Design and testing of a hot redundant structure concept for a hypersonic flight vehicle.

Abstract

A box beam simulating a dry wing structure of a high L/D hypersonic flight vehicle was fabricated and tested under simulated flight conditions. A brief review of the design techniques used to minimize the thermal stresses in a highly redundant structure is presented, along with experimental results demonstrating the structural integrity. The structure utilized brazed honeycomb sandwich skin panels and corrugated plate webs of D-43 columbium and Haynes-25 superalloy. Deleterious temperature differences were reduced by combining the use of insulation with detail design arrangements. A design philosophy was developed for making the structure resist the inelastic thermal stresses that could not be eliminated. Room-temperature stress distributions and deflections indicate a severe joint looseness problem owing to the high tolerances used for the coated columbium fasteners. Quartz lamp units were used to heat the structure to a maximum of 2150 °F on the lower surface and 1400° F on the upper surface for the thermal and load cycling tests. Four thermal plus load cycles were achieved without structure failures or deleterious inelastic deformation. Premature oxidation failures because of improperly coated panels cut short the planned test program.