MALET – DEVELOPMENT OF TECHNOLOGIES FOR HIGH HEIGHT AND LONG FUEL DISTANCE PROPULSION OF UNMANNED AIRCRAFTS founded within Progetti PON “Ricerca e Competitività” 2007 – 2013. The aim of the project is to acquire technologies and their validation in order to develop a propulsion system for Unmanned Aerial Vehicle (UAV) that have a mission at a high altitude for a long duration. The purpose of the research is to find technological solutions that make an internal combustion engine deliver enough power even at a high altitude, respecting the aeronautical constraint of the low value of weight/power ratio. The propulsive system that was suggested, which the technological project derives from, will be based on a two stroke engine with direct injection electronically controlled (common rail). The choice of the Diesel common rail two stroke engine aims to give the best balance between the structural weight, the required efficiency, the necessity to keep low the thermo-mechanical loads in the combustion chambre and the deliverable power.

This engine will be supercharged by a multistage system, which will be light and efficient. In this system an innovative electrical and fluid dynamic machine (MEF) will be integrated, which will recover the overproduced energy, that would be dissipated at low altitude through the wastegate valves, and eventually supply energy in order to compress the air and so aid the supercharging system. The supercharging system with MEF minimizes the use of wastegate valves allowing, when an overuse of overboost is present, the elaboration of supercharged flow and the conversion of mechanical energy in electrical energy available on board. The MEF machine works also as a separated blow for engine ignition, replacing with more lightness and efficiency the classic Roots compressor. All the technologies will be tested at a ground level with the realization of a technological demonstrator, that will be submitted to experimental investigation including simulations at the maximum flight altitude.

The tests will provide the characterization of the principal engine parameters together with those characteristic of aeronautical applications. The tests will come to an end with the integration of the demonstrator on an UAV vehicle in order to test out the main features. She is involved in particular in the CFD fluid dynamic simulations of the two stoke engine.