Project overview

About Horizon 2020

Horizon 2020 is the biggest EU research and innovation programme ever. Almost €77 billion of funding is available over seven years (2014 to 2020) – in addition to the private and national public investment that this money will attract.

Horizon 2020 will help to achieve smart, sustainable and inclusive economic growth. The goal is to ensure Europe produces world-class science and technology, removes barriers to innovation and makes it easier for the public and private sectors to work together in delivering solutions to big challenges facing our society.

About Clean Sky

Clean Sky is the most ambitious aeronautical research programme ever launched in Europe, aimed at reducing CO2, gas emissions and noise levels produced by aircraft. Funded by the EU’s Horizon 2020 programme, Clean Sky is a Public Private Partnership between the European Commission and the European aeronautics industry. Clean Sky coordinates research and innovation between industrial leaders, universities, research centres and SMEs.

The original Clean Sky 1 programme was launched in 2008 and ran to 2017.

Following the success of the initial Clean Sky Programme, its successor, Clean Sky 2 was launched in 2014, and runs until 2024. Clean Sky 2 aims to be the main contributor to the Commission’s Flightpath 2050 goals set by ACARE, which are more ambitious than those of the initial Clean Sky Programme.

Clean Sky’s core mission is to develop breakthrough technologies to significantly increase the environmental performance of aircraft. Specific environmental aims are fourfold:

  • to reduce fuel burn
  • to lower CO2 emissions
  • to mitigate external noise levels by up to 50%
  • to reduce NOx emissions by up to 80% by 2020, compared to 2000 levels

Complementing environmental targets, Clean Sky also aims to contribute to European competitiveness and mobility, with the creation of sustainable growth and skilled employment in the air transport sector.

Clean Sky 1 had a budget of €1.6 billion

Clean Sky 2's budget is €4 billion

Company Profiles



SMA was formed as part of a joint venture between Socata and Renault Sport F1 in 1997, and then became a 100% subsidiary of Safran in 2005, which in turn became a subsidiary of Snecma (now Safran Aircraft Engines) in 2006. Since January 2018 SMA is the Piston Engine Division of Safran Aircraft Engines.

SMA designs and produces "Jet Fuelled" piston engines for general aviation and aeronautical applications.

SMA develops, manufactures, and sells a new generation of compression ignition engines, purposely-designed for aeronautical applications. SMA engines are specifically designed for single and multi-engine aircraft.

SMA supports OEMs for new applications, by offering specific versions of engines adapted to their application requirements, and providing technical assistance through integration and certification.

Reflecting a constant focus on innovation, SMA dedicates a large part of its resources to R&D. SMA is continually investing on the technologies needed to guarantee the future of its technology which offers derivative applications. SMA is a co-partner in leading R&D programs.

IlmorIlmor Engineering      

Ilmor Engineering Ltd. was founded by Mario Illien, Paul Morgan and Roger Penske in 1984, initially to design, develop and manufacture engines for the IndyCar series.  Since then Ilmor have gone on to win more than 300 IndyCar races including 17 Indy 500 wins.

In the early nineties Ilmor made the natural progression to Formula One, supplying Leyton House, March and Tyrrell. In 1993 Mercedes-Benz announced their collaboration with Ilmor, providing the financial backing for the V10 engine supply to Sauber.

In 1997 David Coulthard took the first Ilmor Formula 1 race win, then in 1998 and 1999 Mika Hakkinen raced the Ilmor engines to the Formula 1 World Championship.

In 2001, Ilmor began to develop the GM IRL engine, which led to a speculative engine design for the new 2003 IRL rules and the beginning of the relationship with Honda. The design, manufacture and joint development of this engine resulted in a further expansion into what became known as the Special Projects Group, forming a discrete business with its own dedicated resources, within the rest of the company. In late 2002, Mercedes-Benz elected to begin a phased buyout of Ilmor. The Special Projects Group found that this had limited opportunities to expand its business portfolio and so Roger and Mario elected to buy Special Projects from Mercedes, along with the Ilmor name. This was accomplished by the end of June 2005 and a new Ilmor was born.

Racing remains the core part of Ilmor’s business today and it acts as a consultant for motorsport clients from all forms of racing. However, the business is now using its racing expertise to diversify into other areas such as OEM automotive, defence, marine and energy efficient engine applications.

Project Background

The objective of the project is to look at methods of improving the power-weight ratio (power density) of a current state of the art diesel fuelled piston engine for light aircraft use. Improving the power density of the engine will increase aircraft performance as well as reduce fuel consumption / CO2. This has obvious environmental benefits as well as reduced operating costs for the aircraft owner.

Increasing the performance of the engine is easily achieved by changes to the fuel injection system on the engine. However, this increased performance results in higher loads on the engine due to the increase in pressure and temperature within the cylinders during combustion.
The project is therefore challenging in that it requires many of the components to have increased strength and stiffness but also reduced mass.  This can only be achieved by careful detail design of components along with the use of alternative materials and methods of construction. A significant amount of computational analysis was used to predict that the revised components could meet the durability requirements.

The certified engine selected for this project by Clean Sky management was the SMA SR305-230E.


The current version of SMA’s SR305-230E designed for the general aviation market, specifically for jet fuels aircraft, was certified by EASA and FAA in 2011.

The SR305-230E is mounted on C182 aircraft (SMA STC) and has been selected by Odessa aircraft plant for the DELFIN aircraft, as well by Diamond Aircraft for DA50 aircraft.

Sr305-230e engine

Figure 1 - SR305-230E engine


Power: 169kW (227 hp)
Critical altitude: 10,000 ft
Certified ceiling: 20,000 ft
Displacement: 5 litres (305 cu. Inch.)
Fuels: Jet-A, Jet-A1, Russian TS-1, Chinese N° 3, JP-8
Brake S.F.C.: 219 g/kW/hr (0.36 lb/hr/hp)
Diesel oil: Aeroshell
Engine speed: 2,200 rpm
Weight: 206Kg (455 lb)
TBO: 2,400 hours

Project aims

In order to improve the power density of the SR305-230E engine, the following improvements to the engine specifications were set out:

  1. Reduce mass of engine
  2. Increase the engine cooling performance

Reducing the overall mass of the engine has obvious benefits in terms of fuel consumption and aircraft performance.

Increasing the power output of the engine to 265hp, which is easy to do, raises the temperatures and pressures which the engine components are subjected to. Increasing the cooling performance of the engine has benefits in terms of reducing the stresses and maintaining component life.

Project structure

The project was composed of 4 stages, termed Work Packages.  The details of each Work Package were as follows:

WP1: research and definition of scope of work – 22 weeks

In order for Ilmor to gain a thorough understanding of the current engine, a series of regular teleconference meetings were conducted, as well as a facility visit to SMA.  Ilmor was provided with the necessary details to allow an exchange of ideas to take place, to highlight areas where mass could be reduced.

SMA also provided Ilmor with a complete digital model of the current engine, along with analysis test data which would later form the baseline against which the new design could be assessed.

Based on initial discussions, the digital data was used to carry out a preliminary Finite Element Analysis (FEA) of the crankcases and the con-rod.  The results of these allowed Ilmor to understand the nature of the stresses within the current engine at the increased power output.

With this knowledge an informed and detailed scope of work was defined with SMA.  This addressed exactly which components would be modified, and the depth of analysis required.  In turn, a comprehensive timing plan and project budget was finalised.

WP2: analysis and part redesign – 35 weeks

Work package two dealt with all of the component design and analysis.  A team of three engineers worked full time for a period of 35 weeks, with additional analysis staff deployed when required.

Components were designed using Catia V5 CAD software.  Structural and thermal analysis were carried out using ANSYS Workbench, and fluid calculations of oil cooling and air flow management were completed using Converge CFD.  Engineering drawings were produced for all manufactured components.

The project provided Ilmor with a good opportunity to introduce some novel and advanced methods of design and manufacturing to the aerospace industry.

WP3: manufacture of prototype parts – 36 weeks

All casting work was carried out at Grainger & Worrall, located in Bridgnorth, UK.  The existing SMA cylinder heads were all cast at G&W, so there was a large experience base to call upon.  For this project, considering the complexity and small volumes involved, G&W used rapid prototype cores (printed sand).  This allowed the production of the cores to take place very quickly, and incorporate highly complex geometry in both the cylinder heads and barrels.

For the larger crankcase components, introducing steel inserts into the cast aluminium structure was a technical highlight which was designed to give increased strength around the main bearings.

Ilmor has its own on-site manufacturing facility, with a wide ranging machining capability.  All crankcase, cylinder barrel and cylinder head machining was carried out at Ilmor.

Manufacture of certain parts, like the inlet and exhaust valves, and the 850mm long main studs were carried out at external suppliers. Specialist processes like plasma coating and honing of the cylinder barrels, were also left to companies whose skill and experience in those areas were required.

WP4: engine assembly, test, disassembly and evaluation – 26 weeks

The prototype parts were shipped to SMA’s Villaroche facility where they were assembled by the same engineers who assemble the existing SR305-230E.  Much of the process and the tools required for assembly are common to both the existing and prototype engines.  Where the process differed, Ilmor supplied SMA with a comprehensive set of build instructions.

In order to monitor the running temperatures, the engine was equipped with two specially machined cylinder heads and barrels which were fitted with a total of 76 thermocouples.

The build took place over a period of 2 weeks, then the engine was transported to EMC France, the external test facility used regularly by SMA for testing their aero engines.

The engine was tested in accordance with SMA’s test procedures, and then returned to Villaroche for disassembly, and analysis.

Post-test evaluation included analysing the test data, and Ilmor visiting the SMA facility to assess the condition of the engine components. Many of the components were returned to Ilmor for more detailed evaluation.

Design and analysis tools

The design work was carried out using Dassault Systeme’s Catia V5, which is the software used by both Ilmor and SMA for mechanical design. Collaboration using digital data was carried out using SMA’s secure file transfer protocol.

Finite Element Analysis was carried out by Ilmor using ANSYS.  Computational Fluid Dynamic studies were carried out using Converge CFD.

Machining and inspection of parts

Ilmor’s state of the art machine shop is AS9100 certified and used for machining of all of its in-house racing projects and many customer projects. Typical components range from large castings (such as for this project) to machined-from-solid components, through to more intricate parts requiring 5-axis control.

Customers are primarily from the automotive industry, but also from other industries, including Aerospace.

For the Horizon 2020 project, all castings were machined in-house, including crankcase halves, the crankcase assembly, cylinder heads and barrels.

Ilmor’s inspection department is a key part of the production cycle, and is used to ensure that parts are produced to the specifications defined on the drawings.

Plasma coating of the cylinder barrels was done at Oerlikon Metco, and the subsequent honing was carried out at an external supplier.

Main and auxiliary studs were machined by the supplier of the existing studs, Lisi Aerospace. Inlet valves were produced by Zanzi, a specialist valve manufacturer, and the combustion seals are manufactured by Trelleborg.

European logo
This project has received funding from the Clean Sky 2 Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 686533