A digital elevation model (DEM) can be generated using a gradient of a single image and a stereo image pair from an imaging sensor or laser altimeter sensor on an orbiter. These DEMs are affected by intrinsic problems such as stereo noise in the triangulation process or low spatial resolution from sparse measurement points. Various image-based techniques are presently used to enhance the resolution

This paper addresses an impact angle control guidance problem for nose-dive missiles to achieve the maximum terminal speed against a fixed target in the same vertical plane. By modeling the aerodynamic drag as a drag polar, we set up the nonlinear system equations needed to pursue an analytic closed-form solution. This paper shows that maximizing the terminal speed is equivalent to minimizing a weighted

The coupling between different disciplines for multi-disciplinary optimization greatly increases the complexity of a computational framework, while at the same time increasing CPU time and memory usage. To overcome these difficulties, first, proper orthogonal decomposition and radial basis function were used to generate a reduced-order model from the initial experimental points. Second, analysis results

To model 3-Dimensional woven composites, the width and thickness of the yarn are generally used as input parameters. However, since these parameters can only be obtained after the composites are molded, it is not efficient in the initial stages of design using woven composites. Therefore, a geometric modeling method using weaving parameters that can be known before manufacturing is required. In this

In this paper, a novel adaptive fast nonsingular terminal sliding mode (FNTSM) control approach is proposed for the robust adaptive finite-time prescribed performance attitude tracking control of spacecraft subject to inertia uncertainties, external disturbances, and input saturation. First, a simple error transformation is introduced to guarantee the attitude tracking errors always stay within the

In this paper, a linear acceleration control algorithm is proposed. The proposed algorithm aims to follow a given linear acceleration command accurately to enable precise trajectory tracking flights especially for a quadrotor unmanned aerial vehicle under high-wind environments. Existing linear acceleration control algorithms are based on feedforward control concept only, however the proposed algorithm

A previously developed estimation technique, of the minimum energy required for complete fin deployment under an operational requirement of gust speed, was modified to consider time consumed for fin unfolding as an additional requirement, which might lead to an increase of the required energy. Some modifications were made such as non-zero kinetic energy of unfolding fin when completely deployed and

This paper proposes an integrated framework for staging and trajectory optimization of a launch vehicle under a constraint on the instantaneous impact point (IIP) of the separated stage. The proposed framework iterates between the optimal staging module and the trajectory optimization module to minimize the lift-off mass of a launch vehicle for a given payload mass. The trajectory optimization module

To improve the aerodynamic performance of tiltrotor aircraft, the flow characteristics of the V-22 airfoil without and with one, two parallel rows of vortex generators (VGs) were investigated using numerical simulation methods. The results were obtained with three-dimensional compressible Reynolds-averaged Navier–Stokes equations, and the turbulence was simulated with the SA-based DES model. The influence

Multi-packet whole bladed disks are found in some turbo engines. At the same time, mistuning of blades is inevitable and it will lead to the vibration localization in which vibration energy mainly locates in some blades in the bladed disk system. It can accelerate the high cycle fatigue of the bladed disk. It is critical to search for an efficient way to control the level of vibration localization

Compared with UAVs controlled by aerodynamic surfaces, mass-actuated UAVs have higher aerodynamic efficiency and better stealth performance. This paper focuses on the dynamics and attitude control of a mass-actuated fixed-wing UAV (MFUAV) with an internal slider. Based on the derived mathematical model of the MFUAV, the influence of the slider parameters on the dynamical behavior is analyzed, and the

A new method to estimate the aircraft heading angle, wind velocity, and airspeed bias error is proposed without relying on the magnetometer. A GPS, rate-gyro, pitot-static tube, and sideslip angle sensor are combined through a design of an extended Kalman filter based on a vectorial geometric relation among the ground, air, and wind velocity. The feasibility of the method is validated through a desktop

Rotors with active flap control have considerable potential in reducing vibration and noise and improving aerodynamic performance. However, due to the movement of the flap, there are unavoidable gaps between the components that will lead to significant changes in the aerodynamic characteristics. Moreover, considering the difficulties in motion modeling and the accuracy of the simulation of the flow

To achieve supermaneuverability, the flight envelope for modern fighter aircraft should be extended beyond 40 \(\sim \)60° angles of attack region, where unstable and undesirable flight characteristics such as wing rock may occur. This paper investigates the wing rock phenomenon of a fighter configuration having conventional conical forebody through free-to-roll (FTR) wind tunnel tests. The time history

Research on cooperation missions of multiple unmanned vehicles (UVs) is growing to overcome the limitations of conventional missions and to increase the variety of missions. In this study, a vision-based recognition and position measurement system was developed to cooperate with an unmanned aerial vehicle (UAV) in case an unmanned ground vehicle (UGV) is unable to drive due to terrain obstacles. Phase

With the development of supersonic/hypersonic vehicles, the influence of non-uniform flow has attracted increasing attention. Non-uniform flow exists everywhere in a scramjet, which is a potent engine for supersonic/hypersonic vehicles. Most flows entering the isolator, combustor, and nozzle exhibit high non-uniformity. Thus, several design methods for generating non-uniform flow have been proposed

In this study, we proposed concepts of a vertiport airspace design that must precede for the practical operation of urban air mobility, an emerging new urban mobility solution. We developed algorithms to find the optimal radius of airspace for each concept and, through simulations, derived comparisons among them. We also introduced the concept of a vertiport terminal control area where an personal

Two-dimensional numerical simulations of a nanosecond pulsed single dielectric barrier discharge (SDBD) are performed in air. Streamers produced in nanosecond SDBDs have filamentary properties and generate a strong electric field and high-density gradient of charged particles. This results in non-equilibrium effects of electrons, which makes analysis of the plasma physics challenging. To simulate the

Understanding the effect of fluctuating wind on the aerodynamic performance of the wing is important for designing practical using flapping-wing micro air vehicles (FMAV). This paper aims at providing a systematic synthesis on the fluctuating wind influence on the performance of the three dimensional lumped flexibility wing based on the numerical analysis approach. The fluctuating wind is simplified

This paper addresses the control issue of the integrated attitude and orbit tracking of spacecraft in the presence of inertia parameter uncertainty and spatial disturbance. By considering thruster as the control actuator, the 6-degree-of-freedom integrated model consisting of attitude and orbit dynamics is formulated. Based on the backstepping design, an adaptive control strategy is developed by exploiting

To solve a problem of bi-criteria optimization of an aircraft flight trajectory using the data of satellite navigation systems, the authors suggest an approach based on the game theory methods. The target was set to organize trajectory control with two partial criteria of optimality (desired track deviation and position-fixing error) minimized simultaneously. It is shown that the minima of individual

Delayed detached eddy simulation (DDES) has been proved to be suitable for the numerical simulation of massively separated flow. Whereas, there are still some drawbacks in the treatment of gray area, which is the transition zone between Reynolds-Averaged Navier–Stokes (RANS) and large eddy simulation (LES). In this paper, a modified DDES with shear layer adapted (SLA) subgrid length scale was employed

This study aims to develop a simple and efficient design optimization methodology for the low Reynolds number airfoils. XFOIL is used as an aerodynamic solver while modeFRONTIER workflow is employed for the design optimization purpose. The airfoil SG6043 is used as the reference airfoil for optimization due to its common applications when long-endurance characteristics are desired. A simple design

This paper proposes a practical optimal guidance law that can handle terminal angle and acceleration constraints while providing robustness against uncertainty in autopilot dynamics. Building upon a well-established linear-quadratic optimal guidance framework, we first derive an energy-minimizing guidance scheme that nullifies terminal acceleration called optimal guidance law with impact angle and

Safe and efficient training using flight simulation training devices (FSTD) is one of the fundamental components of training in the commercial, military, and general aviation. When compared with the live training, the most significant benefits of ground trainers include improved safety and the reduced cost of a pilot training process. Flight simulation is a multidisciplinary subject that relies on

The safe exploitation of the buckling and post-bulking region of stiffened composite panels is of prime interest in aerospace engineering. Experiments were carried out to investigate the effects of stringer design on the buckling and post-buckling behavior of stiffened composite panels subjected to in-plane shear loading in this study. Three configurations of I-shape stringers were designed with the

In the event of an aircraft crash, the impact resistance performance of the fuel tank is essential to maximize the survivability of the crew. Damage caused by excessive load on the fuel cell and interference between the fuel cell and the surrounding structure is a main cause in case of an aircraft accident. The fuel system of fuel tank for aircraft should be designed to prevent fuel cell damage by

Ridge-cut explosive bolts are a type of pyrotechnic release devices in which two connected structures are separated by explosives. They are designed such that shock waves can interact with and cut their body. Furthermore, they provide a clean separation surface and require a smaller explosive amount compared with other types of explosive bolts. In this study, ridge-cut explosive bolts of various diameters

This paper aims to propose a new guidance algorithm for intercepting a high-speed maneuvering target, such as a tactical ballistic missile that flies in a quasi-ballistic trajectory. The motivation of this study lies in the fact that the classical proportional navigation guidance (PNG) undergoes the performance degradation under the above engagement scenario due to its intrinsic property. To deal with

This paper describes the combination of a Kriging surrogate model with a micro-genetic algorithm for studying the influence of circumferential perturbations from the stack line on the high-cycle fatigue (HCF) weak link of a fan blade in a high-bypass-ratio turbofan engine. Based on the circumferential perturbations of the fan blade stack line, an automated system is developed for the parameterized

A new combined electric anti-skid braking system of a high-speed unmanned aerial vehicle is designed to improve the stability and to reduce the system sensor noise. An electric anti-skid braking mechanism model considering the sensor noise effect is built in MATLAB/Simulink. The stability of a slip ratio braking system and a deceleration braking system is analyzed using the Routh criterion and Lyapunov

The structural integrity of aircraft structures under vibratory loads is primarily evaluated through vibration tests, but it is necessary to predict the design life through vibration fatigue analysis at the design stage. Vibratory loads affect the durability of aircrafts by combining with the dynamic characteristics of their structures. The generation of stress spectrum in the vibratory loads, which

This paper presents fault tolerance control (FTC) of a quadrotor under actuator faults. A complete FTC design approach with fault detection and diagnosis (FDD) is addressed. The proposed FTC is based on the model predictive control, which can be applied to nonlinear systems using the so-called successive convexification algorithm, which converts a nonconvex function to a convex function in a successive

Due to an unfortunate oversight the acknowledgment section has been omitted.

Atomic oxygen (AO) is a major threat to satellites in Low Earth Orbits (LEO). AO causes serious damage to satellites such as erosion, corrosion and damage to almost all satellites surfaces. This study presents numerical prediction for the space environment effects on NARSSCube satellite using ATOMOX module in Space ENVironment Information System (SPENVIS) online simulation tools. Indeed, the prediction

Discrete cavities with guide vanes were developed and optimized to improve the operating stability of a centrifugal compressor. Various combinations of search algorithms and surrogate models were tested to find the best optimization methods. Aerodynamic analysis was performed using three-dimensional Reynolds-averaged Navier–Stokes equations. The numerical results obtained for the total pressure ratio

In this paper, a pressure-based coupled computational fluid dynamics algorithm for numerical analysis of all Mach number region flow is developed. For this purpose, an enhanced pressure based coupled algorithm was developed through the pressure–velocity coupled algorithm and the pressure-enthalpy coupled algorithm were combined. In additional, the Kurganov–Tadmor flux splitting scheme, which is mainly

Complex and unsteady flow patterns occur around rotating rotor blades owing to the generation of shock waves at the blade tip and interference between the blade and tip wake when the blade rotates at high speeds, thereby resulting in specific noise characteristics. Furthermore, these noise characteristics cause noise pollution in private areas and degrade detectability of helicopters in military applications

This paper introduces improved weighted A* (WA*DH), an advanced version of the weighted A* (WA*). To increase the performance of WA*, we suggest a new parameter, the heuristic angle, which is defined as the angle between the direction of an nth node to the target and the direction of the heading from the (n−1)th node to the nth node on the path. The process of WA*DH involves searching nodes that degrade

This paper presents a wind profile estimation method for test flight of a short-range air-to-surface missile. The method integrates the telemetry data (e.g., navigation data, fin control history), empirical regional wind profile data, and a high-fidelity flight dynamics simulator to infer on the vertical wind profile that the missile has experienced during the flight. The inference procedure works

Aiming at the problem of insufficient availability in the satellite receiver autonomous integrity monitoring (RAIM) method, an improved aircraft autonomous integrity monitoring (AAIM) method aided by barometric altimeter based on weight optimization is proposed under the actual configuration of the airborne navigation system. The information of satellite navigation system and barometric altimeter is

With the increased use of composite materials in aircraft structures, continuous and thorough monitoring of structural conditions is highly required for the assurance of safety and reliability. In this study, as part of the fiber Bragg grating (FBG) sensor-based aircraft health and usage monitoring system (HUMS) development research, in-flight strain monitoring of an aircraft tail boom structure using

The propellant supply system of a liquid rocket engine using an electric pump has high reliability because of the relatively small number of components. The system also has the merit of a quick response and ease of control owing to its simple configuration. Recently, the rocket lab developed the Rutherford engine, which has an electric pump cycle, because of the improved technology in the electric

In the aircraft operation, the metallic airframes are usually exposed to the extreme loading conditions during the flights due to which the risk of failure should be assessed and held to an allowed level to prevent the associated loss. If the components are inspectable, the components should be inspected routinely so that the fatigue damage can be detected before failure, which usually requires non-destructive

Recently, electrically driven pump-fed cycle rocket engines (i.e., ElecPump engines) have received considerable attention. ElecPump engines are superior to pressure-fed engines and will likely replace gas generator cycle engines under a 100 kN thrust level. This study focuses on LOX/methane ElecPump engines with a low-thrust level and estimates the nominal operation point of the engine. The objective

This paper proposes the engagement model and optimal task assignment algorithm for small-UAV swarm operations in hostile maritime environments. To alleviate the complexity of a real engagement environment, several assumptions are made: in the proposed engagement model, a vessel can attack the UAV within a certain range with a constant kill probability rate; and the ability of a vessel to attack UAVs

This paper presents a collaborative experimental and numerical research to investigate the influences of the installation of propeller on aircraft aerodynamic performance, and two approaches to mitigate the propeller installation effect are also analyzed. The configuration under investigation is based on a real flying wing unmanned aerial vehicle with a two-bladed pusher-propeller mounted on the aft

The Abrupt Wing Stall (AWS) at moderate Angle-of-Attacks (AoA) and transonic flight conditions can result in uncommanded lateral motions such as heavy wing, wing drop and wing rock that degrade handling qualities, mission performance and safety of flight for the aircraft. This phenomenon caused by asymmetric wing flows makes it difficult to perform precision tracking or maneuvering in the transonic

Among many composite material structures, honeycomb sandwich composites have been used in various ways. The honeycomb sandwich is adhered by polymer resin adhesive and the stiffness of honeycomb sandwich structures is determined by adhesive characteristics. This study is intended to evaluate adhesive characteristics after surface treatment and lateral compressive characteristics before and after thermal

Rotorcraft composite structures are required to satisfy desired reliability levels when analyzing the scatter of material properties at coupon and element levels in accordance with the Federal Aviation Regulations “FAR 29.573” and the Advisory Circular “AC 29.573”. By estimating the strength and life shape parameters from static and fatigue test results, load enhancement factors can be obtained. Thus

CubeSats are becoming increasingly popular in the scientific community. While they provide a whole new range of opportunities for space exploration, they also come with their own challenges. One of the main concerns is the negative impact which they can have in the space debris problem. Commonly lacking from attitude determination and propulsion capabilities, it has been difficult to provide CubeSats

This paper presents a study on airworthiness of fuel system for an unmanned air vehicle. The presented contents consist of network modeling for analysis and flight test results on fuel system airworthiness. First, performance prediction of fuel system for unmanned air vehicle was achieved using software tool based on theoretical analysis and empirical data. And also flight tests were performed for

In the present study, the interaction effect by inter-rotor spacing of coaxial rotor blades in hovering and forward flight is studied by using a Reynolds-averaged Navier–Stokes CFD flow solver based on mixed meshes. The meshes were composed of unstructured near-body region and Cartesian off-body region. The flux-difference splitting scheme of Roe was used for computing inviscid fluxes on the near-body

During service, a turbine engine undergoes frequently dynamic operations. Because of the changes in mass flow, temperature, pressure, as well as the different reaction of the components of turbine to these changes, the turbine performances may vary significantly. It is critical to understand and quantify these variations to design and integrate the turbine to the engine. This paper presents a study

In the present study, numerical simulation was conducted to study both the internal and external flows of a fluidic oscillator in a quiescent environment and with a crossflow. Unsteady Reynolds-averaged Navier–Stokes analysis was used to evaluate the flow field. The blowing ratio was varied to understand the interaction between the free stream and the oscillating jet. Results for the time-averaged

Detached Eddy Simulation is used to study the interaction flowfields of a supersonic lateral jet penetrating into the crossflow of projectiles with cruciform or X-type fin configurations at \({\text{Ma}} = 0.3\) and \(\alpha = 0^\circ ,30^\circ \sim 60^\circ\). For \(\alpha = 0^\circ\), typical flow structures such as barrel shock, Mach disk and counter-rotating vortex pair(CVP) induced from the jet

The tangential injection flow commingled with the mainstream could be abstracted as mixing layer, and profound importance is attached to aero-optical reduction for film-cooling target-seeking vehicles in engineering application. Leveraging the in-house code based on explicit fifth-order Weighted Compact Nonlinear Scheme and ray-tracing method, the supersonic mixing layer is numerically simulated to

In space exploration missions, the spacecraft have limited computing resources. In particular, the communications environments for these spacecraft, whether in deep space or the cislunar region, are characterized by intermittent connectivity loss, long signal-propagation delay, and high bit-error rates between spacecraft and their ground stations. Delay-Tolerant Network (DTN) has been introduced to

The effects of flow structure and particle size in the secondary combustor of a ducted rocket on mixing are investigated using a two-phase large eddy simulation analysis. The corner recirculation zone and central recirculation area appear in the combustor. Vortexes are generated mainly by the axial inlet flow. The stretched eddies along the axial direction appear on the rear section of the combustor

This paper proposes a new cooperative homing guidance to enhance the survivability of multiple anti-ship missiles against a high-value target such a frigate or a battleship when prior information on the target is unknown. In this paper, the survivability enhancement for the multiple anti-ship missiles against the battleship with no preliminary information on its current heading direction and weak spot