The simulation procedure for GNSS-based position estimation of a launch vehicle in a gravity turn trajectory is presented. A detailed mathematical model of the dynamics of a multi-stage launch vehicle is developed. In the mathematical model, the aerodynamic drag force and the jerk produced during the stage separation are considered, specifically for the SpaceX Falcon 9 V1.1 launch vehicle in the Commercial Resupply Service (CRS)-5 mission. The trajectory of the launch vehicle is simulated by using the vehicle and mission-specific parameters in the developed model. The SPIRENT GNSS simulator is used to generate the received GPS signals for the launch vehicle trajectory. The signals are acquired by the UNSW Kea GPS receiver which is optimized for acquiring GPS signals under high dynamics. The pseudo-range measurements received by the Kea receiver are used to test the performance of various estimation algorithms. This simulation procedure is convenient and efficient for testing new GNSS receivers and new navigation algorithms for launch vehicle applications.