Hybrid-Electric Amphibious Aircraft for Runway Independence in Agile Combat Employment

Tidal is developing Polaris, a 12500 lb clean-sheet, hybrid-electric, monohull amphibious aircraft built with composite materials that offers a useful load of 3300 lb and a maximum range of 1750+ nmi. Polaris’ monohull design improves sea state tolerance and brings structural and aerodynamic efficiency, driving high payload-range performance. Further, composite construction reduces corrosion-related maintenance, an important challenge in saltwater environments. Polaris’ powertrain architecture is a plug-in serial hybrid that couples fuel-efficient compression ignition engines with batteries and electric motors driving twin propellers. With this powertrain, Polaris achieves 85% lower fuel burn than existing aircraft over typical stage lengths while enabling fully-electric takeoffs, landings, harbor operations, and short-hop missions. In addition, Polaris’ hybrid powertrain is not dependent on charge infrastructure.With private investment, Tidal is developing a hybrid powertrain test stand with an electric motors powering propellers, a compression ignition engine coupled with a generator, and a large battery pack capable of full takeoff power. Unlike previous hybrid powertrain systems for aviation, Tidal’s powertrain utilizes compression ignition engines that burn kerosene or diesel fuels in a plug-in series architecture that enables the pilot or autopilot to dial-in the power allocation between the fuel-burning engines and the battery pack. This enables the fuel burn, speed, range, endurance, and external noise level of the vehicle to be dialed in to specific missions based on the control strategies for the hybrid powertrain management and vehicle.This SBIR proposal is focused on the development of novel approaches to hybrid power management, flight control, and fault tolerance/survivability for Polaris in Air Force missions. Under this SBIR proposal, Tidal will expand the full-scale hybrid powertrain test stand into an integrated aircraft test unit with hardware-in-the-loop simulation capability (HILSIM) by including critical low voltage systems (avionics, actuators, etc.) and pilotable flight simulation. Controls software and power management hardware for both the powertrain and low voltage systems during specific Air Force mission profiles will be developed. Failure tolerance and survivability of the hybrid powertrain and aircraft system in Air Force applications will be developed and demonstrated using the HILSIM. The integrated aircraft HILSIM capability will also be used to evaluate and demonstrate aircraft-level performance in specific Air Force mission profiles, providing hardware-informed insight into Polaris’ capability to meet Air Force mission needs.