Lidé na fakultě
Ing. Daniel Urban

2024, Journal of Aerospace Engineering, 37 (4), ISSN 0893-1321

The conventional pitot-static tube's accuracy in measuring indicated airspeed is compromised by its longitudinal inclination during forward flight, causing errors when the angle surpasses a critical threshold. This study aimed to propose and assess new designs for pitot-static tube ports to mitigate the angle of attack. Modifications, such as enlarging the inlet cross section, altering the tube port's leading surface angle, and introducing new inlet openings, were implemented in five prototypes. After 2D CFD simulations, these prototypes were 3D printed, and experiments were conducted in a wind tunnel across angles from 0° to 55° at three airflow speeds. CFD results indicated increased error with larger inlet diameters and revealed an oscillating error phenomenon for multiple inlet openings. Experimental tests contradicted expected accuracy issues with extended diameters, suggesting superior characteristics at higher angles of attack. An oscillating error of pitot-static tubes with multiple holes was affirmed. The study targeted a pitot-static tube port design with a maximum 5% error in airspeed measurement within attack angles from 0° to 40°, showing promise for vertical takeoff and landing vehicle airspeed measurement during horizontal forward flight.

Článek v periodiku excerpovaném SCI Expanded

2024, New Trends in Civil Aviation: Proceedings of the 24th International Conference on New Trends in Civil Aviation 2024, Praha, České vysoké učení technické v Praze), p. 247-251), ISBN 978-80-01-07181-6, ISSN 2694-7854

The propulsion systems of unmanned aircraft such as multicopters are very vulnerable to any kind of damage. Thus, the presented study introduces the possibility of using vibration sensing to determine the condition of the rotating propeller to detect possible damage or contamination. For the purpose of this study, a test stand was designed and a total of 3 different propeller damages were tested. These included minor and major damage to the tip of the propeller blade as well as disruption of the leading edge profile geometry. Propeller vibration was captured within the operating range of propeller (from 3 500 to 6000 RPM) in the axial X-axis and radial Y-axis. The measured data were processed by spectral analysis, i.e., by calculating the amplitude spectrum using a Fourier Transform. The outputs in the form of spectograms for each damage type and individual RPM were further processed by Principal Component Analysis (PCA). From the PCA, it was possible to identify the vibration frequency spectrum of the tested propeller and the individual damaged states.

Stať ve sborníku z prestižní konf.

2024, New Trends in Civil Aviation: Proceedings of the 24th International Conference on New Trends in Civil Aviation 2024, Praha, České vysoké učení technické v Praze), p. 147-152), ISBN 978-80-01-07181-6, ISSN 2694-7854

This study focuses on the influence of specific sound frequencies on pilot psychophysiological condition within a simulated cockpit environment. Conducted using a flight simulator, the study involved fifteen male pilots with an average of 175 flight hours. The experiment consisted of three key phases: a hearing test, a familiarization flight, and the experimental flight where specific sounds within the 498 Hz to 4000 Hz range were played at 64 dB. These sounds, typical of cockpit noise, were integrated into flight scenario to assess their physiological impact on pilots, monitored via electrocardiograms and focused on heart rate variability, respectively. Also, subjective data were collected using questionnaire. The results suggest, that the specific noise can negatively affect pilots' psychophysiological conditions, increase perceived workload and decrease comfort.

Stať ve sborníku z prestižní konf.

2024, New Trends in Civil Aviation: Proceedings of the 24th International Conference on New Trends in Civil Aviation 2024, Praha, České vysoké učení technické v Praze), p. 253-259), ISBN 978-80-01-07181-6, ISSN 2694-7854

The subject of this paper is validating the applicability of a wind wall as opposed to a wind tunnel in testing the performance parameters of a propeller propulsion unit. The primary focus is on unmanned aircraft, a sector experiencing continuous growth and integration into everyday life. This is closely tied to the development of new technologies, particularly in propulsion units, aiming for maximal efficiency and the associated reduction in energy consumption. However, current testing methods for these propulsion units are both costly and time-consuming. Additionally, when utilizing wind tunnels, constraints in terms of space availability pose further challenges. Consequently, verifying the performance parameters of propeller units becomes exceedingly difficult, if not impossible, for many manufacturers and institutions. The implementation of a wind wall would offer an affordable testing alternative, concurrently addressing space constraints when compared to a wind tunnel. This would facilitate further advancements in the realm of unmanned aircraft propulsion. In the presented study, two selected propellers were tested in flow created by wind wall. The acquired data were analysed and subsequently compared with relevant studies focusing on wind tunnel testing. The study's results indicate that the wind wall yields satisfactory results compared to the wind tunnel, suggesting its viability for use, at least in the initial stages of propeller propulsion unit development.

Stať ve sborníku z prestižní konf.

2023, 2023 New Trends in Aviation Development (NTAD), Praha, IEEE Czechoslovakia Section), p. 262-269), ISBN 979-8-3503-7042-3, ISSN 2836-2756

Spatial orientation is very important during flight for the pilot and his ability to correctly perform several parallel tasks related to piloting, navigation and communication. In the event that the pilot loses his own spatial orientation, he must rely solely on the on-board instruments, increasing his workload and the likelihood that the pilot will make a mistake. Further, flight illusions are associated with the loss of spatial orientation and may cause the pilot to perceive inconsistent information about his or her position. Despite the fact that loss of spatial orientation may be commonly encountered by civilian pilots, they are not prepared for these situations as part of their practical training. Although full-flight simulators adapted to induce illusions can be utilized in this context, they are expensive and essentially unused in the training of civilian pilots. This has led to the proposal of a potentially usable and cost-effective technical solution that could be employed in inducing certain types of illusions. Therefore, the article specifically deals with the design of a rotary chair suitable for inducing vestibular nystagmus and the validation of this solution, along with an introduction to the practicality of this solution in the aviation training and research environment.

Stať ve sborníku z prestižní konf. (Scopus)

2023, Applied Sciences, 13 (5), ISSN 2076-3417

With the expanding electrification in all sectors of transport, it is necessary to look for new efficient solutions for propulsion systems for use in air transport. One of the approaches can be the use of electric ducted fans (EDFs), especially in, but not limited to, the case of unmanned aerial vehicles with vertical takeoff and landing. This concept has been known for several decades but has been used very little and therefore has been almost unexplored. This opens up opportunities for investigating the performance characteristics, electrical consumption or efficient thrust vectoring of EDFs with respect to their design and operational use. The presented study therefore deals with the influence of the EDF design change on its performance characteristics. These design changes mainly concerned the geometry of the cowling, i.e., reduction and increase of outlet cross section, and arrangement of fans, i.e., one- and two-rotor specification. The comparison was based on measuring of vertical thrust and power consumption during static testing. The results showed that the increasing outlet is the most suitable construction for the generation of vertical thrust during static testing, considering the specifically used EDF construction arrangement. Based on the findings, it can also be concluded that EDFs are a suitable option for use in unmanned aircraft as a competition to other propulsion systems.

Článek v periodiku excerpovaném SCI Expanded

2023, 2023 International Conference on Military Technologies (ICMT), Vienna, IEEE Industrial Electronic Society), ISBN 979-8-3503-2568-3

The subject of this research is the development of ducted propulsion systems as replacements for traditional propeller propulsion systems intended for unmanned aircraft (UA). With the increasing number of operating UA and level of their automation, new possibilities for using UA in a number of applications are emerging. According to current legislation, one of the main limitations of the use of UA to date is the insufficient safety of UA operations over populated areas. Current UA equipped with propeller drive units do not achieve the required safety due to the rotating propeller blades. Ducted propulsion systems eliminate this shortcoming and provide other advantages that find their place mainly in conditions with space limitations. It is therefore necessary to find an optimal solution to these urban traffic problems. It is thus offered as a safety solution when operating in shared spaces near non-involved persons. The proposed specifications in this study are tested and the data subsequently compared with selected reference propeller drives from the point of view of energy consumption and generated thrust value. The aim of this study is to propose an optimal operational specification of the EDPS engine, suitable for UA operation from the point of view of better energy consumption and generated thrust compared to propellant systems. The results of the study prove that EDPS propulsion systems generate more thrust with lower total energy consumption than conventional propeller systems.

Stať ve sborníku z prestižní konf. (Scopus)

2022, 2022 New Trends in Civil Aviation (NTCA), Praha, České vysoké učení technické v Praze), p. 115-122), ISBN 978-1-6654-5190-1

Vertical Take-off and Landing Unmanned Aerial Vehicles (VTOL UAVs) are operated at low flight levels, close to the ground, where they are exposed to meteorological conditions, which are difficult to predict and can cause severe degradation of their aerodynamic, performance and flight characteristics. Of these meteorological conditions, icing is one of the most dangerous for the operation of VTOL UAVs. Although icing poses significant safety and operational risks, it has not yet been taken into account in their operation and there are no certified and verified anti-icing and de-icing solutions against it. The aim of this work is to propose a concept together with testing methodology, which would allow to determine the influence of individual meteorological conditions of icing on selected performance characteristics of propulsion systems of VTOLUAVs. Testing and exposure of propulsion systems to icing conditions took place in the climatic chamber. Several series of measurements were performed in the climatic chamber, in which the propulsion systems were exposed to a temperature of 15, of −5, of −10 and of −15°C and a flow of super-cooled water droplets of 1.43 g/s. The mutual comparison of the performed measurements made it possible to determine the influence of individual conditions on the decrease of the thrust, the increase of the consumed electric current and the occurrence of vibrations.

Stať ve sborníku z prestižní konf.

2021, Proceedings of the “Transport Means 2021”, Kaunas, Kaunas University of Technology), p. 354-358), ISSN 1822-296X

This paper is focused on the analysis of the applicable technologies of the e-ID for UAS and the identification of key barriers that need to be mitigated when the technologies are implemented into the airspace. The approach is focused on the system evaluation of airspace from the point of view of the possibility of integrating unmanned operations using U-space airspace. The use of U-space airspace in different parts of the current airspace classification entails different requirements for surveillance and anti-collision technologies. Current technologies are therefore evaluated against different airspace structures and obstacles are identified that prevent their use and the overall integration of unmanned aviation into airspace. The biggest obstacle found is a uniform reference height system, which does not yet exist. To implement it, a proposal has been created which, with the help of U-space service providers, will make it possible to ensure a uniform reference height for drones, thus helping to continue the integration.

Stať ve sborníku z prestižní konf. (Scopus)