Munich-based battery-electric regional aircraft manufacturer Vaeridion has successfully started an extensive functional test campaign of its Electric Propulsion Unit (EPU) demonstrator.

The novel electric propulsion system powers a single nose-mounted propeller by redundant and isolated electric drives. In accordance with current certification definitions, each independent drive is denoted as 'electric engine'. In case of an engine failure, the remaining engine(s) continue to drive the propeller. This electric powerplant architecture is unique in fixed-wing aircraft to date.

The test campaign validates the functional EPU behaviour for normal operation as well as engine failure conditions. Dedicated mission scenarios are run in a total of more than 150 test points. It is demonstrating that power loss failures of an engine will not stop or interrupt propeller operation.

The equipment under test comprises of two electric engines based on aviation qualified hardware and their respective mechanical coupling as well as the single output shaft, while the propeller is simulated by a laboratory load machine. The setup is at reduced scale regarding the final aircraft level performance rating.

"We direct our forces to early technology demonstration through relevant and representative testing as opposed to showcasing," says CTO Dr Sebastian Seemann. "The team has now demonstrated that our mechanical decoupling of the electric engines fully works. Our objective is that no single failure of any engine whatsoever will impair continued safe flight and landing. By this novel propulsion approach the Microliner has the potential to feature an even enhanced level of operational safety compared to today’s twin-engine or turbine aircraft, let alone single engine propeller aircraft."

Since November 2023, Vaeridion and EASA have worked on a pre-application contract to determine the preliminary certification basis of the Microliner. The innovative propulsion architecture has been the core focus of both teams.