AiMT Volume 13 (2018), Issue 2

TECHNICAL INFORMATION
Statistics of Ejections in Military Jet Aircraft in Czechoslovakia and the Czech Republic

O. Zavila

The article deals with the statistics of aviation accidents associated with the ejection of the crew in military jet fighter, fighter-trainer and trainer aircraft in the service of Czechoslovakia and the Czech Republic from 1948 until the end of 2016. It presents a unique, previously unpublished comprehensive overview of aviation accidents (disasters, air crashes and damage) in which the crew ejected, as well as a critical analysis of types of events involved, date of their origin, type and version of the aircraft and also the number of killed and rescued crew members. The figures are accompanied by numerous annotations and an overview of still accessible reference and information sources on the subject.

Keywords: Army of the Czech Republic, Czechoslovak People’s Army, ejection, aviation accident, jet fighter, statistics.

Pages: 141–156  [References]   [Download Citation]

TECHNICAL INFORMATION
State of the Art and Problems of Defeat of Low, Slow and Small Unmanned Aerial Vehicles

A. Dudush, V. Tyutyunnik, I. Trofymov, S. Bortnovs’kiy and S. Bondarenko

The article deals with one of the most intensively developing threats for civilian and military spheres – hostile use of Low, Slow and Small Unmanned Aerial Vehicles (LSS UAVs). The classification of the LSS UAVs is given. The existing threats of using LSS UAVs are divided into three categories. Special attention is paid to the third category of threats, the main feature of which is a high level of training of the operator. Main advantages and drawbacks of LSS UAVs are considered. It is determined that the best strategy is to employ a hierarchy of countermeasures including regulatory countermeasures (prevention, deterrence, denial), passive countermeasures (detection and interruption) and active countermeasures (destruction). State of the art and current problems of possible countermeasures are analysed. The most promising LSS UAVs’ counteraction technologies are described. Most attention is paid to specialized sensors and modern active counteraction means, such as programmable air burst munition and high-energy laser systems.

Keywords: Low, Slow and Small Unmanned Aerial Vehicles (LSS UAVs), LSS UAVs classification, threats categories of using LSS UAVs, advantages and weak sides of LSS UAVs, hierarchy of countermeasures.

Pages: 157–171  [References]   [Download Citation]

Dynamic Lift and Vortex Breakdown during an Unsteady Flow over a Pitching Airfoil

A. Svoboda and D. Rozehnal

Computational fluid dynamics techniques are used to give a detailed insight into unsteady phenomena taking place in the vicinity of a pitching airfoil. The vortex formation and breakdown are analyzed using the time history of pressure distribution, vorticity and injected massless particle trajectories. Different cases of flows are modeled to determine the effect of reduced frequency on unsteady lift. Finally, a comparison of lift coefficients for steady and unsteady cases is provided.

Keywords: unsteady aerodynamics, dynamic lift, vortex, pitching, airfoil, NACA 0012, CFD.

Pages: 173–183  [References]   [Download Citation]

TECHNICAL INFORMATION
Automatic Evaluation of Spatial Disorientation

P. Frantis and A. Petru

The paper discusses the automated detection of spatial disorientation from recorded flight data. The first part of the paper briefly introduces middle ear function and its influence on spatial disorientation. The specially developed simulator and aerodrome manoeuvre flown by the pilot during the experiment is also mentioned. The second part of the paper analyses the recorded data from experimental flights and proposes an algorithm for the automatic evaluation of spatial disorientation. An example graphical interpretation of the recorded data is provided with a clear explanation of the important parameters. At the end of the paper, the most important conclusions of the work are presented.

Keywords: flight illusion, detection, simulator, spatial disorientation.

Pages: 185–192  [References]   [Download Citation]

Real-time Optimal Control of Multi-wheeled Combat Vehicles – using Artificial Neural Network and Potential Fields

A. Mohamed, M. EI-Gindy, X. Huang, J. Ren and H. Lang

This paper presents a real-time path planning algorithm for autonomous multi-wheeled combat vehicles using Artificial Neural Network (ANN), Artificial Potential Fields (APFs) and optimal control theory. Real-time navigation of autonomous vehicles is a very complex problem and it is crucial for many military operations. This paper proposes an optimal control and ANN approach for a dynamic model of the multi-wheeled combat vehicle to generate the possible optimal paths that cover every part of the workspace.

Consequently, the obtained paths are used to train the proposed ANN model. The trained ANN has the capability to control the movement of combat vehicle in real time from any starting point to the desired goal position within the area of interest. The vehicle path is autonomously generated from the previous vehicle location parameter in terms of lateral velocity, heading angle and yaw rate of the vehicle. APF is proposed for preventing the vehicle from colliding with obstacles in border destination. The effectiveness and efficiency of the proposed approach are demonstrated in the simulation results, which show that the proposed ANN model is capable of navigating the multi-wheeled combat vehicle in real time.

Keywords: real-time, optimal control theory, path planning, autonomous multi-wheeled combat vehicle, Artificial Neural Network, artificial potential fields.

Pages: 193–207  [References]   [Download Citation]

Indirect Method Usage of Distance and Error Measurement by Single Optical Cameras

M. Tuan Bui, R. Doskocil, V. Krivanek, T. Hien Ha, Y. Bergeon and P. Kutilek

In this paper, we proposed an indirect method to measure the distance of an object accurately by single visual cameras using triangulation. The object can be seen as the third point of a triangle with two known sides and one known angle. Distance to object can be determined indirectly on the base of known sides and angle, rather than being measured directly. It would be very useful in case there is no line of sight to object (inaccessible) or an obstacle interrupts it. Furthermore, the results show that the measured distance using the indirect method has a lower measurement error than the one using the direct method. This method establishes a basis for the implementation of the position algorithm into the navigation subsystem of swarm robots and will be very helpful especially in robot cooperation.

Keywords: distance measurement, indirect method, measurement error, single optical camera, uncertainty.

Pages: 209–221  [References]   [Download Citation]

TECHNICAL INFORMATION
Finite Element Approach of Interior Permanent Magnet Motor Acoustics Noise

P. Vyroubal, J. Maxa, T. Kazda and M. Maèák

IPM (Interior Permanent Magnet) motors produce torque based on two different mechanisms. The first of them is permanent-magnet torque, which is generated by the flux linkage between the PM (Permanent Magnet) rotor field and the electro-magnetic field of the stator. It is the same torque as produced by SPM (Surface Permanent Magnet) motors, however, IPM designs produce another force known as reluctance torque. The second one, the shape and location of the slots in the rotor laminations are designed to channel magnetic flux so that even if the slots were left as air gaps, the rotor would experience a force to align the magnetic flux lines with those generated by the stator coils. IPM motors are now very popular in industrial and military applications by providing high power density and high efficiency compared to other types of motors. This paper presents the use of finite element method harmonic analysis for investigation of IPM motor acoustics noise. This method is useful for DC (Direct Current) motor designs in many industrial and military applications.

Keywords: IPM motor, noise, finite element method, vibrations, model, acoustics, transient, electromagnetic.

Pages: 223–235  [References]   [Download Citation]

Ballistics of Supercavitating Projectiles

D. Nguyen Thai, V. Horák, D. Nguyen Van, D. Dao Van, H. Nguyen Van and L. Do Duc

The article is focused on the development of the underwater ballistic model of a supercavitating projectile fired from an underwater firearm. The supercavitating flows and their influences on the ballistic characteristics of the projectile are studied. The presented mathematical model is validated and experimentally verified for the supercavitating projectile of 5.7 mm in diameter fired from a smooth bore underwater rifle.

Keywords: underwater projectile, supercavitation, cavity, underwater ballistics, supercavitating ammunition.

Pages: 237–248  [References]   [Download Citation]

Novel Tactical Ballistic Shield Technology: A Blast Injury Mitigation Evaluation

G. T. Desmoulin, and M.–A. Nolette

This study investigates the performance of a shield appliqué technology designed to protect the user from blast injury. This technology was compared against three other ballistic shields of varying mass using a fixed charge configuration. An instrumented anthropomorphic test dummy (ATD) was used along with pressure sensors to determine injury risk. Results showed that lighter shields offered less protection than their heavier counterparts with higher probability of head, chest, arm and leg injuries. Additionally, when comparing the appliqué to a mass-matched shield, relevant loadings were reduced on average by 21 %. Overall, the ballistic shield appliqué technology shows promise for becoming a tool for blast mitigation in the short to medium term.

Keywords: blast, shield, injury, biomechanics, tactical.

Pages: 249–264  [References]   [Download Citation]

TECHNICAL INFORMATION
Design and Static Load Analysis Comparing Steel, Grey Cast Iron and Titanium Alloy as Materials for Breech Hinged Lugs in Recoil Weapons

E. Chaturvedi and R. K. Dwivedi

This design innovation work is related to design validation of short recoil weapons mechanism’s critical components in context of upper receivers. It explains a new mechanism for locking and unlocking of bolt with the breech and subsequent advantageous design changes in the bolt’s construction. This design intends to build a new platform for a short recoil weapon chambered in 5.56×45 NATO ammunition which promises competency with its existing counter parts of the same domain, but exhibiting exceptionally improved reliability due to elimination of interdependence of reciprocating cycles of barrel and bolt assemblies. This work involves the design of the whole functioning system using Solidworks 2015 version and a static structural analysis to compare and choose the most suitable material among commonly used ones: steel AISI 4340, grey cast iron and titanium alloy Ti-6Al-4V, for locking lugs, being critical pair of components, using ANSYS 14.5. Results showed that titanium alloy was the most suitable material for the strength purpose. It is to be noted that this system may not only be utilized for assault rifles, but also for sub-machine guns, machine gun variants and even in handguns.

Keywords: short recoil weapons, wedge cam lugs, breech, barrel assembly, cam frame.

Pages: 265–275  [References]   [Download Citation]

Modelling and Simulation of Surface to Surface Missile General Platform

M. K. Elbaioumy, M. M. Elkhatib and A. E. Khalifa

In this paper, a general platform of a surface-to-surface missile model is presented. An accurate missile system model was made with consideration of the rigid body dynamics in space with six degrees of freedom and equation of motion starting from Newton second law to the non-linear state space model of the missile. Computer simulations have been executed using the MATLAB / Simulink software. Verification of the system model has been made.

Keywords: missile modelling, surface-to-surface missile, 6 degrees of freedom, equation of motion, non-linear state space model.

Pages: 277–290  [References]   [Download Citation]