Smartflyer SF-1 is a four seater, hybrid powertrain, interchangeable energy storage, vertical stabilizer mounted propeller prototype plane. Pure electric, range extender hybrid ICE, hydrogen fuel cell configurable, relatively easily so. A particular focus seems to be on flight training as its serial hybrid enables simulating different flying conditions in real life. The startup claims CO2 emissions can be up to 50% lower than with comparable ICE aircraft. Some of its efficiency is also attributed to the propeller positioning in free flow.
https://www.smartflyer.ch/aircraft.html
