Advanced Sizing Methodology for a Multi-Mode eVTOL UAV Powered by a Hydrogen Fuel Cell and Battery

Abstract

A critical drawback of battery-powered eVTOL UAVs is their limited range and endurance, and this drawback could be solved by using a combination of hydrogen fuel cells and batteries. The objective of this paper is to develop a sizing methodology for the lift+cruise-type eVTOL UAV powered by a hydrogen fuel cell and battery. This paper presents the constraints analysis method for forward flight/VTOL multi-mode UAV, the regression model for electric propulsion system sizing, a sizing method for an electric propulsion system and hydrogen fuel cell system, and a transition analysis method. The total mass of the UAV is iteratively calculated until convergence, and the optimization method is used to ensure that the sizing results satisfy the design requirements. The sizing results are the UAV’s geometry, mass, and power data. To verify the accuracy of the proposed sizing methodology, the sizing and the conceptual design phase results of a 25 kg hydrogen fuel-cell-powered UAV are compared. All parameters had an error within 10% and satisfied the design requirements.

Conceptual design and sizing optimization based on minimum energy consumption of lift-cruise type eVTOL aircraft powered by battery and fuel cell for urban air mobility

“…( 15). Finally, the difference between stall and cruise velocities is the inequality constraint (16) in the sizing problem.…”

“…To better exploit the specification of the battery and the fuel cell system, in this investigation, battery provides energy in the hover and transition+climb flight modes of the aircraft, while the fuel cell is used for the cruising and accel+climb flight modes of the aircraft. This approach has been accepted in the literature and has examples for some UAVs (example of [14]- [16]). Nevertheless, after this preliminary work, more advanced energy management strategies will be taken into account [17] .…”

Large-Scale Multidisciplinary Design Optimization of an eVTOL Aircraft using Comprehensive Analysis

“…SUAVE [10] is a conceptual-level aircraft design environment that uses physics-based methods to size novel configurations and unconventional propulsion architectures. An et al [11] described a detailed sizing process considering constraint analysis, electric propulsion system sizing, mission analysis, and structural weight estimation. Regressions were developed for the disciplinary analysis based on simulations and experimental data.…”

Control moment coefficient methodology validation for eVTOL sizing

“…They employed the momentum theory to estimate the energy required for hovering during takeoff and landing. In another paper, An et al [6] developed a sizing methodology for a liftand cruise-type eVTOL Unmanned Aerial Vehicle. They utilized a regression model based on existing UAV electric propulsion system data to perform the sizing.…”