Urban Air Vehicle Mission Sizing and Performance Estimation Using Pacelab APDTM

Abstract

Modern aviation has been focusing on hybrid-electric propulsion in recent years, aiming for concepts with lower atmospheric and acoustic pollution to improve social acceptance of the sector. Development of such new enabling technologies results in emergence of whole new aircraft concepts like Electric Vertical Take-Off and Landing (eVTOL) for urban air mobility. The present work focuses on the preliminary design of a hybrid-electric Vertical Take-Off and Landing (VTOL) air vehicle with multiple ducted fans. A theoretical preliminary sizing model is proposed and then implemented in Pacelab APD(TM), a commercial preliminary design tool developed by PACE Aerospace Engineering and Information Technology GmbH. The performance deck for electric ducted fans is developed in parallel using PROOSIS(TM), a separate dedicated propulsive system simulation software, using flight conditions as input and providing appropriate performance characteristics as output. The targeted powertrain is completed with a turbogenerator, also modelled in PROOSIS as a generic turboshaft engine with an additional electric generator efficiency accounting. After having sized it at cruise condition, a specific fuel consumption map is retrieved. A typical urban air mobility operational framework is considered when building the design mission - composed of vertical take-off, hover, cruise and vertical landing - as well as a range of off-design use case scenarios. Power requirement in vertical flight segments is also estimated. An example of the developed model application in Pacelab APD is provided; it is inspired by existing concepts on the market. It presents a hybrid-electric powertrain with eight ducted fans and a fully composite airframe. The model is implemented in a customized version of APD, along with coding of the missing engineering objects and the propulsive system performance decks exported from PROOSIS. The design mission is then simulated and analysed, suggesting a feasible aircraft solution, which is later subject to sensitivity studies.