I am a novice with PX4 and pixhawk and could use some help with my quadcopter project. I am trying to fly my quadcopter without a GPS using Manual mode. I have found topics about flying with a PX4Flow and flying in OFFBOARD mode. From what I can tell manual mode does not require position data. Is it possible to fly in manual mode without a GPS? If so, what is the process for disabling the GPS requirement so that the drone can takeoff? Let me know if you need me to be more specific.