Being the first four-seat passenger plane relying primarily on a hydrogen fuel cell, the HY4 will take off to its maiden flight during the upcoming summer. The powertrain of this twin-fuselage, single-engine plane consists of a hydrogen storage unit, a low-temperature hydrogen fuel cell and a high-performance battery. The fuel cell converts the hydrogen energy directly into electric energy, powering the propeller. The only by-product in this process is pure water. If the hydrogen needed for the conversion process is generated in an electrolysis process powered through renewables, the HY4 flies completely emission-free.
The HY4 powertrain has already been tested successfully in the lab. To create enough lift to take off, the system must provide the maximum takeoff performance reliably for at least three minutes. During the test, the developers already succeeded in running the system for more than ten minutes at maximum power. The interplay between fuel cell and the battery, which unites the functions of an energy buffer and back-up power system, has also been proved. This paves the way to integrate the powertrain into the plane.
Implementing the hybrid drive concept of the HY4 research platform is regarded as an important milestone on the way to establish electric drives in commercial passenger airplanes. “Hybrid drives promise high energy efficiency at low local emissions. We think that they son will have the potential to safely carry passengers over short distances,” comments DLR aeronautics board member Rolf Henke. “In the long term, aircraft with higher capacities are perceivable.”