Perpustakaan Digital ITB

Most small satellites reach orbit through ridesharing, which limits the launch schedule and target orbit selection. The Air-Launch to Orbit (ALTO) method offers an alternative in which the launch vehicle is released from a carrier aircraft at an altitude, where it can operate from existing runways and fly over wide areas, providing operational flexibility. However, air-launch vehicles flight profile exhibits a rapidly changing dynamics driven by dynamic pressure changes, staging events, and control e!ector transitions from aerodynamic fins, thrust vectoring control, and reaction control system. This research aims to develop a longitudinal trajectory control architecture for Pegasus XL air-launch vehicle from Stage 1 ignition to orbital insertion. The dynamics of the vehicle is approximated by a set of local Linear Time Invariant (LTI) models. For each stage, a guidance reference command is constructed and a set of Linear Quadratic Regulator tracking controller is designed using the corresponding local LTI model. The vehicle model and control framework are implemented in MATLAB/Simulink. The results show that the designed control architecture meets the orbital insertion targets at t = 584.75 s with near-zero flight-path angle and small residual radial velocity, resulting in a slightly elliptical orbit.