Mass Efficiency Considerations for Thermally Insulated Structural Skin of an Aerospace Vehicle

Abstract

An approximate equation was derived to predict the mass of insulation required to limit the maximum temperature reached by an insulated structure subjected to a transient heating pulse. In the course of the derivation two figures of merit were identified. One figure of merit correlates to the effectiveness of the heat capacity of the underlying structural material in reducing the amount of required insulation. The second figure of merit provides an indicator of the mass efficiency of the insulator material. An iterative, one dimensional finite element analysis was used to size the external insulation required to protect the structure at a single location on the Space Shuttle Orbiter and a reusable launch vehicle. Required insulation masses were calculated for a range of different materials for both structure and insulator. The required insulation masses calculated using the approximate equation were shown to typically agree with finite element results within 10 to 20 percent over the range of parameters studied. Finite element results closely followed the trends indicated by both figures of merit.

Applications of thermal insulation materials by aircraft

“…According to the paper, materials shouldn't absorb moisture from the atmosphere since water vapour in solid form might cause unfavourable structural alterations [13]. At an altitude of 11,000 meters, where the pressure is around one-fifth that of sea level and the humidity is roughly zero, these materials should be subjected to harsh circumstances, as is known [14,15]. A cross-section of an aeroplane cabin is shown in Figure 1 with the insulation indicated in grey [16].…”