AiMT Volume 14 (2019), Issue 1

Ejection Causes in Military Jet Aircraft in Czechoslovakia and the Czech Republic

O. Zavila and R. Chmelík

The article deals with the causes of ejections of crew members 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 list of ejection causes by aircraft types on a timeline as well as historical and technical contexts, facts and development trends of these causes. Importantly, the role of the human factor in the causes of fire and false fire alarm emergency occurrences is also analyzed. The study is accompanied by a unique overview of reference and still accessible information sources on the subject.

Keywords: Army of the Czech Republic, ejection, aviation accident, human factor, jet aircraft, cause, statistics.

Pages: 5–20  [References]   [Download Citation]

Computationally Fast Dynamical Model of a SATCOM Antenna Suitable for Extensive Optimization Tasks

J. Najman, M. Bastl, M. Appel and R. Grepl

Development of new SATCOM (Satellite Communications) antennas and their control systems is a complex problem, in which strict requirements for mechanical design, drives, sensors and the overall speed and accuracy of the control algorithm must be met. Therefore, a simulation model is often used at different stages of development, which greatly accelerates the process of designing and optimizing the whole system. The computationally most demanding part of the simulation is the dynamical model of antenna. This article proposes an alternative approach for dynamical model creation, and the results are compared to a model created by using a universal multibody simulation environment. It is shown that the proposed new approach gives nearly the same-quality results and it is several times computationally faster.

Keywords: mobile SATCOM, antenna pointing, dynamical model, simulation, MATLAB, Simulink.

Pages: 21–30  [References]   [Download Citation]

The Military Specifications of Remote Control Tower Technology

T. Vas

Nowadays the Remote Control Tower (hereafter RTWR) appears as a piece of modern ATM (Air Traffic Management) technology in many European countries, including Hungary. After a successful validation process at a medium-sized civilian aerodrome called Liszt Ferenc, co-operation began between HungaroControl1 and the Hungarian Ministry of Defence concerning the introduction of the RTWR in the military environment. The author makes an attempt to determine the safety and the security aspects of RTWR in the military environment, its specifications for the handling of military air traffic and makes suggestions for further installations at given military airfields.

Keywords: remote control tower, military aerodrome traffic, air traffic controller procedures, visualization, safety enforcement, enhanced technology.

Pages: 31–45  [References]   [Download Citation]

Modelling Missile Flight Characteristics by Estimating Mass and Ballistic Parameters

J. Farlik, I. Hamtil and M. Kratky

This paper deals with one of the possible methods of a qualified estimation of tactical and technical parameters of surface-to-air or air-to-air guided missiles. This method is designed to estimate missile flight parameters if they are unavailable from public sources. Although the method does not provide exact values, it is sufficient for modelling and subsequent simulation. This method is based on the use of so-called “characteristic numbers” of the missile and on the assumption of validity of the hypothesis about the similarity of characteristic missile numbers of equal or, respectively, similar technological levels. To validate the obtained parameters, a method of mathematical modelling of the missile guidance process is used. The method can also be used for a qualified estimation of missile parameters in the case of an acquisition process.

Keywords: mass parameters, ballistic parameter, characteristic number, mathematical modelling.

Pages: 47–57  [References]   [Download Citation]

Investigating T-finned Barrels for Machine Guns: Enhancement in Heat Dissipation and Flexural Rigidity along with Weight Reduction

E. Chaturvedi

This design innovation work is related to design and comparison of thermo-structural characteristics of a light-weight machine gun barrel. Compared to traditionally used thicker profile counter parts of machine gun barrels, these barrels were concluded to have lighter weight, better heat dissipation capability and better flexural rigidity. These barrels do not have rigidity problems like finned pencil barrels; neither have they extra weight addition, as in case of thicker profile barrels (H-Bars). To conduct the analysis, two same-length models of barrels bored for 5.56 × 45 mm, were modelled using Solidworks 15 software. The subsequent analysis using ANSYS 14.5 multi-physics solver simulated the condition of cook-off, which is an almost steady state reached after sustaining firing of 600 rounds (for 5.56 × 45 mm ammunition). It is a usual technical requirement expected from every durable machine gun, before the barrel is changed. The results showing maximum heat flux were transported to structural analysis workbench to measure the longitudinal deformation in both barrels under the gravity. The results concluded that T-finned barrels even after having less material, thus less weight, portrayed better heat dissipation characteristics and significantly less longitudinal deformation, thus better flexural rigidity and at the same time better accuracy retention than the conventional unfinned H-Bars.

Keywords: machine gun barrel, high rate of fire, long duration of fire, heat dissipation, pseudo-I section, FEM analysis.

Pages: 59–69  [References]   [Download Citation]

Changes of On-board Power Systems of Modern Aircraft in the Context of Wider Electrification

F. Adamčík and M. Schrötter

This article analyzes the changes of on-board electrical power systems of modern transport aircraft with a higher degree of electrification, so-called MEA (More Electric Aircraft) compared to the traditional architectures, in the field of standardized electrical power parameters. Developments in this field are characterized by increased requirements for power of installed power sources and switching to higher voltage values and source units with a non-stabilized frequency value of the generated voltage, so-called frequency wild systems.

Keywords: aircraft, electrification, power systems.

Pages: 71–78  [References]   [Download Citation]

From Old Ciphers to Modern Communications

C. Flaut, D. Flaut, S. Hoskova-Mayerova and R. Vasile

The security of the information transmitted, irrespective of the era and the channel selected, has always been one of the main concerns of those using various communication systems. This is particularly the case nowadays, when the Internet has made the mass distribution of any kind of information possible. Codes can be used to transmit data through various noisy channels and any errors that might occur can be corrected; it is therefore very important to design gappropriate codes with adequate parameters. This survey briefly outlines the evolution of the ways in which information has been collected, transmitted and used from the past to the present.

Keywords: code, crypto–system, communication.

Pages: 79–88  [References]   [Download Citation]

Methodologies for Reliability Prediction of Electronic Component in Military Vehicles

P. Xuan Cu and A. Ha Bui

Reliability prediction is conducted in all phases of the product life cycle. The purpose of these predictions is to identify the potential weaknesses in design, to evaluate the design feasibility, to compare alternative designs, to provide the model for reliability analysis, to track reliability improvement, etc. Reliability of electronic component is predicted by using statistical prediction methods (standards-based), statistical analysis of operation & maintenance data or by performing reliability testing. The article describes statistical prediction methods such as MIL-HDBK-217, RIAC 217Plus, FIDES Guide 2009, which are widely used for predicting the reliability of electronic components. In addition, we have calculated and compared the failure rate of electronic components in military vehicles conducted with the use of these different methods.

Keywords: reliability, failure rate, electronic components, LED .

Pages: 89–98  [References]   [Download Citation]

Beeswax Material: Non-Conventional Solid Fuel for Hybrid Rocket Motors

A. El-S. Makled

Traditional solid fuel for Hybrid Rocket Motor (HRM) is characterized as a low regression rate, aiming to develop a new generation of solid fuel material that combines at the same time good ballistic properties, easy manufacture, safe exhaust emission and low cost. Beeswax as bio-derived hydrocarbon fuel has been evaluated to be used as solid fuel in HRM. Firing tests are carried out at the average pre-chamber pressure of 2.90 bar, the oxidizer mass flow rate of 9.34 g/s and the regression rate of 1.5 mm/s at combustion efficiency reaches 60.3 %. Beeswax as pure solid fuel grain at 7 mm active channel port with 100 mm length is tested with gaseous oxygen (gO2) as oxidizer and it showed a regression rate at least three times as high as traditional hybrid propellant, such as Polymethyl methacrylate (PMMA) and Polyethylene (PE)/gO2. This provides a promise for high performance parameters with a special regression rate to overcome the main drawbacks of traditional hybrid propellant. Experimental evaluation parameters (regression rate, fuel mass flow rate and combustion efficiency) are carried out for beeswax/gO2. Combustion shows fairly successful results for lab scale testing but it needs further enhancement, especially in combustion efficiency and theoretical studies for combustion efficiency.

Keywords: hybrid rocket motor, solid fuel grain, beeswax, combustion, ignition system.

Pages: 99–113  [References]   [Download Citation]

Space Positioning and Tracking Solutions for Military Applications

D.S. Ilcev

This paper is discussing the current and new satellite transponders for global tracking and detecting of military assets and personnel at sea, on the ground and in the air for enhanced traffic control and management. These transponders are able to monitor all military mobile vehicles, to improve safety of movements and collision avoidance, especially for navy and air forces assets. By using Global Navigation Satellite System (GNSS) in integration with Inmarsat, Iridium and other satellite systems in one unit with antenna, it is possible to provide reliable positioning and tracking solutions for civilian or military mobiles and personnel. The existing and forthcoming space and ground segment for positioning and tracking solutions as a modern Satellite Asset Tracking (SAT) onboard mobiles and other relating systems are discussed and benefits of these new technologies and solution for improved positioning and tracking are explored.


Pages: 115–131  [References]   [Download Citation]

Detection of Unobserved Ground Targets by Use of Seismic Location Stations

E. Hashimov, A. Bayramov and E. Sabziev

The detection method of moving unobserved ground military heavy trucks is considered in paper. The 3D coordinates detection set and the seismic location method are used in our study. The computational algorithm of determination of the bearing angle and distance to unobserved ground target are presented, the computational uncertainties are estimated. The triangular form of 3D detectors in one seismic location cell is offered. It allows minimizing distance and angle uncertainties in target direction. To improve the detection effectiveness, the optimal geometry disposition of 3D detectors in seismic location cells is determined. The offered method is effective in case of terrain relief where seismic-acoustic signal is propagated by approximately straight line. Therefore, this method can be applied only to homogenous medium, for example, to mountainous, solid rocky soil.

Keywords: bearing angle, computational algorithm, seismic location cells, seismic-acoustic signal, unobserved target.

Pages: 133–138  [References]   [Download Citation]

Numerical Simulation of Flow Field in Coaxial Tank Gun Recoil Damper

W. Elsaady, A. Ibrahim and A. Abdalla

To know the hydraulic resistance of tank gun hydraulic damper is essential to determine the barrel recoil parameters. Usage of one-dimensional analytical models simplifies the determination of the hydraulic resistance; however these models do not provide data about the flow nature inside the hydraulic damper. This paper studies the internal flow inside the hydraulic damper of the gun recoil system. The dynamic mesh technique using two-dimensional flow computational solver has been used. A User Defined Function (UDF) has been developed to feed the solver by the measured recoil velocity. The study shows that the liquid flow inside the hydraulic damper is complicated at the start of the gun recoil and it is quickly changing to a simpler flow pattern until the end of the recoil. Also, the liquid pressure inside the hydraulic damper has been measured and compared to the computational values.

Keywords: coaxial recoil system, dynamic mesh, hydraulic damper, recoil simulation.

Pages: 139–150  [References]   [Download Citation]

Analysis of Impact of Conic Aperture in Differentially Pumped Chamber

J. Maxa, P. Hlavatá and P. Vyroubal

The paper focuses on the simulation of medium dynamics in the environmental scanning electron microscope. In particular, the paper examines the conical aperture location effect in the differentially pumped chamber and the width of the pumping channel in this chamber. The solution is based on the Taylor-Maccoll theory about the impact of the shock wave and was obtained by the use of continuum and finite volume methods in the ANSYS Fluent system.

Keywords: ANSYS Fluent, differentially pumped chamber, environmental scanning electron microscope (ESEM), finite volume method, Taylor-Maccoll theory.

Pages: 151–161  [References]   [Download Citation]

Impressions from the ICMT 2019

Press Release