Flight Characteristics Research Articles

Plasma preheating technology for replicating planetary re-entry surface temperatures

AbstractArc-jet facilities have been the norm for ablation experiments used to calibrate computational models to date. However, the arc jet has a few major limitations and challenges, including non-uniform enthalpy distribution, non-equilibrium state, change of surface quality during testing and the extent of oxidation, to name but a few. A novel plasma technique for preheating axisymmetric heatshield samples in hypersonic impulse facilities is presented herein. The major aim of this innovative work is to help reduce the large variations of ablation rate predictions, space vehicle materials and missile design/testing, obtain strongly coupled hypersonic boundary layers and achieve lower cost of aerothermodynamics experiments. This present work remains one of the most highly anticipated solutions to maximise payload success and replicate high surface temperatures identical to those experienced by real flight vehicles. This work makes a useful contribution to re-entry studies under conditions that replicate the characteristics of re-entry flights. Future applications for the technique are expected to be found in hypersonic impulse facilities that can simulate the true flow energy under re-entry conditions.

“Red Bird Collaborative” Fighter Design

The main purpose of this project is to design an unmanned aerial vehicle that can cooperate with the main engine in the future. The unmanned aerial vehicle must have the following physical characteristics: detectable, cooperative flight, super maneuverability and other general characteristics [1]. The design of the aircraft mainly highlights the future. The characteristics of high-precision strikes against enemy aircraft in warfare. The performance of UAVs is optimized and innovatively designed. The aircraft mainly relies on the transmission sensor on the head to accelerate and hover around the enemy aircraft in a short period of time to seize the initiative in air combat [2]. Right to protect the host and destroy the enemy aircraft. In the future, this type of fighter will become Universal design direction.

DEM-Based UAV Flight Planning for 3D Mapping of Geosites: The Case of Olympus Tectonic Window, Lesvos, Greece

Geosites are an important part of geoheritage, thus their detailed mapping is crucial for their management, protection and promotion processes. However, there is no specific approach to three-dimensional (3D) mapping of geosites and a full investigation is required, considering the current advances in the science of Geoinformatics and the need for setting up an integrated system that will suggest a suitable way of mapping areas of geological significance. The main purpose of this study is to explore new approaches to the 3D mapping of geosites, where the unmanned aerial vehicles’ (UAVs) flight planning is based on the digital elevation model (DEM). The case study that is being examined is the tectonic window of Mount Olympus, located in the southeast of Lesvos island, Greece. In this paper, a methodology has been developed to create flight plans for geosite 3D mapping. This methodology consists of three main stages: (a) flight planning based on SRTM-DEM, (b) data acquisition and image-based 3D modelling, and (c) comparison (flight plans and results). A semi-automated algorithm was developed for designing the flights, taking into account the topography of the mapped area (slope, aspect, elevation) and the final cartographic derivatives. The flight plans were compared with each other in levels of data collection, flight characteristics and their results. The results of this study are dense point clouds, DEMs and orthophotomaps. The algorithms that have been used for the comparison of point clouds were (I) surface density, (II) number of neighbours (NN), and (III) roughness and surface profile. The conclusion drawn from this study is that the DEM is a valuable source of information that can be used in designing flight plans specially shaped on the topography of each geosite.

High-fidelity prediction of flight trajectories of plate-type debris in boundary layer winds

From reconnaissance surveys, plate-type objects, such as roof shingles and tiles, are known to be among the most common types of debris objects. Therefore, a reliable prediction of their flight trajectories is instrumental for evaluating the vulnerability of building envelopes, especially in the regions with severe windstorms. Despite the development of several quasi-steady models for this purpose, the current literature lacks high-fidelity models to predict the flight pattern and impact velocity of the windborne debris objects separated from the ground and/or buildings. To address this gap, a coupled computational fluid dynamics and rigid body dynamics simulation framework was developed in the current study to capture the flight trajectories of plate-type debris objects in atmospheric boundary layer winds. Upon establishing a fundamental understanding of main flight characteristics, this study was extended to investigate the effects of initial pitch and yaw angles, plate characteristics, mean wind velocity, and release height on the flight of plate-type debris. In addition, a set of models were developed to predict debris travel distance, as well as linear and angular velocities associated with it. This can be directly employed to assess the impact-induced loading demand that building envelopes are expected to resist due to windborne plate-type debris.

Swing-Reducing Flight Control System for an Underactuated Indoor Miniature Autonomous Blimp

This article presents the first swing-stabilization control for indoor miniature autonomous blimps (MABs). Indoor MABs are safe to operate in close proximities to humans and can fly for multiple hours, but swing oscillation is commonly observed due to their underactuated design and unique aerodynamic shape. In this article, we analyze the flight characteristics of indoor MABs, and describe the design of the swing-reducing flight control system in detail. Key mechatronic designs for swing-stabilization control are also presented. Experimental results show that the proposed controller can keep the blimp travel at the desired velocity while effectively stabilizing the swing oscillation. The swing-reducing velocity controller is then expanded for station keeping and waypoint navigation in a 3-D space.

On the Aerodynamic Analysis and Conceptual Design of Bioinspired Multi-Flapping-Wing Drones

Many research studies have investigated the characteristics of bird flights as a source of bioinspiration for the design of flapping-wing micro air vehicles. However, to the best of the authors’ knowledge, no drone design targeted the exploitation of the aerodynamic benefits associated with avian group formation flight. Therefore, in this work, a conceptual design of a novel multi-flapping-wing drone that incorporates multiple pairs of wings arranged in a V-shape is proposed in order to simultaneously increase the propulsive efficiency and achieve superior performance. First, a mission plan is established, and a weight estimation is conducted for both 3-member and 5-member configurations of the proposed air vehicle. Several wing shapes and airfoils are considered, and aerodynamic simulations are conducted, to determine the optimal planform, airfoil, formation angle, and angle of attack. The simulation results reveal that the proposed bioinspired design can achieve a propulsive efficiency of 73.8%. A stability analysis and tail sizing procedure are performed for both 3-member and 5-member configurations. In addition, multiple flapping mechanisms are inspected for implementation in the proposed designs. Finally, the completed prototypes’ models of the proposed multi-flapping-wing air vehicles are presented, and their features are discussed. The aim of this research is to provide a framework for the conceptual design of bioinspired multi-flapping-wing drones and to demonstrate the sizing, weight estimation, and design procedures for this new type of air vehicles. This work establishes the first multi-flapping-wing drone design which exploits the aerodynamic features of the V-formation flight observed in birds to achieve superior performance in terms of payload and endurance.

Environmental assessment of entropy control in flight process

PurposeThis study aims to examine exergy efficiency of engines and entropy performances at the flight process. In addition, the improvements that can be achieved in the system with the effective parametric controls of the engine have been evaluated in terms of both efficiency and entropy in the system.Design/methodology/approachAccording to the flight characteristics of the engine, the altitude-dependent irreversibilities and their environmental effects were discussed with two developed indicators, energy performance indicator (EPI) and sustainability indicator (SI).FindingsAccording to the results of both indicators, the energy efficiency potential of the engine during the flight process was found to be 15.02%, while the fuel-based efficiency potential was 18.84%.Research limitations/implicationsIt is limited by the flight process of a Turboprop engine.Practical implicationsThe management tools and criteria of entropy are very difficult model studies. The study offers an evaluable approach based on two basic criteria developed for engines.Social implicationsIn monitoring and review of entropy management related to fossil fuel technologies, key indicators developed can be used as benchmarks for managing emission sourcesOriginality/valueThe two basic indicators developed can be used as monitoring measurement tools of sustainable energy and environmental performances for engines and applications.

Influence of surface permeability on gas-dynamic characteristics of high-speed flight

This paper covers the use of gas-permeable materials as the outer surface of a high-speed aircraft. The gas-dynamic structures of supersonic flows are compared in the presence of blowing from the body surface and in its absence. The influence of the blowing speed on the structure of the formed gas-dynamic discontinuities is determined.

Estimation of Vertical Take-off Unmanned Aircraft Flight Characteristics and Algorithm of Required Roll Angle Calculating for Trajectory Tracking

Estimation of Vertical Take-off Unmanned Aircraft Flight Characteristics and Algorithm of Required Roll Angle Calculating for Trajectory Tracking

CREATION OF MATHEMATICAL MODELS FOR PARAMETRIC IDENTIFICATION DURING TESTS TO DETERMINE THE FUEL CONSUMPTION OF THE HELICOPTER WITH EXHAUST- HEAT SHIELDS

With the increasing effectiveness of guided missile weapons, the problem of protecting helicopters from these means of destruction is becoming increasingly important. To date, the issue of assessing the protection of helicopters in tests of helicopter equipment are insufficiently developed and require more careful consideration. Therefore, the research of the protection of helicopters equipped with an integrated protection system against guided missiles with infra-red target seeker devices and the impact of exhaust-heat shields on the values of flight characteristics of the helicopter is quite relevant.
 The article researches the influence of exhaust-heat shields on the flight technical characteristics of helicopters, their change during the installation of exhaust-heat shields. The estimation of the change in geometric, mass and center characteristics of helicopters by the calculation method is given and the method determining the characteristics of fuel consumption by the calculation and experimental method is given. The methodology and results of experimental researches of flight technical characteristics of the helicopter with the established exhaust-heat shield are described.
 The basic result of the research is the study of existing methods for determining the impact of exhaust-heat shields on the flight characteristics of helicopters. Methods of parametric identification for determination of fuel consumption are worked out and the analysis of flight technical characteristics of the helicopter is developed. The fuel consumption of the helicopter with exhaust-heat shield is defined. Integrated assessment of the effectiveness of protection of helicopters from guided missiles with infra-red targeting device can be directly used in practice in test systems for the protection of upgraded and the latest models of helicopters. According to the results of research, mathematical models for determining the fuel consumption of a helicopter with exhaust-heat shields have been developed.

An Improved Island Algorithm and Its Application in Model Optimization of Micro Soft Robot

Aiming at the shortcomings of the original island algorithm (IA), which has a slow convergence speed and is prone to local optimality, the island algorithm with the characteristics of Levy flight (LevyIA) was proposed by introducing the Levy flight strategy, which replaced the position update method in the original algorithm and made use of the occasional long jump of Levy flight strategy to jump out of the local optimal solution. The simulation test of the improved algorithm is carried out with 6 test functions, and the experimental results show that the improved algorithm LevyIA can effectively solve the problems of slow convergence speed and local optimization of island algorithm. For the micro-soft robot model with multi-mode movement, IA and LevyIA algorithms were used to optimize the size of the robot and the appropriate magnetic field intensity needed to drive the robot to deform and move. Finally, the experimental data of swimming speed of the robot obtained by simulation shows that, among the three optimization results obtained by LevyIA algorithm and IA algorithm, LevyIA algorithm can make the robot swim faster when moving forward with minor perturbations.

Development of optimal scheduling strategy and approach control model of multicopter VTOL aircraft for urban air mobility (UAM) operation

Urban air mobility (UAM) is emerging as a new alternative to solve the traffic problem in the metropolitan area. Industries and government agencies are preparing for the future UAM system and operation. A new ATC (Air Traffic Control) strategy or aircraft separation method that reflects flight characteristics of multicopter VTOL (Vertical Take-off and Landing) aircraft is required. Particularly, approach control around the vertiport is one of the essential issues for the safe and efficient operation of UAM, and strict safety standards are required for service in populated urban areas. In this study, the concept of holding points where multicopter aircraft can hover is introduced, and three scheduling strategies for arriving aircraft are developed and evaluated by comparing the on-time performance (OTP) with hovering time and ground time. BQA (Branch Queuing Approach), SBA (Sequence-based Approach) and, SBAM (sequence-based approach with moving circles) models are proposed and compared. BQA model prioritizes airspace safety by limiting the aircraft’s travel path; SBA model allows the aircraft to move freely within the airspace and prioritizes aircraft’s arrival sequence; and finally, SBAM adds the moving circle concept to the SBA model. For each model, OTP and loss of separation (LOS) risk of the proposed models are found and they are compared by simulations. The simulation result shows that SBA and BQA have similar punctuality performance and BQA model with no LOS risk is the most efficient approach control model for multicopter VTOL aircraft of UAM.

DEFINITION OF THE CHARACTERISTICS OF THE UNMANNED AVIATION SYSTEM WHEN CARRYING OUT SEARCH AND RESCUE OPERATIONS IN WETTED AREAS

The article presents the problems of conducting search and rescue operations in wetlands and forest areas. The relevance of the use of unmanned aerial vehicles of the helicopter type for the search for victims was substantiated. The main parameters affecting the quality of image formation are considered. A method for calculating the information recognized from unmanned aerial vehicles is presented, and their flight characteristics are substantiated. The minimum size of objects that can be confidently recognized in images was calculated.

Noctuid and geometrid moth assemblages show divergent elevational gradients in body size and color lightness

Previous macroecological studies have suggested that larger and darker insects are favored in cold environments and that the importance of body size and color for the absorption of solar radiation is not limited to diurnal insects. However, whether these effects hold true for local communities and are consistent across taxonomic groups and sampling years remains unexplored. This study examined the variations in body size and color lightness of the two major families of nocturnal moths, Geometridae and Noctuidae, along an elevational gradient of 700 m in Southern Germany. An assemblage‐based analysis was performed using community‐weighted means and a fourth‐corner analysis to test for variations in color and body size among communities as a function of elevation. This was followed by a species‐level analysis to test whether species occurrence and abundance along an elevation gradient were related to these traits, after controlling for host plant availability. In both 2007 and 2016, noctuid moth assemblages became larger and darker with increasing elevation, whereas geometrids showed an opposite trend in terms of color lightness and no clear trend in body size. In single species models, the abundance of geometrids, but not of noctuids, was driven by habitat availability. In turn, the abundance of dark‐colored noctuids, but not geometrids increased with elevation. While body size and color lightness affect insect physiology and the ability to cope with harsh conditions, divergent trait–environment relationships between both families underline that findings of coarse‐scale studies are not necessarily transferable to finer scales. Local abundance and occurrence of noctuids are shaped by morphological traits, whereas that of geometrids are rather shaped by local habitat availability, which can modify their trait–environment‐relationship. We discuss potential explanations such as taxon‐specific flight characteristics and the effect of microclimatic conditions.

Study of Mosquito Aerodynamics for Imitation as a Small Robot and Flight in a Low-Density Environment.

In terms of their flight and unusual aerodynamic characteristics, mosquitoes have become a new insect of interest. Despite transmitting the most significant infectious diseases globally, mosquitoes are still among the great flyers. Depending on their size, they typically beat at a high flapping frequency in the range of 600 to 800 Hz. Flapping also lets them conceal their presence, flirt, and help them remain aloft. Their long, slender wings navigate between the most anterior and posterior wing positions through a stroke amplitude about 40 to 45°, way different from their natural counterparts (>120°). Most insects use leading-edge vortex for lift, but mosquitoes have additional aerodynamic characteristics: rotational drag, wake capture reinforcement of the trailing-edge vortex, and added mass effect. A comprehensive look at the use of these three mechanisms needs to be undertaken—the pros and cons of high-frequency, low-stroke angles, operating far beyond the normal kinematic boundary compared to other insects, and the impact on the design improvements of miniature drones and for flight in low-density atmospheres such as Mars. This paper systematically reviews these unique unsteady aerodynamic characteristics of mosquito flight, responding to the potential questions from some of these discoveries as per the existing literature. This paper also reviews state-of-the-art insect-inspired robots that are close in design to mosquitoes. The findings suggest that mosquito-based small robots can be an excellent choice for flight in a low-density environment such as Mars.

Changes in airport operating procedures and implications for airport strategies post-COVID-19

Covid-19 is demanding a lot of changes in the realm of our daily lives. The aviation industry is also facing unprecedented changes in the management environment. Financial tensions across the sector are rising. This study suggests that the airport strategy's direction focusing on commercial revenue management. After Covid-19, safety and hygiene will be the top priority. As a result, changes in airport operating procedures are inevitable. The most noticeable difference will be the strengthening of the verification process for passengers' health conditions. Dwell time increase can be the by-products. This study identifies a dwell time increase has a more significant impact on increasing the existing purchasers' spending than creating new buyers. Airport operators can introduce a service differentiation perspective, such as a dedicated service, to utilize the current buyers' dwell time more faithfully. Also, the rise of online channels requires airport operators to change sales strategies, reinforcing emotional promotion to stimulate impulse buyers' willingness-to-buy. Before Covid-19, there was little effort to reconcile operation policies and commercial revenue despite the growing importance of revenue management. However, now it is time to change. Pre-Covid-19, passengers were advised of using off-airport processes, such as online check-in and mobile boarding passes. Now, getting passengers to the airport quickly and securing their dwell time can be financially more beneficial. It is necessary to incorporate the commercial revenue perspective into operation policies post-Covid-19 actively. Our finding indicates that even a passenger with solid purchasing power may lose the purchasing intention when assigned to an unfavorable gate or terminal. Airport operators need a better understanding of passenger and flight characteristics when determining operation policy, such as gate allocation or membership services.

Results of simulation and scaled flight tests performed on a rocket-plane at high angles of attack

PurposeAccording to the study of the space flight market, there is a demand for space suborbital flights including commercial tourist flights. However, one of the challenges is to design a mission and a vehicle that could offer flights with relatively low G-loads. The project of the rocket-plane in a strake-wing configuration was undertaken to check if such a design could meet the FAA recommendation for this kind of flight. The project concept assumes that the rocket plane is released from a slowly flying carrier plane, then climbs above 100 kilometers above sea level and returns in a glide flight using a vortex lift generated by the strake-wing configuration. Such a mission has to include a flight transition during the release and return phases which might not be comfortable for passengers. Verification if FAA recommendation is fulfilled during these transition maneuvers was the purpose of this study.Design/methodology/approachThe project was focused on the numerical investigation of a possibility to perform transition maneuvers mentioned above in a passenger-friendly way. The numerical simulations of a full-scale rocket-plane were performed using the simulation and dynamic stability analyzer (SDSA) software package. The influence of an elevator deflection change on flight parameters was investigated in two cases: a transition from the steep descent at high angles of attack to the level glide just after rocket-plane release from the carrier and an analogous transition after re-entry to the atmosphere. In particular, G-loads and G-rates were analyzed.FindingsAs a result, it was found that the values of these parameters satisfied the specific requirements during the separation and transition from a steep descent to gliding. They would be acceptable for an average passenger.Research limitations/implicationsTo verify the modeling approach, a flight test campaign was performed. During the experiment, a rocket-plane scaled model was released from the RC model helicopter. The rocket-plane model was geometrically similar only. Froude scales were not applied because they would cause excessive technical complications. Therefore, a separate simulation of the experiment with the application of the scaled model was performed in the SDSA software package. Results of this simulation appeared to be comparable to flight test results so it can be concluded that results for the full-scale rocket-plane simulation are also realistic.Practical implicationsIt was proven that the rocket-plane in a strake-wing configuration could meet the FAA recommendation concerning G-loads and G rates during suborbital flight. Moreover, it was proven that the SDSA software package could be applied successfully to simulate flight characteristics of airplanes flying at angles of attack not only lower than stall angles but also greater than stall angles.Social implicationsThe application of rocket-planes in a strake-wing configuration could make suborbital tourist flights more popular, thus facilitating the development of manned space flights and contributing to their cost reduction. That is why it was so important to prove that they could meet the FAA recommendation for this kind of service.Originality/valueThe original design of the rocket plane was analyzed. It is equipped with an optimized strake wing and is controlled with oblique, all moving, wingtip plates. Its post-stall flight characteristics were simulated with the application of the SDSA software package which was previously validated only for angles of attack smaller than stall angle. Therefore, experimental validation was necessary. However, because of excessive technical problems caused by the application of Froude scales it was not possible to perform a conventional test with a dynamically scaled model. Therefore, the geometrically scaled model was built and flight tested. Then a separate simulation of the experiment with the application of this model was performed. Results of this separate simulation were compared with the results of the flight test. This comparison allowed to draw the conclusion on the applicability of the SDSA software for post-stall analyzes and, indirectly, on the applicability of the proposed rocket-plane for tourist suborbital flights. This approach to the experimental verification of numerical simulations is quite unique. Finally, a quite original method of the model launching during flight test experiment was applied.

Wind Tunnel Experiments on Flight Characteristics of Windborne Debris upon Low-Rise Building

In strong wind events such as hurricanes and tornadoes, windborne debris is the main cause of disasters and buildings destruction. Roof slabs, tiles, and other enclosure components may become potential windborne debris. In the present research, a series of wind tunnel experiments were carried out to investigate the flight characteristics (i.e., the trajectory distribution and the flight speed) of debris released at different positions on the windward roof of a low-rise building. The results show that the initial position of debris has an important influence on the trajectory distributions and flight speed. Along the Y-axis, the trajectory distribution of debris released near the central axis of the roof is wider than those of debris whose initial positions lying closer to the side. As for debris which is closer to the central axis of the roof, a wider trajectory distribution in the vertical direction and higher flight speed are observed when the debris is released closer to the windward eave. And for debris whose initial positions have the same distance from the windward eave, the closer the initial positions to the central axis, the lower the total speed is. The total speed of the debris is mainly composed of the vertical (Z-axis) speed component at the beginning of the flight, and gradually, the proportion of horizontal (X-axis) speed keeps increasing with time passing by.

The morphological characteristics of the Muradiye Dönek pigeon, a native Turkish genetic resource

This study was conducted to investigate the morphological characteristics of Muradiye Dönek pigeon. It is a local animal genetic resource and cultural heritage and has an important place among the genotypes of domestic pigeons in Turkey. The animal material of this study consisted of 100 pigeons (50 females and 50 males) from seven pigeon enterprises. In the study, morphological characteristics were evaluated and morphometric measurements were determined. Body plumage colors of pigeons were determined as black (70%), red (16%) and blue (14%) galaca. In some birds, the yellow beaks and nails may bear black spots, which pigeon breeders refer to as ‘zikir’. The term ‘biyik’ (mustache) is used when black feathers appear among the white feathers on the head, and the term ‘kemer’ (belt) is used when black feathers appear in the tail. The differences between the mean values of body weight and wingspan (P<0.001), chest depth (P<0.05) values were statically significant for age groups, which were reported to affect flight characteristics in birds. As a result, when the morphological characteristics obtained in Muradiye Dönek pigeons are compared with other researchers, it is thought that the selection of these birds were carried out by the breeders in terms of the game behavior such as rotation movement during the diving and landing. Although the data obtained in the study support the hypothesis that Muradiye Dönek pigeons should be defined as a different breed, further studies with DNA analysis are required to confirm this situation.

UAV Recognition Based on Micro-Doppler Dynamic Attribute-Guided Augmentation Algorithm

A micro-Doppler signature (m-DS) based on the rotation of drone blades is an effective way to detect and identify small drones. Deep-learning-based recognition algorithms can achieve higher recognition performance, but they needs a large amount of sample data to train models. In addition to the hovering state, the signal samples of small unmanned aerial vehicles (UAVs) should also include flight dynamics, such as vertical, pitch, forward and backward, roll, lateral, and yaw. However, it is difficult to collect all dynamic UAV signal samples under actual flight conditions, and these dynamic flight characteristics will lead to the deviation of the original features, thus affecting the performance of the recognizer. In this paper, we propose a small UAV m-DS recognition algorithm based on dynamic feature enhancement. We extract the combined principal component analysis and discrete wavelet transform (PCA-DWT) time–frequency characteristics and texture features of the UAV’s micro-Doppler signal and use a dynamic attribute-guided augmentation (DAGA) algorithm to expand the feature domain for model training to achieve an adaptive, accurate, and efficient multiclass recognition model in complex environments. After the training model is stable, the average recognition accuracy rate can reach 98% during dynamic flight.