The project could lead to significant changes in the aeronautics industry and bring huge benefits to environmental quality.
1. Milestone in aviation
Engineering researchers at the University of Arkansas (UoA) achieved a major milestone with the successful test flight of an electric motor drive on a hybrid electric aircraft. Used primarily as air taxis in island regions and remote areas, researchers transformed the Cessna 337, a small plane that typically feature two gasoline-powered engines and performs demanding tasks such as air propulsion and acceleration, as well as lighter tasks such as taxiing, cruising and landing.
For the past years, researchers led by Alan Mantooth, Professor of electrical engineering and executive director of the National Center for Reliable Electric Power Transmission (NCREPT) have engaged in this project to design and develop battery-powered motor drives that can be used instead of the gas-powered engines.
“With recent refinements, we’ve managed to optimize design of the electrical-thermal-mechanical-control systems — in other words, all aspects of the motor drive are now simultaneously optimized,” Mantooth said.
This has major implications for the new and emerging era of electrification of transportation vehicles, whether they be planes, trains, automobiles, heavy equipment, ships or drones. We’re extremely excited about this work.Alan Mantooth, Professor of electrical engineering and executive director of NCREPT
2. Partners in innovation
Mantooth and researchers David Huitink, Yue Zhao and Chris Farnell designed a 250-kilowatt motor drive to power a rear electrical engine in a hybrid electric aircraft testbed developed by Ampaire, an electrified aircraft company in Southern California. In combination with a gasoline-powered engine in the front of the aircraft, the rear electrical engine propels aircraft during taxiing, takeoff, cruising and landing.
Led by Nenad Miljkovic, professor of mechanical science and engineering, the University of Illinois researchers focused on thermal-management design, while the UoA researchers contributed expertise on electrical and mechanical and controls.
Wolfspeed, a trademarked manufacturer of silicon-carbide semiconductors, contributed with commercial power modules and integration expertise to the development of the electronic motor drive. Ampaire coached the academic-led team through environmental testing requirements, derived from aerospace hardware standards and necessary to qualify and validate the motor drive’s performance and reliability on a pathway to test flight.
3. Test flight
Finally, after roughly 18 months of ground tests and validations proving the technology, Ampaire successfully piloted the plane powered by the research team’s inverter technology on February 20 at the Camarillo airport near Los Angeles.
4. ARPA-E Energy Innovation Summit
The hybrid aircraft was displayed at the ARPA-E Energy Innovation Summit in Denver in 2022 and inspected by US Secretary of Energy Jennifer Granholm. After extensive testing and evaluation, the test flight came before the 2023 ARPA-E Energy Innovation Summit that was held in Washington, DC, on March 22-24. Aided by the research team, Ampaire conducted additional test flights and continue to collect data to improve future designs.
“The flying testbed capability, supported by ARPA-e, gives Ampaire a rapid test tool for evaluation of emerging technology in a relevant environment,” said Ed Lovelace, chief technology officer and vice president of engineering at Ampaire.
Successfully evaluated technologies have an opportunity to become part of Ampaire’s commercial electrified aviation product roadmap, providing greater capabilities.Ed Lovelace, chief technology officer and vice president of engineering at Ampaire
The project was funded by the US Department of Energy/Advanced Research Projects Agency–Energy CIRCUITS program, or ARPA-E, a US government agency promoting and funding early-stage research and development of advanced energy technologies.
“Testing transformative electric aviation technologies on an aero-platform in actual flight environments enables validation of the technology in real-world conditions, which will greatly accelerate the adoption of the technology. The UoA motor drive was the first of soon-to-be-many ARPA-E-funded electric aviation technologies, such as circuit breakers, inverters, motors, power distribution systems, batteries, fuel cells and even high-efficiency combustion engines that will be tested in flight as the agency tackles the electrification of aircraft to bring us towards a more electrified future,” said Isik Kizilyalli, ARPA-E associate director for technology.
The project was an outgrowth of collaborations established as part of the National Science Foundation Center for Power Optimization of Electro-Thermal Systems. Based at the University of Illinois Urbana-Champaign, the center focuses on increased electrification in all modes of mobility and transport.