The motivation behind solving the issue of estimating the flow parameters of the pneumatic system of a launcher was the need to obtain the take-off energy with a value exceeding 80 kJ. The take-off ...energy and the initial speed of the unmanned aerial vehicle (UAV) depends on the pressure drop time in the launcher’s pneumatic system. The aim of the research was to estimate the flow parameters of the trigger system of the UAV launchers in order to achieve the shortest time of its operation. Due to the lack of a description of the selection of pneumatic elements and their flow characteristics in the available literature, the article attempts to analytically describe the air flow through pneumatic units. The trigger system is described using the sonic conductivity and the critical pressure ratio. Due to the lack of numerical data on the flow parameters of pneumatic units, a test stand was designed and constructed to determine these parameters. The values of the sound conductivity and the critical pressure ratio were determined for each of the pneumatic units and for the entire system. The proposed method makes it possible to determine the relationship between the operating time and the values of the flow parameters of the pneumatic launch tube release system. It also provides guidelines for design and technological solutions for the trigger system of any pneumatic launcher.
One of the possible tasks for unmanned aerial vehicles (UAVs) is field capturing of object images. The field capturing of object images (scenes) is possible owing to the UAV equipped with ...photographic cameras, TV cameras, infrared camer-as or synthetic aperture radars (SAR). The result of the recognition is a metric mapping of space, i.e. 2D flat images. In order to increase the quality of image recognition, it is necessary to search for and develop stereoscopic visualization with the possibility of its mobile use. A pioneering approach presented in the research paper is using a UAV with an imagery intelligence system based on structured light technology for air reconnaissance of object over
a selected area or in a given direction in the field. The outcome of imagery intelligence is a three-dimensional (3D imaging) information on the geometry of an observed scene. The visualization with
a stereoscopic interface proposed in the work allows for a natural perception of the depth of the scene and mutual spatial relationships, as well as seeing which objects are closer and which are further. The essence of the article is to present the application of three-dimensional vision measurement technology on UAVs. The paper presents an analysis of the possibilities of using UAVs for image recognition and a method of image recognition based on the technology of structural lighting using the method of projection of Gray’a fringes and codes. The designed image recognition system based on the structural lighting technology is described. It also discusses task modules forming a measuring head, i.e., projection, detection and calculation modules, and the exchange of control or measurement data between imaging system components. It presents the results of tests on the possibility of rapidly acquiring images using a UAV. The test results and the analyses indicate that using a UAV with an imaging technology based on structural light can contribute to improving the abilities to detect, identify, locate and monitor objects at close range, within a selected direction outdoors or indoors.
This study presents a method of computer support for the design of a hydraulic servo dedicated to the aircraft control system. A 3D geometric model of the servo was developed, which enabled the ...simulation of its kinematics. The paper presents a simulation model of a hydraulic servo that enables simulation of the dynamics of its mechanisms. The servomechanism model takes into account the dynamics of the movement of the distributor slider and the dynamics of the actuator piston rod movement under the influence of forces occurring in the servo. As a result of the simulation, step characteristics and static characteristics of the servo response were obtained. The presented model makes it possible to visualize the dynamics of operation of the prototype servo in various modes of its operation with different parameters of its control. It allows you to quickly and conveniently test the concept of an hydraulic servo and evaluate its functioning.
One of the most important factors for increasing the durability of turbine engines is the use of turbine blades characterized by the best possible convergence of the thermophysical properties of the ...protective coating and the base material of the blade. The aim of the research was to evaluate the heat resistance of prototype two-layer protective coatings applied to turbine blades. The inner layer of the coating enables shaping the thermophysical convergence of the coating and the base material of the blade. The outer layer is used for thermal protection of the blade material. The inner layer was applied to the blade by plasma spraying, and the outer layer was diffusion aluminized for the first type by a non-contact gas method, for the second type by a slurry method, and for the third type, the ceramics were plasma sprayed. Turbine blades with prototype coatings were subjected to an engine test, and after the test, macro- and microstructure tests were performed. The tests showed that the prototype protective coating with an inner layer of the MCrAlY type applied to the blade by plasma spraying and an outer layer aluminized by diffusion by a non-contact gas method protects the blade material against oxidation and ensures its thermal insulation.
During the ongoing operation of the hydraulic system you need a drive control information capable of maintaining fitness. Existing methods for assessing the technical condition of the hydraulic ...system require dismantling the hydraulic units and their research on test rigs. These methods are expensive, time consuming and do not provide a quick assessment of the technical condition. The aim of the study is to present the possibilities of using the evaluation of technical aviation hydraulic drive method which involves the use of objective information from the aircraft's flight control. In the proposed method, the carrier of information to the ongoing evaluation of the technical condition of the hydraulic system aviation as a whole is the pressure prevailing in it. With pressure and its features is inextricably bound up time. This relationship may be obtained directly from the objective flight control of the aircraft. The greatest credibility and the diagnostic value of two control parameters are obtained from the flight control objective. The first time the air pressure drop in the hydraulic drive from the top to the bottom of the measured value of the measured value after switching off the power unit. The second time the pressure falls below a certain value, and its return to the values of the movement during the hydraulic motor. The method enables the ongoing assessment of the technical condition of the hydraulic system is a fast and costless.
The paper explains how to benefit from information acquired from means for unbiased flight control and to use it for technical condition assessment demonstrated by the aircraft. There are two control ...parameters that are provided by the means of unbiased flight control and convey the highest trustworthiness and troubleshooting content. The first one is the duration of pressure drop across the avionic hydraulic drive after switching the driving unit off with the span from the upper measured limit to the lower limit. The second one is the total time of the cycle when the pressure drops below the specific threshold and then is restored to that threshold during a hydraulic motor movement (an on-board aircraft actuator). The suggested method enables real time evaluation of technical condition attributable to avionic hydraulic drives, is quick and entails no additional expenses.
Celem pracy jest przedstawienie możliwości wykorzystania do oceny stanu technicznego lotniczego napędu hydraulicznego metody polegającej na wykorzystaniu informacji ze środków obiektywnej kontroli lotu. Największą wiarygodność oraz wartość diagnostyczną mają dwa parametry kontrolne uzyskane ze środków obiektywnej kontroli lotu. Pierwszy to czas spadku ciśnienia w lotniczym napędzie hydraulicznym od górnej wartości pomiarowej do dolnej wartości pomiarowej po wyłączeniu zespołu napędowego. Drugi to czas spadku ciśnienia poniżej określonej wartości i jego powrotu do tej wartości w czasie ruchu silnika hydraulicznego. Proponowana metoda daje możliwość bieżącej oceny stanu technicznego lotniczego napędu hydraulicznego, jest szybka i bezkosztowa.
Throughout previous practice, estimating the life of aviation hydraulic drive assemblies has been utilizing a variant, which requires
conducting long-lasting studies of the drive assemblies until ...they move to the unfitness state. Such studies, which enable estimating life a posteriori, are costly and long-lasting. Hence the need to look for new strategies for estimating life. The article presents
a method of estimating the durability of a hydraulic drive assembly based on the control of its change in technical condition. Inspection of the technical condition enables timely detection of the condition before the emergency hydraulic assembly. The novelty of the
method is to use, to detect the condition before the emergency team, the principle of determining the pre-emptive control parameter
tolerance. Pre-emptive tolerances are a set of control parameter values between threshold levels and pre-emergency (allowable)
levels. The intensity of depletion of durability (intensity of aging, wear) is random. The paper presents a stochastic description of
the control parameter change and the resulting empirical relationships between the control parameter verification time probability
density (verification periodicity) and the control parameter value change probability density. The inter-relations between these two
functions were described. It also presents empirical relationships enabling the determination of the permissible value for the control
parameters and the periodicity of the control parameter checks after exceeding the limit value. An example of estimating the life of
a hydraulic piston pump on-board an aircraft operated in the Polish Air Forces was shown. The permissible values and the time
for the first control parameter verification after exceeding the limit value were determined for selected control parameters of the
hydraulic pump. The proposed method binds life (fitness time) with the physical wear mechanisms concerning the assemblies. It
can be applied in work aimed at determining the resource life of technical equipment. Furthermore, it enables utilizing technical
equipment according to a technical state strategy with monitoring the parameters.
The occurrence of an external leak in the aviation fuel unit leads to a catastrophic aviation event. The aim of the research was to estimate the flow of the fuel stream through the fuel filter ...chamber with its external unsealing. The research was carried out using experimental methods and computer CFD modelling. Experimental studies were carried out on a specially designed test stand. During the tests, the flow rate of the fuel stream flowing out to the environment was changed. Numerical calculations allowed to obtain the values of the stream and pressure inside the leaky filter chamber. The results of numerical calculations were compared with the results of experimental measurements. The CFD method significantly supplemented the information on the fuel flow inside the considered filter chamber at its external unsealing. The use of software based on the CFD method allows to obtain reliable values characterizing the fuel flow in the aviation fuel unit.
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