A First-Principle Power and Energy Model for eVTOL Vehicles
A number of well-established aircraft manufacturers, such as Airbus, Boeing, or Bell, along with new startups have begun developing flying prototypes of electric Vertical Takeoff and Landing vehicles (eVTOL). To certify this emerging type of air mobility vehicles for commercial use, the Federal Aviation Administration (FAA) is considering adjusting currently used certification procedures for small aircraft to include eVTOL vehicles. One of the hurdles to this approach is that eVTOL vehicles are neither able to glide like a small, fixed-wing aircraft, nor to autorotate, like a helicopter, if the batteries are depleted. Therefore, active energy management and energy awareness by the pilot is needed to safely operate an eVTOL vehicle. To do this, the cockpit must be equipped with an energy management display, informing the pilot about momentary power demand and about projected energy expenditures. To assess the operational capabilities and safety of eVTOL vehicles, the civil aviation authorities require simulation tools to evaluate the energy consumption of standard flight profiles. No published research addresses the need for energy-based trajectory simulation and for real-time power draw prediction. This thesis fills this capability gap by developing a way to simulate power and energy consumption for an eVTOL vehicle over variety of user specified two-dimensional flight profiles. Depending on the propulsion approach, four major eVTOL vehicle types are recognized by the model based on the currently developed prototypes: tilt propulsion, tilt wing, distributed propulsion, and fixed propulsion. The model accepts user input specifications for these vehicle types, along with information on the desired flight profile and environmental disturbances. To allow for multiple flight profile iterations to be run in sequence, the model also accepts batch input for the range of flight profile variations to be simulated. Forces acting on the vehicle at each time step of tis flight are then computed, and power and energy related outputs are generated. The first-principle power and energy model developed within this thesis can serve as a first step towards an inflight power and energy management system for eVTOL vehicles, to satisfy the near future certification requirements associated with these vehicles. The model provides estimates on instantaneous battery power draw throughout the simulated flight profile along with energy requirements for the vertical, transition, and cruise flight phase. Although generating results within expected theoretical magnitudes, the model is yet to be validated experimentally.