What is the Engines ITD and what are the challenges?

The Engines ITD will build on the success of the Sustainable and Green Engine (SAGE) ITD of Clean Sky 1, working towards radical engine architectures and new engine technologies to power the aircraft of the future. All the activities under the Engines ITD in CS2 have a common goal: to increase fuel and energy efficiency of the engine and reduce environmental impact, regardless of whether the engine is powering a large airliner or just a small utility aircraft, meaning more thrust while burning less fuel and emitting less CO2, NOx and noise.

But what exactly is an engine?

The main function of an engine is to convert fuel - basically stored energy - into mechanical or propulsive power to overcome gravity and air resistance, allowing aircraft to take off and fly. But they are also essential for generating power for a long list of important features and functions, e.g. in the cabin for the galleys, or for the inflight entertainment systems, or in the cockpit for the navigation and communication systems. The power that is needed to actuate the many moving surfaces on the wings and empennage (the tail) to manoeuvre the aircraft in the right direction is also generated by the engines.

All of that is a colossal workload for the engines, which have to function efficiently for hundreds of hours between major inspections, maintenance and overhaul.

In turn, it's the skill of the designers, engineers and manufacturers of those engines that determine their efficiency and reliability, and the fuel consumption determines the cost of the flight tickets. In 2015, 29% of airline operating expenditure was on fuel. So in the end, society in Europe benefits twice: cheaper flights and less pollution.

The challenge for the players in the Engines ITD Programme of Clean Sky 2 is to use the achievements gained in Clean Sky 1's SAGE Programme to advance aero-engine technologies to a state of eco-compliance and technological readiness that can be employed in a whole range of aircraft that will take to the skies in the 2025 to 2050 timeframe.

That challenge requires unprecedented capacity for foresight, imagination and innovative thought, for the efficiencies required – as the planet's finite fuel resources become ever-precious – are almost unimaginable.



In Clean Sky 2, the Engines ITD will build on the success of Clean Sky 1's SAGE. The main objectives are to deliver substantial improvements in engine technology. In particular, the following challenges will be addressed:

  • Developing full engine and major engine system solutions that can deliver a step change reduction in emissions.
  • Taking a step-by-step approach to progressing the technology’s maturity or "Technology Readiness Level" (TRL), utilizing design studies and rig tests to explore and understand the technologies under development, their system interactions and the risks associated with their implementation. The ultimate goal of the project is to achieve TRL6.



Eight groups of platforms or demonstrators are planned, catering to the full spectrum of aircraft in commercial operations – from 4-19 seater aircraft in the SAT category – to the largest wide-body aircraft:

Open Rotor Flight Test, 2014-2023:

A 2nd version of a Geared Open Rotor demonstrator, building on Clean Sky SAGE 2 achievements and aimed at validating the demonstrator to TRL 6, will be ground-tested and then assessed on the Airbus A340 flying test bed (see IADP LPA Programme). From the initial SAGE 2 demonstrator, some engine modifications aimed at various improvements, control system updates, and engine/aircraft integration activities will be necessary.


Ultra High Propulsive Efficiency (UHPE) demonstrator addressing Short / Medium Range aircraft market, 2016-2021:

Design, development and ground testing of a propulsion system demonstrator will be carried out to validate the low pressure modules and nacelle technology bricks necessary to enable an Ultra High Bypass Ratio engine (e.g. advanced low pressure fan, innovative nacelle modules, gearbox, pitch change mechanism - if any, and high speed power turbine). This ground demonstrator will be built around an existing high pressure core.


Business aviation / Short range regional Turboprop Demonstrator, 2015-2020:

Design, development and ground testing of a new turboprop engine demonstrator in the 1800-2000 thermal hp class will be made. The base line core of ARDIDEN3 will be improved, specifically for turboprop application (compressor update, combustion chamber, power turbine), and then integrated with an innovative gear box, new air inlet and innovative propeller.


Advanced Geared Engine Configuration (HPC and LPT technology demonstration), 2015-2020:

Design, development and ground testing of a new demonstrator to validate key enablers to reduce CO2 emissions and noise as well as engine weight. Key elements are: improvement of efficiencies, reduction of parasitic energy flows, innovative lightweight and temperature resistant materials, low pressure turbine and exhaust noises reduction.


Very High Bypass Ratio (VHBR) Large Turbofan demonstrator, 2014-2021:

Design, development, construction, ground testing and flight testing of an engine to demonstrate key technologies on a scale suitable for large engines. An existing engine will provide the core gas generator used for the demonstrator. Key technologies included in this demonstrator will be: an integrated low pressure system for a high power very-high bypass ratio engine (fan, compressor, gearbox, LP turbine, VAN), Engine core optimisation and integration, and optimised control systems.


Very High Bypass Ratio (VHBR) Middle of Market Turbofan technology, 2014-2021:

Development and demonstration of technologies in each area to deliver validated power plant systems matured for implementation in full engine systems. Research and demonstration will focus on assessing the behaviour of fans at low speeds and fan pressure ratios and structural technology, aerodynamic and structural design of low pressure turbines for high speed operation, Systems Integration of novel accessory and power gearboxes, optimised power plant integration, Compressor efficiency, and control & electrical power system technology developments.


Light weight and efficient jet-fuel reciprocating engine

The Small Aero-Engine Demonstration projects related to SATs (Small Air Transports) will focus on small fixed-wing aircraft in the general aviation domain, with power-plant solutions ranging from piston/diesel engines to small turboprop engines. These technologies will bring new solutions to replace old gasoline leaded fuel pistons or small turbines for single and twin engine aircraft. The scope includes the core engine in order to improve the power density. Other equipment including the turbocharger, the propeller integration and the aircraft installation optimisation will also form part of these projects.


Reliable and more efficient operation of small turbine engines

This area in the Engines ITD will focus on the reliability and efficiency gains in a small turbine engines demonstration project for business and general aviation for 19 seat aircraft, developing leading edge technologies, design tools and manufacturing technologies for application in spiral development programmes as well as in new engine architectures.




Tomorrow’s challenge, today’s call to action

Rolls-Royce's Market Outlook for the period 2014-2023 sees a need, globally, for 27,000 new aircraft, requiring 55,000 engines, spanning large passenger aircraft, regional planes, and business jets. It's a huge market opportunity for the EU aviation industry to maintain and extend its global leadership, but also a major challenge to deliver radical new engine architectures and advanced technologies which are much needed to continue the emissions reductions and to meet overall sustainability targets to comply with ACARE and Flightpath 2050 Goals.



The Clean Sky initiative will focus on fuel efficiencies - and ecological compliance. The new technologies being developed within the Clean Sky ecosystem get to the heart of the challenge – more intelligent use of scarce resources and less impact on the environment. As a result, the global air transport of the future will be ready to operate aircraft equipped with the latest, cleanest and most efficient engines, thanks to Clean Sky.

Clean Sky E-News

Have a look at the latest editions of our monthly newsletter. You can read the previous version here. To get E-News delivered directly to your inbox, subscribe here:

Discover past E-News