Development of a Series Hybrid Propulsion System Using Heavy Fuels

ABSTRACT: The objective of this SBIR topic is to develop a hybrid electric propulsion system to support a Rapid Response Small SUAS (<30lb) capability. This requires fast dash (>150mph) while maintaining extended endurance (>15 hrs) on station and low acoustic noise operation. Full details of the requirements are provided in the solicitation. These UAVs use combustion engines for propulsion and often carry a payload specific to their mission. Currently however, these propulsion systems must be sized for take-off power and are therefore oversized and less efficient for part-load cruise conditions. The proposed engine has much greater efficiency, when compared to a turbine engine, so to reduce overall take-off weight (of engine and fuel) for a 15-25 hour endurance. Furthermore, Mainstream"s patent-pending design that integrates the electrical and mechanical systems also reduces the size of the generator and provides far greater motor starting torque, whenever low-temperature starting is required. MEC is uniquely qualified for this type of work with years of experience in energy conversion and the development of lightweight engines, permanent magnet motor/alternators, and power electronics. In phase I, MEC will also construct and test a bench-top, proof-of-concept hybrid system to confirm simulated component efficiency and fuel savings. BENEFIT: The Phase I effort will provide the proof-of-concept needed by the Air Force and Mainstream to decide whether or not the product is technically and commercially viable. The system-level modeling in Phase I will provide a clear picture of the benefits in terms of flight endurance and operational capability (i.e., silent mode endurance) of the proposed hybrid drivetrain. The engine, alternator, and charge management system will be designed in Phase I. The value proposition for the electric propulsion product is a significant increase in operational capabilities for small UAVs, namely increased flight endurance and the capability for silent mode operation. MEC"s approach is composed of several components that have a high likelihood of being commercialized: 1) a heavy-fuel, high power-density engine, 2) a power dense alternator, 3) a power converter, and 4) a power management system.