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The Research of Acoustic Emission of a Low-Power Aircraft Engine

Abstract

This paper presents the methodology and investigation of the sound power level produced by a radial piston aircraft engine operating at varied speeds. The research model aircraft engine of a maximum power of 5.5 kW with a two-bladed airscrew was placed on a test bend. Its sound power level was calculated from the sound pressure level measured at 9 measurement points distributed on a hemispherical surface in a confined space in line with PN-EN 3744. Mean sound power generated by the ASP FS400AR engine is 96 dB at idle (2,880 rpm) and 105 dB at a cruising speed (4,740 rpm). Accordingly, it can be concluded that a sound level meter registered a higher sound power level at the points in front of the model aircraft engine than at the points behind it, whereas the lowest sound power level was registered directly above the engine.

Open access
Strain Optical Analysis of 3D Printing Elements in Different Additive Technologies in Comparison with the Finite Element Method

Abstract

Research included in this article were conducted with a project: ‘Additive technology used in conduction with optical methods for rapid prototyping of 3D printed models’. In this article intellectualized three various 3D printing technologies: Fused Deposition Modelling (FDM), Selective Laser Sintering (SLS) and Material Jetting (PolyJet). Also, there was presented theory of Digital Image Correlation (DIC) as an optical method for strain analysis. The limitations of DIC system have been tested and detected. The test result for DIC system were shown for each method of additive technologies and the results were compared to Finite Element Method (FEM). Test specimens were printed in selected technologies for reference. DIC system has been used for displacement state in loaded objects. The last paragraph contains both summary and tests results.

Open access
Temperature Measurements using Thermal Sensitive Paint

Abstract

Article highlights practical issues concerning temperature measurements using thermal sensitive paint (abbrev. TSP). TSP paint after blue light excitation emits red light with intensity dependent on its temperature. Temperature measurements are preceded with paint calibration, according to exact experiment conditions. Purpose of calibration is to find transfer function between intensity of emitted radiation and surface temperature. To achieve this goal, special computational procedure is implemented. Devices and methodology used for paint calibration are briefly described as well as measuring sample preparation process. Short description is devoted to the procedure for calculation temperature using recorded intensity. Results obtained during calibration are presented. Final conclusions about perspective of using thermal sensitive paint in laboratory are presented, as well as advantages and disadvantages of TSP method versus other methods currently used in temperature measurements.

Open access
Acoustic Characteristics of the Cabin of the Research Platform on the Airbag IL-PRC-600m

Abstract

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 [1].

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.

Open access
Analysis of Methods Used to Eliminate the Propeller Slipstream Effect in Single-Engine Aircraft

Abstract

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 [6]. 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.

Open access
Experimental Verification of Numerical Calculations with the Use of Digital Image Correlation

Abstract

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.

Open access
Implementation of Automatic Sample and Composite Element Cutting Technologies

Abstract

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.

Open access
Measuring Stand Tests of a Michell-Banki Waterturbine Prototype, Performedunder Natural Conditions

Abstract

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

Open access
Mi-2 Helicopters Operating at Sea

Abstract

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.

Open access
Mi-2 Helicopters Used Within the Structures of the Aviation Detachment of the Ministry of Interior

Abstract

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.

Open access