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The electric backup system (EBS) Airbus Helicopters is studying could bring benefits in safety, payload and noise footprint for single-engine helicopters, said Tomasz Krysinski, the company’s vice president of research and innovation.
The manufacturer is planning on demonstrating the use of the EBS, which it describes as a “hybrid propulsion system,” on an H130 light single in 2020.
The EBS would be based on a 100 kW motor and 1 kWh lithium-ion batteries. Under a parallel hybrid architecture, the motor will be connected to the main gearbox. The EBS will thus be able to power the rotor for about 30 seconds.
The main improvement from an EBS, as shown in flight on a modified AS350 AStar in 2011, would be seen in case of an engine failure.
The system would not be powerful enough to act as a second engine. But it would make autorotation safer by maintaining the rotor’s rotation speed constant. The pilot would have more time to react. He would not have to push the collective stick within a critical couple of seconds.
The EBS would then provide some power at flare, making that final landing phase easier.
The technical demonstration eight years ago was successful. However, due to the weight of the system, which was cutting the payload by an unspecified but significant proportion, no business case could be found.
Key in the current project is the swift progress electric devices have made. This is the case for the motors Thales will supply, at 5 kW/kg (2.3 kW/lb.), Krysinski noted. The batteries Airbus Defence & Space will provide will have better energy density, by a factor of two, than the ones used in 2011.
As a result, the system is expected to weigh 75 kg (165 lb.), said Krysinski.
But the second source of power will be harnessed to increase the certified payload. Thanks to the electric 100 kW, the same flight envelope (defined in altitude and speed) can be used with a greater maximum takeoff weight. In case of engine failure, the EBS will help keep the helicopter in the certified flight envelope.