Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 84 for “"rotorcraft"”.
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Validation of interpolative interfaces for rotorcraft applications
The study uses computational methods to simulate fluid flow on the NASA ROBIN helicopter model and on a simplified rotor geometry previously tested at Mississippi State. The ROBIN model and the rotor are run using an unstructured grid. Results from the Tenasi flow solver are compared against both …
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Mechanisms of Sediment Entrainment and Transport in Rotorcraft Brownout
To advance the understanding of the phenomenon of rotorcraft brownout, a dual-phase flow environment induced by a small-scale rotor hovering above a sediment bed was studied using high-speed flow visualization and particle image velocimetry (PIV). The high frame rate of the camera, combined with …
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Vision-Based Control and Flight Optimization of a Rotorcraft UAV
<p>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 …
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Investigation of alternative rotorcraft powerplant configurations for improving airframe performance
Alternative rotorcraft powerplant configurations were analyzed to determine their improvements to airframe performance capabilities, with the main goal of increasing an aircraft's range. The helicopter's engine was the focus of this thesis, with emphasis on improving its specific power (power vs …
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Development of Robust Control Laws for Disturbance Rejection in Rotorcraft UAVs
… control algorithms for disturbance rejection in rotorcraft UAVs. The main focus is the rejection of external disturbances caused by wind influences. Four control algorithms are developed in an effort to mitigate wind effects: baseline nonlinear dynamic inversion (NLDI), a wind rejection extension …
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Preliminary design capability enhancement via development of rotorcraft operating economics model
… direct operating cost (DOC) for new commercial rotorcraft early in the design process. This project leverages historical efforts to model operating costs in the aviation industry coupled with a physics-based approach. The physics governing rotorcraft operation are combined with fundamental …
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Perception-based synthetic cueing for night-vision device rotorcraft hover operations
Helicopter flight using night-vision devices (NVDs) is difficult to perform, given evidence by the high accident rate associated with NVD flight compared to day operation. A mishap analysis of NVD-related helicopter accidents was conducted which found approximately 70% of the accidents attributable …
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A comparative analysis of technological learning systems in emerging rotorcraft companies
… of this research is to understand how emerging rotorcraft companies in various countries accomplished technological learning over the last sixty years. Owing to its unique products and growing market demand, rotorcraft industry is one of the most globalized and dynamic sectors of the aerospace …
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An acoustical based approach to conceptual design of non-traditional rotorcraft configurations
… research investigates three configurations of rotorcraft: coaxial rotors, ducted rotors, and ducted coaxial rotors, to provide insight on how design configuration changes the acoustics of these vehicles. The methodology developed is a parametric environment to provide detail on influential …
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A Versatile and Computationally Efficient Condition Indicator for AH-64 Rotorcraft Gearboxes
… at achieving some of the CBM objectives for rotorcrafts in collaboration with South Carolina Army National Guard. The current research study is motivated by the endeavor to enhance condition monitoring objectives by evaluating the condition indicators (CI) that have been implemented currently …
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Empirical Evaluation of Ground, Ceiling, and Wall Effect for Small-Scale Rotorcraft
… that are often not realistic for small-scale rotorcraft because it was developed specifically for conventional helicopters. It is clear that the Cheeseman-Bennett model cannot be applied to today's multirotor UAVs. Experimental findings suggest that some of the conventional thinking …
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Behavioral representation of military tactics for single-vehicle autonomous rotorcraft via statecharts
… operations as reconnaissance platforms. These rotorcraft, however, require ground-based human controllers varying in number based on the size and complexity of the system controlled. The automation these platforms have achieved is limited to takeoffs, landings and navigation of pre-programmed …
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Safety Return on Investment (ROI): The Broader Adoption of Rotorcraft CFIT-Avoidance Technology
… considered the suitable metric. For the rotorcraft industry, the ROI estimation methodology was not readily available, and this study sought to fill that gap. The purpose of this study was to estimate the potential ROI by determining the costs associated with the outcomes of …
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Rotorcraft Flight Dynamics and Control in Wind for Autonomous Sampling of Spatiotemporal Processes
… seeks to use multi-agent teams of autonomous rotorcraft to sample spatiotemporal fields in windy conditions. For many sampling objectives, there is the problem of how to accomplish the sampling objective in the presence of strong wind fields caused by external means or by other rotorcraft …
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Real-time simulation of full-field atmospheric turbulence for a piloted rotorcraft simulator
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1994.
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Development of a Method for Analysis and Incorporation of Rotorcraft Fluctuation in Synthesized Flyover Noise
Rotorcraft flyover noise has long been a field of study for researchers. This is because for many people, the sounds produced by these vehicles are found to be extremely annoying. The focus of this thesis is to recreate the time-varying rotorcraft noise at the source for a single emission angle. …
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Performance enhancements to Joint Army/Navy Rotorcraft Analysis and Design (JANRAD) software and Graphical User Interface (GUI)
The Joint Army/Navy Rotorcraft Analysis and Design (JANRAD) computer program was developed at the Naval Postgraduate School to perform performance, stability and control, and rotor dynamics analysis during preliminary helicopter design efforts. This thesis is the continuation of a previous work in …
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The assessment of a rotorcraft simulation model in autorotation by means of flight testing a light gyroplane
… the ability of a mathematical model to simulate rotorcraft in the autorotative flight state. Additionally, the results acquired were to enhance the understanding of an aircraft class for which the existing database of knowledge is limited, particularly with regards to its flight mechanics …
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Real-time Evaluation of Vision-based Navigation for Autonomous Landing of a Rotorcraft Unmanned Aerial Vehicle in a Non-cooperative Environment
Landing a rotorcraft unmanned aerial vehicle (RUAV) without human supervision is a capability that would significantly broaden the usefulness of UAVs. The benefits are even greater if the functionality is expanded to involve landing sites with unknown terrain and a lack of GPS or other positioning …
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