Mitigating Electric Aircraft Noise

VerdeGo Aero, a hybrid-electric aerospace powertrain firm and tenant in Embry-Riddle Aeronautical University’s Research Park, has teamed up with the university to develop and commercialize patent-pending technology designed to mitigate electric aircraft noise.

Under an exclusive option agreement, VerdoGo Aero CEO Eric Bartsch and Executive Chair Erik Lindbergh will further develop the Embry-Riddle technology for commercialization.

“Although electric aircraft show great promise for reducing carbon emissions, fossil fuel use and operating costs, the propellers or rotors can be relatively noisy,” Bartsch explained. “Traditionally, electric aircraft rotors can spin faster to gain efficiency while also increasing noise levels or spin slower and be less efficient but quieter.”

The invention sprang from work by an Embry-Riddle graduate student, Lenny Gartenberg (now a Northrop Grumman engineer), Aerospace Engineering professor and Eagle Flight Research Center Director Dr. Richard Anderson, and research engineer Dr. Borja Martos.

The technology being commercialized by VerdeGo Aero would automatically adjust the pitch of rotating propeller blades, while also adjusting motor torque to maintain constant thrust, Bartsch said.

In this way, it is possible to reduce noise or increase efficiency, while maintaining substantially constant thrust, altitude and airspeed. “Previously, electric aircraft have had to prioritize either efficiency or noise abatement,” Bartsch explained, “but electric aircraft using the new technology could be designed to operate most efficiently at cruising altitude, where noise abatement is less of a concern. For example, they could switchover to a lower-noise mode as they descend over urban areas.”

For urban air mobility vehicles, reducing noise levels is a top performance metric, Embry-Riddle’s Pat Anderson noted. “To imagine our noise-mitigating technology,” he said, “think about the 1980s movie Blue Thunder, in which a police helicopter had a silent mode. Our technology balances efficiency and noise pollution to provide a clean, quiet option for future public transportation.”

Traditionally, he added, “Electric aircraft designers have tended to focus on attempting to get maximum range and performance out of the vehicle while also reducing noise during critical phases of flight. This technology gives the aircraft designer the best of both worlds – reduced noise without having to pay a penalty in efficiency.”

Bartsch and his team are developing a mechanical demonstration of the noise-mitigation technology, to be showcased at Embry-Riddle’s Research Park.