Technological conditions of flight instrument development

Razvoj avijacije postavio je tehnološke zahteve koji su uslovili nastanak i neprekidan razvoj instrumentalizacije leta. Praktična primena avijacije u vojne i civilne svrhe, razvoj vazdušnog saobraćaja i tehnike uopšte, povećavaju brzine, visine i dužine preleta, dok letelice postaju sve veće i složenije. Od lakih drvenih konstrukcija sa otvorenom pilotskom kabinom, danas avioni po svim vremenskim uslovima prelaze velike razdaljine što pilota i konstrukciju letelica dovodi granica izdržljivosti. Na početku, tokom pionirskog perioda, letenje je bilo u potpunosti u rukama pilota i sve odluke je donosio na osnovu svog iskustva i psihofizičkih sposobnosti. Sa povećanjem složenosti letelica i dužine preleta, sve veći uticaj na tehniku pilotiranja imaju tehnološki, ergonomski i bezbednosni uslovi. Ovaj rad se osvrće na tehnološke uslove i razvoj sistema instrumentalizacije i automatizacije leta. Primena digitalne pilotske kabine uspostavlja mnoge pozitivne standarde ali i postavlja pitanja daljeg pravca razvoja vazduhoplovstva. Poseban prikaz opisuje upotrebu i razvoj jednog od osnovnih instrumenata u pilotskoj kabini – kompasa. Ovaj instrument se i dalje, u skoro nepromenjenom obliku, nalazi u modernom digitalnom kokpitu – glass cockpit-u.The development of aviation has set technological requirements that have conditioned the emergence and development of flight instrumentalization. The practical application of aviation for military and civilian purposes, the development of air traffic and technology in general, increase speeds, altitudes and flight lengths, while aircraft are becoming larger and more complex. From light wooden constructions and open cockpit, today planes fly long distances in all weather conditions, which brought the pilot and the construction of the aircraft to the endurance limit. At the beginning, during the pioneer period, flying was completely in the hands of the pilot and he made all the decisions based on his experience and psychophysical abilities. With the complexity of aircraft and flying, technological, ergonomic and safety conditions have an increasing influence on piloting technique. This paper describes the technological conditions and the development of instrumentation and flight automation systems. The application of the digital cockpit establishes many positive standards, but also raises questions about the further direction of aviation development. A special review describes the use and development of one of the basic instruments in the cockpit -the compass. This instrument is still, in an almost unchanged form, in the modern digital cockpit -glass cockpit

Determination of the ductile-to-brittle transition temperature of NIOMOL 490 K steel welded joints

This paper is dedicated to the ductile–brittle transition behaviour of the microalloyed structural steel NIOMOL 490 K. This steel grade is used for welded pressure vessels subjected to dynamic loads and operating at sub-zero temperatures. Therefore, it must have an acceptable toughness. Due to its importance for the safety assessment of pressure vessels, a characterization of this steel was carried out using the Charpy V-notch impact test in the temperature range between - 60 ◦C and + 60 ◦C. The notches were located in parent material, heat affected zone and weld metal. In this paper, the tensile strength properties at ambient temperature and the nil ductility temperature in the temperature range from - 60 ◦C to + 60 ◦C are presented

Influence of Raster Angle on Tensile Properties of FDM Additively Manufactured Plates made from Carbon Reinforced PET-G Material

Tensile properties of thin plate specimens made from short carbon fiber reinforced PET-G material are experimentally evaluated for various raster angles (printing directions). In additive manufacturing (AM), raster angle is recognized as one of the key printing parameters which strongly influences the strength and stiffness of the final part. The relatively high average value of ultimate tensile strength was obtained for specimens printed with the 0° raster angle, compared to the value obtained for specimens printed with the 90° raster angle - 52.2 MPa and 25.4 MPa, respectively. Similarly, noticeably higher average value of modulus of elasticity was obtained for specimens printed with the 0° raster angle, compared to the value obtained for specimens printed with the 90° raster angle - 4752 MPa and 1569 MPa, respectively. Scanning electron microscopy (SEM) was used for analysis of specimens’ fracture surfaces. SEM images revealed considerable volume fraction of voids (porosity). Тhe porosity, together with weak bonding between two adjacent rasters, could be one of key factors for poor tensile properties of samples printed with rasters perpendicular to direction of load application (90° raster angle

Magnetic and mechanical characteristics of nickel-based superalloy after laser induced deformation

Nickel-based superalloys are used in load-bearing structures at elevated temperature and pressure and in harsh environment. Nickel based superalloys have good mechanical properties, good oxidation and corrosion resistance. Among the most demanding applications for a structural material are those in the turbine engines, in first place for turbine blades. Nickel based superalloys consist of nickel solid solution, strengthening ϒ’ phase (Ni3Al) and carbides. At room temperature turbine blades are paramagnetic. The earlier studies reported increase in magnetic properties of Ni3Al after induced deformation. In this paper, the magnetic properties of nickel based superalloy after deformation induced by laser waves are investigated and discussed. Mechanical characteristics are analyzed with regards to changes of magnetics properties

Mikromehanička analiza loma laminatnog staklo-epoksi kompozitnog materijala ispitivanog na zatezanje

The main objective of this study is to determine tensile properties of the glass-epoxy polymer composite material. The material is glass fiber 280 g/m², 'twill woven' with 100 cm width, type - Interglas 92125, and epoxy resin type MGS L-135, where samples are molded using hand manual method with 35% fiber weight per volume. Orientations were 0/90° i ±45°. In accordance with appropriate standards, tensile strength and modulus of elasticity were determined. Beside the analysis of the results obtained during the experiment, micro-mechanical analysis of the tensile failure appearance and development was conducted based on the observed cracked surface, which led to a confirmation of all characteristic mechanisms and cracks expected for this type of material and study. Micromechanical analysis performed on the cracked surfaces of the investigated samples, has led to a definition of a structure which is more suitable for exploitation of this material in a presence of this type of external load.Predmet i cilj ovog rada je određivanje statičkih zateznih svojstava staklo-epoksi polimernog kompozitnog materijala. Ispitivani materijal je kompozitni materijal stakleno platno 280 g/m², 'twill tkanje' širine 100 cm, tip - Interglas 92125 i epoksi smola tip MGS L-135, a uzorci su oblikovani ručnom metodom sa 35% zapreminskog udela vlakana. Ispitivane su orijentacije 0/90° i ±45°. Određeni su zatezna čvrstoća i modul elastičnosti prema odgovarajućim standardnim ispitivanjima. Pored izvedene analize dobijenih rezultata, a na osnovu izgleda prelomnih površina uzoraka izvedena je i mikromehanička analiza nastanka i razvoja oštećenja pri zatezanju čime su potvrđeni svi mehanizmi i oštećenja karakteristični za ovakvu vrstu materijala i ispitivanja. Mikromehaničkom analizom na prelomnim površinama ispitivanih uzoraka se došlo do strukture koja je povoljnija u eksploataciji pri ovakvog tipu spoljašnog opterećenja

Mikromehanička analiza loma laminatnog staklo-epoksi kompozitnog materijala ispitivanog savijanjem

The object and purpose of this work is the micromechanical analysis of failures caused by mechanical tests of laminate glass-epoxy composite material in bending. The structure of glass-epoxy composite material is a glass fabric 280 g / m2, 'twill weave', width 100 cm, type - Interglas 92125 and epoxy resin type MGS L-135. Samples are shaped manual method with 35% volume fraction of fibers. Previous mechanical tests were obtained relevant data on tensile and flexural mechanical properties. By analyzing the images of fracture surfaces of larger magnification with a scanning electron microscope (SEM) will be performed micromechanical analysis that will lead to the knowledge of the mechanisms of damage and crack growth to final fracture in action bending loads.Predmet i cilj ovog rada predstavlja mikromehanička analiza lomova nastalih mehaničkim ispitivanjima laminatnog staklo-epoksi kompozitnog materijala na savijanje. Struktura staklo-epoksi kompozitnog materijala je stakleno platno 280 g/m2, 'twill tkanje', širine 100 cm, tip - Interglas 92125 i epoksi smola tip MGS L-135. Uzorci su oblikovani ručnom metodom sa 35% zapreminskog udela vlakana. Prethodnim mehaničkim ispitivanjima su dobijeni relevantni podaci o zateznim i savojnim mehaničkim svojstvima. Analizom sa fotografija na prelomnim površinama većih uvećanja i sa skening elektronskog mikroskopa (SEM) biće izvedena mikromehanička analiza kojom će se doći do saznanja o mehanizmima oštećenja i razvoju prsline do konačnog loma pri delovanju savojnog opterećenja

Effectivity of Hypergeometric Function Application in the Numerical Simulation of the Helicopter Rotor Blades Theory

Efficiency and justification of hypergeometric functions application in achieving simple formulas used in numerical simulation of helicopter rotor blades theory are presented in this paper. Basic equations of stream field over helicopter rotor are formulated, their decomposition is made and mean induced velocity harmonics are integrally presented. Theoretical basis of hypergeometric function application in transformation of integral equations of k-bladed rotor average induced velocity into special functions follows. The necessary conditions for transformation hypergeometric functions into special functions are defined. Variants of integral transformation of expressions obtained are presented by a numerical simulation and solutions are found. This approach to cecure the effectivity of hypergeometric function application in helicopter rotor blades theory by numerical simulation provides a synthetic method, which can be used to define helicopter k-bladed main rotor optimal characteristics

Improved solution approach for aerodynamics loads of helicopter rotor blade in forward flight

This paper presents the numerical model developed for rotor blade aerodynamics loads calculation. The model is unsteady and fully three-dimensional. Helicopter blade is assumed to be rigid, and its motion during rotation is modeled in the manner that rotor presents a model of rotor of helicopter Aerospatiale SA 341 "Gazelle" (the blade is attached to the hub by flap, pitch and pseudo lead-lag hinges). Flow field around the blade is observed in succession of several azimuth locations. Flow field around helicopter rotor is modeled as fully three-dimensional, unsteady and potential. Blade aerodynamics is modeled using a lifting surface model. Rotor wake is generated from the straight elements of constant vorticity, released from the trailing edge, at fixed azimuth angles. These vortices represent both trailed and shed wake components, and are allowed to freely convect along local velocity vectors. Wake is modeled as free one, and its shape at certain moment can be calculated from simple kinematics laws applied on collocation points of the wake. Wake distortion is calculated only in the rotor near-field, i.e. in finite number of rotor revolutions. Vortex elements are modeled with vortex core. The radius of the vortex core is assumed independent of time, and it depends on circulation gradient at the point of vortex element released from the blade

An Optimal Main Helicopter Rotor Projection Model Obtained by Viscous Effects and Unsteady Lift Simulation

This paper presents on airfoil model which provides a method for optimal main helicopter rotor projection by viscous effect and unsteady lift simulation through algorithm and set of program entireties, applicable to the ideological and mail project of helicopter rotor. Based on real rotors theoretical consideration and the, numerical analysis considerations in this paper can be applied with sufficient accuracy in the analysis and constructive realizations of helicopter rotor in real conditions. The method for unsteady viscous flow simulations by inviscid techniques is developed. The aim of this paper is to determine helicopter rotor blade lift with the highest possible accuracy by using a singularity method and to define an optimal conception model of aerodynamic rotor projection corresponding to rotor behavior in real conditions and with sunk:lent quality nom the aspect of engineer use