Tecnam has revealed a new hybrid-electric technology aircraft demonstrator with a Rolls-Royce and Rotax propulsion system.
Originally published by Rolls-Royce.
With the call to make flight more sustainable and environmentally friendly, comes the need for propulsion systems that enable reduced fuel consumption and emissions – without compromising aircraft endurance and performance.
Together with the Italian aircraft manufacturer Tecnam and the Austrian engine producer BRP-Rotax, Rolls-Royce has been developing a prototype parallel-hybrid electric powertrain to achieve exactly that. The companies joined forces on the “H3PS” project in 2018, under the framework of a European Horizon 2020 fund.
H3PS encompasses three ‘Hs’: ‘high power’, ‘hybrid powertrain’ and ‘high-scalability aircraft’, and involves equipping a 4-seat Tecnam P2010 with a parallel-hybrid electric powertrain – believed to be the first of its kind ever developed for general aviation – to help reduce fuel consumption, while maintaining and even extending aircraft range. The project introduces advanced technology for a smaller power class, while being scalable for larger general aviation aircraft.
The project has successfully tackled the challenges presented by parallel-hybrid electric architectures, with the purpose of de-risking a technology that is novel to aerospace propulsion applications and to further mature it into a commercially viable solution. Rolls-Royce has been responsible for the electrical part of the parallel-hybrid electric propulsion system. A Rolls-Royce Electrical team based in Budapest, Hungary, developed the 30 kW electric machine, electric controls and the complete battery system.
All-electric aircraft, like the Rolls-Royce powered eFlyer 2 prototype, are already flying and continuous improvements in energy storage technology promise to allow for adequate range for many flight missions in the smaller aircraft classes in the near future.
In a serial-hybrid electric set-up, the propeller is always powered by the electric motor, while a combustion engine and generator set create the required on-board power to charge the batteries to support a longer flight range. In this architecture the engine-generator set does not directly contribute to the generation of thrust.
For the H3PS project it was decided to develop a parallel-hybrid electric system: the aircraft propeller can be powered by the combustion engine directly, by the electric motor, or by both at the same time with the electric motor adding extra torque to the propeller shaft.
“Through the H3PS project we have gained valuable insights into the integration of hybrid-electric systems. We have solved the highly complex task of mechanically coupling a piston engine with a high-power electric generator to combine their torques efficiently,” explained Gergely G. Balázs, Engineering Director at Rolls-Royce in Hungary.
The 30 kW electric machine developed for H3PS serves both as a motor and as a generator. It works as the starter-motor to start the combustion engine. During take-off and climb it is a thrust booster-motor adding extra torque to the propeller shaft. In the air, when the aircraft is cruising, it operates as a generator and converts the shaft movement into electric energy to re-charge the batteries.
As the electric motor contributes to the aircraft propulsion, the combustion engine can be reduced in size. For the Tecnam P2010, the 180 hp standard engine has been replaced with a smaller engine with only 141 hp – and this leads to a significant reduction in fuel consumption.
The reduction in engine size has further benefits. It means the aircraft can go further on its existing fuel tank, and because the engine is always running at its optimal operating level it is more efficient and experiences less wear and tear, resulting in reduced maintenance costs and ultimately a lower cost of ownership. It is also lighter.
As downsizing the engine frees up payload, the battery can be accommodated without adding significant extra weight to the overall system, therefore maintaining the aircraft’s positive efficiency balance.
Balázs is convinced that small electric and hybrid-electric planes will have an enormous impact on the way the public and pilots experience electric flight and will help accelerate demand for such solutions in larger aircraft.
“They are ideal for our pioneering work — for testing electric engines, and for training pilots and operators on new drive systems. With research projects such as the H3PS, in close collaboration with our partners, we can demonstrate highly innovative technologies for a small plane, learn key lessons and stimulate innovation that will reduce the environmental impact of air travel in the long run, even in larger aircraft classes.”
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