Innovative methods for aeronautical piston engine

Aeronautical piston engine should be 99.9999% reliable, efficient and very compact. Emissions are not very critical: since requirements are not as stringent as in automotive application and power output is kept very close to the maximum all flight long. Another advantage of the aeronautical field is that noise is not so important: propeller/fan noise usually overcomes engine noise. Engine design is mostly technology driven: manufacturing methods like precision casting, friction stir welding and investment casting should be used to obtain optimum results. Fuel management and combustion control system are also critical for optimum efficiency: FADEC (Full Authority Digital Control) and high pressure injection systems are commonplace. Material choices are driven by reliability and weight. Aluminium, titanium and magnesium alloys, CFRP (Carbon Fibre Reinforced Plastic) and thermoplastics are to be included. Engine architecture and choices are oriented to obtain the most compact and lightweight solution. In this field the installation of accessories and modularity for power output increase are also considered. In this paper the design process of a new family of engine is introduced with the results of different design strategies and concepts. Several engines have been modelled and compared. At the end a very small engine was designed from the inside to the outside. The evolution of an already experimented combustion system has been adopted. The final result demonstrated that extensive CAD, FEA and CAM work with selective methodology should be performed well before the first component is manufactured and tested.