The only way is up: NextGenCTR takes shape
The NextGen Civil Tiltrotor project, led by Leonardo, is poised to become one of Clean Sky's flagship full-scale technology demonstrators when it takes to the skies in 2023. Therefore 2020 is an important year as the major milestones of critical design review and assembly of the fuselage and wings get underway.
Congested roads and airports reaching capacity are just two of the main obstacles in Europe's path towards better door-to-door mobility. What if these infrastructural constraints could be circumvented? That's a key premise of the tiltrotor paradigm, a passenger aircraft that can take off and land vertically without airports. Beyond civil air transport, tiltrotor aircraft are ideal for a range of missions that serve specialised societal needs, such as medical evacuation, search and rescue, and other utility roles where airport infrastructure is limited or unavailable. Developing and maturing the enabling techno-bricks that transform the concept into a viable aircraft – while meeting stringent environmental criteria – depends on bringing together the best of European aerospace industry expertise. Clean Sky has been enabling this collaboration, and a good example is the NextGen Civil Tiltrotor (NextGenCTR) technology demonstrator. The ambitious environmental goals for the NextGenCTR, which are relative to the Leonardo AW139 helicopter, aim to cut CO2 emission by half, to lower NOx by 14%, and to mitigate noise by 30%.
‘To reach the planned goals, ground-breaking technologies need to be considered and developed to be integrated into the flight demonstrator. This ambition could not be achieved without the Clean Sky 2 programme, which brings together different yet complementary competences from every part of Europe. The grants scheme and the public private partnerships facilitated through Clean Sky enables the development of techno-bricks and innovative design and manufacturing processes including composites, additive manufacturing and low weight solutions,’ says Antonello Marino, Clean Sky project officer.
‘The NextGen Civil Tiltrotor involves a numerous amount of organisations — universities, SMEs and major aerospace companies. The interaction between the different partners involved is very significant for European aviation beyond the NextGenCTR project itself, with various companies interacting during different grant projects, and creating new synergies between companies that were unknown to each other prior to the programme,’ says Marino.
Regarding the NextGenCTR configuration specifically, the focus at this stage is mainly on the wing, the tilting mechanism and the relevant sub-systems (e.g. fuel tanks). 2020 is set to be an eventful year with significant milestones:
‘The Critical Design Review (CDR) of NextGenCTR will take place in 2020 and that should be the trigger for the manufacture of the main parts and sub-assemblies, so that at the end of the CDR we will have drawings released for internal manufacturing within Leonardo's facilities,’ says Andrea Artioli, the NextGenCTR programme manager at Leonardo. ‘Concurrently, the specifications for the manufacturing will be released. Clearly, the manufacturing will take a couple of years, through 2021 and 2022, and then in 2023 we will make the necessary set up for the first ground run and the first flight.’
Taking part in Clean Sky enables aviation stakeholders of all sizes to work together, developing stronger connections and networks, as Artioli points out. ‘Leonardo is taking huge benefit from this. First of all, we have been establishing a number of relationships with partners and we'll reach more than 25 different partnerships, just within the NextGenCTR. These partnerships are a mix between specific relationships with major industrial players, SMEs, research institutes and academia. Within the NextGenCTR programme we will have to develop the design of parts supporting the technology demonstrator but we will also have to perform a number of tests, supported by a relevant post-processing analysis that will be performed by a number of players within Europe, including the Netherlands Aerospace Centre (NLR), the German Aerospace Centre (DLR), Politecnico Milano, the Italian Aerospace Research Centre (CIRA) and other research innovation centres across Europe.’
‘We are taking an active part in the Clean Sky ecosystem, and that ecosystem is structured in a versatile way that provides opportunities to grow in terms of shared knowledge across partners and our supporting partners,’ adds Artioli. ‘It also opens doors to develop potential relationships for the future of European aviation. Our main objective is to leverage this NextGenCTR programme to acquire the necessary knowledge in order to be able to perform our own design and development for a new family of tiltrotor products within the 2030 to 2035 timeframe. Leonardo has been developing tiltrotor technologies and R&D for more than 20 years. Over this period, we've entered into various partnerships, on a smaller scale in terms of budget and ambition, with the intent of developing a new vision for tiltrotors. But now with Clean Sky 2 we can take a bigger step forward.’
Pierre Abdel Nour, chief of design and aircraft system integration for the NextGenCTR programme at Leonardo, adds that ‘the tiltrotor architecture will enable European aviation to demonstrate operational flexibility through the development of a “statement aircraft” that can take off and land without requiring significant infrastructure. This will be very beneficial in terms of facilitating transportation between cities, towns and big hubs in Europe that will have to cope with unprecedented congestion in the future. The tiltrotor is a unique solution, offering the capability of flying as fast as an aeroplane at high altitude with a pressurised cabin and producing low noise. That combination of NextGenCTR's technical capabilities will be highly beneficial for the future of European transportation.’There’s been a recent focus on VTOLs – aircraft that can hover, take-off, and land vertically – in urban environments. Another potential benefit of the programme could be a leveraging of the vertical take-off architecture currently being matured for the NextGenCTR project, says Abdel Nour: ‘Part of the exploitation is that as we deal with the tiltrotor, we will become familiarised with how to integrate and manage complex and sophisticated control systems for managing tilting and lifting surfaces, and how to control aircraft tilting rotors and tilting adapted fans. So what we learn through the development of the NextGenCTR may also be reusable and relevant to VTOL urban mobility.’
Nour considers that one of the biggest challenges of the NextGenCTR programme is how to integrate different and complex technologies so that significant operational and environmental improvements are delivered, surpassing the state-of-the-art:
‘The current tiltrotors are based on configurations and technologies that have developed and matured over 40-50 years, so the biggest challenge we are going to face is to develop a completely different configuration of tiltrotor. The key is to have a good interpretation of the past and a good vision for the future, to make it better.’
Another challenge is to reach a 30% noise reduction compared to Leonardo's AW139 helicopter, as the next generation of tiltrotors will have to operate quietly over towns and cities.
‘We have already analysed the impact of noise, and through the Clean Sky 2 Technology Evaluator we have shown that compared to the standard legacy aircraft, when flying over populated areas there will be tremendous benefits because the technologies we are working on will make the NextGenCTR much quieter than a helicopter,’ says Abdel Nour. ‘The tilting rotor enables us to modulate the approach and landing phases and manage the noise in a different way. Also in terms of internal noise, in the passenger cabin, this will be very quiet during the cruise, just like airliner comfort. Comfort on board is equally important.’