Development of a Safe Powertrain System Architecture for the HorizonUAM Air Taxi Concept

Abstract

The German Aerospace Center project HorizonUAM encompasses numerous research areas regarding urban air mobility. Whithin this context, this presentation aims to explain the design process for deriving a safe all-electric multirotor propulsion system for one of the HorizonUAM air taxi concepts. The main challenges for the multirotor propulsion system are the highly demanding certification requirements, especially in terms of system reliability, which are laid down within the means of compliance of the EASA SC-VTOL. Using a model-based systems engineering design approach which follows the safety design methods of ARP4761, different multirotor propulsion system architectures were iteratively developed, analyzed and further optimized to meet the required system reliabilities. The result of one proposed powertrain propulsion architecture, incorporating 4 main rotors and two push propellers, is presented herein. In addition to the powertrain architecture design each powertrain component, like the electric motor, the motor controller as well as a gearbox, was sized and compared with current state of the art technology. To verify the dynamic behavior of the whole powertrain a simulation model was set up. It could be shown that the powertrain can be build up using currently commercially available components and that the rotor reaction times seem to be acceptable. However, due to the low rotational speeds of the rotors, it is highly advisable not to use a direct drive but rather a gearbox to avoid high thermal losses. In the next future step, the different system models, which were implemented will be integrated to achieve a holistic integrated system model.