Motivation
As emissions by aircraft are deemed particularly climate-damaging and contribute a growing share to global CO2 emissions, electric propulsion receives increasing attention. Besides its potential of emitting zero emissions at high altitude, the scalability and low complexity of electric motors allow their use in new configurations as „distributed, electric propulsion“. A larger number of small, electrically driven propellers could reduce energy consumption by using propeller-wing interaction effects for higher aerodynamic efficiency. From a flight mechanics point of view distributed, electric propulsion opens up new possibilities for flight control.
Research Activities
The iFR develops and operates an unmanned, autopiloted, modular test platform (picture) in collaboration with the Institute of Aircraft Design (IFB) at the University of Stuttgart to investigate new configurations based on distributed, electric propulsion with respect to performance and efficiency. The test platform is a scaled (1:3) version of the record-winning e-Genius aircraft that can be equipped with additional electric motors in various configurations and is currently used to measure the influence of wing-tip propellers on the induced drag. Subsequently, the test platform will be modified to investigate the influence of a larger number of small, distributed electric propellers on the aircraft drag, noise emissions and high lift potential. The UAV is equipped with an autopilot developed at the iFR which provides highly accurate trajectory tracking for automated flight testing, yielding a test setup with high accuracy and repeatability.
At the same time the UAV is used to develop and test algorithms for the efficient control of new, electric configurations. In order to also test this on larger, manned systems, the solar powered icaré aircraft operated by the IFB has been equipped with electrically driven wing tip propellers. Their use for yaw control has recently been demonstrated during manned flight tests.
Objectives
The goals of the activities at the iFR within the field of distributed electric propulsion are
- To investigate the effects of distributed electric propulsion configurations on the aerodynamic drag and flight dynamics properties through flight testing and parameter estimation methods.
- To develop and flight-test new control and allocation methods for over-actuated, electric aircraft configurations.
Publications
Pfeifle, W. Fichter, D. Bergman, J. Denzel, A. Strohmayer, M. Schollenberger and T. Lutz, „Precision Performance Measurements of Fixed-Wing Aircraft with Wing Tip Propellers" in AIAA Aviation Forum, Dallas, 2019
Bergmann, J. Denzel, O. Pfeifle, S. Notter, W. Fichter and A. Strohmayer, „In-flight Lift and Drag Estimation of an Unmanned Propeller-Driven Aircraft“ in Aerospace, Vol 8, No. 2, 2021
Pfeifle, M. Frangenberg, S. Notter, J. Denzel, D. Bergmann, J. Schneider, W. Scholz, W. Fichter and A. Strohmayer, „Distributed Electric Propulsion for Yaw Control: Testbeds, Control Approach, and Flight Testing" in AIAA Aviation Forum, Washington, 2021 (accepted for publication)
