Rolls-Royce Hybrid Flight Engine's First Fuel Burn

Rolls-Royce's new gas turbine for hybrid-electric flight has completed its first fuel test.

The engine has been designed using novel combustion technology to produce ultra-low emissions and this test confirms the effectiveness of the compact, power-dense turbine that will be integrated into a light-weight turbogenerator system, the company said in a release.

The complete turbogenerator system is being developed for the Advanced Air Mobility (AAM) market. This includes electrical vertical take-off and landing (eVTOL) or electric short take-off and landing (eSTOL) aircraft for Urban Air Mobility (UAM) and commuter aircraft applications up to 19 seats. The gas turbine under test also has potential applications within helicopter, auxiliary power unit (APU) and defense markets.

The turbogenerator system will complement Rolls-Royce’s electrical propulsion portfolio by delivering an on-board power source with scalable power offerings between 500 kW and 1,200 kW enabling extended range on sustainable aviation fuels and later, as it becomes available, through hydrogen combustion. This will open up new, longer routes than electric battery powered aircraft can support today.

"The development of the turbogenerator solution combines Rolls-Royce's capabilities in designing compact and lightweight high-speed rotating electric machines and gas turbines, along with their ability to integrate them at a system and platform level.

Test facilities and equipment, comprising 14 subsystems in total, were designed, procured and built – or adapted – in abiut a year. The test set-up comprises commodity components such as valves and hoses, and bespoke subsystems such as the fuel injection systems, oil and ventilation systems, engine mount and water brake that were tailored to the specific test requirements for this new technology.

The first tests helped the team generate real data to verify key technical attributes of the design. This will allow for design adaptations for the next set of testing, ultimately pushing towards the maturity of a certified engine.

The turbogenerator can be used in serial or parallel hybrid applications. It is well suited to recharge batteries as well as provide energy to electrical propulsion units directly and therefore enables aircraft to switch between power sources in flight. The research and development of this technology is being partially funded by the German Ministry for Economic Affairs and Climate Action.