The article presents ‘state-of-the art’ on joining fibre reinforced thermoplastic composites with the use of resistance welding technique. Their welding process and potential difficulties connected with the process and quality control of a manufactured element are presented. The structure of a typical thermoplastic composite welding stand was also presented. The main welding technology elements were characterized: structure of the resistance element, implementation of the thermal process and pressure application required for joining materials. The paper also presents the required calibration ranges for a technological process with the use of strength test types SLS, DCB, SBS and nondestructive testing of joint with the ultrasonic method.
This work presents selected results of I-31T propulsion flight tests, obtained in the framework of ESPOSA (Efficient Systems and Propulsion for Small Aircraft) project. I-31T test platform was equipped with TP100, a 180 kW turboprop engine. Engine installation design include reverse flow inlet and separator, controlled from the cockpit, that limited ingestion of solid particulates during ground operations. The flight tests verified proper air feed to the engine with the separator turned on and off. The carried out investigation of the intake system excluded possibility of hazardous engine operation, such as compressor stall, surge or flameout and potential airflow disturbance causing damaging vibration of the engine body. Finally, we present evaluation of total power losses associated with engine integration with the airframe.
This paper presents a concept of a small scale liquid-propellant rocket engine designed in AGH Space Systems for sounding rocket. During preliminary design of thermal aspects various ways of cooling were evaluated and described. Possible issues and design approaches for ablative, radiation and regenerative cooling are raised. The authors describe available solutions. Regenerative cooling is especially concerned as it is most popular solution in bi-liquid engines, in which alcohol fuel acts as coolant and is preheated before it reaches combustion chamber. To estimate a possible temperature distribution - and thus an applicability of such a system in the engine - a mathematical model of heat transfer was developed. Unique element of said engine is its oxidizer - nitrous oxide, which have been rarely used to date. Comparison between typical LOX bi-liquids is given and major differences that affect cooling arrangement are discussed. The authors compared different combinations of coolants, fuel/oxidizer ratios etc. to optimize the temperature distribution which is a key factor for the engine performance.
Michał Gęca, Konrad Pietrykowski and Karol Rosiński
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.
Ewelina Kluska, Piotr Gruda and Natalia Majca-Nowak
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.
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.
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.