With such a small battery powering the electric motor, though, the emergency backup system isn’t designed to get a plane to its original destination should the primary engine fail. Instead, it gives a craft an additional range of just 12 miles to find a safe place to land in an emergency. In other words, it’s really only there to prevent a deadly crash.


However, since the electric motor’s backup battery is constantly being charged by the main engine, it can actually be used outside of emergency situations as a sort of hybrid powertrain. Pilots can turn it on for an extra 40 horsepower for takeoffs, or to improve fuel efficiency during a long flight. But only as long as the plane’s main engine is running, to ensure the electric motor’s backup battery remains fully charged.

[Universidad Carlos III de Madrid via Gizmag]