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Iosif Taposu has formulated a mathematical model and generated a family of airfoils whose geometry resembles the dolphin shape. These airfoils are characterized by a sharp leading edge and experiments have proven that they can achieve better aerodynamic characteristics at very high angles of attack than certain classical airfoils, with the nose geometry inclined downwards. On the other hand, they have not been applied to any commercial general aviation aircraft. The authors of this paper have been motivated to compare the aerodynamic characteristics of widely used NACA 2415 airfoil with Taposu’s dolphin that would have the same principal geometric characteristics. A CFD calculation model has been established and applied on NACA 2415. The results were compared with NACA experiments and very good agreements have been achieved in the major domains of lift and polar curves. The same CFD model has been applied on the counterpart Dolphin 2415. Results have shown that the Dolphin has a slightly higher lift/drag ratio in the lift coefficient domain 0.1 ÷ 0.35 than NACA. On the other hand, at higher and lower lift coefficients, its aerodynamic characteristics were drastically below those of the NACA section, due to the unfavorable influence of the Dolphin’s sharp nose. A series of the Dolphin’s leading edge modifications has been investigated, gradually improving its aerodynamics. Finally, version M4, consisting of about 70% of Dolphin’s original rear domain and 30% of the new nose shape, managed to exceed the NACA’s characteristics, thus paving the way to investigate the Dolphin hybrids that could be suitable for the general aviation industry.

The goal of this research is to assess the different low-cost sensors for flight altitude measuring of a multirotor UAV at low altitude flight. For optimizing the sensor performances and accuracy, data filtering and other methods were applied. The flight altitude data were collected and stored for later analysis with reference to the true altitude. The correlation coefficient and the mean squared error were calculated in order to assess the sensors' performance. On the basis of the results of the study, it was possible to determine the choice of the adequate sensor for this specific use. The study showed that the best characteristics for this experiment conditions had the Garmin LIDAR-Lite V3HP sensor and the Bosch Sensortech BME280 that combined air humidity, atmospheric pressure, and air temperature sensor.

The goal of this work is to build a unique numerical method to obtain the basic aerodynamic characteristics of the aircraft and to enable a wide application of the method in the analysis of some aerodynamic characteristics of the aircraft, without use of empirical methods. The Computational fluid dynamics (CFD) simulation method was being calibrated based on test results of the standard AGARD-B (Advisory Group for Aerospace Research and Development) test model, which were obtained in the T-38 trisonic wind tunnel facility of the Military Technical Institute (VTI) in Belgrade, Serbia.The paper presents the CFD simulation through a description of the conditions of flow, geometry of the computer domain, grid density and mesh strategy, boundary conditions, initial strategy and turbulence model. The CFD simulation was carried out for flow cases with similarity parameters M = 0.6, M = 0.85 and M = 1.6 and Re = from 7.7(x106) to 9.9(x106) . The results of calculations were compared with the appropriate experimental ones and presented in the form of comparative diagrams for the drag, lift and pitching moment coefficients. The results of investigation presented in divergence diagrams show very good agreement between numerical and experimental ones. Simulated flows are illustrated by the distribution of pressure and velocity components on the surface of the tested model and the computational domain. This CFD simulation will be applied to other similar aerodynamic designs for a wide range angles of attack and Mach numbers and can be a strong point for the development of different aerodynamic designs.The ultimate aim of the work is to use the previous calibrated CFD simulation method as the basis for future determination of the aerodynamic characteristics of aircraft in non-stationary flight modes, caused by motion of the aircraft and/or by changing the free-velocity vector.

This paper presents modification of the existing guided missile which was done by replacing the existing front part with the new five, while the rear part of the missile with rocket motor and missile thrust vector control system remains the same. The shape of all improved front parts is completely different from the original one. Modification was performed based on required aerodynamic coefficients for the existing guided missile. The preliminary aerodynamic configurations of the improved missile front parts were designed based on theoretical and computational fluid dynamics simulations. All aerodynamic configurations were tested in the T-35 wind tunnel at the Military Technical Institute in order to determine the final geometry of the new front parts. The 3-D Reynolds averaged Navier-Stokes numerical simulations were carried out to predict the aerodynamic loads of the missile based on the finite volume method. Experimental results of the axial force, normal force, and pitching moment coefficients are presented. The computational results of the aerodynamic loads of a guided missile model are also given, and agreed well with.

In this paper is presented a new conceptual design of the light aircraft for Mars atmosphere, ALPEMA. It allows atmospheric dropping (aeroshell), as well as direct take-off from Martian surface. Complex atmosphere demanded for simplified yet efficient wing geometry, capable of maximizing Lift-to-Drag ratio. Martian atmospheric pressure, density, temperature and speed of sound variations, demand a scrutinized powerplant choice. Efficient aspect ratio and drag polar lead to optimal flight envelopes as a proof of sustainability of ALPEMA project. Special performances and basic aerodynamics provide boundaries and constraints of the project, in line with similar approaches. Chosen propeller allows for ALPEMA to use maximum power capabilities of its engine, described through Vmin and Vmax, which are significant inputs for flight envelope. Envelope provides effective width and profile for a variety of possible missions. ALPEMA’s specific propeller and engine are a certain comparative advantage, together with its flight envelope.

This research is an effort to contribute to the human exploration of Mars by simulating phases of the Mars flight envelope in a high performance human centrifuge. The crushing sensation experienced at high-G levels during take-off, the experience of zero and microgravity, can result in many psycho-problems to astronauts, obviating the need for realistic training protocols. The flight envelope for the first manned mission to Mars is proposed, and simulated in terms of G- load. Some training profile suggestions are given. A special emphasis is placed on the Earth launch phase, and on the Earth re-entry and landing phase. Re-entry can be especially dangerous with much higher accelerations. Accurate simulation requires a proper adjustment of rotational angles of the centrifuge. Angle adjustments are made in order to minimize side-Gy and transverse-Gx load. This study will hopefully help to move faster towards the dream of “Humans on Mars”.

In this paper the harmonization of new wind turbine rotor blades development is given as well as the analysis of behavior by verification testing for a wind turbine rotor blade of composite materials. The design, fabrication, the status of wind energy standards and the analysis of behavior by full-scale verification testing for wind turbine rotor blades of composite laminated materials is given, too. The experimental methodology of static, vibratory and fatigue tests for the wind turbine rotor blade of composite laminated materials is presented. These verification tests were performed after the rotor blade development had been completed. The development of the rotor blade was performed using the PC computer with the CATIA designing system and the Gerber Garment cutter system. The blade was fabricated from composite laminated materials. The contour of airfoil was formed by a continuous structural pocket and a fiberglass skin.

Povećanje udobnosti pilota zrakoplova zahtijeva kontinuiran rad na smanjivanju vibracija koje djeluju na sjedište pilota. U cilju određivanja pogodnosti i potencijala veze pod kabine - sjedište pilota za pasivno prigušenje vibracija, proveden je eksperiment s mjerenjem i analizom vibracija na sjedištu. Parametri vibracija su izmjereni za režime leta zrakoplova s maksimalnim brojem okretaja motora i elise. Ova analiza ukazuje da kvaliteta pasivnog prigušenja vibracija, odnosno funkcionalnost veze pod kabine - sjedište, ovisi o režimu leta zrakoplova i frekvenciji vibracija. Na pojedinim analiziranim režimima leta veza pod - sjedište ponaša se kao multiplikator vibracija na 3. i 4. harmoniku, kao i na 3,5 poluharmoniku osnovne frekvencije okretaja elise, dok se na ostalim analiziranim frekvencijama ova veza ponaša kao prigušivač vibracija. Analiza ovog eksperimenta pokazala je da je opravdano započeti razvoj vlastitog prilagodljivog uređaja za aktivno prigušenje vibracija na sjedištu pilota., Improving aircraft pilot comfort requires continuous work in decreasing vibrations in the seat. In order to determine the suitability and potential of cockpit floor - seat connections we conducted an experiment where measurements were taken and seat vibration analysis conducted. Vibrations parameters were measured for maximum engine and propeller speed. This analysis indicates that passive vibrations damping or cockpit floor - seat connections functionality depends on flights profile and vibrations frequency. The connection in question was behaving like a vibration multiplier on the 3rd and 4th harmonic as well as on the 3,5 sub-harmonic in individual flight modes on basic propeller rotation frequency, however, it behaved as a vibration silencer on all other frequencies. Analysis of the experimental data has shown that it would be justified to start improving the self adaptive unit for active vibration reduction for pilot seats.

This paper presents the numerical model developed for rotor blade aerodynamicsloads 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 bothtrailed 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 independentof time, and it depends on circulation gradient at the point of vortex element released from the blade. V prispevku je predstavljen numerični model, razvit za izračun aerodinamičnih obremenitev lopatice rotorja. Model je nestacionarnega in popolnoma trirazsežen. Predpostavili smo, da je lopatica rotorja toga, njeno gibanje med vrtenjem pa smo modelirali za primer modela rotorja helikopterja "Gazela" Aerospatiale SA 341 (lopatica je pritrjena v sredisče z loputo in tečaji). Tokovno polje okrog lopatice smo opazovali v sosledju večih azimutnih leg. Tokovno polje okrog rotorja helikopterja smo modelirali kot popolnoma trirazsežnega, neustaljenega in potencialnega. Aerodinamiko lopatic smo modelirali z uporabo dvižnega površinskega modela. Vrtinec rotorja se sestoji iz premih elementov s stalno vrtilnostjo, ki izhaja iz roba pri stalnih kotih azimuta. Ti vrtinci predstavljajo tako vlečne kot tudi sled zagonske komponente in se lahko prosto prenašajo vzdolž krajevnih vektorjev hitrosti. Vrtinec smo modelirali kot neodvisnega, njegovo obliko pa lahko v določenih trenutkih izračunamo iz enostavnih kinematičnih zakonov, uporabljenih na kolokacijskih točkah vrtinca. Zmaličenje vrtinca smo izračunali le v polju blizu rotorja, tj. pri končnem številu vrtljajev rotorja. Elemente vrtinca smo modelirali z jedrom vrtinca. Predpostavili smo, da je jedro vrtinca neodvisno od časa ter da je odvisno od spremembe kroženja v točki, v kateri se element vrtinca odlepi od lopatice.

This paper presents a method for determination of optimum positions of single wind turbines within the wind farms installed on arbitrary configured terrains, in order to achieve their maximum production effectiveness. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)

This paper studies the interaction (influence) of perforated walls of transonic wind tunnels in two-dimensional investigations which employ the generalized method for solving Dirichlets problem formulated for the rectangle of the transonic wind tunnel work section. The algorithm has been applied to the aerodynamic experimental results from investigations of NACA 0012 airfoil obtained at the VTI – Aeronautical Institute and the Faculty of Mechanical Engineering in Belgrade to demonstrate in two-dimensional investigations the appropriateness of the presented advanced algorithm for the calculation of the interference of the transonic wind tunnel wall. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)