Can Solar Sails Flutter

I N A widely cited report, MacNeal [1] has pointed out the advantages of a heliogyro, a solar sail that rotates and responds in ways similar to a helicopter blade, with the driving force being the solar pressure, as distinct from the aerodynamic pressure of more conventional rotorcraft. In this brief Note we consider the possible interaction between the deformation of the solar sail and the solar pressure. The solar pressure acts normal to the surface of the sail; thus, as the sail deforms, the direction of the solar pressure changes. This provides an opportunity for feedback between the loading of the solar pressure and the deformation of the sail. Indeed, as is shown implicitly by MacNeal [1] andmore explicitly here, for small elastic deformations of the sail, the solar-pressure-loading/solar-deformation relationship has essentially the same mathematical form as the aerodynamic-loading/ elastic-structural-deflection relationship for (two-dimensional, static Ackeret) supersonic flow aerodynamic theory. This suggests that many of the known methods and, to some extent, the known results from aeroelasticitymay be immediately adapted to the analysis of the solar sail. In particular, solar sails have the potential to undergo flutter.