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

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

To ensure high-resolution image acquisition for a spaceborne parabolic synthetic aperture radar (SAR) antenna, an appropriate thermal design is important to minimize the thermal distortion of the antenna reflector in severe on-orbit thermal environments. This paper describes the results of a preliminary thermal design and the analysis of a carbon fiber reinforced plastic skin-based unfurlable parabolic

This study considers intermittent maneuver based on line-of-sight rate bounding to improve target observability for passive homing guidance. Target observability is critical for the performance of the target tracking filter and indirectly affects the guidance accuracy. This paper derives an observability measure associated with the Fisher information matrix for the adaptive intermittent maneuver strategy

This study conducts an aeromechanics analysis of a modern lift-offset coaxial rotor in high-speed flight. A lift-offset coaxial rotor of the Sikorsky X2 technology demonstrator (X2TD) is considered for the present study. For the analyses of rotor performance, blade airloads, and hub vibratory loads, a rotorcraft comprehensive analysis code, CAMRAD II, is used. For the rotor performance analysis at

Multi-DOF flexible space robots play a significant role in the on-orbit service. The flexibility of the robots is mainly caused by the flexible links and some flexible drive elements in joints. The vibration generated by the component flexibility can affect the accuracy of control. In this paper, the dynamics and control issues of flexible-link flexible-joint (FLFJ) space robots considering joint friction

To address standoff target tracking using a fixed-wing UAV in unknown background wind, a wind estimation based on Unscented Kalman Filter (UKF) is proposed. In the paper, UAV dynamic model and target state estimation are constructed, and Lyapunov vector field guidance (LVFG) framework is introduced to achieve standoff target tracking. The unknown target state and wind dynamic model have seldom been

In this paper, environmental tests were conducted with a MEMS (micro-electro mechanical system) oscillator, which is known to be robust under harsh environmental conditions, and comparisons with the existing TCXO (temperature-controlled crystal oscillator) were conducted. And the results of the environmental tests of a GNSS receiver equipped with the MEMS oscillator were compared with the test results

Target tracking using pseudo-measurement is widely used because of its simple implementation and computational advantages despite biased behavior. The biasedness of the pseudo-measurement tracking filter originates from a measurement-dependent Kalman gain and a state-dependent non-Gaussian biased noise. This paper proposes a bias-compensated pseudo-measurement filter considering a range rate measurement

Super-resolution reconstruction refers to the technique of reconstructing a high-resolution image from a single or a series of low-resolution images by digital image processing. This technology can not only increase the high-frequency information of the image, but also eliminate the low-resolution. Deep Learning has made breakthroughs in modern digital image processing. Compared to traditional algorithms

This paper intends to compare the effect of the attitude parameterization method on the performance of the attitude controller designed with the direct feedback of corresponding attitude states. To achieve this, the proportional-derivative controllers using the finite rotation angles and the modified Rodrigues parameters are designed with the same structure and equivalent performance of the direct

The flow field structure of a single injection port fluidic thrust vectoring nozzle was studied by introducing secondary flow injection in the expansion section of the two-dimensional convergent-divergent nozzle. To determine the motion characteristics of unsteady flow in a shock-induced fluidic vectoring nozzle, detached eddy simulation was conducted to simulate the three-dimensional flow field, and

The noise sources of the tip-jet driven rotor are mainly classified as rotor blade noise and jet noise. The rotor blade noise includes thickness noise, loading noise, and nonlinear quadrupole noise, while the jet noise includes nozzle momentum noise and jet radiation noise. Each noise component has different noise source mechanisms related to flow characteristics and the rotating motion. Especially

This paper proposes generalized polynomial guidance for controlling the terminal velocity vector (speed and flight path angle), which could be critical for the effectiveness of the warhead of tactical ballistic missiles. A polynomial reference trajectory satisfying the initial and terminal altitudes and flight path angles is introduced with a guidance parameter that can be chosen to change the terminal

This study proposes an algorithm to calculate fast the predicted intercept point (PIP) of the anti-ballistic missile system. A neural network system is trained to learn the motion of the ballistic target to predict the future target position. Then a prediction algorithm iteratively calculates PIP and the launch time of the interceptor. PIP calculation enables the missile to effectively approach to

An Improved Delayed Detached Eddy Simulation (IDDES) model as a kind of hybrid RANS/LES approach has been developed and applied to calculate tip leakage flow in a linear compressor cascade with moving casing, and the result was compared with the experimental results and LES results. The hybrid approach combines delayed detached eddy simulation (DDES) with an improved RANS–LES hybrid model aimed at

Propellant sloshing is one of the potential sources of disturbance which affects the stability and structural integrity of space vehicles. In this study, using a small scale model of the first Korean lunar orbiter fuel tank, which is partially filled with liquid fuel, the dynamic lateral sloshing has been simulated by CFD analysis for various fill-levels. Spherical tank geometry was assumed, because

An integrated guidance and control problem under state constraints is considered for terminal homing of missile engagement. The problem is formulated as a moderate-size convex optimization problem, which can be efficiently solved via existing techniques such as interior point methods or alternating direction method of multipliers. Two different formulations are presented, and their computation time

Fiber metal laminates, as the new generation of aircraft structural materials, are widely concerned by material researcher. This paper presents a study on the life prediction problems of fiber-reinforced Al–Li alloy laminates under spectrum loading by applying the cumulative damage and residual strength models. Firstly, fatigue life performance of the laminate materials is tested under different loading

Herein, the characteristics of the Moon-to-Earth (M–E) trajectory satisfying the point return orbit (PRO) conditions are analyzed and optimized. A numerical three-step approach is proposed to serve as a useful tool to generate trajectory while preparing for real-world missions. To formulate the given problem, each step properly adapts different equations of motion with design parameters suitable to

In this study, the nozzle flow influence on the forebody aerodynamics has been numerically investigated and validated with experiment. To understand the nozzle flow aerodynamics on the forebody, five different nozzle-exit profiles, which are often encountered in the experiments, are considered one at a time. One flow condition is considered at a nominal freestream Mach number of 4. The CFD simulations

Ablation experiments of four thermal protection system (TPS) candidate specimens, including two UHTCs-coated (HfC and HfC–TiC) specimens, were performed. The specimens were tested at the VKI’s 1.2 MW ICP plasma wind tunnel. Intrusive flow diagnostic techniques (calorimetric probe and Pitot tube) were used to experimentally determine cold wall heat flux and dynamic pressure. Using the wind tunnel operating

Icing encountered by an aircraft in flight can pose a great threat to flight safety, which is the foremost concern in aviation. Ice accretion has nonlinear and coupling properties, and therefore, a conventional envelope protection system cannot successfully deal with the condition. A safe flight envelope based on reachability analysis is proposed in this paper as a basis for designing an online envelope

In this study, a flight control design strategy based on incremental nonlinear dynamic inversion (INDI) and smoothing algorithm is presented. The INDI is an enhanced version of the nonlinear dynamic inversion technique with a better robust performance. It reduces the aircraft model dependence via the feedback information of the state derivative, that is, angular acceleration for the aircraft attitude

An air compressor has been adapted to a high-speed train to reduce the aerodynamic problems when passing through a tunnel. To evaluate the feasibility of the air compressor to attenuate the aerodynamic drag, pressure transient and the micro-pressure wave, the flow around the high-speed train has been simulated using the unsteady axisymmetric compressible Navier–Stokes equation. The simulation results

This paper introduces a load monitoring device and its flight test applications for military aircraft. The device can digitize and record signals from optical fiber sensors and strain gauges. Some key flight parameters can be simultaneously recorded in the device, which is connected to an aircraft data bus cable. The device was installed on a low-speed aircraft and multiple sensors including fiber

This paper proposes a global path planning for lunar rovers in polar regions under static and dynamic constraints. Prior to lunar mission launch, a specific mission path must be set for a lunar rover. The mission path is generated under uncertain information. Only lunar digital elevation model (DEM) and secondary parameters derived from DEM are available. The parameters can be divided into two categories:

Position and time information provided by the satellite navigation system is important in many application fields. However, the satellite navigation signal is vulnerable to interference signals due to the low navigation signal strength. This interference signal for the satellite navigation signal is being advanced to the spoofing signal, which can adjust the position and time information of the satellite

The Hall effect thruster (HET) is an electric propulsion system in which electrons confined in a certain region collide with neutral particles due to the Hall effect. The neutral particles are ionized, and the ions are accelerated by the electric field to produce thrust. Thus, a Hall thruster has a simpler structure than an ion thruster. To improve the accuracy of the HET performance analysis, the

Effect of hump shape on boundary layer instability is investigated for incompressible, supersonic, and hypersonic speed regimes. Flat-plate boundary layers over a two-dimensional smooth hump of five different geometries are considered. The linear evolution of instability waves is analyzed by using the parabolized stability equation. The resulting growth rate and N-factor are compared for several frequencies

AFDX (Avionics Full Duplex switched Ethernet) standardized as ARINC 664 is chosen as the backbone network for distributed real-time avionics systems as it offers high throughput and does not require global clock synchronization. A deterministic upper bound of the end-to-end transmission delays for packets of each flow should be guaranteed to ensure the network performance. In this paper, we focus on

To increase the effectiveness of a glide-bomb attack, it must be able to control the direction in which it strikes the target. Since glide bombs have different characteristics from missiles, it would not be suitable to attack at the high speed; so, it is not appropriate to use the guidance laws for the typical missiles directly. While there are many similarities with TAEM guidance for re-entry vehicle

In the present study, a numerical model is developed to research the effect of the heat input on fluid sloshing. The volume of fluid method is used to simulate fluid reciprocating motion during sloshing with the mesh motion treatment being coupled. The external sloshing excitation is realized by user-defined functions and the convection thermal boundary condition is adopted to consider the heat exchange