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This article deals with the design, manufacturing, and testing of a propeller for a general aviation aircraft fuelled by hydrogen. The feasibility of the ENFICA-FC project depended on several key-enabling technologies. In order to minimize the power required from both the batteries and the fuel cell, a highly efficient electrical propulsion system was required, in which all the components would need to yield the highest possible efficiency. The choice of the propeller for this specific aircraft was more difficult, above all because the electric motor was limited as to the torque it could handle. In addition, the propeller would also have to provide the necessary airflow for the motor, electronics, and fuel cell cooling to ensure that the temperature did not exceed the limits imposed by the manufacturer. Although a designer may be aided by modern numerical design and analysis programmes to optimize propellers, structural and manufacturing constraints can influence the final choices. Finally, the calculated performance would always have to be validated with experimental tests. An optimal propeller has been designed and manufactured to be installed on the Rapid 200 FC aeroplane. Static tests on the manufactured two-blade propeller were performed by means of a static test facility. Specific tests have also been performed to check the efficiency of the propeller when installation effects (blockage and scrubbing drag effects) are included and to verify the real efficiency of the propulsion and cooling systems, with the propeller installed in the complete converted aircraft. A good agreement between the theoretical and experimental data was obtained.

The main objective of the project is to develop and validate the use of a fuel cell based power system for the propulsion of more/all electric aircraft. The Rapid 200-FC two-seater electric-motor-driven aeroplane which is powered by fuel cells is at present being completed and will be validated during a flight test in Autumn 2009. Several configurations have been evaluated in order to install the new energy and propulsion system on board while maintaining the centre of gravity within allowable limits. The fuel cell system and the electric motor are being integrated on board. The FC stack will be able to deliver a maximum continuous power of 20kW. A battery pack has to guarantee another 20kW of maximum continuous power for a limited time period (15 minutes), during take-off, climbing and, in the case of emergency, during landing. The main goal of the project is to validate the overall high performance of an all electric aircraft system which is capable of remaining aloft for one hour. A parametric analysis has also been carried out to evaluate which key technologies influence the performance of future aircraft to the greatest extent.