Structural dynamics of spin-stabilized solar sails with applications to UltraSail

The sail dynamics of spin-stabilized solar sail designs are examined in this paper. The nonlinear governing equations of motion are derived for four different and progressively more complex dynamical scenarios: pitch (one dimensional); pitch and sweepback (two dimensional); pitch and lead/lag (two dimensional); and pitch, sweepback, and lead/lag (three dimensional). These equations are applied to UltraSail, a novel solar sail design developed at the University of Illinois at Urbana-Champaign, which relies on small-tip satellites to provide tension in rectangular sails. Steady-state and time-dependent characteristics are numerically calculated and discussed. Properties such as the spacecraft acceleration are predicted, and transient sail responses to an applied perturbation are simulated. Results place UltraSail as a strong candidate for future solar sail missions with performance challenging previously proposed concepts.