I am looking to hire an expert in MATLAB/Simulink to build a high-fidelity 6-DoF simulation of a Reusable Launch Vehicle (RLV) covering all flight phases — from vertical ascent, gravity turn, and orbital insertion, to de-orbit, reentry, and powered soft landing. The simulation should incorporate quaternion-based attitude dynamics, realistic force modeling (gravity, drag, thrust), mass variation, and environmental effects like wind and atmospheric density. Advanced Guidance, Navigation, and Control (GNC) logic is required, including PID-based TVC, reference quaternion tracking, and optionally Model Predictive Control (MPC) and Reinforcement Learning (RL). The system should simulate drag with Mach-dependent Cd, CG shifts, RCS thrusters, and landing leg deployment, with clean modular design and visual outputs of altitude, velocity, attitude, and control signals. Deliverables include the complete Simulink model, configurable parameters, and documentation.