Distributed electric propulsion and boundary layer ingestion are two attractive technologies to reduce the power consumption of fixed wing aircraft. Through careful distribution of the propulsive system elements, higher aerodynamic and propulsive efficiency can be achieved, as well as a lower risk of total loss of aircraft due to foreign object damage. When used on the wing, further reductions of the bending moment on the wing root can even lead to reductions of its structural weight, thus mitigating the expected increase of operating empty weight due to the extra components needed. While coupling these technologies in fixed-wing aircraft is being actively studied in the big aircraft segment, it is also an interesting approach for increasing the efficiency even for aircraft with maximum take-off masses as low as 25 kg, such as the A3 open subcategory for civil drones from EASA. This paper studies the effect of changing the propellers’ position in the aerodynamic performance parameters of a distributed electric propulsion with boundary layer ingestion system in a 25 kg fixed-wing aircraft, as well as in the performance of the propellers. The computational results show the trade-offs between the aerodynamic efficiency and the propeller efficiency when the vertical position is varied.

Surge occurrence in automotive engine turbochargers is known to be dependent on the installation conditions. It is proven that the flow pattern produced by the inlet ducting at the compressor inducer modifies surge margin. But also the engine intake line acoustics, both compressor upstream and downstream, affects turbocharger surge. In the paper the effect of different parameters in the intake line geometry on compressor surge is investigated. Modifications in the air filter volume, compressor inlet geometry and compressor outlet length have been considered. Surge limit obtained on a steady gas-stand is compared to those measured on the engine test bench using two different methodologies. Testing results show significant differences in term of surge line shift and the corresponding engine low end torque.A 1D model of the engine has been built using a non-steady compressor model able to predict surge occurrence. This model is based on the Greitzer's lumped model and uses the steady flow map extended to the surge and negative flow zones. In the paper some results of the model are presented showing the difficulty of predicting surge limit in engine steady conditions.