Apollyon Dynamics is developing autonomous fixed-wing UAVs, VTOL platforms, and defence-grade flight systems. We are looking for a GNC Engineer with a strong hands-on background to own flight control, navigation, and guidance across our vehicle programs. This is a technical role with real ownership from architecture through to flight test. Experience with autopilot development and a demonstrated contribution to open-source flight stacks is expected. Responsibilities Define and own GNC architecture across vehicle programs, driving requirements into avionics, embedded, and mechanical teams Develop 6-DOF flight dynamic models and tune PID, LQR, MPC, and adaptive controllers across the full flight envelope Implement guidance algorithms for waypoint navigation, autonomous takeoff and landing, terrain following, and mission autonomy Develop and customise autopilot firmware, covering hardware bring-up, integration, and flight-ready software delivery Actively contribute to PX4 and/or ArduPilot...