Rolls-Royce turbogenerator for electric hybrid aircraft

Rolls-Royce has announced a turbogenerator project, for hybrid-electric aircraft and eVTOLs. It will run on SAF and eventually on hydrogen.

Image: Rolls Royce

We have seen and continue to visit several initiatives around battery or hybrid electric aviation projects. They tend to involve small aircraft with single-digit seating capacity, or eVTOL (electric vertical take-off and landing). Some are expressing concerns about the feasibility of these projects, in terms of range or gross weight – or both. And some are of the opinion that at least initially, hybrid electrics can offer more options.

So that brings us to Rolls-Royce and its development of a turbogenerator for advanced air mobility applications. In simple terms, it is a device that works thanks to a gas turbine, to produce electricity. This type of generator is quite common for large-scale applications, such as a backup power source for city networks. Rolls-Royce and its subsidiaries have considerable experience with these huge machines.

Rolls-Royce turbogenerator for electric hybrid aircraft

Image: Rolls Royce

But this application will be much smaller. Rolls-Royce will design a family of turbogenerators serving a power range between 500 kW and 1,200 kW. This range is needed to cover a variety of different Advanced Air Mobility (AAM) applications. Rolls-Royce will design the entire unit, including the jet engine, generator and power electronics and distribution systems.

Rolls-Royce – Manufacture of the AAM turbogenerator

By designing the entire turbogenerator as a unit, Rolls-Royce wants to make it as light as possible. And in terms of applications, the company believes there will be a need for such a system for multiple designs. Operating as a small APU, it could provide backup power and/or extend the range of battery-powered designs. Thus, the system will operate as a series hybrid, charging the batteries. Or, it could directly power electric motors.

VX4 vertical aeronautics. Image: Vertical Aerospace

The company wants to make it hydrogen-capable, offering similar functionality on hydrogen-electric or hydrogen-burning aircraft. Rolls-Royce is developing this turbogenerator in Germany, Norway and Hungary. He receives funding for this project from the German Ministry of Economic Affairs and Climate Action.

The goal of the program is to create a base system, which will be certifiable on specific eVTOLs and other aircraft designs. Part of the skepticism about AAM vehicles is that they often involve startups, with little experience in aircraft certification. In that sense, Rolls-Royce is in a better position than most.

Tecnam P-Volt

We have seen that the turbine manufacturer is directly involved in several battery-electric projects. So it will be interesting to see if Rolls-Royce and its partners will use a turbogenerator on models like the P-Volt. Range will likely be an issue with early versions of these planes. But to use a turbogenerator as a range extender, these planes will also need to carry fuel.


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