Trajectory simulations, qualitative analyses and parametric studies of a laser-launched micro-satellite using OTIS

This paper will discuss Air Force Research Laboratory (AFRL) Propulsion Directorate's theoretical and computational results regarding trajectory simulations, qualitative analyses and parametric studies of a 25-cm focal diameter Laser Ramjet (X-25LR) using Optimal Trajectories by Implicit Simulation (OTIS). OTIS has been used to produce an optimized trajectory simulation of a laser ramjet's flight to Low Earth Orbit (LEO). The baseline case that has been simulated is a flight vehicle powered by a 1 MW, 10.6 μm, CO₂, ground-based laser (GBL) with an initial power capture of 82%. The fuel that is used during rocket flight is Delrin® doped with energetic additives to increase the coupling coefficient and thrust by a factor of five. Additionally, a nozzle extension was considered which increased performance by 40%. The flight trajectory was separated into three phases: 1) Air-breathing ramjet flight to a specified altitude of ∼30 km and Mach number of ∼10; 2) Rocket powered flight into a trajectory with a final Mach number ∼27; and 3) Un-powered coasting flight to the final altitude of 185 km. Additional sounding rocket trajectory flights with 10-kilowatt class CO₂ lasers have been assessed for a variety of laser powers. Also to be discussed in this paper are the parametric trade studies of the rocket phase comparing high thrust vs. low thrust and the effects of different-size vehicles.