Developing a state-of-the-art generator for AAM

Rolls-Royce motor demonstrator for UAM passed to test
Andrew Everitt - Assistant Chief Design Engineer at Rolls-Royce Electrical

We spoke to Andrew Everitt, Assistant Chief Design Engineer at Rolls-Royce Electrical in Dahlewitz about the development of our liquid-cooled, power-dense and highly integrated generator. In the future, this generator design could find applications in the hybrid-electric propulsion systems or on-board power generation. The generator is being developed as part of the EU-funded HE-ART programme where it will be tested in a parallel hybrid-electric turboprop for regional aircraft.

The generator was launched as part of the scaleable 800 kW turbogenerator system developed to enable eVTOLs and fixed wing aircraft to fly electrically with a longer range. 

What’s your role within the generator programme?

I lead the generator team as part of our turbogenerator project and work closely with the chief design engineer. I started with Rolls-Royce in Derby and spent most of my career since then working on the Pearl 15 and Pearl 700 projects, mainly focussing on the technical development of various sub-systems. In 2012, I moved over to join the team in Dahlewitz and became part of Rolls-Royce Electrical in June 2022.

Electrical engineering was a discipline I hadn’t worked with before. However, I’m able to draw upon my experience of similar technical challenges in Civil Aerospace and look at other high-speed rotating machines to consider all the technical justifications and design experience from the products we have in service and flying today. We can build on that knowledge for the future.

We have a large and experienced European team working on the project, across Budapest, Trondheim and Dahlewitz. Having the electrical technology experience from the Norwegian and Hungarian teams, as well as experience with rotating machines like gas turbines in Germany, we’re able to utilise a lot of expertise.


Rolls-Royce motor demonstrator for UAM passed to test
Turbogenerator for Advanced Air Mobility

How is the generator being developed?

What we’re developing is a state-of-the-art, cutting-edge and power-dense solution, so the conceptual work to develop this idea took longer than anticipated. The generator and turbine are designed specifically with the idea of a highly integrated complete turbogenerator system in mind, making it light and small in length and volume which is quite important for airframers.

We’ve now progressed into the detailed design phase of the generator programme and are looking to have that completed by the middle of 2024. After that, we’ll start bringing together parts to run our first tests on our test bench in Trondheim towards the end of the year.

We’ll carry out what we call back-to-back tests with two machines connected to each other. Over the next year, we’ll adapt our existing facilities to the machine’s unique specifications, but we’ll also be repurposing a lot of the state-of-the-art equipment we used to test our E-Fan X demonstrator and 320 kW motor for Regional Air Mobility.

Motor demonstrator for 150 kW electric propulsion unit
Electrical 2.5 MW electric generator on test

How are we drawing upon previous generator experience for this programme

Across Budapest and Trondheim, we have a wealth of experience with generator technology including the E-Fan X demonstrator, the APG80, the M250H and other smaller machines.

For the E-Fan X project, we developed a 2 MW electric generator – the world’s so far most powerful generator designed for aviation – and put it through ground tests. The APG80 is a demonstrator for an auxiliary power unit for aviation applications in the power class under 100 kW, featuring a highly compact design with integrated power electronics. And as part of the M250H project, we designed a complete hybrid-electric system using our proven M250 turbine as energy source, which included novel design of 500 kW generators.

We’ve been able to look at some of these relatively high-speed generators and draw upon experience with proven materials from the E-Fan X or design insight from the M250H, for example, as well as important test data from the APG80 that can help to support our assumptions for this programme.

As we develop our turbogenerator system, we bring together this expertise in electric machine design with decades of experience with the development of turbines, e.g. from our Trent aero engine programmes. We work closely with colleagues in our Civil Aerospace business who can support this technology.

Motor demonstrator for 150 kW electric propulsion unit
Hybrid-electric eVTOL over Budapest

What are the next steps?

As we’ve developed such a mature concept, we’ve been able to progress through the design phase quickly and are on track to hit all our development milestones.

Alongside the testing we have planned in Trondheim, we’re planning to integrate power electronics around the machine as part of our integrated approach in the next year, as well as running some component tests in parallel.

Register for news and stories

Our Alert service delivers the latest press releases, stories and regulatory news directly to your mailbox.