Beam riding performance of asymmetrically propelled laser vehicle

We have developed a three-dimensional hydrodynamics code coupled with six-degree-of-freedom equation of motion of laser propulsion vehicle for analyzing flight dynamics through numerical simulations of flowfield interacting with unsteady motion of the vehicle. Using ray-tracing method, an asymmetrically deposited energy corresponding to laser offsets was initially added to the flowfield around the vehicle in order to estimate the beam riding physics against lateral or angular offset and these combination for a single pulse. Centering performance of "lightcraft" is excel for the lateral and the combined offsets, but recentering force becomes weak with larger angular offset. If the vehicle inclines toward the axis of the incident laser beam, angular restoring moment is generated for the angular offset. Also, flight dynamics simulations were performed for multiple pulse by integrating aerodynamic responses based on the single pulse results, and spiral flight motion and deviation from the laser path were successfully reproduced. When we rotate the laser axis following the gyro motion of the vehicle, the angular restoring moment is maintained for a longer time, and the vehicle is able to fly to a higher altitude.