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Airbus reveals plans for the E-Fan X

by Ian Homer. Posted to category: General

Electric Aircraft come nearer


This article is kindly reproduced from an original feature in the Air League newsletter and is published with their full permission. Find out more on The Air League here 


The modified BAE 146 which will fly initially in 2020 with an electric engine replacing the inner starboard turbofan ­­­engine. (Image courtesy of Airbus)

There have been numerous studies and research programmes, government and industry-funded, and work in universities, aerospace academies and other science-based organisations, looking into alternative powerplant solutions for next generation civil air transport aircraft that could reduce today’s dependency on oil-based fuels and meet increasingly demanding environmental requirements. These visionary projects, which have been slowly emerging over the last decade on both sides of the Atlantic, often included futuristic looking proposals that would look the part in any science fiction movie. In the meantime, the global airline sector has continued to add thousands of aircraft orders to the sales backlogs of the leading aerospace manufacturers, taking the production of existing, conventional designs right through towards the end of the next decade. So long as customers were happy to keep buying low-risk established products it seemed as if there would be little room for any seriously disruptive moves in the civil market any time soon.

However, on November 28 in London, a new industry teaming agreement was announced that could lead to one of the most significant shifts in recent times towards the practical application of hybrid-electric technology for commercial aircraft, and with a test-bed aircraft that will take to the air in just over two years. This new partnership between Airbus, Rolls-Royce and Siemens will develop a near-term flight demonstrator which will combine some of the world’s most expert experience in electrical and propulsion technologies in a modified airframe that will be the largest yet hybrid flying research and development platform.

Introducing the E-Fan X

The new partnership programme has been given the title E-Fan X and the propulsion system is to be installed in a modified BAE 146 four-engine jetliner, the design of which is ideally suited for this application as it has a large cabin, high wing and easily accessed pylon mounted underwing engines. It is intended that following extensive ground-testing, and provisionally fitted on the 146, it will undergo flight testing from 2020, with one of the standard turbofan engines replaced by a two megawatt electric motor. Once the maturity of the system has been proven provision has been made to replace a second gas turbine engine with another electric motor.

Airbus Chief Technology Officer Paul Eremenko said, “The E-Fan X is an important next step in our goal of making electric flight a reality. We see hybrid-electric propulsion as a compelling technology for the future of aviation.” Airbus has invested much time and effort in previous electric-powered test aircraft, starting with the Cri-Cri, and including the e-Genius, E-Star and the more recent E-Fan 1.2. This work and Airbus E-Aircraft Systems House collaboration with Siemens is seen as paving the way for a future hybrid single-aisle commercial aircraft that is safe, efficient and cost effective. The E-Fan X demonstrator will look at and explore all the Challenges of developing a high-power propulsion system, including thermal effects, electric thrust management, altitude and dynamic effects on electric systems and other issues such as electromagnetic compatibility. The objective is to push forward and mature the technology, performance, safety and reliability of hybrid-electric technology. Other major aspects of the program will be to establish new requirements for future certification of electrically powered aircraft and the training needs of a new generation of designers and engineers to bring such commercial aircraft closer to reality.

Partner expertise

The three partners will be exploiting to the full their extensive specialist experience. Airbus will be responsible for overall integration as well as the control architecture of the hybrid-electric propulsion system and batteries, and integration with the flight controls. Rolls-Royce will be responsible for the turbo-shaft engine, two-megawatt generator and power electronics. The engine company will also work on the fan adaption to the existing nacelle and the Siemens electric motor. Siemens will deliver the two-megawatt electric motors and their power electronic unit, as well as the inverter, DC/DC converter and power distribution system. This comes on top of the E-Aircraft Systems House collaboration launched in 2016, which aims at development and maturation of various propulsion system components and their terrestrial demonstration across various power classes. Speaking at the launch, Paul Stein, Chief Technology Officer at Rolls-Royce, said, “The E-Fan X enables us to build on our wealth of electrical expertise to revolutionise flight and welcome in the third generation of aviation. This is an exciting time for us as this technological advancement will result in Rolls-Royce creating the world’s most powerful flying generator.” Speaking for Siemens, Roland Busch, Chief Technology Officer, said, “In April 2016 we opened a new chapter in electric-mobility with the collaboration with Airbus. Building up electric propulsion for aircraft we are creating new perspectives for the company and also for our customers and society. With this partnership we now take the next step to demonstrating the technology in the air.”

The schematic drawing showing the main components in the new propulsion test-bed development aircraft.

(Image courtesy of AIRBUS)

What has been driving this move towards a radical new approach to aircraft propulsion has been the ever stricter moves, globally, towards improved environmental performance. Conventional gas-turbine technology has been advanced greatly with new blade technology, and the use of new materials, to the point where low-noise and emission levels and fuel consumption are reaching near optimum performance. Even such big steps as geared turbofans, in conjunction with new materials and manufacturing methods, are probably getting close to the point where it is difficult to make further substantial game-changing improvements to the performance of jet engines, and undoubtedly electric propulsion, via the path of hybrid designs, now seems an inevitable future course for aerospace. Piston engines reached their zenith in the 1950s and soon declined as pure jets and turbo-props took over, and we may be set to see the last generation of new jet engines over the next twenty+ years, so beyond that there is an emerging market for another propulsion revolution, and electrics and hybrids will be part of that.

Tougher targets

The European Commission has established a 2050 target goal in its Flightpath 2050 Vision for Aviation of reducing CO2 by 60%, NOx by 90% and noise by 75%. At present these ambitious targets are unreachable with today’s technologies, so change must come. This new initiative could start to turn the corner in finally ending the status quo when it comes to designing and powering up new aircraft. For the first time it will be possible to fully appreciate and test solutions towards solving the technical challenges that lie ahead by flying a comparatively large platform test-bed in its natural element – the sky. If all goes well then scaling up the results into a genuine all new narrow body Airbus product will truly be disruptive, and this will pose a challenge Boeing, and others, will not be able to ignore. A Boeing Phantom Works team, based in Spain, has already followed a similar R&D path to Airbus, flying a small general aviation size aircraft with an electric powerplant, and its 787 model features many electrically driven features, but the Airbus, Siemens, Rolls-Royce E-Fan X ups the game considerably by applying the new technology to a much larger platform than any previous programme.

The UK’s aerospace industry has played a massive role in taking forward innovation in aviation technology, from the jet engine to automatic flying controls, blind landing aids, supersonic transport and vertical take-off and landing.

All too often game-changing aviation developments have been left to be more successfully exploited commercially by the industries of other nations, and today Britain’s aerospace sector no longer builds and integrates complete commercial aeroplanes. No other major aerospace nation has adopted such a self-restricting vision, but there can be no doubt that the combined resources of Airbus, Siemens and Rolls-Royce should provide a very impressive line-up of technological expertise which could help drive the next revolution in aerial propulsion. It is to be hoped that if the outcome lives up to the promise then this could contribute to keeping the UK in a world class position as legacy activities decline, providing there is a strong political and industrial will to see it happen. With the world looking for 21st Century solutions to sustain commercial aerospace as demand continues to grow exponentially, this new initiative enjoys perfect timing – the lead must not be squandered.

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