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Operating cost components for current vertical lift aircraft and technologies that enable total operating cost reduction
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Citations
... Since electric motors are simpler, mainly due to the smaller number of moving parts, and operated at lower temperatures relative to combustion engines, their maintenance cost is lower [7]. In some territories, electric energy costs as little as 30% of the equivalent energy delivered from aviation fuel [8,9]. Moreover, UAM vehicles can be operated autonomously and thus save costs relative to means of transport depending on a driver or pilot. ...
In the near future, urban air mobility (UAM) will let an old dream of human society come true: affordable and fast air transportation for almost everyone. Among the various existing designs, the multicopter configuration best combines the advantages of compactness, simplicity, and maturity. These aspects are important for actual use, particularly during the early stage of this market. This study elaborates on the design principles of UAM multicopters by examining existing models in terms of their configuration, weight, and range specifications. In particular, the weights of the different components are estimated based on empirical models, aerodynamic fundamentals for the analysis of UAM multicopters are derived from momentum theory, and the power and energy requirements for hovering and cruise flight are evaluated, thereby enabling estimation of the maximum hovering time and flight range. Finally, a sizing method is introduced and validated against an actual UAM design.
... Pad and gate times are based on Preis and Hornung, where it should be noted that gate tasks such as boarding, deplaning, and rotor spinup and spin-down are assumed to occur within 90 s and 350 s, respectively (7). Lastly, battery charging time is a function of the charge rate and is defined using a simple energy model by Equation 2, where the average eVTOL power consumption P avg À Á is based on estimates for existing vehicle designs, and the chosen battery charge rate range B charge À Á is based on 100% to 150% of existing electric-car fast-charging capabilities to consider both existing and near-term battery technologies (30)(31)(32)(33). ...
An understanding of fleet size and vertiport size sensitivity to demand and operational parameters is necessary to quantify the scalability of urban air mobility (UAM) services. In this work, we implement a bilevel rolling window fleet scheduling formulation that includes vertiport area as a secondary objective. We also present a simple vertiport area estimation methodology that leverages the fleet scheduling results and provides a lower bound on vertiport infrastructure area requirements. Lastly, we explore the sensitivity of fleet size and vertiport infrastructure requirements to several vehicle and operational parameters, including geographical demand distribution, daily passenger volume, vehicle passenger capacity, passenger aggregation window, battery charge rate, pad separation, and pad size. We find that, although the fleet size is reasonable for a UAM commuting service scaled to serve 10,000 passengers per day, vertiport area requirements are likely problematic under current sizing guidance from the Federal Aviation Administration, particularly area requirements for vertiports that serve as workplace hubs located in dense urban centers.
... Because an EPS draws energy solely from batteries, it has the potential to avoid greenhouse gas emissions and fossil fuel use during flight. In addition, an EPS relieves the mechanical complexity between the drive system and thruster shaft, providing new design freedom for lift and thrust around the vehicle [5]. ...
This paper proposes novel enhancements to the electric propulsion system analysis method for electric vertical takeoff and landing (eVTOL) aircraft conceptual design by considering the electrical characteristics of each electrical device in a more accurate manner. To this end, three modules for motor, inverter, and battery analysis are constructed using equivalent circuits and semi-empirical models. First, the motor analysis module is developed using equivalent circuit analysis with the operation control strategy for a permanent-magnet synchronous motor. Second, the inverter analysis module is built using average loss models for the switching and conduction losses. Third, the battery analysis module is improved using the near-linear discharge model to consider the voltage drop during operation. Moreover, additional modules, such as those for calculating the battery stack in series and parallel, as well as regression models for the motor and inverter performance parameters and consideration of the drive system type (direct or indirect, including a reduction gear), are implemented. A comparative study is presented from an analysis and design perspective while changing the drive system type (direct or indirect) and gear ratio, which highlights the importance of modeling electrical characteristics during eVTOL aircraft conceptual design.
... Duffy et. al. [2] show in a feasibility study that an electrically driven 4-passenger rotorcraft vehicle can provide reductions in seat per mile costs by about 26% compared to its conventional fuel powered counterpart, regardless of the size and number of the rotors. ...
... In commonly known practice of today's aircraft design [9,10], the design process is broken into three major phases: Conceptual design, preliminary design and detailed design. 2 In the conceptual design phase, studies are conducted to find answers to fundamental questions emerging on a new design, such as What requirements should be considered?, What should the configuration look like?, How much does it weigh?, What does it cost?, What technologies should be used?, etc. [9]. To find the answers, multiple disciplines are synthesized to determine the external configuration of an aircraft with all its dimensions and performance parameters. ...
Most of the introduced eVTOL models in the UAM market utilize electrically driven rotors with fixed pitch blades, controlled by their rotational speed. This design approach brings new features and challenges that need to be considered during the conceptual design stage, taking new aspects into account, among them the rotor dynamic response. This paper presents an initial parameterization of the rpm-controlled rotors along with the electric motor, based on the conducted literature research. Several isolated rotor variants are modeled and analyzed in terms of performance, and the dynamic response of the rotor rotational speed. The relations between aerodynamics and inertia are discussed, and their effects on the rotor dynamic response are elaborated on.
... Fully electric UAMV power plants are expected to have far less unique rotating parts due to a reduction of complexity compared to other aircraft designs [6,38,46,47]. Therefore, the material costs cannot be transferred directly, but must be scaled down. ...
The novel aircraft architectures for Urban Air Mobility (UAM), combined with pure on-demand operations, mean a significant change in aircraft operation and maintenance compared to traditional airliners. Future flight missions and related variables such as the aircraft position or utilisation are unknown for on-demand operation. Consequently, existing methods to optimise aircraft assignment and maintenance planning cannot be transferred. This study examines the behaviour of an aircraft fleet in an on-demand UAM transport system regarding the interlinking between operation and maintenance. Initially, a potential maintenance schedule for UAM vehicles is deduced. A transport and maintenance simulation is introduced where aircraft are modelled as agents servicing a simple network. As aircraft reach their maintenance intervals, they transfer to one of the maintenance bases and compete for that resource. Since that competition can result in avoidable waiting times, the maintenance costs are extended by running costs for the bases and opportunity costs for missed revenue during these waiting periods. Opportunity costs are cost drivers. To reduce the waiting times, two operational approaches are examined: Extending the opening hours of the maintenance facilities and checking the aircraft earlier to reduce simultaneous maintenance demand. While an extension of operating hours reduces the overall maintenance costs, the adjustment of tasks is more effective to lower waiting times. Thus, an improved system needs to use a combined approach. That combination results in overall maintenance costs of approximately $ 58 per flight hour of which about seven percent account for the opportunity costs.
... Electric propulsion, a key and revolutionary technology for the new generations of satellites, has attracted considerable attention in recent years due to its outstanding advantages such as superior fuel efficiency, unprecedented specific impulse, high thrust precision, low costs, and long endurance [1][2][3][4]. These properties make it promising technology for potential applications in a broad range of fields such as orbit correction and deep space exploration [5,6]. ...
Ion thruster is a revolution technology with potential applications in space mission but the thruster’s operation lifetime is limited by the sputtering from thruster components. In this work, molecular dynamic simulations are performed to explore the dependence of deformation characteristics of an aluminum surface on incident angle and kinetic energy under low-energy xenon-ion impact. The fraction of non-12-coordinated atoms is used to quantitatively characterize the microstructural evolution and defect density levels. It is found that defect density level has a linear relation with incident energy, and there exists a critical incident angle around 20°, at which the aluminum surface has the maximum defect density level. In addition, a collision model is developed to theoretically reveal the physical mechanisms behind the dependence. Our findings may helpful in developing long endurance electric propulsion devices for practical applications.
... From one commercial datasheet to another, the reported metrics vary, leading to trends rather than rules for what is included. Various groups have tackled this difficult subject by mentioning important criteria for batteries based on the application [1][2][3], focusing in-depth on a single application [4][5][6][7][8][9][10][11][12][13][14] or a single criteria [13,[15][16][17][18][19][20][21], comparing performance based on chemistry or internal components [2,3,22,23], or discussing criteria and considerations for multiple battery application [24][25][26][27]. Some online sources also address the topic of battery criteria and applications [28]. ...
... From one commercial datasheet to another, the reported metrics vary, leading to trends rather than rules for what is included. Various groups have tackled this difficult subject by mentioning important criteria for batteries based on the application [1][2][3], focusing in-depth on a single application [4][5][6][7][8][9][10][11][12][13][14] or a single criteria [13,[15][16][17][18][19][20][21], comparing performance based on chemistry or internal components [2,3,22,23], or discussing criteria and considerations for multiple battery application [24][25][26][27]. Some online sources also address the topic of battery criteria and applications [28]. ...
Six technical criteria { cell-level specific energy, cell-level specific power, cycle life, affordability, safety, and storage characteristics { are defined and discussed as applied to six high-impact battery applications: Electric vehicles, renewable energy, consumer electronics, unmanned aerial vehicles (UAV), medical, and military batteries. Sub-applications, additional criteria, and other applications are briefly discussed. Strengths and weaknesses of commercial and start-up technologies such as Panasonic nickel cobalt rechargeable (NCR), Altairnano lithium-titanate (LTO), Venom lithium-polymer (LiPo), Oxis Energy lithium-sulfur (Li-S), Polyplus lithium-oxygen (Li-O2), and Sion Power lithium-metal (Li-metal) batteries are given.
... Today, it is appropriate to design a vehicle that uses aircraft-certified eAPUs, with the possibility to update the vehicle to retrofit the future battery later as it becomes available. In fact, in a few studies found in the literature, the eVTOL aircraft was designed with a futuristic 300-400 W hr/kg battery [10,11]. Air transportation safety requires the use of already tested power packs, and costs require the use of mass-produced batteries. ...
... The complete "PowerWall 2" power pack, also from Tesla, has an SED of 106 Wh/dm 3 and a VED of 118 Wh/kg. Nonetheless, actual technology is far from the level of 400 Wh/m 3 assumed by a few authors [10,11]. In addition, fast discharge during vertical takeoff and landing will face lower efficiency with loss of energy. ...
On-demand air transport is an air-taxi service concept that should ideally use small, autonomous, Vertical Short Takeoff and Landing (VSTOL), “green”, battery-powered electric aircraft (eVSTOL). In addition, these aircraft should be competitive with modern helicopters, which are exceptionally reliable machines capable of the same task. For certification and economic purposes, mobile tilting parts should be avoided. The concept introduced in this paper simplifies the aircraft and makes it economical to build, certify and maintain. Four contrarotating propellers with eight electric motors are installed. During cruise, only two of the eight rotors available are not feathered and active. In the first step, a commercial, certified, jet-fueled APU and an available back-up battery are used. A second solution uses a CNG APU and the same back-up battery. Finally, the third solution has a high-density dual battery that is currently not available. A conceptual design is shown in this paper.
... Advances in battery technology, environmental concerns, urban congestion, and other factors have recently converged to produce a sudden growth of interest in electric vertical takeoff and landing (eVTOL) aircraft [1,2]. Due to the scalability of electric motors (relative to internal combustion engines used by traditional helicopters), a much wider variety of design configurations are up for consideration in this space, with no consensus on even high-level design features, such as the optimal number and placement of motors, batteries, lifting surfaces, etc. [3] This situation is in sharp contrast to helicopters and fixed-wing aircraft that use traditional modes of propulsion, which are mostly variations of mature, decades-old design templates. ...
... Section 3 then describes our FEniCS-and tIGAr-based implementation of this method, which is available as the open-source library PENGoLINS (PENalty-based GLuing of Isogeomet-ric Non-matching Shells) [40]. 1 Section 4 verifies that PENGoLINS accurately solves a collection of linear and nonlinear benchmark problems from the literature, before Section 5 demonstrates its application to stress analysis of an eVTOL wing with internal structural members. Lastly, Section 6 draws conclusions and outlines plans for future research. ...
We introduce an open-source framework to directly analyze aerospace structures represented as collections of untrimmed NURBS patches, which is the representation used by NASA's Open Vehicle Sketch Pad (OpenVSP) for aircraft conceptual design. Airframes are modeled mechanically as Kirchhoff–Love shells and discretized isogeometrically for computational analysis. Coupling between separately-parameterized patches uses a slight modification of the penalty formulation proposed by Herrema et al. (2019) [31], which we verify using a similar suite of benchmark problems. Our open-source implementation leverages both advanced code generation through the FEniCS toolchain and efficient computational geometry operations through the Open Cascade modeling kernel. To demonstrate the framework's applicability to complicated industrial geometries, we perform stress analysis of the wing of an eCRM-002 electric vertical takeoff and landing (eVTOL) aircraft, with skin geometry designed in OpenVSP and internal stiffener geometry generated by an auxiliary tool. Source code for our non-matching shell analysis library PENGoLINS (PENalty-based GLuing of Isogeometric Non-matching Shells) will be maintained at https://github.com/hanzhao2020/PENGoLINS.
... Electrification of aircraft is generally seen as a chance to lower carbon emissions associated with aviation and significantly reduce cost. Duffy et al. analyze and confirm the general economic feasibility of UAM and find that the total operating cost of eVTOL is lower compared to aircraft powered both by a turbine and by a piston engine [36]. Fredericks et al. account this mostly to comparably lower prices of electricity over aviation fuel (in the U.S.) and a reduction of labor and maintenance cost as a result of a simplified drivetrain architecture [35]. ...
... Based on the RCDA suite, Hirsh et al. perform parameter studies and demonstrate the ability of multidisciplinary analyses to cut development time by at least an order of magnitude if compared to traditional methods of passing data among the disciplines' designers [79]. Furthermore, Duffy et al. have developed a multidisciplinary design analysis & optimization (MDAO) tool to explore eVTOL and perform comparative cost assessments of electric and conventional eVTOL aircraft [36]. As a case study using the tool, they demonstrate the cost-saving potential of a potential Boeing eVTOL powered by future battery technology compared to state-ofthe-art helicopters using piston and turboshaft engines [36]. ...
... Furthermore, Duffy et al. have developed a multidisciplinary design analysis & optimization (MDAO) tool to explore eVTOL and perform comparative cost assessments of electric and conventional eVTOL aircraft [36]. As a case study using the tool, they demonstrate the cost-saving potential of a potential Boeing eVTOL powered by future battery technology compared to state-ofthe-art helicopters using piston and turboshaft engines [36]. ...
How should electric Vertical Take-Off and Landing aircraft (eVTOL) be designed to
facilitate a sustainable Urban Air Mobility? Many different concepts in development
promise to provide an emission-free alternative to ground-based transportation in urban
and regional areas. To investigate the promise, this thesis assesses the environmental
life cycle impact of eVTOLs in terms of carbon emissions.
The thesis develops and implements a methodology for the integrated conceptual
design and life cycle assessment of eVTOL. The computational framework allows an
evaluation of arbitrary configurations using alternative electrochemical energy carriers
in diverse scenarios. It facilitates a discussion of existing eVTOL configurations and
provides a baseline for a regression-based conceptual design of environmentally optimized
configurations. The framework further supports depicting the effects of uncertainties
present in the involved domains through a sensitivity analysis module.
The application of the methodology shows that eVTOLs can, given a set of coinciding,
advantageous circumstances, be designed and operated so that their associated carbon
emissions are comparable to or below those of electrically powered cars. The environmen-
tal competitiveness is facilitated by the following factors: First, a high cruise efficiency
of aircraft, as in fixed-wing concepts, given the expected short hover shares of transport
missions. Second, the availability of energy carriers that exceed the specific energy of
today’s Lithium-Ion Batteries, like Lithium-Air Batteries and hydrogen, especially on
longer ranges. Third, the operation of eVTOLs on routes close to their specified design
range, excluding short urban commutes below 25km due to their relatively high hover
share. Fourth, a high seat utilization and high circuity factor compared to ground-
based routes. And fifth, low carbon emissions in the primary energy production and
the sourcing of often-replaced components like batteries and fuel cells. In essence, the
carbon impact of eVTOL is dominated by the consumed specific energy per transported
passenger, the system’s energy conversion efficiency, and the primary energy produc-
tion impact. As the latter can be even more decisive than the choice of configuration,
it illustrates the importance of the manufacturers’, operators’, and regulator’s policies
regarding sustainable sourcing and supply. The author concludes that eVTOL may pro-
vide a sustainable transport mode if applied complementarily to ground-based modes,
but suggests further, individual analyses.
The thesis demonstrates that the applied modeling fidelity using system-level metrics
is sufficient to assess an eVTOL’s sustainability. To handle the apparent uncertainties
it suggests scenario-based assessments, complementing sensitivity analyses, and data
improvements. Future research may consequently improve data and modeling fidelity,
implement additional environmental and techno-economic metrics, and focus on the
methodologies evolution toward eVTOL design optimization.
