Development of a Hybrid Electric-Combustion Propulsion System for Long-Range UAVs

Context & Justification

The operational autonomy of UAVs represents one of the most significant bottlenecks in their scientific and inspection applications. Purely electric systems are limited by current battery energy density (250–300 Wh/kg), while conventional internal combustion engines present problems of vibration, emissions, and startup difficulties at high altitude.

Hybrid propulsion systems combine an internal combustion generator with electric motors, leveraging the higher energy density of liquid fuel (approximately 12,000 Wh/kg) to extend flight autonomy while maintaining the smoothness and controllability of electric propulsion. This project designs and validates a series hybrid powertrain for fixed-wing UAVs with a target autonomy of over 4 hours.

Main Research Goal

Specific Scopes

• Model and simulate the series hybrid powertrain in MATLAB/Simulink, defining the energy management strategy and optimal operating points of the combustion engine.
• Select and characterize system components (combustion engine, generator, power controller, buffer batteries, and electric thrust motor) according to target UAV weight and power constraints.
• Manufacture and integrate the powertrain test bench and perform consumption tests in steady-state and dynamic regimes at various simulated altitudes.
• Integrate the system into the UAV airframe and validate flight performance, comparing autonomy, thrust stability, and thermal signature with the purely electric reference system.

Research Products