Tension string structure for planetary entry vehicles.

Abstract

This paper provides a brief description and analysis of a new ultralightweight, high-drag concept for the construction of planetary entry vehicles. This concept employs structural principles similar to those used in suspension bridges or bicycle wheel design: high-strength filamentary strings in pure tension, a central support member, and an equatorial ring that is stabilized against buckling by the forebody and afterbody strings. Preliminary designs and a manufacturing technique have been developed, and 12-in.-diam models have been constructed from trilene monofilaments with plexiglass rings and central supports. Tradeoff studies suggest that the following materials might be best for flight vehicles: strings of S glass yarn (Owens Corning Fiberglas Corp.), a toroidal ring of aluminum, and a central support of aluminum honeycomb sandwich. The negative Gaussian curvature of the axisymmetric forebody should provide aerodynamic characteristics between those of the sphere-cone and the Langley tension shell. An elastomeric material can be applied to the forebody strings to form a heat shield. Further work on this concept appears to be warranted.