Flight Mode Research Articles

Design of the parametric appearance of the power plant for modifications of the regional passenger aircraft An-158

The object of research is the process of remotorization of a regional passenger aircraft to increase its fuel efficiency. Based on the conceptual requirements for the remotorization of the An-158 aircraft with turbojet bypass engines, a parametric appearance of three modifications of this aircraft with turboprop engines for 80, 100, and 120 passenger seats was formed. The study was carried out on the basis of the well-known modular software systems «Integration 2.1» and «Air propeller 2.2» for typical flight profiles of the An-158 aircraft. Improved procedures of weight design and determination of the takeoff characteristics of aircraft with different types of power plant engines have made it possible to identify the most advantageous flight speeds of aircraft modifications with a turboprop engine corresponding to different flight masses. The results of the study of flight performance for optimal and «non-optimal» modifications of the aircraft are reported. The parametric appearance of the propeller was formed, the shape of the propeller blade for the cruising flight mode was determined for modifying the aircraft with a maximum number of passengers – 120 people. It is shown that the propeller for this modification of the aircraft cannot have less than 8 blades since with a smaller number of blades, the maximum chord of the propeller blade increases. The inductive power costs increase significantly due to the small elongation of the blades and, as a result, the flight efficiency of the propeller decreases. It is shown that the total fuel consumption for the entire typical flight of all modifications of the aircraft with turboprop engine at all studied flight speeds is less than the total fuel consumption of the An-158 base aircraft

Observed Causal Relationship Between Eczema and Inflammatory Bowel Diseases

Over the past 27 years in my functional medicine clinical practice, I have had 10 or more patients present with chronic and acute cases of eczema. After taking a thorough history, ordering blood tests and food intolerance panels, all of them were positive for signs and symptoms of intestinal permeability and positive IgA markers to predominantly; gliadin, agglutinins and casein, as well as a plethora of other food proteins, due to the nature of molecular mimicry. After placing patients on an antigen free food plan for 3-6 months, prescribing demulcent herbals, L-glutamine, anti-inflammatory supplements, and counseling them on stress reducing strategies, there was a resolution of the eczema and a healing of the intestinal lining. There is a misconception in traditional allopathic medicine that the problem resides at the dermis, where the symptomatology is observed and expressed. However, the skin is just a reflection and extension of the inflammatory cascade occurring at the intestinal lining which leads to the erosion of the tight junctions of the microvilli, which causes intestinal permeability [1,2]. These erosions open the door to undigested proteins which end up in the enteric blood vessels, subsequently triggering white blood cells to tag these proteins with antibodies. These proteins are almost identical to body tissues (molecular mimicry) , leading to autoimmune reactivity. Eczema is a direct expression of this immune system response and loss of oral and self-tolerance. The road to healing the tight junctions begins with an elimination food plan that excludes all the proteins which have become antigens. I have found it necessary to prescribe demulcent herbs such as; slippery elm, aloe vera gel, marshmallow root, deglycyrrhizinated licorice, rhubarb, immunoglobulin compounds, turmeric, vitamin D3/K2, glutathione, resveratrol and omega 3’s, as well as counseling patients on stress reduction strategies, given that production of high levels of cortisol and norepinephrine contribute to erosion of tight junctions [3]. The more a patient unburdens their body from causative factors, the faster the transformation and quicker the necessary scaffolding is built, to provide significant symptom relief and restoration of functional physiological processes that render a vital healthy human being, who is capable of developing immune and chemical tolerance to living in this “modern” hectic world. We live in a world where we spend 80% of our daily lives running from the “tyrannical lion(ness)” inside our busy monkey minds. In “flight or fight mode”, we are running tons of adrenaline epinephrine, norepinephrine, putting out fires, disasters, unknowns, daily to-do lists, answering phone calls, typing on the computer, driving around freeways, and encountering angry, impatient beings along the way. We are also near-constantly bombarded by lights, sounds, smells, EMF’s, microwaves, 4G and now the 5G radiation grid, toxins, infections, and stressors of all kinds [4]. Taking time to counter these daunting and relentless “flight or fight” drivers is imperative if we are to survive as beings and as a collective species. Stimulating your parasympathetic nervous system is a MUST when leading patients towards successful restoration of health and wellness.

A simulation model for the electrical rotary-wing aircraft (eVTOL) performance estimation for the urban air mobility purposes

The present paper presents a simulation model description developed for the aircraft performance estimation of the most popular electric vertical takeoff and landing aircraft (eVTOL) aerodynamic configurations with the electric (hybrid) power plant for the urban air mobility purposes. It focuses on the quadcopter-type eVTOL aircraft aerodynamic configurations using the unshrouded-propellers or ducted fans driven by electric motors. The aircraft performance analysis for aerodynamic configurations of the quadcopter and tilt rotor-quadcopters with the tilt rotors and wing with the all-electric (EP) or hybrid power plant (HP) is given. To compare aircraft performance, the estimation results for a conventional single-rotor helicopter with EP or HP are given. Based on the numerical solution equation of the aircraft existence, feasible structural components mass distributions for various types of eVTOL configurations were obtained. eVTOL aircraft performance, including the estimation of apparent and drag power for the airspeed range, from hovering to the maximum airspeed, as well as for the transition modes (tilt rotor aircraft and quadcopters) were estimated. The eVTOL aircraft flight range and duration with EP and HP at the straight and level flight mode were calculated. Specific mass characteristics of EP and HP components (batteries, generators, electric motors, etc.) to ensure acceptable eVTOL aircraft performance were identified. A comparative evaluation of considered eVTOL configurations for the purpose of their efficiency was performed. Aerodynamic calculations were carried out based on the known analytical techniques of the lifting propeller momentum theory with the data correction capability according to test results. The simulation model, obtained in this paper, can be considered in the phase of the preliminary choice as the first approach of structural parameters and aerodynamic configurations of prospective electric (hybrid) eVTOLs designed for the use as an urban air taxi.

Determination of the most dangerous flight modes of aircraft in icing conditions

In this paper, the object of research is the icing of aircraft surfaces during flight in the atmosphere. On many light aircraft, as well as on unmanned aircraft weighing less than 30 kg, there are no on-board de-icing systems. Nevertheless, aviation events occur with these aircraft, which are a consequence of their icing. Therefore, determining the most dangerous flight modes of aircraft in icing conditions is an urgent task. In view of the high cost of conducting flight tests and the impossibility of covering all possible events due to their potential danger, the complexity of creating flight conditions for aircraft in icing conditions on the ground, the mathematical modeling method was used in this study. To solve this problem, the analysis of the airworthiness standards of civil light aircraft, transport category aircraft, rotorcraft of normal and transport category was carried out within the framework of the work, the influence of various parameters on the thickness of ice build-up was investigated using a computational experiment conducted on the software developed by the authors of the article. On the basis of the results of the computational experiment, the dependences of the ice thickness on various icing parameters were obtained, a method was developed for determining the combination of heights and flight speeds of an aircraft, at which ice of the greatest thickness is formed on the surface of aircraft, other things being equal. Possession of this information will allow the aircraft crew and air traffic control specialists to avoid the most dangerous flight modes in terms of icing.

Закони керування авіаційним газотурбінним двигуном з турбовентиляторною приставкою

The main aspects of the general task of integrating an aviation engine (AE) with a turbofan additional unit (TAU) of a multi-mode aircraft are the selection of the scheme and design parameters of the AE with the TAU (including parameters of the work process), as well as methods and means of automatic control of the AE with the TAU for better matching its characteristics with certain flight modes. These two tasks are closely interrelated: on the one hand, when determining the appearance of the aircraft and its power plant (PP), it is necessary to consider what means will ensure the adaptation of its characteristics to the variable flight mode, and on the other hand, the purpose of the aircraft, its parameters and parameters of the PP, and the flight modes mostly determine the choice of control laws. The subject of the research is the formation of the laws of control of the aviation gas turbine engine with TAU. The goal is to improve the dynamic characteristics of the aviation gas turbine engine by applying adaptive control of the gas turbine engine with the use of wireless information exchange technologies. Objectives: to generalize the concept of adaptive control at the stage of determining the appearance of an engine with TAU; to determine the methods of regulating the GTE with TAU and their influence on the speed characteristics; to describe the process of formation of the laws governing AE with TAU; to investigate thermal processes in order to find functional dependencies in the optimal control of gas turbines with TAU. Research methods: system analysis, mathematical and computer modeling were used in the formation of control laws; the methods of philosophical knowledge were used to build an approach to the design of adaptive control systems of gas turbines with TAU. The theory of aircraft engines, the theory of differential equations, difference grids, and numerical methods were used to optimize the control of gas turbines with TAU. Results: methods of regulating the GTE with TAU and their influence on the speed characteristics of the aviation engine; formulas for researching the thermal processes of the working blades of the GTE with TAU in order to form the influence of the regulator on the executive mechanisms. Scientific and practical novelty: formation of a paradigm for the development of models of adaptive control of GTE with TAU, considering different flight modes of the aircraft and engine operation modes. The selection of control laws using multi-parameter optimization methods for finding the relationship between structural and component schemes of the gas generator and turbofan additional unit. The character of the engine thrust change depending on the input temperature is shown, which in turn, will allow to increase the efficiency of the fan and obtain a thrust reserve. The research directions of the temperature field and stress field were formed.

Rubber Tree Recognition Based on UAV RGB Multi-Angle Imagery and Deep Learning

The rubber tree (Hevea brasiliensis) is an important tree species for the production of natural latex, which is an essential raw material for varieties of industrial and non-industrial products. Rapid and accurate identification of the number of rubber trees not only plays an important role in predicting biomass and yield but also is beneficial to estimating carbon sinks and promoting the sustainable development of rubber plantations. However, the existing recognition methods based on canopy characteristic segmentation are not suitable for detecting individual rubber trees due to their high canopy coverage and similar crown structure. Fortunately, rubber trees have a defoliation period of about 40 days, which makes their trunks clearly visible in high-resolution RGB images. Therefore, this study employed an unmanned aerial vehicle (UAV) equipped with an RGB camera to acquire high-resolution images of rubber plantations from three observation angles (−90°, −60°, 45°) and two flight directions (SN: perpendicular to the rubber planting row, and WE: parallel to rubber planting rows) during the deciduous period. Four convolutional neural networks (multi-scale attention network, MAnet; Unet++; Unet; pyramid scene parsing network, PSPnet) were utilized to explore observation angles and directions beneficial for rubber tree trunk identification and counting. The results indicate that Unet++ achieved the best recognition accuracy (precision = 0.979, recall = 0.919, F-measure = 94.7%) with an observation angle of −60° and flight mode of SN among the four deep learning algorithms. This research provides a new idea for tree trunk identification by multi-angle observation of forests in specific phenological periods.

Research on Pilot Control Strategy and Workload for Tilt-Rotor Aircraft Conversion Procedure

This paper studies the pilot control strategy and workload of a tilt-rotor aircraft dynamic conversion procedure between helicopter mode and fixed-wing mode. A nonlinear flight dynamics model of tilt-rotor aircraft with full flight modes is established. On this basis, a nonlinear optimal control model of dynamic conversion is constructed, considering factors such as conversion corridor limitations, pilot control, flight attitude, engine rated power, and wing stall effects. To assess pilot workload, an analytical method based on wavelet transform is proposed, which examines the mapping relationship between pilot control input amplitude, constituent frequencies, and control tasks. By integrating the nonlinear optimal control model and the pilot workload evaluation method, an analysis of the pilot control strategy and workload during the conversion procedure is conducted, leading to the identification of strategies to reduce pilot workload. The results indicate that incorporating the item of pilot workload in the performance index results in a notable reduction in the magnitude of collective stick inputs and longitudinal stick inputs. Moreover, it facilitates smoother adjustments in altitude and pitch attitude. Additionally, the conversion of the engine nacelle can be achieved at a lower and constant angular velocity. In summary, the conversion and reconversion procedures are estimated to have a low workload (level 1~2), with relatively simple and easy manipulation for the pilot.

Adaptive Fault-Tolerant Control of a Hybrid Canard Rotor/Wing UAV Under Transition Flight Subject to Actuator Faults and Model Uncertainties

This paper proposes an adaptive fault-tolerant control scheme for an over-actuated hybrid vertical take-off and landing (VTOL) canard rotor/wing unmanned aerial vehicle (UAV) to simultaneously compensate actuator faults and model uncertainties without the requirement of fault information and uncertain bounds. The proposed control scheme is constructed with two separate control modules. The high-level control module is developed with a novel adaptive sliding mode controller, which is employed to maintain the overall system tracking performance in both faulty and fault-free conditions. The low-level control allocation module is used to distribute the virtual control signals that are generated by the high-level control module among the available redundant actuators. In the case of actuator faults, the proposed adaptive scheme can seamlessly adjust the control parameters to compensate the virtual control error and reconfigure the distribution of control signals among the available redundant actuators. A significant feature of this study is that the stability of the closed-loop system is guaranteed theoretically in the presence of both actuator faults and model uncertainties and overestimation of the adaptive control parameters can be avoided. The effectiveness of the proposed control strategy is validated through comparative simulation tests under different faulty and uncertain scenarios.

The interplay of kinematics and aerodynamics in multiple flight modes of a dragonfly

This paper presents the effects of wing kinematics on both normal forward flight and escape flight of a dragonfly. A Navier–Stokes-based numerical model has been adopted, and results have been substantiated by experimental data. The wing kinematics of tethered specimens and the prescribed wing morphology of a free-flying dragonfly were used in the simulation. To shed light on the interplay between kinematics and aerodynamics, a parametric study of the kinematics has been conducted. It is found that in escape flight, the dragonfly generates additional lift while the thrust reduces and the overall efficiency drops. Compared with normal forward flight, the escape mode produces larger lift force peaks. When the kinematics change to facilitate escape flight, the aerodynamic forces are affected by not only the flapping kinematics but, in the case of the hindwing, the varied wing–wing vortex interactions. The direction of the resultant force on each wing changes according to the change of the mean of pitching angle and stroke plane angle. We found that in the studied configurations, the varied phasing of the wings has a marginal effect on the aerodynamics of the dragonfly. It reduces lift and increases thrust, and this force modulation is slightly more efficient when the local angle of attack also changes. On the other hand, the change of angle of attack played a major role in leading-edge vortex formations and directing the resultant forces of the wings. The results can be useful in developing flight control strategies for micro air vehicle design.

ENSURING SPEED STABILITY OF THE UNMANNED AERIAL VEHICLE IN DIF-FERENT FLIGHT MODES

The publication deals with the issue of ensuring the stability of an unmanned aerial vehicle flight by speed. An analysis of the physical essence of the process of ensuring the unmanned aerial vehicle stability by speed is presented. Attention is paid to the flight modes in which the operator (external pilot) may encounter difficulties in the practical piloting of the unmanned aerial vehicle. The possible causes of abnormal situations when flying the unmanned aerial vehicle at speeds close to the borderline low are analyzed. Possible actions of the operator (external pilot) to return the unmanned aerial vehicle to the operating speed range from the area of instability are considered. The article shows the features of stability and controllability of an unmanned aerial vehicle in a route flight mode. Attention is paid to the complexity of piloting and safety of flight in the second modes. The article demonstrates the method of determining the boundary between the first and second flight modes. The features of unmanned aerial vehicle management and ensuring stability in the first and second modes are shown. The issue of dynamic stability of the unmanned aerial vehicle is investigated. Numerical modeling of the longitudinal movement of the unmanned aerial vehicle in free, uncontrolled flight was carried out, trajectories for the unmanned aerial vehicle of the selected configuration with a change in speed and angle of inclination of the trajectory in time were obtained. Graphs of movement trajectories with changes in speed and height over time were constructed, graphs of transient processes were constructed for cases of stable and unstable flight modes. An analysis of the external factors that most affect the flight parameters in various conditions of unmanned aerial vehicle use was carried out.

Feasibility of Accurate Point Cloud Model Reconstruction for Earthquake-Damaged Structures Using UAV-Based Photogrammetry

Camera-enabled unmanned aerial vehicles (UAVs) provide a promising technique to considerably speed up the inspection and visual data collection from regions that may otherwise be inaccessible. In addition, the technology of image-based 3D reconstruction can generate a point cloud model using images captured by UAVs. However, the performance of the point cloud modeling may be affected by multiple factors, such as the modeling software, ground control points (GCPs), and UAV flight modes. In this study, three common software packages were compared, and Pix4Dmapper was considered a suitable software for point cloud modeling for earthquake-damaged buildings. The accuracy and resolution of point cloud models are usually evaluated by root mean square error (RMSE) and ground sampling distance (GSD). The effects of the main factors, including the number of GCPs, distribution of GCPs, flight manner of the UAV, and distance from the UAV to the target, were investigated on the basis of two real-world multistory earthquake-damaged structures. The influence rules of the main factors revealed that a close range, automatic flight mode of the UAV, a large number of GCPs, and a relatively wide distribution of the GCPs may generate a point cloud model with low computational costs, high accuracy, and high resolution. In the particular illustration example here, the RMSE is 6.78 mm while the GSD is 1.60 mm. Finally, rapid structural damage inspection was demonstrated using an accurate point cloud model and compared with the inspection results of a total station and terrestrial laser scanner point cloud models. The comparison of different inspection results showed that the relative errors were relatively acceptable within 4%.

Experimental Investigation for a Small Helicopter in Hovering and Forward Flight Regimes

In this effort, experiments are conducted for a small-scale remotely controlled (RC) helicopter in both hovering and forward flight modes. An open wind tunnel type is used as a source of forward airflow for the helicopter model with flow speed (v∞) ranges from 3 to 12 m/s. A test rig was designed and manufactured to provide safe and reliable averaged thrust measurement in hovering and forward flight regimes. The helicopter is controlled via an adhoc-designed graphical user interface program using a microcontroller along with sensors to measure the blade collective pitch (θ0), rotational speed (Ω), and shaft angle of attack (αs). The averaged thrust for the helicopter is measured and compared with blade element theory and an unsteady model based on strip theory. Measurements are conducted for six rotational speeds and five collective pitch angles in hovering mode. Additionally, forward flight measurements were conducted for five rotational speeds, five collective pitch angles, two forward airflow speeds, and two shaft angles of attack. Uncertainty analysis is performed to certify a statement of the obtained results by combining both bias uncertainty from measuring instrument specifications and precision uncertainty through experimental repeatability. Results can be used for preliminary sizing of rotors for such small helicopters in both flight modes.

De-Orbit Maneuver Demonstration Results of Micro-Satellite ALE-1 with a Separable Drag Sail

ALE-1, a micro-satellite created for the demonstration of artificial shooting stars, required orbital descent before mission execution due to safety aspects in orbit. ALE-1 utilized a drag sail called SDOM (Separable De-Orbit Mechanism) for a passive de-orbit maneuver, which was successfully completed, lowering the orbit from about 500 km down to about 400 km. This paper summarizes the detailed history of satellite operation and the results of the de-orbit maneuver demonstration during the past three years. Although the SDOM sail faced difficulty in keeping the desired deployed shape of the drag sail due to mechanical troubles, by letting the sail be a drag flag instead, it could still deliver a meaningful de-orbit performance to allow the satellite to successfully lower the orbit as planned. The de-orbit effect of the drag flag was evaluated using comparisons between orbit propagation simulations and the actual orbit transition flight data provided in the form of TLE (Two-Line Element) sets. Through this study, it is demonstrated that the SDOM can provide orbit transfer capabilities for satellites. Furthermore, the de-orbit performance of the drag flag can be evaluated, which could be an important reference for the future implementation of de-orbit devices to solve space debris problems.

Departure delay prediction and analysis based on node sequence data of ground support services for transit flights

Delays frequently occur during ground support services for transit flights. Due to the limitation of related data acquisition, the delay occurred during this process has seldom been explored. Toward the purpose of departure delay mitigation, the present research provides the node sequence data to identify the critical ground support service nodes that associate with departure delay. Machine learning techniques are used for accurate departure delay prediction of transit flights. First, the topological structure of the neural network is constructed according to the ground service support procedure of transit flights. The flight data from Shanghai Pudong and Kunming Changshui International airports are collected for delay description and model evaluation. Then, similarity of delay scenarios are illustrated and the typical delay patterns are explored based on clustering methods. It is found that there are some node sections that delays routinely occur. Third, a Bayesian network is constructed for delay probability analysis. The conditional probability table describing the impact of delay occurred during each section on the departure delay for transit flights is provided. Finally, the performance of two classes of approaches to predict departure delays are constructed and compared, including three traditional machining learning methods denoted as random forest, decision tree, XGBoost models, and four graph convolutional neural network models namely Graph convolutional network (GCN), Graph attention network (GAT), Graph sample and aggregate (GraphSAGE) and integrated Graph convolutional network and Graph sample and aggregate (GCN-GraphSAGE) models. In general, the proposed GCN-GraphSAGE method achieves the most stable and satisfactory performance for departure delay prediction. The research results can support the dynamic and accurate prediction of departure delays and the refined management of transit flights for delay alleviation.

Analysis of navigation system accuracy characteristics for micro UAVs

The article analyzes the noise influence of the main types that arise in the process of exchanging navigational information between the GPS receiver of an micro-class unmanned aerial vehicle and the global satellite navigation system using an improved advanced simulation model in the Matlab – Simulink software environment, which allows building a representative statistical model in the process designing algorithms of the navigation system of unmanned aerial vehicles. With the help of modeling the process of choosing the receiver gain factor of an unmanned aerial vehicle and the study of the influence of the quality of reception and processing navigation signals during the increase of the distance relative to the satellite signal of the global navigation satellite system, it was established that with an increase in the gain factor of the antenna, the noise level decreases. However, an increase in the amplification factor leads to an increase in the dimensions of the antenna, as well as, accordingly, an increase in energy consumption, which does not meet the requirements for the mass-dimensional indicators of the microclass of unmanned aerial vehicles. Also, the article investigated the operation process of microelectromechanical systems of platformless inertial navigation systems, namely, at the moment of the disappearance of global satellite systems at a time interval of up to 300 seconds, to determine the error of calculating the parameter of the vertical component (height) and vertical speed of an unmanned aerial vehicle. According to the simulation results, it was found that the orientation and navigation of unmanned aerial vehicles in autonomous flight depend significantly on random errors of microelectromechanical systems of platformless inertial navigation systems, these include random angle wandering (zero noise drift); the influence of linear acceleration of the accelerometer sensor, by studying the noise model of errors microelectromechanical systems to determine the eight velocity parameter in autonomous flight mode, which is of a significant nature.

Analysis of the Sound Field Structure in the Cabin of the RRJ-95NEW-100 Prototype Aircraft

The results of in-flight experiments to determine the structure of the sound field in the cabin and pressure fluctuation fields on the surface of the fuselage of the RRJ-95NEW-100 prototype aircraft are presented here. Wall pressure fluctuation spectrums are obtained for three zones of measuring windows (forward, center, and rear fuselage) in cruising flight mode. The effect of the jet on the pressure fluctuation levels in the tail fuselage is considered. For an aircraft without an interior, the contribution of the main sources to the total intensity calculated through A-weighted overall sound pressure levels is determined. It has been determined that the main noise sources in the cabin of the RRJ-95NEW-100 prototype aircraft in cruising flight mode are pressure fluctuation fields on the fuselage surface (turbulent boundary layer noise) and the air conditioning system. The ratio between the sources varies along the length of the cabin.

An Experimental and Simulation Study of the Active Camber Morphing Concept on Airfoils Using Bio-Inspired Structures.

Birds are capable of morphing their wings across different flight modes and speeds to improve their aerodynamic performance. In light of this, the study aims to investigate a more optimized solution compared to conventional structural wing designs. The design challenges faced by the aviation industry today require innovative techniques to improve flight efficiency and minimize environmental impact. This study focuses on the aeroelastic impact validation of wing trailing edge morphing, which undergoes significant structural changes to enhance performance as per mission requirements. The approach to design-concept, modeling, and construction described in this study is generalizable and requires lightweight and actively deformable structures. The objective of this work is to demonstrate the aerodynamic efficiency of an innovative structural design and trailing edge morphing concept compared to conventional wing-flap configurations. The analysis revealed that the maximum displacement at a 30-degree deflection is 47.45 mm, while the maximum stress is 21 MPa. Considering that the yield strength of ABS material is 41.14 MPa, this kerf morphing structure, with a safety factor of 2.5, can withstand both structural and aerodynamic loads. The analysis results of the flap and morph configurations showed a 27% efficiency improvement, which was confirmed through the convergence criteria in ANSYS CFX.

An efficient intelligent energy management strategy based on deep reinforcement learning for hybrid electric flying car

Hybrid electric flying cars hold clear potential to support high mobility and environmentally friendly transportation. For hybrid electric flying cars, overall performance and efficiency highly depend on the coordination of the electrical and fuel systems under ground and air dual-mode. However, the huge differences in the scale and fluctuation characteristics of energy demand between ground driving and air flight modes make the efficient control of energy flow more complex. Thus, designing a power coordinated control strategy for hybrid electric flying cars is a challenging technical problem. This paper proposed a deep reinforcement learning-based energy management strategy (EMS) for a series hybrid electric flying car. A mathematical model of the series hybrid electric flying car driven by the distributed hybrid electric propulsion system (HEPS) which mainly consists of battery packs, twin turboshaft engine and generator sets (TGSs), 16 rotor-motors, and 4 wheel-motors is established. Subsequently, a Double Deep Q Network (DDQN)-based EMS considering ground and air dual driving mode is proposed. A simplified method for the number of control variables is designed to improve exploration efficiency and accelerate the convergence speed. In addition, the frequent engine on/off problem is also taken into account. Finally, DDQN-based and dynamic programming (DP)-based EMSs are applied to investigate the power flow distribution for two completely different hypothetical driving scenarios, namely search and rescue (SAR) scenarios and urban air mobility (UAM) scenarios. The results demonstrate the effectiveness of the DDQN-based EMS and its capacity of reducing the computation time.

Geometrically compatible integrated design method for conformal rotor and nacelle of distributed propulsion tilt-wing UAV

The inner rotors of distributed propulsion tilt-wing Unmanned Aerial Vehicles (UAVs) are often folded in the cruising state and deployed in vertical take-off and landing to cope with the huge difference in thrust requirements. However, the blades of the conventional rotor have poor conformality with the nacelle profile, which will greatly increase the drag of the UAV after folding. This paper proposes an integrated method for the design of rotor and nacelle considering geometric compatibility to reduce the drag of the folded rotor and nacelle, so as to further improve the aerodynamic efficiency in cruise while ensuring the rotor efficiency in the vertical flight mode. A geometric mapping model based on nacelle design parameters and rotor design parameters is established, and a parametric model and aerodynamic optimization model of the outer arc airfoil family are developed. In addition, a rotor performance analysis model and a neural network response surface model for nacelle drag prediction that meet the requirements of confidence level are established. Based on the oblique inflow blade element momentum theory method, numerical simulation method, and genetic algorithm, an integrated optimization framework of the design of the conformal rotor and nacelle is built. Then, a geometrically compatible integrated optimization for the rotor and nacelle is carried out with the objective of maximizing energy efficiency in the full mission profile. Finally, a conformal rotor and nacelle design solution is obtained, which satisfies geometric compatibility and thrust constraints while providing high thrust efficiency and low cruising drag. A comparison of the results of the integrated design and the conventional rotor optimization design shows that the drag of the conventional rotor is 3.45 times that of the conformal integrated design in the cruising state, which proves the effectiveness and necessity of the proposed method.

Cook Ice Shelf and Ninnis Glacier Tongue Bathymetry From Inversion of Operation Ice Bridge Airborne Gravity Data

AbstractThe seafloor depths under the Cook Ice Shelf and Ninnis Glacier Tongue have not been directly measured, despite their importance for understanding ocean circulation and ice shelf change. We model the bathymetry underneath the floating ice and surrounding ocean using airborne gravity data. Our model is constrained by few ship‐based seafloor measurements near the ice front and by ice‐base measurements over areas of grounded ice from radar data. Localized basins (∼1,400 m deep) are found beneath both ice shelves. The shallowest modeled bathymetry (∼200 m) represents the offshore extension of Cape Freshfield. Near the grounding line, seafloor depths are found to be deeper than the observed depth of the modified Circumpolar Deep water in the region (<350 m), key factor for basal melt analyses. From transit flight gravity anomalies, we suggest the relocation of the mapped edge of the continental shelf and a narrowing of the Cook Shelf Depression.