DLR HY4

HY4 is a four seat hydrogen fuel cell powered aircraft. It made its maiden flight on 29 September 2016 from Stuttgart Airport, powered by gaseous hydrogen. It was designed by DLR Institute of Engineering Thermodynamics of the German Aerospace Center,  based on the Taurus G4, manufactured by Pipistrel.

The HY4, operated by DLR spinoff H2Fly, completed the world's first piloted electric flights powered by liquid hydrogen in September 2023, with one flight lasting over three hours.