Tactical Missiles Research Articles

Numerical Characterisation of Jet-Vane based Thrust Vector Control Systems

<p>Computational fluid dynamics methodology was used in characterising jet vane based thrust vector control systems of tactical missiles. Three-dimensional Reynolds Averaged Navier-Stokes equations were solved along with two-equation turbulence model for different operating conditions. Nonlinear regression analysis was applied to the detailed CFD database to evolve a mathematical model for the thrust vector control system. The developed model was validated with series of ground based 6-Component static tests. The proven methodology is applied toa new configuration.</p><p><strong>Defence Science Journal, Vol. 65, No. 4, July 2015, pp. 261-264, DOI: http://dx.doi.org/10.14429/dsj.65.7960</strong></p>

Internal Ballistic Code for Solid Rocket Motors using Minimum Distance Function for Grain Burnback

A computer code has been developed for internal ballistic performance evaluation of solid rocket motors, using minimum distance function (MDF) approach for prediction of geometry evolution. This method can handle any complex geometry without the need to define different geometrical shapes and their evolution as used in several existing analytical geometry evolution-based methodologies. The code is validated with both experimental results published in literature, as well as for solid rocket motors of tactical and strategic missiles and a very good match is obtained with static test results. The output of the code gives p-t (pressure-time) curve as well as the detailed parameters of the flow along the axial direction, and geometries in the form of mesh file, which can be further used as input to codes for CFD analysis. Defence Science Journal, Vol. 65, No. 3, May 2015, pp.181-188, DOI: http://dx.doi.org/10.14429/dsj.65.8304

Dual-Thrust Rocket Motor with an intermediate Nozzle at the condition of higher boosting pressure than the sustaining pressure

Boost-sustain solid propellant rocket motors have been used to meet the demand for short and medium range tactical missiles. These motors obtain a wide variety of thrust-time profiles if the propellant characteristics and grain geometry are properly selected. These Dual Thrust Rocket Motors (DTRM) can have various designs; the DTRM with an intermediate nozzle is one design that yields a high boost-sustain thrust ratio with a stable operation. Under certain conditions, the flow through the intermediate nozzle at the start of motor operation can be reversed. The present paper is intended to understand the phenomena and determine the operating parameters of DTRM with the reverse flow intermediate nozzle. In this study, a mathematical model describing the performance is derived from the main governing equations of internal ballistics (IB). Also, a set of experiments are conducted so as to inspect the details of the physics of such configuration DTRM. The experimental findings are utilized to validate the mathematical model. Results of the theoretical and experimental investigation explain most of the IB characteristics that were not discussed before in the open literature.

Performance investigation of extended-state-observer-based roll autopilot design

In this work, performance analysis of the recently appeared extended-state-observer (ESO)-based roll autopilot design is carried out. Firstly, considering a more realistic roll dynamics, performance comparison of the ESO-based design with several classical roll autopilot structures is carried out and the related results are presented. Next, the better performing designs are implemented and validated through a high fidelity nonlinear 6-DOF environment for a typical tactical missile in a realistic engagement scenario. Lastly, performance of the ESO-based design is investigated using Monte Carlo simulations under several subsystem parameter uncertainties. The results show that the ESO-based design offers satisfactory performance in controlling roll angle and its rate in the presence of significant disturbances, parameter uncertainties and cross-coupling effects and thus offers a viable approach towards design of roll autopilot for high performance tactical missiles.

Evaluating Tactical Missile Systems by Using Fuzzy AHP and TOPSIS Technique

Evaluating tactical missile systems is a complex system of interacting elements. For example, a good missile system requests good missile performance and minimal cost; the performance and cost depend on improvement of science and technology and economic resources; technology depends on ideas and resources; ideas depend on politics for their acceptance and support; and so on. In such an intricate network of factors, first causes and then final effects cannot be identified easily. These factors directly depend on the expectations of the decision-maker, and on additional complex subfactors, etc. In the complex system, our minds have not yet evolved to the point where we can clearly see these ultimate relationships and readily resolve important issues. Evaluating tactical missile systems is a multi-criteria decision-making (MCDM) problem. This paper presents an evaluation model based on the analytic hierarchy process (AHP) and the technique for order performance by similarity to ideal solution (TOPSIS) in a fuzzy environment where the vagueness and subjectivity are handled with linguistic values parameterized by triangular fuzzy numbers. The AHP is used to analyze the structure of systems evaluating and to determine weights of the criteria, and fuzzy TOPSIS method is used to obtain final ranking.

Effective multi-objective optimization for aerodynamic and stealthy performance of tactical missiles

Effective multi-objective optimization for aerodynamic and stealthy performance of tactical missiles

Optimization process for concept design of tactical missiles by using pareto front and TOPSIS

Concept design requiring complicated feed-forward and feed-back processes makes it difficult for engineers to determine the global behaviors of design variables and objective functions in a design space. Although design of experiments and response surface models have been applied to overcome these problems, the design variables satisfying the objective functions can’t be found due to violations of given constraints. In this study, a new optimization process, i.e., the GEO (Generate, Explore and Optimize) process for the concept design of a tactical missile, based on a MOGA (Multi-Objective Genetic Algorithm) was proposed, which was first adapted to generate a Pareto Front in order to simultaneously satisfy the constraints and the objective functions. In the first step, the weights between the objective functions were determined by using an AHP (Analytic Hierarchy Process). Then, the design space exploration followed, and was implemented by surrogate models constructed from the Pareto Front with a neural network. In the last step, a TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) and a desirability function were applied together to determine the optimal solution. The TOPSIS merged the multi-objective design problem to a single entity, and the desirability function normalized each objective function.

Quantification of projection angle in fragment generator warhead

Abstract Tactical Ballistic Missile (TBM) class target neutralization by the fragment spray of a Fragment Generator Warhead (FGW) calls for quantification of fragment projection angle scatter to finalize the end game engagement logic. For conventional axi-symmetric warhead, dispersion is assumed to be normal with a standard deviation of 30. However, such information is not available in case of FGW. Hence, a set of experiments are conducted to determine the dispersion of fragments. The experiments are conducted with a specific configuration of FGW in an identical arena to quantify the scatter and then verified its applicability to other configurations having a range of L/D and C/M ratios, and contoured fragmenting discs. From the experimental study, it is concluded that the scatter in projection angle follows normal distribution with a standard deviation of 0.75° at Chi-square significance level of 0.01(χ20.99).

Bounds on the Miss of Multiple-Model-Based Terminal Guidance Laws

In previous papers, bounds on the root-mean-square miss of a radar-guided missile for different types of target maneuvers and the terminal phase period have been presented. In this paper, bounds on the miss of multiple-model-based terminal guidance laws are presented. Analytical formulas of bounds on the root-mean-square miss of a radar-guided missile that implements multiple-model estimation and guidance scheme against a maneuvering target are presented. These formulas use a set of core parameters that affect the miss distance, thus, they can be used for synthesis and analysis of the performance of radar-guided tactical missiles with the multiple-model estimation and guidance. The bounds are derived subject to the assumption that the missile guidance law and the estimator are fully matched to the missile dynamics, target maneuver, and glint noise. The glint is the dominant noise source, the missile applies frequency agility, there is no missile acceleration limit and heading error, and there is no limitation on the computing resources.

초고속 표적의 탄도계수와 예상요격지점 정확도의 상관관계 분석 연구

A recent air defense missile system(ADMS) is required to have a capability to intercept super-high speed targets such as tactical ballistic missiles(TBMs) by performing engagement control efficiently. The air defense missile system should be ready to engage the TBMs as soon as the ADMS detects TBMs because falling velocity of TBM is very high and remaining time interval to engage TBM is very short. As a result, the ADMS has to predict the trajectories of TBMs accurately with estimated states of dynamics to generate predicted intercept point(PIP). In addition, it is needed to engage TBMs accurately via transmitting the obtained PIP data to the corresponding intercept missiles. In this paper, an analysis about the relationship between ballistic coefficient and PIP accuracy which is depending on geodetic height of the first detection of TBM is included and an issue about effective engagement control for the TBM is considered.

Calculation of Kill Probability for Kinetic Energy Rod against TBM Warhead

Kinetic energy rod (KE-rod) warheads are one of the most efficient types against tactical ballistic missile (TBM) that exist today, so the kill probability of KE-rod is extremely important. The paper firstly describes the necessity of KE-rod warhead, and then analyzes the separation velocity of KE-rod, the effective kill radius, static dispersal, dynamic kill zone, and the computational model of mathematical expectation for the hit rod number, and then presents the calculation method of kill probability for KE-rod. Finally, the kill probability of the KE-rod is simulated, the results show that the probability decreases rapidly with the increase of distance between the KE-rod warhead and the target, when the distance between the interceptor and target is less than 5 meters, the kill probability is up to 50%.

Estimator design for re-entry targets

This study proposes a trajectory estimation scheme for tactical ballistic missiles (TBMs). Target information acquired from the ground-based radar system is investigated by incorporating input estimation (IE) and extended Kalman filtering techniques. In addition to estimate the missile's position and velocity, our special focus is put on the estimation of the TBMs evasive acceleration and ballistic coefficient. In the demonstrative example, radar measurement errors are served as specifications while characterizing the acquirable zone of the ground-based radar system. Effect of the proposed design is fully verified by examining the estimation performance.

Research on the Hardware-in-the-Loop Simulation for High Dynamic SINS/GNSS Integrated Navigation System

In the process of developing guided munitions, ground test can only verify the performance of integrated navigation system in low dynamic condition, and its costly and risky to use means of authentication such as flight test and throw experiment. This paper proposes a kind of hardware-in-the-loop simulation (HILS) scheme with tri-axial turntable for verifying the performance of navigation system in high dynamic condition. It respectively uses quaternion method and four-sample rotation vector algorithm as attitude updating algorithms for comparison. On the basis of analyzing the characteristics of some tactical missile and the HILS system, the error sources of integrated navigation system in the simulation with turntable and that without turntable are discussed in detail. The results of HILS show that integrated navigation system is of good performance under high dynamic environment; moreover, for the fiber optic gyroscope (FOG) inertial measurement unit (IMU) which outputs angular rate, quaternion method is better than four-sample rotation vector algorithm.

Design of Midcourse Trajectory for Tactical Ballistic Missile Intercept on the Basis of Zero Effort Miss

Since the maneuverability of the tactical ballistic missile, the midcourse trajectory of interception missile needs design online. Firstly, this paper reasonably simplifies the models and explores the analytical expressions of their relative motion state to obtain a kind of rapid and high-precision computing method of zero effort miss. Secondly, it applies constant thrust for the interception missile, burns out shut-down solid engine, reflects on the index requirement of overloaded interception missile, and designs midcourse trajectory of the interception missile with Pontryagin maximal principle, in accordance with the analytical expressions of zero effort miss. Finally, with the simulating calculation, the prediction methods of zero effort miss and trajectory design method provided by this paper are applied to a situation simulation which is close to the fact as much as possible so as to verify the applicability in the interception of tactical ballistic missile.

큐잉 데이터 기반 하층방어 요격체계의 초고속 표적 탐지 방향 지정을 위한 정밀 궤적예측 기법

A recent air defense missile system is required to have a capability to intercept short-range super-high speed targets such as tactical ballistic missile(TBMs) by performing engagement control efficiently. Since flight time and distance of TBM are very short, the missile defense system should be ready to engage a TBM as soon as it takes an indication of the TBM launch. As a result, it has to predict TBM trajectory accurately with cueing information received from an early warning system, and designate search direction and volume for own radar to detect/track TBM as fast as it can, and also generate necessary engagement information. In addition, it is needed to engage TBM accurately via transmitting tracked TBM position and velocity data to the corresponding intercept missiles. In this paper, we proposed a method to estimate TBM trajectory based on the Kepler's law for the missile system to detect and track TBM using the cueing information received before the TBM arrives the apogee of the ballistic trajectory, and analyzed the bias of prediction error in terms of the transmission period of cueing data between the missile system and the early warning system.

Damage Radius Study of Gimbaled Forward-Firing Warhead to Tactical Ballistic Missile

Gimbaled forward-firing warhead (GFFW) is one of the most efficient types for killing enhancement that exist today. This is because almost all the fragments of the warhead are deployed to the targets direction. Static explosion experiment was performed to investigate the spatial distribution of the spray pattern as well as its deployment velocity. The cone angle (θs) of fragments bundle at static conditions is 15°, and fragments in the mesial area is dense than that in the marginal area. The average velocity of the fragment in mesial area is 1712m/s, and that in marginal area is 1408m/s. In conjunction with deployment experiments, damage radius study is conducted with the basic criterion that one fragment must hit target payload at least. Damage radius at the dynamic conditions is 150m~165m, which is more farther than conventional uniform warhead.

Five Myths about India's Nuclear Posture

For a democracy that otherwise leaks secrets like a sieve, India's entire nuclear journey has been shrouded in remarkable secrecy. It is therefore unsurprising that India has closely guarded the de...

Comparison of Classical and Predictive Autopilot Design for Tactical Missile

Because the missile is autonomous, its control system must provide adequate flight stability while ensuring sufficient response to track commands. This paper is devoted to investigate the usefulness of the classical and modern control techniques for autopilot design for different evaluation approaches. The present work is concerned with improving theperformance of a surface-to-surface controlled aerodynamically guided missile system via both classical PID and predictive autopilots. The design and analysis necessitate somehow accurate system model with different uncertainties via 6-DOF simulation. The governing differential equations of the missile motion are derived with the aerodynamic model of themissile constructed by means of the Missile Datcom software. After obtaining the required aerodynamic stability derivatives using the generated aerodynamic data, the necessary transfer functions are determined based on the equations of the missile motion. Next, the normal acceleration autopilot is designed using the determined transfer functions. The autopilot is designed to realize the command signals generated by the guidance laws which are in theform of normal acceleration components. Using the entire system model, the computer simulations are carried out using the Matlab-Simulink software where the classical and predictive autopilots are compared via time response along the flight path

EULER ANGLE ERROR COMPUTATION AND THRUST VECTOR CONTROL SCHEME FOR INITIAL TURNING PHASE OF A VERTICAL LAUNCH SURFACE TO AIR MISSILE

A vertical launch missile requires to be turned towards the Predicted Interception Point (PIP) with the target within few seconds from the launch. The autopilot used for the same requires the error in Euler Angles between the missile and the target to be supplied, which is generally computed using Error Quaternions approach [1]. For some kinds of engagement scenarios, say a Near Boundary Low Altitude target, the turn angle required in the pitch plane during the initial phase can become more than 90 degrees. In such cases, the conventional 3-2-1 frame transformation method fails to compute the Euler Angle errors correctly. As an alternative approach the Euler Angle error computation using 2-3-1 frame transformation is proposed in this paper. After computing the Euler Angle Errors, the desired turning is achieved by Thrust Vector Control [2] using jet vanes or thrusters. The initial turning using Aerodynamic control is not desirable because of low dynamic pressure, where as the usage of jet vanes brings more hardware complications for small tactical missiles. The possibility of using thrusters for initial turning phase in a short range tactical missile is studied in this paper with the help of simulation results.

Composite guidance laws based on sliding mode control with impact angle constraint and autopilot lag

For the terminal phase of tactical missiles intercepting maneuvering targets, the terminal guidance problem is studied. Based on an integral sliding mode (ISM) control method and nonlinear disturbance observer technique, a novel composite guidance law is designed in the case of constrained impact angle and a first-order-lag autopilot. Regarding the target acceleration and the external disturbance of autopilot as unknown bounded disturbance, a nonlinear ISM guidance law is designed. The obtained guidance law guarantees the line-of-sight (LOS) angular rate and LOS angle a finite-time convergence characteristics. Then, to alleviate the chattering problem and guarantee the disturbance rejection performance, the composite guidance law combining the ISM guidance law with feedforward compensation terms based on nonlinear disturbance observers is obtained. Finally, simulation comparison results are provided to demonstrate the effectiveness of the presented methods.