze acquired using a deep-throatmicrometer. Cold-wall heat rates are eomputcd fromthe measured hot-wall heat rates acquired duringcalibration runs at Marshall Space Flight Center(MSFC) Improved Hot Gas Facility (IHGF) using theUSA/IRGF data reduction procure, REDUCT. Thecorrelation between cold-wall and hot-wall heat rates isdefined in the following relation: