Sławomir Cieślak, Wiesław Krzymień and Krzysztof Szafran
Hovercrafts are a universal means of transport intended for use on flat surfaces such as water, ice, snow, swamp, or sand. They are used in rescue operations and patrolling difficult areas inaccessible to other means of transport. The Institute of Aviation conducted acoustic measurements inside the cabin of the hovercraft to determine the source of the noise and the sound pressure exerted on the pilot and passengers. Assessment of the sources of noise in the cabin is made using the acoustic beamforming method. Assessment of the level of noise to which a pilot is exposed during the operation was prepared on the basis of a standard specifying the requirements and methods of determining occupational noise exposure .
The test results indicate a significant penetration of noise from the drivetrain into the cabin. It is recommended that a hovercraft pilot and operators use hearing protection in some specified conditions and during testing. Thus it is pointed out in the summary that additional soundproofing of the cabin is needed. The points of the greatest penetration of noise into the interior have been indicated.
Propeller-driven single-engine aircraft are affected by unsymmetrical flow of air around the fuse-lage, and especially around the vertical stabilizer [1-3]. This unsymmetrical, propeller-induced slip-stream produces sideslip [4,5] that needs to be compensated by the pilot using the rudder . In order to relieve the pilot from this additional task, automatic rudder deflection systems are used that compensate for sideslip by trimming the rudder accordingly. Such compensation algorithms are based on flight parameter measurements.
This paper presents more complex systems used to eliminate the phenomenon in question. In addition, it analyzes the existing solutions, based on patents divided into two groups. The first group deals with active slipstream effect compensation solutions, based on aircraft movement parameters that are derived from aircraft performance characteristics defined in advance. The other group comprises solutions that are based directly on feedback containing actual or estimated sideslip angle values. The most advanced systems rely on a combination of the two methods described above.
The article presents the results of research work performed under the TEBUK project, aiming primarily to develop a reference methodology for assessing the impact of damage on the strength of structures made of carbon epoxy prepregs. The tests described in the paper were concerned with a fragment of the structure (FS) of the TEBUK project demonstrator, made of carbon epoxy composite, with an artificial circular delamination measuring 40 mm in diameter. Numerical and experimental test of FS have been performed under quasi-static compression load. The buckling of the skin observed in the delamination area, as well as the propagation of the latter were investigated. The numerical calculations have been performed with the use of the commercially available MSC Marc/Mentat calculation suite based on the Finite Elements Methods. Results of the numerical calculations have been compared with experimental measurements made with the use of the Digital Image Correlation (DIC) method. The tests performed aimed to provide a preliminary verification of the numerical model. The results obtained have shown a very good correlation between the numerical and experimental results concerned with critical load levels at which stability of the layers separated by delamination is lost (buckling). The lack of convergence of the numerical model’s results after exceeding the critical load values has rendered it impossible to unequivocally compare the results concerned with propagation of the delamination area.
The article presents the methodology of introducing automatic carbon fiber panel cutting technologies at the Composite Testing Laboratory of the Institute of Aviation. It describes the process of implementing the new cutting technology which boosts the efficiency of preparing composite samples for strength testing, with the requirements applicable to edge smoothness and dimension tolerances taken into consideration. It also reviews the literature concerned with three most popular composite material cutting methods: laser cutting, abrasive water jet cutting and machining, presenting the strong and the weak points of each one of them. After selecting the machining technology relying on a disc, cutting tests have been performed. Cutting discs coated with diamond particles, and carbon fiber panels were used during the tests. The tests were performed with the use of the INFOTEC CNC machine, with an adapter enabling the installation of cutting discs with the maximum diameter of 150 mm.
The article presents the result of tests of a single segment of a prototype water turbine, performed in order to determine its shaft power output as a function of rpm, and to verify the declared performance. The results have been compared with the outcomes of numerical calculations performed, for the same conditions, with the use of FLUENT software. The work presents information of crucial importance for presenting the process of testing the piece in question, such as: test environment, properties of the test piece, testing equipment used, as well as the methodology and the course of hydromechanical measurements, along with the characteristics of the results obtained. Then, the measurement results are discussed and analyzed. Conclusions are presented as well. Analysis of the results, taking into consideration the physical image of phenomena occurring in the case of flow-devices, such as water turbines, has made it possible to define other, important characteristics of the turbine, such as: output, shaft torque and efficiency, as a function of rpm and head of turbine. Test results have confirmed the expected mechanical and power-related properties of the turbine and have proved the numerical flow modeling model used effective.
A brief description of the prospects concerning new applications of the turbine discussed has been presented as well
The article describes participation of Mi-2 helicopters in both military and civilian operations at sea. Although the multipurpose Mi-2 rotorcraft were not designed to operate in the harsh environment over the sea, they became - in the second half of the 1960s and in the 1970s - a standard type performing a wide array of tasks at sea. Modern turboshaft engines, a favorable weight-to-power ratio and a dual engine configuration were all factors enabling safe flight over the sea, at considerable distances from land. The specialized Mi-2RM variant designed by WSK PZL Świdnik provided the Naval Aviation with an opportunity to establish, in the 1st half of the 1970s, a unique marine air rescue system. The last Mi-2RM used for rescue missions was decommissioned as late as in 2010, although at that stage it was only used for aircrew training purposes. The Navy was also using the Mi-2Ch variant tasked with creating smokescreens to conceal vessels and port facilities. General purpose variants of the helicopter were used to transport people and goods. They also performed well during patrolling missions and while identifying various types of contamination.
As far as civilian use of the helicopters is concerned, Mi-2 versions equipped with special purpose on-board systems supported scientists in the exploration of the Antarctica at two stations of the Polish Academy of Science. The Maritime Authority in Gdynia was also using its own Mi-2 helicopter for over 30 years - until 2015 - for patrolling the Gdańsk and Puck Bays and waters around the Hel Peninsula. The missions were focusing primarily on detecting potential contamination of the coastal areas.
In the former Soviet Union, civilian Mi-2 variants were (and still are) standard equipment of deep sea icebreakers operating in the Arctic and around the North Pole. The machines are mainly used for safety purposes, as well as for transporting scientists and groups of extreme tourists. Approximately a dozen Mi-2 purchased from Russia in the mid-1990s, in turn, were used by the Aviation Force of the Mexican Navy. Unfortunately, no further details regarding their use are available.
In the article, the author presents the wide-scale use of Mi-2 helicopters in the different entities subordinated to the Minister of Interior - from the introduction of the design, until the present. Insights are presented pertaining to the early stages of the helicopter’s service life within the structures of the 103rd NJW MSW Aviation Regiment in the 1960s. The article describes selected aspects related to the introduction of the design, training, operational use and problems encountered. The service life of Mi-2 helicopters operating within the structures of the Ministry of Interior ended upon liquidation of the Ministry’s Aviation Detachment. That is when another chapter in the history of the helicopters was started, this time operated within the structures of the Police and Border Guard forces, where their service life has not been fully used up until this day. The paper describes the reality of every-day use to perform specific tasks, presents the location of aerodromes, touches upon a shift in the philosophy behind the use of the helicopters, and describes their strong and weak points. The PZL-Kania helicopter has been also presented, being a modernized version of the Mi-2, and still used in Poland within the aviation forces of the Ministry of Interior and Administration.
The article presents an aerodynamic concept of UAV in the gyrodyne configuration, as a more efficient one than the currently used UAV airframe configuration applied for monitoring tasks of power lines and railway infrastructure. A sample task which is realised by conceptual gyrodyne based on monitoring aerial power lines was characterised and described. The assumed idea of UAV was shown in comparison to the currently used aircraft configuration presented in the introduction. Referring to momentum theory, hover efficiency of the multicopter and the helicopter was evaluated. In relation to the helicopter, an initial draft of the airframe conception accompanied by a description of advantages of the gyrodyne configuration was exposed. Problems related to the gyrodyne configuration were emphasised in the summary.
Tomasz Seredyn, Adam Dziubiński and Piotr Jaśkowski
The article describes a computational study, using CFD models, of droplet spray dispersal in the wake of a ‘Turbo Kruk’ airplane up to 500 m downstream. The CFD Reynolds-averaged Navier-Stokes (RANS) models use a Lagrangian (droplet phase) and Eulerian (fluid phase) procedure to predict the droplet trajectories trough the turbulent aircraft wake. The methods described in the work have the potential to improve current models for aerial spraying and will help in the development of new spraying procedures. In this study, the CFD models are used to describe the phenomenon of sprays released from atomizers mounted on the plane. A parametric study of the aircraft model examines the effects of crosswind on the aircraft’s vortex structures and the resulting droplet trajectories. The study shows, that such influence is underestimated in the current models. A comparison of the present results to AGDISP predictions is provided.
The paper presents results of simulation calculations concerning an influence of stiffness of blade-hub connection on rotor loads and blades deflections in hover, level flight and pull up maneuver. The three versions of rotor are considered with articulated, elastic and stiff connections of blades and hub. The blades with the same distributions of stiffness, mass and the same aerodynamic characteristics are applied for all rotor cases. The rotor loads are calculated applying Runge-Kutta method to solve the equations of motion of deformable blades. According to the Galerkin method, the parameters of blades motion are treated as combination of considered blade bending and torsion eigen modes. The results of calculations indicate for possibility to generate the greater rotor control moments and to improve helicopter maneuverability in the case of applying the non-changed blade of articulated rotor combined with elastic rotor hub.