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The balance of power: Clean Sky's Energy Optimised Regional Aircraft

Regional air traffic is growing at an average annual rate of 6% (versus 5% of total commercial aviation), and regional aircraft represent over 33% of the worldwide commercial fleet and perform over 40% of total commercial flights. With that level of growth, and with the scale of regional flight activity, it is essential to find innovative ways to counter the environmental footprint of regional aviation. Industry consensus is that electrification is the direction that aviation must take towards making flight greener and more efficient. Indeed, there's been a lot of media coverage of electric and/or electric/hybrid powered aircraft in the future for regional aviation. For example, the Government of Norway announced last year its intention to mandate that all of its domestic flights will be electrically propelled by 2040. But in the nearer term future, electrification can be applied in many other important roles in aircraft, not just propulsion. Clean Sky's Energy Optimised Regional Aircraft project focuses specifically on six new on-board systems for the next generation of regional aircraft where innovative electrical solutions can save energy whilst lowering noise and emissions.

"There's a shift towards electrical systems," says Ruud Den Boer, Project Officer at Clean Sky, highlighting the combination of energy-saving potentials and also the versatility of switching an aircraft's systems to electrical ones: "For instance, if you look at wing ice protection, many aircraft currently use a pneumatic system with a sealed rubber boot that mechanically breaks up the ice, but when you make this wing ice protection function electrical the big advantage is that during the flight you can manage your use of the electricity more efficiently and prioritise the energy use between the aircraft's different on-board systems. For example, for the environmental control system, when you enter icing conditions you can say well I won't put so much electric energy in the environmental control system I'll put the energy in the icing system. So you can optimise the flight scenario and therefore also optimise the electrical generators and the whole electrical system so you have a kind of integration at a higher level".

Seizing the opportunity to bring this versatility and, ultimately, the fuel-saving promise of electrification, Clean Sky's Energy Optimised Regional Aircraft project has been structured around six areas of focus:

  • Low Power Wing Ice Protection System (WIPS)
  • Electrical Landing Gear System (E-LGS)
  • Thermal Management (ThM)
  • Advanced Electrical Power Generation and Distribution System (A-EPGDS)
  • Advanced Environmental Control System (A-ECS)
  • Innovative Low Noise Propeller (LNP)

Electrification of these various systems is seen as a step forward as a means to conserve energy, but there are other benefits too. Electrical systems make it easier to monitor energy consumption, simplify maintenance procedures which, in turn, reduce ownership costs — critical factors for regional aviation, a sector that operates on slim margins.

"Regarding maintenance, when you have all-electrical systems, maintenance becomes more efficient because you can easily measure the status of all the systems through the use of low cost sensors" says Clean Sky's Den Boer. "You can get alerts informing you of when maintenance is really needed instead of at fixed intervals". 

The six work packages of the project are still ongoing, being performed either in synergy with other ITD members (e.g. Liebherr for A-ECS) and/or with participation of several Core Partners and Partners — and a number of measurable results have already been achieved:

The fully electrothermal Low Power Wing Ice Protection System (WIPS) solution has been selected based on integration constraints for the Regional Aircraft. It will be optimized for low power target. In any case, no pneumatic off-take from the engine is expected.

The Electrical Landing Gear system critical design review has been positively concluded, with the innovative electromechanical actuators for both the nose and main landing gear to be subsequently developed by the Core Partner.

The Advanced EPGDS related CfP Projects for an innovative smart grid and decentralized solid-state based secondary distribution concepts are all running.

Following a trade-off study at aircraft level, the advanced Environmental Control System hybrid architecture selection has been performed and technological bricks selected, to be then actually developed and tested by the system partner.

As for the Innovative Low Noise Propeller (LNP), preliminary design has been performed.

"On-ground experimental demonstrations are foreseen for all the involved technologies, with different test beds, depending on the selected technology" says Fabrizio Cuomo, Systems Engineer at Leonardo Aircraft Division. "Each of them will be first validated at TRL 4 by the system manufacturer at its own lab. Then, more integrated testing campaigns are foreseen in order to reach the TRL 5 gate to be completed by the end of the Project in 2022. As an example, both the Landing Gear and Advanced EPGDS technologies will be ground tested on the Regional IADP ground demo platform, namely the Iron Bird, at Leonardo Aircraft premises in Pomigliano D’Arco (Naples). Then, the Advanced ECS coped with innovative Thermal Management technologies will be integrated on the Regional IADP Passenger Cabin demonstrator to be further validated on the Thermal Test Bench at Fraunhofer Institute premises. Finally, ice wind tunnel and wind tunnel tests are foreseen to validate the low power WIPS and the Innovative Propeller technologies, respectively".

By the end of the project, all the six innovative on-board systems technologies are expected to reach TRL 5, in other words each of them will be developed and tested on-ground within an aircraft representative environment. This will pave the way for further validation and qualification (beyond the scope of the Project) on a flying test bed to check their integration aspects on a real aircraft.