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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Helicopter Vibration Reduction Using Single Crystal And Soft Piezoceramic Shear Induced Active Blade Twist

Thakkar, Dipali 04 1900 (has links) (PDF)
No description available.
82

Tail Rotor Drive System for Unmanned Helicopter : From Concept Generation to Detalied Design

Stokov, Matko January 2020 (has links)
This thesis concerns the upgrade of APID One RPAS by The MainBase AB. Due to their wish to explore different options for tail drive of current RPAS and future heavier variant, several concepts have been generated and analyzed. Systemic elimination of proposed concepts has resulted with a belt drive transmission. Basic calculation has been performed to determine estimates of power requirements and positions of the new tail rotors relative to the fuselage. Furthermore, the design process encompassed components from the existing output power shaft within the fuselage to the final blades shaft, including the belt transmission, the truss-type structural support, and additional devices. The work includes material selection, FEA analyses of the structure, and bolts and welds calculations where loads were known. Final result is a tail boom that interchangeably fits both, new light and new heavy variant.
83

Realizace vrtulníku se čtyřmi rotory / Quadrocopter realization

Pekarovič, Ján January 2014 (has links)
This thesis deals with the design of a helicopter with four rotors known as quadcopter. It describes the principles of operation and existing modifications. Part of the work is the selection of a suitable frame, remote control set, engines and propellers, battery, sensors for stabilization and detection of obstacles and microcontroller for their operation. The paper presents the concept of the specific copter design, design and simulation of printed circuit boards to their self-production, activation and testing. The final part of the thesis includes an economic assessment of the project and its comparison with competitors.
84

Předběžný návrh malého dvoumístného vrtulníku / Preliminary Design of a Small Two Seat Helicopter

Junas, Milan January 2016 (has links)
The thesis deals the preliminary draft of the small two-seat helicopter with a piston engine. The aim of the thesis is not to propose a helicopter across the extent of the problems. Therefore we have chosen only selected issues which can be managed in the range of work. The introduction is focused on defining the general requirements imposed on proposed helicopter, formulating the basic conceptual and structural design according to the building regulation the relevant category. These ranges create a based assumption for right evaluation of the statistical analysis of the helicopters of the same or very near parameters category. Subsequently, there were defined the basic parameters of the proposed helicopter which make possible to solve the performance characteristics in the vertical and backward flight. The work is also focused on design of the rotor head of main rotor for the proposed helicopter, the definition of load acting on the rotor head, waving analysis and calculation of centrifugal forces acting on the main rotor blades. The design of the rotor head and also the helicopter as a whole will be graphically processed in the program Dassault Systemes Catia.
85

Pojezdové a zvedací zařízení / Travelling and lifting mechanism

Kratochvíl, Michal January 2016 (has links)
The main objective of this work is to design and calculation of handling means for transporting the Bell helicopter between landing area and the storage place. The first part is a literature search with a general overview of producers who are preoccupied with producing the same or similar equipment. Below is an analysis of the applicable mechanisms for handling the helicopter in terms of structure and a summary of some manufacturers. In the second part the design, calculations, technical and design documentation.
86

Vision-Based Control and Flight Optimization of a Rotorcraft UAV

Hubbard, David Christian 04 June 2007 (has links) (PDF)
A Rotorcraft UAV provides an ideal experimental platform for vision-based navigation. This thesis describes the flight tests of the US Army PALACE pro ject, which implements Moravec's pseudo-normalized correlation tracking algorithm. The tracker uses the movement of the landing site in the camera, a laser range, and the aircraft attitude from an IMU to estimate the relative motion of the UAV. The position estimate functions as a GPS equivalent to enable the rotorcraft to maneuver without the aid of GPS. Flight tests were performed with obstacles and over concrete, asphalt, and grass in daylight conditions with a safe landing area determined by a separate method. The tracking algorithm and position estimation performance are compared to GPS. Accurate time synchronization of the inputs to the position estimation algorithm directly affect the closed-loop stability of the system, proportional with altitude. By identifying the frequency response of each input and adding filters to delay some of the inputs, the closed-loop system maintains stable flight above 18 m above ground, where the system was unstable without the additional filters.
87

Tranquillity mapping in New Zealand national parks - a pilot study

Watts, Gregory R., Pearse, J., Delikostidis, I., Kissick, J., Donohue, B., Dalley, J. 05 January 2021 (has links)
Yes / The tranquillity in national parks worldwide is currently under threat from intrusion of anthropogenic noise of a growing tourism industry and activity related to park management. This was addressed by creating informative tranquillity maps, where perceived tranquillity can be considered a key indicator of soundscape quality in natural areas. Tranquillity of an area can be assessed using TRAPT (Tranquillity Rating Prediction Tool), that has been developed and refined for assessing urban green spaces, national parks and wilderness areas in the United Kingdom. The subjective response to helicopter noise levels of a sample group of 35 people representing the general New Zealand population was obtained, based on visual and audio stimuli that were collected in Aoraki/Mt Cook National Park. These results were used to produce a revised TRAPT equation. It was discovered that levels under 32 dBA correspond to an excellent level of tranquillity. This thresholdwas used to produce a noise level exposure calculation for two national parks using noise prediction model AEDT (Aviation Environmental Development Tool). Contours representing tranquillity duration were then calculated and plotted, to serve as a planning tool for use by the Department of Conservation. A similar approach could be used for other national parks worldwide
88

Upplevelse av teamarbete vid vård av patienter i prehospital miljö. : En intervjustudie med sjuksköterskor från ambulansverksamheten och sjuksköterska/läkare från ambulanshelikopter. / Experience of teamwork in care of patients in prehospital environment. : An interview study with nurses from the ambulance and nurse/doctor from the ambulance helicopter.

Lövqvist, Ulrika, Svensson, Anna January 2016 (has links)
Introduktion: I den moderna prehospitala akutsjukvården kan ambulansens och ambulanshelikopterns samverkan ha stor betydelse för den svårt skadade eller sjuka patienten. Syfte: Syftet med studien var att undersöka vad sjuksköterskor inom ambulansen och sjuksköterska/läkare från helikoptern/akutbilen upplevde kunde påverka teamarbetet i den prehospitala miljön. Metod: En kvalitativ deskriptiv innehållsanalys med semistrukturerade intervjuer användes. 10 informanter från ett län i mellansverige inkluderades, fem kvinnor och fem män. Urvalet bestod i att informanterna skulle ha varit verksamma inom ambulansverksamheten i minst ett år samt ha erfarenhet av det prehospital samarbetet mellan ambulans och ambulanshelikopter. Intervjuerna spelades in, transkriberades till text och analyserades. Resultat: Studiens resultat presenterades i två teman med sju underkategorier. De två temana var: Ett dynamiskt teamarbete påverkas av tydliga roller och ett kontinuerligt förbättringsarbete och Teamarbete och kommunikation mellan kompetenserna i teamet. Konklusion: De olika rollerna vid teamarbetet har blivit tydligare med tiden och teamarbetet upplevdes ha blivit bättre med tiden. Hospitering och tid till övning beskrevs kunna optimera teamarbetet. Informanterna upplevde sig delaktiga i vården. Den prehospitala erfarenheten och bristen på den var av betydelse vid samverkan mellan enheterna. / Introduction: In the modern prehospital emergency care, ambulance and ambulance-helicopter's interactions play an important role for the severely injured or sick patients. Aim: The aim of the study is to examine what nurses in ambulance and nurse/doctor from the helicopter/emergency car experienced could affect the team work in the prehospital environment. Method: A qualitative descriptive content analysis of semi-structured interviews were used. 10 pieces of informants from a province in central Sweden were included five women and five men. The sample consisted of informants would have been active in the ambulance business for at least 1 year and have experience in the full spectrum of cooperation between ambulance and ambulance helicopter. The interviews were recorded, transcribed to text and analyzed. Results: The results of the study were presented in two themes with seven subcategories. The two themes were: A dynamic teamwork are influenced by clear roles and a continuous improvement and Team work and communication between the competencies of the team. Conclusion: The different roles in the cooperation has become clearer with time and team work was perceived to have become better with time. Site visits and time to exercise described to optimize teamwork. The informants perceived themselves involved in care. The prehospital experience and the lack of it was of importance to cooperation between units.
89

Dynamic Wake Distortion Model for Helicopter Maneuvering Flight

Zhao, Jinggen 10 April 2005 (has links)
A new rotor dynamic wake distortion model, which can be used to account for the rotor transient wake distortion effect on inflow across the rotor disk during helicopter maneuvering and transitional flight in both hover and forward flight conditions, is developed. The dynamic growths of the induced inflow perturbation across the rotor disk during different transient maneuvers, such as a step pitch or roll rate, a step climb rate and a step change of advance ratio are investigated by using a dynamic vortex tube analysis. Based on the vortex tube results, a rotor dynamic wake distortion model, which is expressed in terms of a set of ordinary differential equations, with rotor longitudinal and lateral wake curvatures, wake skew and wake spacing as states, is developed. Also, both the Pitt-Peters dynamic inflow model and the Peters-He finite state inflow model for axial or forward flight are augmented to account for rotor dynamic wake distortion effect during helicopter maneuvering flight. To model the aerodynamic interaction among main rotor, tail rotor and empennage caused by rotor wake curvature effect during helicopter maneuvering flight, a reduced order model based on a vortex tube analysis is developed. Both the augmented Pitt-Peters dynamic inflow model and the augmented Peters-He finite state inflow model, combined with the developed dynamic wake distortion model, together with the interaction model are implemented in a generic helicopter simulation program of UH-60 Black Hawk helicopter and the simulated vehicle control responses in both time domain and frequency domain are compared with flight test data of a UH-60 Black Hawk helicopter in both hover and low speed forward flight conditions.
90

Pansarvärnshelikoptrar : Ett instrument för manöverkrigföring? / Anti-tank helicopters : A means for maneuver warfare?

Ekstedt, Anders January 2012 (has links)
Mellan år 1987 och 2000 fanns ett beväpnat helikopterförband inom arméflyget. Dessa två pansarvärnshelikopterkompanier användes för att bekämpa stridsfordon. Efter nedläggningen har Sverige inte haft en helikopter med beväpning för annat än egenskydd. Uppsatsen syftar till att utifrån William S. Linds teori om manöverkrigföring utvärdera om pansarvärnshelikopterkompanierna framgångsrikt bidrog till att besegra motståndaren. Det framkommer att pansarvärnshelikopterkompaniernas taktik väl stämmer överrens med Linds teori vilket pekar på att bestyckade helikoptrar är ett mycket användbart instrument inom manöverkrigföringen. / Between 1987 and 2000 there was an armed helicopter unit in the Swedish armed forces. These two anti-tank helicopter companies where used to destroy armored vehicles. After the companies disbandment there has been no helicopter in the Swedish armed forces with any armament except for self protection. The purpose of this thesis is to evaluate the Swedish anti-tank helicopter companies, based on William S. Lind’s theory of maneuver warfare. In conclusion, the tactics of the anti-tank helicopter companies correlate to a great deal with the theory of Lind, implicating that armed helicopters are very useful within maneuver warfare.

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