Flight Characteristics Research Articles

Determination of the optimal parameters and engine layout for a strike unmanned aerial vehicle

The article describes the solution of a complex problem to determine the optimal parameters and engine layout for the power plant of an advanced unmanned aerial vehicle according to the methodology developed by the authors using the authors complex mathematical model and the well-known method of indirect statistical optimization based on self-organization. At the same time, the main aerodynamic and flight performance characteristics of the unmanned aerial vehicle under study, calculated according to engineering methods, are shown, as well as the parameters and characteristics of its power plant, calculated using the authors algorithm implemented in a complex mathematical model. The results of parametric studies are also presented using the example of assessing the influence of the bypass ratio on the characteristics of a power plant and the parameters of the unmanned aerial vehicle under study. The process of conducting optimization studies of the Unmanned aerial vehicle power plant system with a bypass turbojet engine with mixing of the circuit flows behind the turbine is described. At the same time, special attention is paid to the formulation of the optimization problem, the choice of criteria and changeable variables, as well as the analysis of the results obtained by comparing the efficiency of the system under study with different engine configurations according to the criteria of the aircraft level: maximum range according to two formed flight programs.

The impact of COVID-19 on airlines’ price curves

COVID-19 has had a major negative impact on the travel industry, especially on the aviation sector. Along with travel restrictions to contain the spread of the virus, a drastic drop in demand—mainly caused by the decrease in the willingness to travel—has also been registered. This study explores the impact of COVID-19 on airline pricing curves, in terms of the price level, price dispersion, and the extent to which intertemporal price discrimination is applied. By analyzing all major European flights departing from and arriving in Italy, the results reveal a 31% overall decrease in airline price per kilometer. Additionally, price dispersion dropped, and price discrimination intensity was found to have decreased as a result of COVID-19. These outcomes can be explained in light of two major impacts of the pandemic on air travel demand, namely the variation in the passenger mix and travelers’ higher price sensitivity. Further analyses indicate that—along with other market and flight characteristics—market concentration, introduced interventions to prevent and control COVID-19, and airline- and destination-types play an important role in determining prices, price dispersion, and the price discrimination intensity.

Factors Affecting the International Flight Delays and Their Impact on Airline Operation and Management and Passenger Compensations Fees in Air Transport Industry: Case Study of a Selected Airlines in Europe

This paper aims to analyze the causes of flight delays of a selected airline operating in Europe and identify potential risks and reasons for delays in air transport, which carry risk, especially in connection with passenger dissatisfaction and the resulting need to pay compensation for delayed flights, according to EU law, which brings significant financial costs for airlines. Data collected from the years 2013–2019 have been used for the purposes of this article, including data on the duration and causes of the delays and the characteristics of individual flights, such as the flight type, aircraft type, time of departure, aircraft capacity, and the load factor. Multidimensional statistics methods have been applied for data processing, namely tests of independence and correspondence analysis. Dependencies have been presented in graphical form using correspondence maps. The analysis shows that the total share of delayed flights of the company in question does not increase over the mentioned period of time. The analysis furthermore proved that higher capacity aircraft were rather prone to longer delays. The share of delayed charter flights declined slightly over the period under review, while the number of delays caused by airline operating reasons, aircraft clearance by supplier companies, technical maintenance and aircraft defects, operating procedures, and crew flight standards and airport restrictions is increasing. The analysis also shows that the delays propagated by the delays of the previous flights are becoming more frequent, with the exception of the year 2019. In the last pre-COVID year, air traffic control could boast about a positive trend regarding the number of produced delays over the years, contributing to greater air passenger satisfaction and airline service quality. Due to the gradual revival of air transport after the COVID pandemic lockdowns, the topic of flight delays, passenger customer satisfaction and financial costs for the resulting delays is once again an actual issue for air management and operation.

Three-Dimensional Flight Envelope for V/STOL Aircraft with Multiple Flight Modes

Vertical or short take-off and landing (V/STOL) aircraft generally have three flight modes, namely, vertical take-off and landing (VTOL), conversion, and cruise, according to the variable angle of propulsion direction to the fuselage axis. However, the traditional flight envelope or conversion corridor lacks the capability to comprehensively present the flight characteristics of these three modes. Pursuant to this, the purpose of this paper was to present a three-dimensional (3D) flight envelope that combines propulsion direction, airspeed, and altitude in one figure. The 3D envelope was constructed subject to the constraints of power rating and equilibrium conditions. To verify its effectiveness, the flight data of XV-15 was used to generate the 3D envelope, following the projection along with the cross-section, which was compared with the traditional flight envelope and conversion corridor, respectively. The maximum specific excess power (SEP) of each flight state was also promptly obtained. In the case study, the flight performance of a rotor-wing aircraft was comprehensively analyzed using the generated 3D envelope. The proposed method in this study exhibited its versatility and capability to demonstrate the performance in all flight modes intuitively, which promoted the efficiency of V/STOL aircraft flight performance analysis as well.

Brain signatures of error awareness during cognitive tasks for humans in the flight environment.

At present, many scientific experiments are carried out in extreme conditions. Pilots need to perform high-intensity tasks for a long time. Human error is an essential factor affecting mission execution. To deeply study the physiological characteristics of different erroneous states of consciousness, we used an improved double-choice Oddball paradigm to collect brain electrophysiological signals of volunteers and pilots in missions and analyze event-related potential (ERP), time-frequency, and brain function spectrum, extracting EEG indicators sensitive to error awareness. The results showed that, in the 300∼500 ms time window, the error awareness type was correlated with Pe amplitude. Meanwhile, the time-frequency and brain functional spectrum analysis showed that the amplitude of the aware errors α-ERS oscillation, the functional spectral density of the α-band, and the uncertain errors were more prominent than unaware errors. The error awareness of the pilots showed the same EEG sensitivity characteristics in flight as in the ground volunteer experiment, and the characteristic sensitivity value was higher than that of the ground participants. We analyzed the EEG indicators sensitive to error awareness and determined the differences in EEG characteristics when pilots have error awareness on the ground and in flight. This study provides theoretical guidance for the follow-up research on the intervention measures against error awareness and determines the target point positioning.

Transient bio-inspired gliders with embodied humidity responsive actuators for environmental sensing.

Collecting temporal and spatial high-resolution environmental data can guide studies in environmental sciences to gain insights in ecological processes. The utilization of automated robotic systems to collect these types of data can maximize accuracy, resilience, and deployment rate. Furthermore, it reduces the risk to researchers deploying sensors in inaccessible environments and can significantly increase the cost-effectiveness of such studies. The introduction of transient robotic systems featuring embodied environmental sensors pushes towards building a digital ecology, while introducing only minimal disturbance to the environment. Transient robots made from fully biodegradable and non-fossil based materials, do not develop into hazardous e-waste at the end of their lifetime and can thus enable a broader adoption for environmental sensing in the real world. In this work, our approach towards the design of transient robots includes the integration of humidity-responsive materials in a glider, which is inspired by the Alsomitra macrocarpa seed. The design space of these gliders is explored and their behavior studied numerically, which allows us to make predictions on their flight characteristics. Results are validated against experiments, which show two different gliding behaviors, that can help improve the spread of the sensors. By tailoring the Cellulose-Gelatin composition of the humidity actuator, self-folding systems for selective rainwater exposure can be designed. The pH sensing layer, protected by the actuator, provides visual feedback on the pH of the rainwater. The presented methods can guide further concepts developing transient aerial robotic systems for sustainable, environmental monitoring.

МЕТОД СТВОРЕННЯ НАВЧАЛЬНОГО БПЛА ЛІТАКОВОГО ТИПУ ЗА ДОПОМОГОЮ 3D-ДРУКУ

he concept of specialized training unmanned aerial vehicle (UAV) of aircraft type for operators of unmanned aerial vehicles is proposed. Training opportunities in various areas of operator training are highlighted. A method of manufacturing an aircraft-type training UAV taking into account aerodynamic and weight characteristics has been developed. The developed method is based on the production of aircraft parts using a 3D printer, which is modified to meet the requirements of small aircraft type aircraft. This technique also includes the process of selecting the most advantageous combination of materials to create a small aircraft. Tables with initial data of existing UAVs are given.The flight characteristics, aerodynamic schemes and type of engine that are most rationally suitable for unmanned aerial vehicles in accordance with this class are proposed. Based on these data, a prototype model was built, the method of UAV design was adopted, taking into account the choice of parameters of the power plant. A demonstration example of the choice of the main parameters of the training taking into account the UAV under specific requirements is given. The obtained main technical characteristics of the UAV are presented. Based on the calculated data, a three-dimensional geometric model of the UAV was developed and a flight sample was made. A series of test flights of the flight model was conducted, tested under difficult weather conditions, when the wind force is about 12 m / s. The ways of using the described method of developing UAV training and research, as well as many other factors that affect 3D printing without detecting defects and problems are considered.

Development and experimental characterization of a robotic butterfly with a mass shifter mechanism

The development of biomimetic aerial robots has emerged as a new solution for studying the flight mechanisms of flying creatures. This study designs a biomimetic robotic butterfly steered via a mass shift mechanism named USTButterfly-II and investigates its flight characteristics using an optical tracking facility. First, a planar four-bar linkage was used to drive the flapping of the designed butterfly-like artificial wings. Next, an innovative tailless steering control method was proposed based on a mass shift mechanism. Finally, the wing kinematics and motion trajectory of the USTButterfly-II were measured using a multi-camera motion capture system, and some difficult-to-measure flapping aerodynamic parameters, such as the instantaneous net lift and thrust coefficients, were determined. These findings present a novel experimental framework that not only provides effective data support for the design and improvement of the robotic butterfly but also benefits the study of biological butterfly flight mechanisms.

Modeling, simulation, analysis and control of close formation flight

This paper focuses on the aerodynamic characteristics of aircraft close formation flight. The formation model for small unmanned aircraft is studied, and the disturbance of the wake induced velocity generated by the leader aircraft on the tail aircraft is analyzed. It is found that the lead aircraft has a significant effect on the lift and drag of the tail aircraft. It is also demonstrated that the aerodynamic characteristics of the tail plane can be improved when the following plane is in the proper position of the leader in formation flight. Precise position control of the tail plane in general flight operations is achieved under the influence of the tail vortex. Firstly, a model for the wake vortex of the leader was established, and then computational fluid dynamics(CFD) software was used to simulate the two unmanned aerial vehicles (UAVs) to verify the accuracy of the model. A control algorithm was designed to realize the stability of formation flight. Mathematical simulation and validation were performed. The designed control law is able to keep the tail plane in the appropriate position in the formation flight so that the tail plane is subjected to the maximum lift.

The effect of surface treatments on the interlaminar shear failure of GLARE laminates subjected to pre‐cyclic thermal loads

AbstractIn this study, both the individual and combined effect of thermal cycling and surface treatment on the interlaminar shear strength (ILSS) of glass laminate aluminum‐reinforced epoxy (GLARE) 3/2 sheet material are investigated experimentally. Three kinds of surface treatments including sandpapering, degreasing and both degreasing and sandpapering are applied to AA6061‐T6 sheets before manufacturing of hot‐pressed GLARE 3/2 sheet material. Two different cyclic thermal conditions, which are referred to the flight characteristics of a typical transport category aircraft, are then applied to short‐beam GLARE specimens by changing temperature limits and keeping the number of cycles the same. Three‐point bending tests are lastly performed to examine the effects of surface treatments on the ILSS of GLARE laminates under pre‐cyclic thermal conditions by comparing with the specimens under acyclic condition at room temperature. The results show that the ILSS of surface‐treated laminates have an increase by between 29% and 73% against untreated ones according to the cyclic thermal profile. If sandpapering and degreasing apply together as a combined mechanical–chemical surface treatment process, then ILSS is totally preserved or reduced by only 4% under certain thermal pre‐cyclic conditions.

ЦІЛЬОВІ РІВНЯННЯ РКЛА НА ЕТАПІ РОЗРОБКИ ЕСКІЗНОГО ПРОЕКТУ

The development of each new rocket and spacecraft (RS) must correspond to the target design function, which most often selects the minimum starting mass m0, or the minimum cost of the c0 project. When designing the RS of the minimum starting mass, mass equations of zero, first and second approximations are used. At the stage of development of the terms of reference, a mass equation is drawn up in which the value of the relative dry mass is set on the basis of statistical data from the previous kind of modification of the aircraft of this type and is an approximation of the zero order. After calculating the main flight and technical parameters of the designed RS, the value of the relative dry mass is specified by using the target given mass equations, in which the mass of the main compartments, systems and structures is determined through the basic flight and technical parameters, design parameters and statistical relative mass coefficients. The mass values of the individual components of the RS obtained in this way make it possible to calculate the flight and technical characteristics in the first approximation. After the design calculations of the first approximation, it becomes possible to clarify the values of the static coefficients of the reduced dry weight through the functional and operational parameters affecting the specific design, the physical and mechanical properties of structural materials, and other factors affecting the mass of the structure. The equations obtained in this way are called the detailed mass equations of the second approximation. 
 The presented sequence of compilation and use of target mass equations in the design of the minimum mass RS can also be used in the development of the RS project of minimum cost.

Measuring the impact of long-haul low-cost carriers on lowering fares: A quasi-experimental design to assess the pre-COVID market

This paper aims to investigate the impact of the introduction of the long-haul low cost carrier in the North Atlantic market to present the competitive situation before the COVID-19. There are a number of challenges in estimating the incremental effect of LH LCC. Therefore, several strategies were taken. Firstly, a difference in differences estimation and propensity score matched methods were employed using six major routes in the North Atlantic market with IATA's ticket sale data from January 2015 to December 2019; a granulated data to present the characteristics of flight and economy class fares. The outcomes indicate that a 17.2–20.6% fare reduction in average on the routes where Norwegian operated during 2015 and 2019 after Norwegian's entry, compared to what it would have happened if they didn't operate. It implies the LH LCC entry lowered fares significantly, and the level of fare competition in the North Atlantic market before the COVID-19 was high. In addition, a certain level of viability as an LH LCC has been implicated. This output can be used for the airline's strategic implication and the policy proposition, particularly when LCC expands the longer routes after the COVID recovery. Frequent and specific (detailed) assessments by market and period are imperative.

Performance Evaluation of Badminton Trajectory Error Based on Wireless Sensor Network

The successful holding of the Olympic Games has made the attention to sports continue to rise. China’s badminton has always been at the forefront of the world, and since badminton became an Olympic sport, it has been tasked with winning gold medals. Because the entry of badminton is simple, badminton has a solid mass foundation in China. Badminton has a very high fitness, confrontation, and fun, with speed as the core and stability, accuracy, ruthlessness, and liveliness as the main tactical style. In professional competitions, athlete’s prediction of badminton’s trajectory is of great significance to the performance of the game, so the prediction of badminton’s trajectory is very important. This paper aims to study the performance evaluation of badminton trajectory error analysis based on wireless sensor network. It is expected to predict the trajectory of badminton with the help of wireless sensor network technology, reduce the prediction error, and improve the game performance. Sensors in WSN communicate wirelessly, so network settings are flexible, device locations can be changed at any time, and wired or wireless connections to the Internet are possible. This paper analyzes and compares the commonly used dynamic target capture algorithms, compares the advantages and disadvantages of this wireless sensor network, combines the flight characteristics of badminton, and analyzes the error of its trajectory. Aiming at the vision system in badminton monitoring, the application research on the side detection, tracking, and trajectory prediction algorithm of flying badminton in the two-dimensional image plane video stream is completed. The experimental results of this paper show that the error of using the wireless sensor network is 2 cm and the trajectory error of not using the wireless sensor network is 8 cm. It can be seen that the trajectory extraction error using the wireless sensor network strategy is small.

A Novel Trajectory Planning Method for Parafoil Airdrop System Based on Geometric Segmentation Strategy

Reasonable trajectory planning is the precondition for the parafoil airdrop system to achieve autonomous accurate homing, and safe landing. To successfully realize the self-homing of the parafoil airdrop system, a new trajectory optimization design scheme is proposed in this paper. The scheme is based on the parafoil’s unique flight and control characteristics and adopts a segmented homing design. The current common trajectory design method faces a problem, whereby straight-line flight distance before landing is limited by the radius of the height-reducing area. The core feature of the proposed design scheme is its avoidance of this problem, thereby ensuring landing accuracy and safety. Firstly, the different starting states of the parafoil airdrop system and the landing requirements were comprehensively considered, and the homing trajectory reasonably segmented. Based on the requirements of energy control, stable flight, and landing accuracy, the optimal objective function of the trajectory was established, and the trajectory parameters, calculation methods, and constraints were given. Secondly, the cuckoo search algorithm was applied to optimize the objective function to obtain the final home trajectory. Finally, the trajectory planning under different airdrop conditions was simulated and verified. The results showed that the planned trajectories could reach the target point accurately and meet the flight direction requirements, proving the proposed scheme’s correctness and feasibility.

VR Multiscale Geovisualization Based on UAS Multitemporal Data: The Case of Geological Monuments

Technological progress in Virtual Reality (VR) and Unmanned Aerial Systems (UASs) offers great advantages in the field of cartography and particularly in the geovisualization of spatial data. This paper investigates the correlation between UAS flight characteristics for data acquisition and the quality of the derived maps and 3D models of geological monuments for VR geovisualization in different scales and timeframes. In this study, we develop a methodology for mapping geoheritage monuments based on different cartographic scales. Each cartographic scale results in diverse orthophotomaps and 3D models. All orthophotomaps and 3D models provide an optimal geovisualization, combining UAS and VR technologies and thus contributing to the multitemporal 3D geovisualization of geological heritage on different cartographic scales. The study area selected was a fossilite ferrous site located in Lesvos Geopark, UNESCO. The study area contains a fossil site surrounding various findings. The three distinct scales that occur are based on the object depicted: (i) the fossilite ferrous site (1:120), (ii) the fossil root system (1:20), and (iii) individual fossils (≥1:10). The methodology followed in the present research consists of three main sections: (a) scale-variant UAS data acquisition, (b) data processing and results (2D–3D maps and models), and (c) 3D geovisualization to VR integration. Each different mapping scale determines the UAS data acquisition parameters (flight pattern, camera orientation and inclination, height of flight) and defines the resolution of the 3D models to be embedded in the VR environment. Due to the intense excavation of the study area, the location was spatiotemporally monitored on the cartographic scale of 1:120. For the continuous monitoring of the study area, four different UASs were also used. Each of them was programmed to fly and acquire images with a constant ground sampling distance (GSD). The data were processed by image-based 3D modeling and computer vision algorithms from which the 3D models and orthophotomaps were created and used in the VR environment. As a result, a VR application visualizing multitemporal data of geoheritage monuments across three cartographic scales was developed.

Three-Dimensional Coordinate Extraction Based on Radargrammetry for Single-Channel Curvilinear SAR System

With the rapid development of high-resolution synthetic aperture radar (SAR) systems, the technique that utilizes multiple two-dimensional (2-D) SAR images with different view angles to extract three-dimensional (3-D) coordinates of targets has gained wide concern in recent years. Unlike the traditional multi-channel SAR utilized for 3-D coordinate extraction, the single-channel curvilinear SAR (CLSAR) has the advantages of large variation of view angle, requiring fewer acquisition data, and lower device cost. However, due to the complex aerodynamic configuration and flight characteristics, important issues should be considered, including the mathematical model establishment, imaging geometry analysis, and high-precision extraction model design. In this paper, to address these challenges, a 3-D vector model of CLSAR was presented and the imaging geometries under different view angles were analyzed. Then, a novel 3-D coordinate extraction approach based on radargrammetry was proposed, in which the unique property of the SAR system, called cylindrical symmetry, was utilized to establish a novel extraction model. Compared with the conventional approach, the proposed one has fewer constraints on the trajectory of radar platform, requires fewer model parameters, and can obtain higher extraction accuracy without the assistance of extra ground control points (GCPs). Numerical results using simulated data demonstrated the effectiveness of the proposed approach.

Scale issues for geoheritage 3D mapping: The case of Lesvos Geopark, Greece

A geopark can be composed of many individual geosites of various geographical scales, thus, categorization according to cartographic scale is crucial for their 3D mapping. The UNESCO Global Geopark of the island of Lesvos in the north-east Aegean, Greece, is a distinctive example of this type of geopark as it contains many unique geosites that vary in geographical scale. The geographical scale is interconnected with the cartographic scale in which the geosite is visualized. The desired cartographic scale is an essential user requirement within an unmanned aerial vehicle's (UAVs) 3D mapping project as the basis for the data acquisition strategy. This research investigates the scale issues in 3D mapping of geosites. Furthermore, it contributes to the incorporation of the geographic and cartographical scales in association with UAV flight parameters such as Ground Sample Distance (GSD), altitude, gimbal pitch, orientation, and front and side overlapping. A total of 132 geosites located in Lesvos Geopark are being studied to determine the flight parameters of three different UAVs and their camera characteristics. The methodology followed to collect very high-resolution images suitable for 3D mapping consists of five main stages: i) determining the geographical scale of each geosite, ii) defining the cartographic scale of all geosites, iii) calculation of the GSD based on cartographic scale, iv) calculation of UAV flight altitude and flight characteristics, and v) classification of geosites based on the flight characteristics for their 3D mapping. Five geographic (G1: < 0.1 ha, G2: 0.1–1 ha, G3: 1–10 ha, G4: 10–100 ha, G5: >100 ha) and five cartographic (C1: > 1:50, C2: 1:50–1:100, C3: 1:100–1:250, C4: 1:250–1:500, C5: < 1:500) categories were defined based on the geosites' size and extent. The combination of the two scales determines the most efficient flight characteristics and optimally acquires very high-resolution images required for the 3D mapping of the selected geosites. Finally, the categorization and characteristics of flights for data collection for high-resolution 3D mapping are collected and presented in a web application. The web application is addressed to the management board of Lesvos Geopark and supports the decision-making processes on mapping geosites using UAVs.

Differentiated pricing for airline ancillary services considering passenger choice behavior heterogeneity and willingness to pay

Under the differentiated service reform of Chinese airlines in 2021, it is an inevitable trend to design and develop differentiated ancillary products, which is the optimization scheme of the supply-side for airlines starting from user demands. The trend of domestic air passengers paying for seat selection is becoming increasingly prevalent. By taking the seat selection fee as an example, this study examines the formulation of ancillary service fees based on passengers' willingness to pay. Using a stated preference (SP) experiment method, this study investigates passengers' seat selection behavior and uses the latent class conditional logit model (LCL) to classify passengers based on seat selection preference. Then, considering the passengers' socioeconomic characteristics, travel characteristics, flight characteristics, seat categories, and passenger categories, this study constructs a model of willingness to pay for seat selection through logit regression. Finally, this study further explores the influencing factors that affect passengers' willingness to pay by using the model and conducting a confirmatory analysis between the model results and the investigation data. The research results show that: (1) passengers' cabin seat selection preferences are heterogeneous, and passengers are divided into three categories; (2) the passenger's personal characteristics (gender, age, etc.) have no significant influence on the willingness to pay for the three categories of passengers; however, the flight purpose for business and leisure travel, day flight, flight duration, the number of luggage, person accompanied, person unaccompanied, and preferred seat have a significant impact on it; (3) the model of willingness to pay has strong correctness and practicability, so in practice, with this method, airlines can predict the willingness to pay for seat selection according to passenger categories and then provide differentiated services and charge fees. It provides theory and decision support for airlines to conduct seat management and design differentiated ancillary service products.

Evaluation of unmanned aerial vehicles for surveys of lek‐mating grouse

AbstractUnmanned aerial vehicles (UAVs), or drones, are being utilized by wildlife biologists to monitor populations of birds and mammals. However, the reaction of wildlife to drones varies by species, so a preliminary evaluation must be conducted to determine if the target species can be detected via drone footage and to determine how the target species will react to drone presence. Lek‐mating prairie‐chickens (Tympanuchus spp.) seem amenable to drone‐based surveys because they are relatively large and display in groups on elevated sites with sparse vegetation. The goal of our study was to determine what flight characteristics maximize prairie‐chicken detection on drone video footage, to document the birds' reactions to the drones, and to compare how the noise produced by the drones compares to ambient sounds. We tested 3 sizes of rotary‐winged drones, flown at 3 heights, with 3 different camera angles by flying over known prairie‐chicken leks. We determined that &gt;65% of prairie‐chickens present were detected using video footage at a height of 100 m with a 10° camera angle. Drones of different sizes had similar detectability. However, observers in blinds adjacent to leks routinely detected more birds than were detected on drone footage (detection on drone footage was 39.7 ± 9.6% of birds present). Prairie‐chickens flushed in 96% of trials when a drone was flown over display locations. Time to return to the lek following drone disturbance was similar to prairie‐chickens' reactions to natural predators. Prairie‐chickens flushed when drone sound levels were comparable to ambient noise. Developing guidelines for the ethical use of drones in wildlife research will require quantifying the amount of taxa‐specific disturbance caused by drones. Our study begins to close this knowledge gap by documenting disturbance to upland, lek‐mating grouse of conservation concern, and suggests that the focal species' reaction to aerial predators may provide clues as to how that species may react to drones.

Flight characteristics of rod-shaped windborne debris objects in atmospheric boundary layer winds

The presented study explored the flight characteristics of rod-shaped debris objects in neutrally-stratified atmospheric boundary layer (ABL) winds. Despite the fact that rod-shaped debris objects, such as lumbers, are a common type of debris observed during extreme wind events, their three-dimensional motions had not been fully characterized and the understanding of their flight trajectories was limited to the outcome of only a few wind tunnel tests. To address the outlined research gaps, this study established a coupled simulation framework, which utilized both computational fluid dynamics (CFD) and rigid body dynamics (RBD). After validating this framework using the experimental test data, the flight trajectories of a set of rod-shaped debris objects were first evaluated in uniform winds. With placing the rod's longitudinal axis in both along-wind and cross-wind directions, the debris flight motions were characterized for various initial pitch angles. After appropriate verifications, the simulations were extended to investigate the flight of rod-shaped objects in ABL winds. The main debris flight properties, including displacement and velocity profiles, were systematically extracted over time, taking into consideration various influential factors. With the wealth of debris flight data generated through the conducted CFD-RBD simulations, predictive models were developed for assessing the kinetic energy associated with the flight of rod-shaped debris objects.