Modification of a Scaled Flight Demonstrator for the Implementation and Experimental Investigation of an Energy Harvesting Powertrain in Distributed Electric Propulsion Systems

Distributed electric propulsion (DEP) systems offer a wide range of options for arranging the propulsion units on an aircraft. In most cases, the position of the propulsion systems is optimized for one specific flight phase, e.g., takeoff or cruise. Taking advantage of the high lift potential of the DEP also during descent and approach phases represents a challenge due to increased thrust. Energy harvesting propellers (EHPs) can be used to adapt the resulting thrust, by generation an additional drag force while regenerating a certain amount of energy back into the system. Therefore, the scaled flight demonstrator (SFD) e-Genius-Mod was modified to implement an energy harvesting powertrain in a DEP system. The energy harvesting wingtip propellers are integrated in a pusher configuration. It is possible to investigate different operation modes for recuperation, such as Windmilling and Opposite Pitch, by adjusting different propeller pitch angles. The electronics used for the wingtip propellers (WTPs) enable the control and measurement of the recuperation performance and furthermore to charge recuperated energy back into the battery. The energy harvesting system was tested in a wind tunnel to verify its functionality. In Windmilling mode, the maximum mean electrical power output is −25.7 W. In Opposite Pitch mode, the values were significantly higher, with a maximum mean electrical power of −184 W. This corresponds to up to seven times as much regenerated power in Opposite Pitch mode.