Fraunhofer IISB Clean Aviation electric motor: 1000 horsepower at 94 kg for hydrogen fuel-cell hybrids

Fraunhofer IISB development under the Clean Aviation programme targets aviation and hydrogen fuel‑cell hybrid systems

Fraunhofer’s Institute for Integrated Systems and Device Technology (Fraunhofer IISB) has produced a new electric motor designed for aircraft and hybrid powertrains. The unit delivers 1000 horsepower while weighing just 94 kg, and it fits into a package comparable in size to a 12.5 kg gas cylinder. In doing so, it reaches a power density of 8 kW per kilogram-well above typical electric-car motors (2–4 kW/kg) and even higher than state-of-the-art aviation motors (5–6 kW/kg).

Key engineering choices: hairpin windings and oil-spray cooling

To hit those figures, the motor uses an unconventional layout featuring four three‑phase “hairpin” windings. Instead of flexible round wire, the conductors are rigid copper busbars (rods) bent into a “hairpin” (U‑shaped) form. This approach packs more copper into the same space, enabling higher current and therefore greater power, while also improving cooling performance and mechanical robustness.

Heat is removed via direct oil-spray cooling, which carries thermal energy away efficiently and lets the motor sustain higher output without overheating. The resulting compact build is particularly relevant to aviation, where both installation volume and mass are tightly constrained.

For context, the Tesla Model S Plaid relies on three motors to produce around 1020 horsepower, whereas this design comes close to that level with a single motor.

Materials, speed and power density

Another notable step is the use of NO15 electrical steel just 0.15 mm thick-roughly half the thickness used in most electric motors. Thinner laminations reduce eddy currents, cutting heat generation and improving efficiency, especially at high rotational speeds. The motor is intended to run at around 21 000 rpm.

The system is divided into four independent sections, each with its own winding, inverter and control system. This segmented architecture improves operational resilience: if one section fails, the remaining sections can continue to operate-an important safety consideration for aircraft applications.

Programme context and remaining hurdles

Development took place under the AMBER project within the European Union’s Clean Aviation programme, which is focused on hybrid-electric systems using hydrogen fuel cells for regional aircraft. The project target is to reduce aviation carbon dioxide emissions by at least 30% compared with 2020 levels. Other participants include Avio Aero with its Catalyst turboprop engine and GE Aerospace; however, Fraunhofer IISB states it developed the electric motor end-to-end-from initial concept through to validation in line with aviation standards.

Even with the impressive combination of 94 kg mass and 1000 horsepower output, moving from a laboratory prototype to certified aviation equipment remains a major challenge. It is also still uncertain whether hydrogen fuel cells can provide dependable operation across regional route networks.

Even so, in an industry where progress is often counted in decades, this motor stands out as a substantial engineering achievement.