Cruise Speed Research Articles

Design and Analysis of VTOL Operated Intercity Electrical Vehicle for Urban Air Mobility

This paper discusses the conceptual design of an intercity electrical vertical take-off-and-landing aircraft. A literature survey of existing eVTOL aircrafts, configuration selection, initial sizing, weight estimation, modelling and analysis was conducted. The present intercity eVTOL aircraft has the capability to carry four passengers along with one pilot for a distance of 500 km. Two specific aircraft modes, such as air-taxi and air-cargo mode, are considered in the present design. Market entry is predicted before 2031. Subsequently, innovative technologies are incorporated into the design. The present design features an aerodynamically shaped fuselage, tapered wing and a V-tail design. It can carry a nominal payload of 500 kg to a maximum range of 500 km at a cruise speed of Mach 0.168. The present eVTOL is comprised of a 5 m-long fuselage and an 11 m wingspan. It utilizes six tilt-rotor propeller engines. The maximum take-off weight and empty weight are 1755 kg and 1255 kg, respectively. The unit price is expected to be between USD 14.83 and 17.36 million. This aircraft has an aesthetically pleasing, intelligent and feasible design.

SUPERIOR SEAWORTHINESS OF A RESONANCE-FREE FAST OCEANGOING SWATH

The speed reduction, additional resistance or slamming caused by the large amplitude ship motions, should be completely restricted for a large fast oceangoing ship because of the strict time-punctuality and the high value of the cargo. A “Resonance-Free SWATH (RFS)”, which has negative restoring moments due to the extremely small water plane area, is introduced to minimize the motion responses. A motion control system using small fins is necessary for the RFS, which has no stability during high speed cruising. Theoretical estimations and experiments to search for the optimum values of PD control gains have been performed. Unsteady characteristics of fin-generated lift such as the time lag and the interaction among the fins and lower hulls have been measured and they are taken into account in the motion equations. Then, experiments using the RFS model with controlling fins have been carried out to validate the theoretical estimation for the motion responses of the RFS in waves. The theoretical and experimental results agree well with each other. The motion responses of the RFS in regular and irregular head waves are compared with those of other hull forms, such as a mono-hull, an ordinary SWATH and a trimaran. The clear advantage of the RFS regarding the seaworthiness has been found. In summary, the heave motion response of the RFS is reduced to 1/60 and the pitch motion becomes1/8, compared with those of the existing mono-hull ship.

A multi-objective optimisation study of trimaran hull applying RBF-Morph technique and integrated optimisation platform at two design speeds

ABSTRACT This paper presents an efficient optimisation method to improve the main hull of a trimaran ship, whilst proposing a computational fluid dynamics-based automated approach to reduce total resistance. A mesh-based method is introduced to modify a wave-piercing bow trimaran hull at two cruise and sprint speeds. Therefore, the problem pertains to a hydrodynamic multi-objective optimisation problem. Radial basis function-based mesh-morphing tool is implemented to alter the geometry at the mesh level. Mesh-morphing tool leads to elimination of geometry and mesh regeneration steps that consequently provides a shortcut for the designer's extrication from optimisation time and complexity of geometry modification. Ten global parameters accomplish expansion and contraction of the 10 sections, which are known as Magnification Factor. Optimisation results and design comparison illustrate the applicability and efficiency of the proposed technique. The results demonstrate 6.77% reduction in total resistance at cruise speed and 1.55% at sprint speed.

Simulation-based multi-objective optimization of side-hull arrangement applied to an inverted-bow trimaran ship at cruise and sprint speeds

Numerical optimization of an inverted-bow trimaran is carried out through three simulation-based design (SBD) frameworks. Different positions of the trimaran’s side hull are investigated based on a computational fluid dynamics solver using the non-dominated sorting genetic algorithm-III (NSGA-III), simultaneous hybrid exploration that is robust, progressive and adaptive (SHERPA) and response surface (RS) multi-objective optimization for resistance at cruise and sprint speeds. The aims are to create and develop a convenient tool for optimization and investigate the appropriate position of the side hull. An automated, low-cost optimization platform is achieved that can be implemented in other maritime projects. A 10.5% drag reduction for cruise speed and 6.6% reduction for sprint are obtained, corresponding to lower longitudinal and large transversal distances of the side hull. SHERPA and NSGA-III produce the same results, but SHERPA is 2.5 times faster than NSGA-III. RS obtains less desirable results, but in the lowest central processing unit time.

Holding Area Conceptual Design and Validation for Various Urban Air Mobility (UAM) Operations: A Case Study in Seoul–GyungIn Area

As populations become concentrated in cities, traffic congestion increases, and urban air mobility (UAM) is being considered to face this problem. Accordingly, many institutions and companies around the world are developing UAM vehicles, building infrastructure, and researching flight operating systems. In this study, three holding area concepts have been designed that can control air traffic flows and avoid bad weather conditions when UAM vehicles are operating. These holding areas have been considered to allow UAM vehicles to fly by avoiding collisions with other UAM vehicles or structures such as buildings. After validating the turning radius analysis with existing aircraft, a case study on the holding area concept design for the Seoul–GyungIn area was performed to determine whether UAM vehicles can turn within a narrow radius. It was not possible for winged-type UAM vehicles to turn across the Han River at cruise speed. The holding area concepts and the turning procedure of this study can be used as guidelines when designing UAM corridors or UAM flight routes.

Evaluation of a small drone performance using fuel cell and battery; Constraint and mission analyzes

Drones have important uses such as relief, photography, military purposes. However, designing an efficient propulsion system for the drone that can ensure its reliability and flight endurance is a major challenge. Relying on an all-electric propulsion system can enhance flight endurance and improve drone performance. In this article, two types of fuel cells, proton-exchange membrane fuel cell and solid oxide fuel cell have been considered (individually) to supply the power consumption of the drone. In addition, a battery is embedded in parallel with the fuel cell in the propulsion system. To evaluate the performance of the drone, two constraint and mission analyzes have been established to determine the power consumption of the drone during various flight modes and weight distribution of the drone. Then a comparison on the drone’s performance with respect to the electrochemical behavior of both fuel cells is provided. Finally, the performance of fuel cells in propulsion system based on the International Standard Atmosphere model is discussed. Results revealed that the solid oxide fuel cell and proton-exchange membrane fuel cell can generate 82.1 and 162.7 W of electrical power respectively. In addition, drone needs about 1.46 kW of electrical power. The flight endurance and total weight of the drone are equal to 6.8 h and 6.3 kg, respectively. It was also found that the required area of the solid oxide fuel cell is approximately 98% less than the proton-exchange membrane fuel cell to provide the total electricity consumption of the drone. Furthermore, the effect of increasing cruise speed on drone’s net weight is more remarkable compared to power consumption.

An Eco-Cruise Control for Electric Vehicles Moving on Slope Road with Constant Speed

The unreasonable actuation of electric vehicle’s motor drive system usually results in a lot of unwanted energy consumption on a slope road. This paper proposes an eco-cruise control (ECC) scheme based on the driving condition estimation to decrease electric vehicle’s energy consumption in the constant-speed cruise control mode. The eco-cruise control scheme is realized by reducing the unreasonable actuation of the motor drive system. The vehicle’s total mass and pitch angle are estimated in real time by using an improved base-vector-based cross iteration estimator (BVCIE). Based on the estimated results, the required torque is predicted. Combining the speed deviation between the desired speed and the real speed, and the torque deviation between the required torque and the real torque, a three-power nonlinear controller of the ECC scheme is designed. The ECC scheme is validated on a slope road with different cruise speeds on a cosimulation platform, and the results indicate that the proposed strategy enjoys a better speed maintenance ability and energy efficiency compared with the benchmarked cruise control.

Flutter prediction on combined EPS and carbon sandwich structure for light aircraft wing

Flutter prediction is an important step before conducting a flight test. In this study, we performed flutter prediction of a half-wing structure without control surfaces. The half-wing structure is made to resemble the scaled-down wing of a Boeing 737 NG at a scale of 1:39.34. The airfoil profile used is the wing profile of the Boeing 737 NG obtained from airfoiltools. The structure is constructed using a combination of carbon sandwich andEPS. The advantages of choosing this material are its low-cost and easymanufacture. We used the p-k method in the FEMAP software for flutter prediction. From the prediction results, the calculated flutter speed is ∼14.5 m/s. The flutter mode shape is a combination of lateral bending and twist. Dimensional analysis was also carried out to predict the maximum speed on the scaled model and predicted at 27.88 m/s. Based on calculated flutter speed, the maximum operating speed of a constructed structure should be far less than the flutter speed. Thus, the structure's maximum speed is below the predicted value. Based on carried out flutter prediction, the wing structure, constructed using a combination of carbon sandwich and EPS, can fly safely at a maximum cruise speed of 10 m/s.

Custer Channel Wings for Short Takeoff and Landing of Unmanned Aircraft

The channel wing is a lift-enhancement concept pioneered by Willard Ray Custer in the late 1940s in an effort to provide a fixed-wing aircraft with short takeoff and landing (STOL) capabilities. This paper experimentally investigates the possibility of using Custer channel wings for slow flight and STOL of small (under 35 kg) fixed-wing unmanned aerial vehicles. The Custer unmanned aircraft developed at the University of Southampton is introduced in this paper, including details of the installed channel wings and other systems necessary for slow-flight operation. Results from wind-tunnel tests are presented, showing a significant lift increase due to the channel wings in the range of airspeeds of interest. Flight tests are carried out to demonstrate the slow flight and STOL capabilities of the aircraft, showing superior stall characteristics and a two-thirds reduction of the runway length required when using the channel wings. Flight-test comparisons to a conventional wing–propeller configuration show superior slow-flight performance and 7–9% lower cruise speed of the channel-wing aircraft.

Experimental Study of the Aerodynamic Interaction between Side-by-Side Propellers in eVTOL Airplane Mode through Stereoscopic Particle Image Velocimetry

Side-by-side propellers characterise the architecture of most new electric aircraft (eVTOLs) designed in recent years for urban air mobility. The aerodynamic interaction between side-by-side propellers represents one of the key phenomena that characterise the flow field and performance of these novel aircraft configurations. The present article describes the main results of a wind tunnel campaign that aimed to investigate the flow features that characterise this aerodynamic interaction, with a particular application to cruise flight conditions in eVTOLs. With this aim, stereo particle image velocimetry (PIV) measurements were performed in the wake of two co-rotating propeller models in a side-by-side configuration. The three-dimensional flow surveys provided detailed insights into the flow physics of the interacting propellers, with a particular focus on the interactional effects on the trajectory of the tip vortices and the wake topology provided at two different advance ratios by reproducing a moderate and a fast cruise speed of eVTOLs in urban areas.

Initial sizing of a roadable personal air vehicle using design of experiments for various engine types

Purpose The purpose of this paper is to analyze and compare the performances of novel roadable personal air vehicle (PAV) concepts that meet established operational requirements with different types of engines. Design/methodology/approach The vehicle configuration was devised considering the dimensions and operational restrictions of the roads, runways and parking lots in South Korea. A folding wing design was adopted for road operations and parking. The propulsion designs considered herein use gasoline, diesel and hybrid architectures for longer-range missions. The sizing point of the roadable PAV that minimizes the wing area was selected, and the rate of climb, ground roll distance, cruise speed and service ceiling requirements were met. For various engine types and mission profiles, the performances of differently sized PAVs were compared with respect to the MTOW, wing area, wing span, thrust-to-weight ratio, wing loading, power-to-weight ratio, brake horsepower and fuel efficiency. Findings Unlike automobiles, the weight penalty of the hybrid system because of the additional electrical components reduced the fuel efficiency considerably. When the four engine types were compared, matching the total engine system weight, the internal combustion (IC) engine PAVs had better fuel efficiency rates than the hybrid powered PAVs. Finally, a gasoline-powered PAV configuration was selected as the final design because it had the lowest MTOW, despite its slightly worse fuel efficiency compared to that of the diesel-powered engine. Research limitations/implications Although an electric aircraft powered only by batteries most capitalizes on the operating cost, noise and emissions benefits of electric propulsion, it also is most hampered by range limitations. Air traffic integration or any safety, and noise issues were not accounted in this study. Practical implications Aircraft sizing is a critical aspect of a system-level study because it is a prerequisite for most design and analysis activities, including those related to the internal layout as well as cost and system effectiveness analyses. The results of this study can be implemented to design a PAV. Social implications This study can contribute to the establishment of innovative PAV concepts that can alleviate today’s transportation problems. Originality/value This study compared the sizing results of PAVs with hybrid engines with those having IC engines.

Effects of fuel cell vehicle waste heat temperatures and cruising speeds on the outputs of a thermoelectric generator energy recovery module

A thermoelectric generator (TEG) module is designed to harvest low grade waste heat from a 2 kW fuel cell vehicle and improve its energy utilization. The module integrates a TEG cell with a heat pipe and a finned heat sink. A numerical model is developed based on an experiment setup where the fuel cell temperature is 45–60 °C while the cruise speed is 25 kmh−1. The numerical model is validated with less than 5% deviation. Extended cases are simulated for series and parallel power train configuration under changes to the waste heat temperature and vehicle speeds to evaluate the power and heat recovery ratio. A single TEG cell output between 2 and 3 W is achievable even at low grade heat. The parallel drive generates 50% more power than the series drive at 100 kmh−1 speed. A 2% heat recovery is theoretically achievable for a 16 cell module assembly.

Analysis of Influence of Cruise Speed and Flight Level Change on Fuel Consumption in Air Traffic Flow Management

The problem of flight planning in case of delay demands is considered. The criterion restrictions between fuel consumption and the required flight time when the nominal cruise speed changes are investigated. It is proved that flight delay in the air can be realized without additional fuel costs, which is determined and estimated in the absence or presence of wind. The impact of choosing a different flight level and using additional fuel to obtain a longer delay was also considered and analyzed. The results show that for different flight levels and wind direction the delay may be varied from 3 minutes to 13 minutes. The initial flight level is defined as one of the main parameters that affect the amount of delay in the air.

Design and Optimization of a Large Turboprop Aircraft

This paper proposes a feasibility study concerning a large turboprop aircraft to be used as a lower environmental impact solution to current regional jets operated on short/medium hauls. An overview of this market scenario highlights that this segment is evenly shared between regional turboprop and jet aircraft. Although regional jets ensure a large operative flexibility, they are usually not optimized for short missions with a negative effect on block fuel and environmental impact. Conversely, turboprops represent a greener solution but with reduced passenger capacity and speed. Those aspects highlight a slot for a new turboprop platform coupling higher seat capacity, cruise speed and design range with a reduced fuel consumption. This platform should operate on those ranges where neither jet aircraft nor existing turboprops are optimized. This work compares three different solutions: a high-wing layout with under-wing engines installation and both two- and three-lifting-surface configurations with low-wing and tail tips-mounted engines. For each concept, a multi-disciplinary optimization was performed targeting the minimum block fuel on a 1600 NM mission. Optimum solutions were compared with both a regional jet such as the Airbus A220-300 operated on 1600 NM and with a jet aircraft specifically designed for this range.

Formation Reconfiguration for Fixed-Wing UAVs

This study proposes a coordinated path following approach to solve the formation reconfiguration problem in a guided manner. A novel coordinated path following control law is proposed, which steers a fleet of UAVs towards their closest projection points on their respective paths by controlling the angular velocity of each UAV, and achieves coordinated formation reconfiguration by synchronizing the UAVs’ closest projection points via controlling the linear velocity. Each UAV only uses its neighbors’ destination arc distances for coordination, which as a result saves communication bandwidth. The UAVs’ velocity constraints are also satisfied, with the linear velocity converging to the cruise speed under the proposed control law, which is helpful to prolong the flight time. The hardware-in-the-loop simulation, as well as the field experiments with seven to ten fixed-wing UAVs, are performed to validate the effectiveness of the proposed method.

Automatic estimation of optimal UAV flight parameters for real-time wide areas monitoring

In the last few years, small-scale Unmanned Aerial Vehicles (UAVs) have been used in many video-based monitoring applications, such as search and rescue (SAR) operations, border control, precision agriculture, and many others. Usually, during these missions, a human operator manually selects UAV flight parameters according to the specific monitoring application to be performed. Anyway, regardless a particular mission, some main tasks can be considered common preprocessing steps that require to be accomplished. These tasks include the mosaicking of areas of interest, the detection of changes over time on these areas, finally, the classification of what is present on the ground. The success of these tasks strictly depends on flight and video sensor parameters. In this paper, for the first time in the literature, a method to automatically estimate the optimal parameters, in particular altitude and frame rate, to accomplish the three main tasks reported above is presented and tested. The parameters are estimated according to several factors, including size of the target to be analysed, cruise speed of UAVs, and main internal parameters of the video sensor, i.e., focal length, field of view, and size of the pixel. The full effectiveness of the proposed method, on the three case studies (i.e., main tasks), was proven both by synthetic videos generated with the Aerial Informatics and Robotics Simulation (AirSim) and by real video sequences reported in the UAV Mosaicking and Change Detection (UMCD) and NPU Drone-Map datasets.

Evaluation of Hybrid, Electric and Fuel Cell Powertrain Solutions for Class 6-7 Medium Heavy-Duty Vehicles

<div class="section abstract"><div class="htmlview paragraph">Electrification of heavy-duty trucks has received significant attention in the past year as a result of future regulations in some states. For example, California will require a certain percentage of tractor trailers, delivery trucks and vans sold to be zero emission by 2035. However, the relatively low energy density of batteries in comparison to diesel fuel, as well as the operating profiles of heavy-duty trucks, make the application of electrified powertrain in these applications more challenging. Heavy-duty vehicles can be broadly classified into two main categories; long-haul tractors and vocational vehicles. Long-haul tractors offer limited benefit from electrification due to the majority of operation occurring at constant cruise speeds, long range requirements and the high efficiency provided by the diesel engine. However, vocational applications can realize a significant benefit from electrified powertrains due to their lower vehicle speeds, frequent start-stop driving and shorter operating range requirements.</div><div class="htmlview paragraph">As the heavy-duty industry deals with solving challenges around the application of electrified powertrains, there are multiple pathways that can be explored to meet future regulatory requirements. This paper is the second part of a two-paper series that focuses on evaluating electrified solutions for Class 6-7 medium heavy-duty vehicles in the 2027 and beyond time frame. Using a model-based approach, this paper presents a comprehensive analysis that compares the baseline diesel powertrain against multiple alternative powertrain configurations. These configurations include, an optimized parallel diesel hybrid, all-electric, diesel range extender, gasoline range extender, Compressed Natural Gas (CNG) range extender, and fuel cell range extender; which are evaluated on the basis of cost of ownership, fuel efficiency, emissions, payback period, lost payload opportunity, range, and battery life. The analysis shows that for a near-term less-disruptive scenario wherein the conventional diesel powertrain layout is preserved, a 48V P3 parallel hybrid vehicle configuration is the most cost-effective solution, while for a near-term more-disruptive scenario, the Internal Combustion Engine (ICE) based Range Extender Electric Vehicles (REEVs) have the most potential to reduce greenhouse gas emissions while achieving lower cost of ownership than the baseline vehicle. For a longer-term and more-disruptive scenario, the all-electric vehicle configuration can achieve parity with the baseline vehicle cost of ownership provided the vehicle driving range requirement is limited to 100-150 miles. The analysis further highlights that the overall benefit of an all-electric powertrain solution depends significantly on the future battery technology advancements and vehicle range requirements.</div></div>

On the Handling Qualities of Two Flying Wing Aircraft Configurations

The coupling of the longitudinal and lateral stability modes of an aeroplane is considered in two cases: (i) weak coupling, when the changes in the frequency and damping of the phugoid, short period, dutch roll, and helical modes are small, i.e., the square of the deviation is negligible compared to the square of the uncoupled value; (ii) strong coupling, when the coupled values may differ significantly from the uncoupled values. This allows a comparison of three values for the frequency and damping of each mode: (i) exact, i.e., fully coupled; (ii) with the approximation of weak coupling; (iii) with the assumption of decoupling. The comparison of these three values allows an assessment of the importance of coupling effects. The method is applied to two flying wing designs, concerning all modes in a total of eighteen flight conditions. It turns out that lateral-longitudinal coupling is small in all cases, and thus classical handling qualities criteria can be applied. The handling qualities are considered for all modes, namely the phugoid, short period, dutch roll, spiral, and roll modes. Additional focus is given to the pitch axis, considering the control anticipation parameter (CAP). The latter relates to the two kinds of manouever points, where damping vanishes, that are calculated for minimum speed, take-off, and initial and final cruise conditions. The conclusion compares two flying wings designs (the “long narrow” and “short wide” fuselage concepts) not only from the point of view of flight stability, but also from other viewpoints.

Hypersonic Vehicle Aerodynamic Optimization Using Field Metamodel-Enhanced Sequential Approximate Optimization

Hypersonic vehicle has gained increasing attention due to its high cruise speed and long voyage. In this paper, an enhanced Sequential Approximate Optimization method is proposed for aerodynamic optimization of a hypersonic vehicle. In this method, a constrained design of experiment method is adopted to generate the initial sampling set with adequate number of feasible points. A field metamodel is proposed to surrogate the aerodynamic parameters distributions in the flow field obtained by the aerodynamic simulation. A hybrid metamodel combing radial basis functions and polynomial chaos expansion is applied to construct the field metamodel with good approximate performance. A robust mesh morphing scheme based on radial basis functions is developed to generate high-quality meshes for the sequential optimization scheme. The hypersonic vehicle aerodynamic optimization problem is performed using the proposed optimization framework and satisfactory results are obtained with limited computational budgets. Results show that the proposed field metamodel-enhanced Sequential Approximate Optimization method possesses powerful optimization performance and promising prospects in the field of hypersonic vehicle optimization design.

Maximum Torque per Voltage Flux-Weakening Strategy With Speed Limiter for PMSM Drives

This article presents an enhanced flux weakening (FW) control scheme for permanent magnet synchronous motors, focused on electric vehicle applications. The novelty of the proposed algorithm is the integration in a unified scheme of both the accelerator pedal as torque reference and the cruise speed limiter as speed limit, without interfering between them until this limit is achieved. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> -axis current references are calculated from the proposed algorithm by using a polar coordinate system and a per-unit system. The latter is based on the characteristic machine parameters, which aim to ease and simplify the algorithm implementation. Moreover, it takes advantage of the smooth transition between the low back electromotive force zone and the FW zone thanks to a voltage loop, which changes the current-vector angle. Another fundamental merit of the proposed scheme is its capacity to work in all the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> plane throughout the maximum torque per ampere, constant torque, current and voltage limit, maximum torque per voltage, and constant speed strategies without switching the algorithm. Simulations and experimental results from a real exterior-rotor interior permanent magnet synchronous motor direct-drive e-motorbike verify the effectiveness of the proposed method.