Rolls-Royce has taken one more significant step towards the ambition to provide hybrid-electric propulsion systems for next gen aviation

• Rolls-Royce earlier created an M250 hybrid power system and conducted ground tests
• The APUS i-5 plane will now be used to demonstrate its integration with an aircraft
• The M250 hybrid power pack also complements systems being developed for larger aircraft as seen with the E-Fan X demonstrator

Earlier this year Rolls-Royce announced it had conducted ground tests of a hybrid-electric propulsion system built around an M250 turboshaft engine. All it needed now was to find an airframe to integrate the system into. Rolls-Royce has now found that airframe and taken one more significant step towards realising the ambition to provide hybrid-electric propulsion systems for the next generation of aviation.

“Rolls-Royce has always been a pioneer in aviation and one of the key elements of our strategy is to champion electrification across all our businesses”

Dr Mike Mekhiche, Deputy Director, Rolls-Royce Electrical

Dr Mekhiche added, “Electrification is one of the most exciting developments in aviation since the birth of the jumbo jet. We are determined to use our pedigree in aerospace to be at the forefront of developing innovative propulsion systems to meet the needs of the next chapter in aviation. When this happens, it’s going to transform the way aero transport is designed and produced, reducing the time required to travel, revolutionising cargo delivery and changing the way we design our cities and infrastructure.” 

Who’s Involved

Rolls-Royce will be working with APUS, an aviation engineering company based in Strausberg, close to Berlin, and the Brandenburg University of Technology (BTU), Germany, in developing a hybrid electric flight demonstrator based on its hybrid M250 propulsion system. The project is being supported by the Brandenburg Government under the regional programme to develop research, innovation and technology (ProFIT), managed by the Investment Bank of the State of Brandenburg (ILB), and is scheduled for a duration of three years. The collaboration will enable one of the world’s most comprehensive hybrid aerospace turbine engine development and integration programs and pave the way for experimental flights on aircraft after 2021.

The Aircraft

This project will include an APUS i-5 plane to demonstrate the practical application of hybrid electric technology for a 4000kg conventional take-off and landing flight test vehicle. The system could be used across a range of transport platforms to enable distributed electric propulsion, including EVTOL’s (hybrid electric vertical take-off and landing vehicles), general aviation aircraft and hybrid helicopters in the future.

The M250 Hybrid System

The traditional non-hybrid M250 gas turbine engine has powered more than 170 varieties of helicopters and fixed-wing aircraft, in both military and civilian service. Rolls-Royce selected this engine for hybridisation because of its maturity, power-density, ease of maintenance, and high reliability. The total M250-powered fleet has logged more than 250 million engine flight hours, with more than 33,000 engines delivered to the market.

Rolls-Royce engineers based in the United States, UK, Germany, Norway and Singapore developed the M250 engine into a hybrid-electric propulsion system.

The Rolls-Royce powered APUS i-5 demonstrator project just announced today integrates that new hybrid system using a M250 gas turbine engine with a high energy density battery system, electric generators, power converters and an advanced power management and control system. The power management system optimises overall propulsion performance in order for the system to be suitable across a variety of platforms, including EVTOL, while delivering efficiency gains, reduced noise and lower emissions.

Earlier this year hybrid version tests were successfully carried across three system configurations:

• Series Hybrid: In this configuration, the engine operates as a turbo-generator that charges an on-board battery system, and does not contribute to thrust directly. All power required for thrust and other onboard systems is supplied by the battery.
• Parallel Hybrid: In this configuration, the platform thrust is supplied by a combination of the engine (mechanical thrust) and the electrical system (electrical thrust), while the other power needs of the aircraft are met by the battery.
• Turbo-Electric mode: In this configuration, the battery system is redundant. The engine operates as a pure turbo-generator supplying electric power for thrust and any other power needs on the aircraft.

The M250 hybrid power pack also complements the AE 2100 2.5MW system being developed for larger aircraft, including regional aviation, and is being tested with Airbus on the E-Fan-X demonstrator platform.

Funding

Funding for this hybrid electric flying project was requested within the framework of the ProFIT promotion guideline issued by the Brandenburg Ministry of Economics and Energy. The application was submitted in the typical two-stage process with the support of Wirtschaftsförderung WFBB and the Business Development Bank of the State of Brandenburg, ILB. The financial ProFIT support is provided by the State of Brandenburg from the European Regional Development Fund and federal and state funds. All project partners would particularly like to thank the ILB for the accompanying consultations and the European Regional Development Fund for the co-financing.

What Rolls-Royce Says

Dr. Dirk Geisinger, Director Business Aviation and Chairman Rolls-Royce Deutschland, said: “We thank the Brandenburg Government sincerely for its continued support and are delighted to be working with APUS and the Brandenburg University of Technology on this groundbreaking demonstrator program. This is an important step forward in developing propulsion systems that will enable a new class of quieter and cleaner air transport. At the same time this will further strengthen our Dahlewitz site, which is one of the hubs for the advancement of hybrid-electric propulsion in our company.”

Rob Watson, Director of Rolls-Royce Electrical said: “We have already ground tested the hybrid version of the M250 gas turbine in a demonstration setting in Series Hybrid, Parallel Hybrid and Turbo-Electric operating modes. The M250 hybrid is planned to be used as a propulsion plant with power ranging from 500kW to 1MW and has the potential to transform aviation power. Rolls-Royce has pioneered every significant development of the aviation industry and it is only natural that we play our part in this exciting next step of electrification.”

What Brandenburg University of Technology Says

Prof. Dr. Georg Möhlenkamp, Chair for Power Electronics & Electrical Drive Systems, BTU Cottbus-Senftenberg said: “We are very pleased to be a partner within this important project. Being responsible for electric hybrid system functional modelling, dynamic modelling of system performance and electro-mechanical system test support acknowledges our strong competencies in this field and represents a first visible step in our strategy to collaborate with Rolls-Royce on sustainable aircraft propulsion.”

What APUS Says

Phillip Scheffel, Chief Executive Officer, APUS aeronautical engineering GmbH, said: “As the supplier for the iron bird test airframe, installation hardware design and hybrid system installation partner, we are keen to take this project forward and to achieve experimental flight clearance together. Receiving funding from Brandenburg Government helps greatly to realise our exciting plans and enable significant learnings for a range of other electro hybrid aircraft systems.”