High Power and Torque Electric Motors for Direct-Drive Rotorcraft Applications

Reducing fuel consumption with improvements in propulsion efficiency will significantly enhance the competitiveness of our armed forces. The Army is currently investing in new propulsion technologies including electric and hybrid-electric drive technologies that can improve the flight performance and air platform capabilities of rotorcraft. While most Electric Vertical Takeoff and Landing (eVTOL) aircraft developed recently are direct drive electric multi-rotor, their inherently higher disc loading means that they are not as efficient as conventional single (large) rotor helicopters, furthermore, the rotor speed modulation used for thrust control does not scale efficiently to larger aircraft. The lack of lightweight direct-drive, high-torque, low-speed electric motors is one thing holding back electric propulsion of larger scale rotorcraft. Toyon proposes to apply our patent-pending ultra-torque-dense electric motor technology to the direct-drive rotorcraft propulsion application. A preliminary scaling study and Finite Element Analysis (FEA) simulation shows that our motor can achieve at least 15,000 ft-lbs of torque at 250 RPM (700 hp) with a frameless weight of 326 lbs, an enclosed volume of 4.35 cu ft and an efficiency of 94%. This is a torque/power density improvement of at least 2X over state-of-the-art that has not yet been fully optimized for this application.