The simulation of time varying ascent loads on arrays of Shuttle tiles in a large transonic tunnel

Abstract

A large variety of tests were conducted to determine the strength, fatigue, and thermal characteristics of the thermal-protection system of the Shuttle orbiter. The present paper describes first-flight-critical tests, conducted in the Langley 8-Foot Transonic Pressure Tunnel (8-ft TPT), which simulated the time histories of Shuttle ascent loads on tile arrays bonded to structures which accurately duplicated those of the Shuttle. The time-varying free-stream conditions were provided by controlling the deflection-angle history of diffuser spoiler flaps in an automated way. Time histories of the critical-load parameters imposed on the tile arrays in the tunnel are compared with those expected in flight. In addition, the effect of repeated load pulses on the smoothness of the surface and condition of the tiles is discussed briefly.

Surface Step Induced Gap Heating in the Shuttle Thermal Protection System

“…The figure is a plot of ^piateau/^iocai vs Mach number from test data reported in Ref. 6 and experimental results reported in the literature. 7 ' 9 The data are directly applicable to the lower surface of the Orbiter since the local Mach number behind the bow shock ranges from 2.5 to 3.75 during the high aerodynamic heating period of entry.…”