Artillery Projectiles Research Articles

Optimization of artillery projectiles base drag reduction using hot base flow

The CFD numerical simulations were carried out to investigate the base drag characteristics of a projectile with base bleed unit with a central jet. Different base bleed grain types with different combustion temperatures were used. The goal was to find a way to effectively control the base flow for base drag reduction and optimisate the latter using an adequate CFD software. Axisymmetric, compressible, mass-averaged Navier-Stokes equations are solved using the k-? SST, transition k-kl-?, and RSM turbulence models. The various base flow characteristics are obtained by the change in the non-dimensionalized injection impulse. The results obtained through the present study show that there is an optimum bleed condition for all base bleed grains tested. That optimum is dependent on the temperature of the grain combustion products. The optimum reduces the total drag for 6,9% in the case of air injection at temperature of 300 K and reaches up to 28% in the case of propellant combustion products injection at almost 2500 K. Besides, the increasing of molecular weight has a role no less important than temperature of the combustion products in terms of base drag reduction.

INTEGRATED SYSTEM FOR SPOTTING THE FALLS OF BALLISTIC ARTILLERY SHELLS AND MISSILES

A system monitoring the falls of artillery projectiles within the area of live firings consists of detectors, separated by distances no larger than 50 m in the ground and 100 m in water, having a single core microcomputer with GPS localiser, radio link interface and a powering battery. For this reason a data transmitter is placed near the area and a receiver of transferred data and a computer with the software for visualisation of projectile impact sites is placed on a centre for controlling (commanding) and evaluating the results of firing. The managing software reconstructs an event and its position and displays it in the real time into the picture of the area shown on the monitor by analysing the data received from detectors in the form of compressed records of digital data. The received data can be used for verification and evaluation of performed firing assignments.

Research on Active Disturbance Rejection Control Technology of Electromechanical Actuators

It has been proven that the properties of non-linearity, multi-disturbance, and time-variation are the main factors affecting the performance of the electromechanical actuator (EMA) for guided artillery rockets. In particular, its controller should have good dynamic characteristics and strong anti-disturbance features when the projectile is maneuvered at the end of its guidance. For these reasons, an active disturbance rejection controller (ADRC) was designed for a guided artillery rocket’s EMA with a ball screw drive. Compared to other control methods, it has been shown that the ADRC had a stronger disturbance rejection ability than PID, Fuzzy-PID, and BP-PID under the condition of 20% maximum control torque disturbance, and it also had a large stability margin and bandwidth.

Russia destroys last of its stockpile

Russia has destroyed the last of the massive chemical weapons stockpile it inherited from the Soviet Union at the end of the Cold War, the Organisation for the Prohibition of Chemical Weapons (OPCW) says. The final artillery projectiles filled with VX nerve agent were dismantled on Sept. 27 at a facility in Russia’s Udmurtia region, wrapping up an effort that spanned two decades. “The completion of the verified destruction of Russia’s chemical weapons program is a major milestone,” says Ahmet Uzumcu, OPCW’s director general. OPCW oversees global efforts to eliminate stockpiles under the Chemical Weapons Convention, which took effect in 1997. The group says that over 96% of declared stockpiles have been eliminated by its 192 member nations. Russia declared an arsenal of 39,967 metric tons of chemical warfare agents, including mustard agent, phosgene, and the nerve agents sarin, soman, and VX. In 2012, the U.S. said it had destroyed

Trajectory tracking using robust gain-scheduling control with a new independent variable

To reduce the expenditure, a low-performance guidance and control system is usually employed in the design of guided artillery rockets, which however will induce great difficulties in trajectory tracking because the rocket's parameters vary fast over a large operation range. The traditional time invariant control approaches for trajectory tracking cannot guarantee the adaptability of controller. On the other hand, since time is routinely considered as the independent variable, the dynamic error system varies sharply, resulting in a weak anti-jamming capability. To address these issues, a new trajectory tracking approach for guided rockets is developed by using the robust gain-scheduling control technique based on the linear parameter varying system, in conjunction with a new coordinate transformation that considers the arc length of reference trajectory as the independent variable. Through comparative studies, it is observed that the proposed method outperforms the existing ones in trajectory tracking during the whole flight trajectory, which demonstrates its effectiveness and advantages.

Guidance and control for high dynamic rotating artillery rockets

The acceleration autopilot with a rate loop is the most commonly implemented autopilot, which has been extensively applied to high-performance missiles. Nevertheless, for spinning rockets, the design of the guidance and control modules is a challenging task because the rapid spinning of the body creates a heavy coupling between the normal and lateral rocket dynamics. Nonlinear modeling of the rocket dynamics, control design as well as guidance algorithms are performed in this paper. Moreover, discrete-time guidance and control algorithms for the terminal phase, which is based on proportional navigation, are performed. Finally, complete nonlinear simulations based on realistic scenarios are developed to demonstrate the robustness of the proposed solution with respect to uncertainty regarding launch, environment and rocket conditions. The performance of the proposed navigation, guidance and control system for a high-spin rocket leads to significant reductions in impact point dispersion.

항력감소분석을 위한 항력산출에 대한 연구

본 논문은 비행시험의 결과를 이용하여 항력 및 항력감소 분석을 위한 항력계수 산출기법에 대하여 기술하였다. 2차원 탄도운동방정식의 역산을 통하여 비행시험을 이용한 항력계수 산출방법에 대하여 정리하였으며 155 mm 탄의 비행시험을 통하여 이론적인 항력계수와 시험결과로부터 산출된 항력계수를 비교하여 항력계수 산출 기법에 대한 검증을 수행하였다. 항력감소제가 적용된 탄의 비행시험결과를 이용하여 항력계수 산출 및 항력감소 양상을 분석하였다. In this paper, determination method for drag force and drag coefficient from results of firing test is described. The drag force and drag coefficient are determined through inverse operation of 2-dimensional projectile equation of motion. Determination method was verified by comparing analytical drag coefficient with data from flight test. Analysis of drag coefficient and drag reduction was performed with the data of flight test using artillery projectiles with base bleed unit.

Simulation-Based Early Prediction of Rocket, Artillery, and Mortar Trajectories and Real-Time Optimization for Counter-RAM Systems

The threat imposed by terrorist attacks is a major hazard for military installations, for example, in Iraq and Afghanistan. The large amounts of rockets, artillery projectiles, and mortar grenades (RAM) that are available pose serious threats to military forces. An important task for international research and development is to protect military installations and implement an accurate early warning system against RAM threats on conventional computer systems in out-of-area field camps. This work presents a method for determining the trajectory, caliber, and type of a projectile based on the estimation of the ballistic coefficient. A simulation-based optimization process is presented that enables iterative adjustment of predicted trajectories in real time. Analytical and numerical methods are used to reduce computing time for out-of-area missions and low-end computer systems. A GUI is programmed to present the results. It allows for comparison between predicted and actual trajectories. Finally, different aspects and restrictions for measuring the quality of the results are discussed.

Measurement fusion using maximum‐likelihood estimation of ballistic trajectories

A novel method is proposed for asynchronous measurement fusion using maximum-likelihood (ML) estimator. This method is applied to multiple radar tracking and reconstruction of ballistic trajectories. The performance and robustness of the ML measurement fusion technique are analysed using a generic simulation scenario involving multi-sensor weapon locating in urban environment. Accuracies of firing point and impact point estimation of mortar grenades and artillery rockets are also evaluated taking into account different radars’ characteristics and geometries of the scenario. Immunity to glint noise, limited time of observation, and uncertainty of ballistic coefficient are also investigated. This study shows the effectiveness of the new method, advantages over track fusion approach, and reveals its practical value.

Dispersion reduction of artillery rockets guided by flight path steering method

ABSTRACTArtillery rockets are sensitive to disturbances (total impulse variation, wind, thrust misalignment, etc.). As the range of ground-to-ground rockets increases, the accuracy of free flight rockets decreases. Requirements for the increase of the range and minimisation of the impact point dispersions can be solved by adding guidance and control systems to rockets. Based on the differences between the measured flight parameters and the calculated parameters for the nominal trajectory, the flight path angle correction algorithm is obtained by adding the correction to the nominal value. The flight path steering guidance system with lateral acceleration autopilot in the inner loop, is used for the guidance of hypothetical artillery rockets. The guidance algorithm given in this paper eliminates the time correction due to rocket velocity variations. Efficiency of the proposed algorithm is illustrated by numerical simulation. There is no practical influence of the external disturbances on impact point dispersion. It is also shown that the measurement errors of the inertial measurement unit are the dominant factor affecting impact point dispersion of artillery rockets modified by adding a guidance system based on the flight path steering method.

Mass asymmetry and tricyclic wobble motion assessment using automated launch video analysis

Abstract This paper describes an approach to identify epicyclic and tricyclic motion during projectile flight caused by mass asymmetries in spin-stabilized projectiles. Flight video was captured following projectile launch of several M110A2E1 155 mm artillery projectiles. These videos were then analyzed using the automated flight video analysis method to attain their initial position and orientation histories. Examination of the pitch and yaw histories clearly indicates that in addition to epicyclic motion's nutation and precession oscillations, an even faster wobble amplitude is present during each spin revolution, even though some of the amplitudes of the oscillation are smaller than 0.02 degree. The results are compared to a sequence of shots where little appreciable mass asymmetries were present, and only nutation and precession frequencies are predominantly apparent in the motion history results. Magnitudes of the wobble motion are estimated and compared to product of inertia measurements of the asymmetric projectiles.

„Abgedrehte Kupferwaren‟: Kriegsmaterialexporte der schweizerischen Uhren-, Metall- und Maschinenindustrie im Ersten Weltkrieg

Abstract During the First World War, warfare became more totalitarian and was backed by an economic conflict waged with increasingly harsh methods. In the combatant nations munitions rapidly became an essential “raw material”, with the increasing demand being met either by the expanding domestic arms industry or by munitions imports from neutral countries. The Swiss watch, metal and engineering industries enjoyed a strong international reputation and had a strong focus on exports: by the end of 1914 they began manufacturing precision detonators for artillery projectiles, and rising quantities of these products were sold to both sides. This paper examines what volume Swiss munitions exports assumed during the First World War, how this was compatible with Swiss neutrality and looks at the arguments used to criticise or justify this trade over the course of the war.

The Optimization of Base Bleed Grain Parameters for Maximum Ballistic Performance

Solid propellant Base bleed unit is one of the effective methods to increase the range of artillery projectiles. As far as we search, no published study focuses on the optimal dimensions of the base bleed grain. However, few studies focus on the effect of base bleed grain parameters on its ballistic performance in which each parameter was studied separately. The present optimization study is performed on base bleed grain which performed as longitudinally slotted tubular cylinder. Different case studies have been introduced according to the number of design variables which are: grain outer, inner radius, length, burn rate, base bleed grain unit orifice diameter. Moreover, the study is extended to demonstrate the effect of these parameters on the innovative multi-burn rate base bleed grain. In this new idea, the grain is splitted into two horizontal parts one with higher burn rate than the other part. The idea is to have a grain that provides high mass flow rate in the first seconds of projectile flight, while keeping long bleeding time. The optimization constrains are the upper and lower limits of each design variable. An analytical model has been developed in C++ environment to accurately evaluate the range of the projectile. This model is then utilized in combination with design of experiment (DOE) and the response surface method (RSM) to develop a smooth response function which can be effectively used in the design optimization formulation as the objective function. The objective of the optimization is to find the design variables which contribute the maximum range.

A Rapid Gun Firing Correction Algorithm Using Discrete Time Transfer Matrix Method

To improve the next shot hit accuracy, a firing angle correction algorithm will be developed using the distance error computed between the impact and target coordinates to determine the launch azimuth and quadrant elevation angles for artillery projectiles. This correction method will be developed using the discrete time transfer matrix method of the projectile modified point mass model DTTMM-4DOF to improve correction method performance. To validate the proposed algorithm, a spin-stabilized 155mm-HE projectile flight trajectory will be used, assuming that wind magnitude and direction with the down range are changing as function of projectile altitude.

Developments in unmanned powered parachute aerial vehicle: A review

The U.S. Department of Defense (DOD) defines an unmanned aircraft as the following: A powered vehicle that does not carry a human operator, can be operated remotely or autonomously, can be expendable or recoverable and can carry a lethal or non-lethal payload. Ballistic or semi ballistic vehicle, cruise missiles, artillery projectiles, torpedoes, mines, satellites and unattended sensors are not considered unmanned vehicles. Unmanned vehicles are the primary component of an unmanned system [1].

An Automated Method for Computer Vision Analysis of Cannon-Launched Projectile Video

Abstract This paper describes a cost effective automated methodology to analyze launch video of artillery projectiles. Image processing and computer vision techniques are used to segment and classify the projectile shape in each video frame. Within minutes of being fired, the initial position, velocity, and orientation history of the projectile in three-dimensional space is determined at the gun site. An overview of several standard methods used by the Army to characterize pitching and yawing motion of projectiles is included, as well as a discussion of the limitations of these methods. Results from real artillery testing using the automated video analysis method are validated through comparisons to results measured using conventional techniques.

EFFECT OF BASE BLEED DIMENSIONS ON THE BALLISTIC PERFORMANCE OF ARTILLERY PROJECTILES

ABSTRACTBase bleed unit is one of the active methods to increase the range of artillery projectiles. Ballistic performance of base bleed unit has been experimentally assessed using firing tests and wind tunnel experiments. Meanwhile, analytical and numerical studies have been carried out. In some of these studies, solid propellant is used as the source of the burnt gases ejected into the wake behind the projectile base. But, in other studies, different types of gases such as air, argon, hydrogen, and helium are ejected at different temperatures.In this paper, the effects of the main dimensions of 2-parts tubular base bleed grain unit on its ballistic performance are studied analytically. These dimensions are base bleed grain maximum radius, length, inner diameter of the grain, and exit diameter of base bleed unit. The study is applied to the base bleed unit which is installed to K307 155mm projectile. The study leads to a new method to control the ejected mass flow rate. This method is based on changing the exit diameter of base bleed unit in order to get higher injection parameter in the first few seconds of projectile flight and lower values in the remaining time of base bleed grain burning. Therefore, the base bleed projectile range is increased by 1.7 % when comparing with its counterpart which is supplied with base bleed unit having constant exit diameter and the same base bleed grain.

Parametric analysis for water ricochet studies of ogive nose-shaped projectile

This paper reports important parameters that affect water ricochet studies for artillery projectiles. The factors affecting ricochet are critical angle and critical velocity of impact. This study has developed mathematical models for ricochet studies and derived expressions for critical angle and critical velocity. Simulations have been carried out for standard bullets, the data for which are available in open literature. The effects of mass, diameter, and length of the projectile on critical velocity and angle are studied through two non-dimensional parameters, µ and θ. The results suggest how ricochet conditions can be avoided by defining initial data at launch.

A Computer Vision Approach to Automatically Measure the Initial Spin-Rate of Artillery Projectiles Painted With Stripes

Abstract High-speed video has been used by ballistics engineers as a cost-effective technique to measure the spin-rates of both spin-stabilized and fin-stabilized artillery projectiles. Often at test ranges, state-of-the-art video systems are used to verify critical launch events following muzzle exit. From manual analysis of these videos, important performance metrics such as velocity, pitch angle, and spin-rate can be estimated. To do this, operators step through the video frames and record the time at which certain fiducial markings or numbered stripes are observed on the projectile as it rotates. The different methods evaluated in this paper are automated processes for calculating the muzzle-exit spin-rate from launch videos of spin-stabilized artillery projectiles painted with stripes. Image processing and computer vision techniques are employed to segment the shape of the projectile and extract the stripe pattern in each video frame. The most accurate algorithm estimates are validated to within 0.02 % for both laboratory and computer-simulated flight video and within 0.13 % for manual analysis of real flight video. The sensitivities of the methods to image resolution, video frame-rate, and the length of flight captured are evaluated. Areas of continued research and recommendations for increasing the accuracy of measurements in future tests are also identified.

Accuracy improvement capability of advanced projectile based on course correction fuze concept.

Improvement in terminal accuracy is an important objective for future artillery projectiles. Generally it is often associated with range extension. Various concepts and modifications are proposed to correct the range and drift of artillery projectile like course correction fuze. The course correction fuze concepts could provide an attractive and cost-effective solution for munitions accuracy improvement. In this paper, the trajectory correction has been obtained using two kinds of course correction modules, one is devoted to range correction (drag ring brake) and the second is devoted to drift correction (canard based-correction fuze). The course correction modules have been characterized by aerodynamic computations and flight dynamic investigations in order to analyze the effects on deflection of the projectile aerodynamic parameters. The simulation results show that the impact accuracy of a conventional projectile using these course correction modules can be improved. The drag ring brake is found to be highly capable for range correction. The deploying of the drag brake in early stage of trajectory results in large range correction. The correction occasion time can be predefined depending on required correction of range. On the other hand, the canard based-correction fuze is found to have a higher effect on the projectile drift by modifying its roll rate. In addition, the canard extension induces a high-frequency incidence angle as canards reciprocate at the roll motion.