FURLABLE SHEET STRUCTURES AND METHODS OF FURLING

摘要

The sail of a solar spacecraft or related structure can be furled by rotation about a central hub. Alternatively, hill and valley folds extend in a logarithmic spiral from the hub and the sail can be furled without strain, without multiple folds and without departing to any great extend from the plane of the unfurled sail. Support ribs every n'th hill fold take the form of flattenable tubes which are wound spirally about the hub in the furled structure. The set of the unfurled sail can be controlled by programmed flexure of the ribs to adjust the attitude of the craft relative to the direction of solar radiation.