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Landolfo, GiuseppeAerodynamic and Structural Design of a Small Nonplanar Wing UAV
Master of Science (M.S.), University of Dayton, 2008, Aerospace Engineering
The overall air vehicle performance of a multiple lifting surface configuration has been studied with respect to both structural and aerodynamic considerations for a candidate mission similar to that of the AeroVironment Raven. The configuration studied is a biplane joined at the tips with endplates. More specifically, this study aims to determine if this particular nonplanar wing concept can meet the requirements of the mission for a small Reconnaissance, Surveillance and Target Acquisition UAV. The mission capabilities of small UAVs are constantly growing by implementing recent developments in miniature computers and peripherals, electronic sensors, and optical sensing equipment at affordable cost. The requirements for the mission profile of a small UAV using the aforementioned equipment are defined with an emphasis on the potential advantages that can be offered by the nonplanar concept wing under investigation. A structural analysis using the finite element software ADINA and an aerodynamic analysis based on wind tunnel experimental data and vortex panel code results are performed. The results, compared under varying assumptions specific to an equivalent monoplane and a biplane, suggest potential efficiency gains for the new configuration may be possible using the nonplanar wing configuration under explicit conditions. The results also show structural characteristics and not aerodynamics alone are critical in determining the utility of this nonplanar concept.

Committee:

Aaron Altman (Advisor)

Subjects:

Engineering

Keywords:

Aerospace; aircraft design; aerodynamics; structural analysis; UAV; unmanned aircraft; biplane

Belzer, Jessica A.Unmanned Aircraft Systems in the National Airspace System: Establishing Equivalency in Safety and Training Through a Fault Tree Analysis Approach
Master of Science (MS), Ohio University, 2017, Electrical Engineering & Computer Science (Engineering and Technology)
With approval of UAS for civilian use in the National Airspace System, comes the need for formal integration. Manned and unmanned aircraft will share the same volumes of airspace, for which the safety standards must be upheld. Under manned aircraft operations, certain implicit assumptions exist that must be made explicit and translatable to the unmanned aircraft context. A formal system safety assessment approach through a fault tree analysis was used to identify assumptions contingent on a pilot’s presence inside the fuselage and areas of weakness in operational equivalency of UAS. The UAS fault tree framework developed is applicable to unmanned aircraft systems of different sizes and complexity, while maintaining a semblance to the framework accepted within the manned aircraft community. In addition, a database of UAS incidents and accidents occurring internationally 2001-2016 was developed from published materials and databases of various sources. Database events were categorized according to the UAS Fault Tree Framework Level 1 Subsystems, the International Civil Aviation Organization (ICAO) Aviation Occurrence Categories, and the Human Factors Analysis and Classification System (HFACS). ICAO Aviation Occurrence Category specific fault trees were constructed for the three most commonly occurring categories in the database results. Significant sources of risk for UAS operations lie in Aircraft/System and Flight Crew/Human Factors failures. Commonly occurring Occurrence Categories in the results of the UAS database were different than those identified for fatal accidents occurring in manned commercial aviation operations. Increased system reliability and standardization is needed to ensure equivalent levels of safety for UAS operations in the NAS. Additionally, needs of UAS pilots are different than those for manned and model aircraft. Training requirements must be approached independently and formally evaluated for their effectiveness in risk mitigation.

Committee:

Frank van Graas, Ph.D. (Advisor); Maarten Uijt de Haag, Ph.D. (Committee Member); Jeffrey Dill, Ph.D. (Committee Member); Robert Stewart, Ph.D. (Committee Member)

Subjects:

Engineering

Keywords:

Fault Tree Analysis; UAS; UAV; Unmanned Aircraft System; FTA; System Safety Assessment; SSA; sUAS;

Bradley, Cullen PhilipLADAR: A Mono-static System for Sense and Avoid Applications
Master of Science (M.S.), University of Dayton, 2013, Electro-Optics
In this thesis we study a laser radar, aka LADAR, system design to be mounted in an Unmanned Aircraft Systems (UAS) to prevent collisions with other aircraft. This system is called a Sense and Avoid technology and it is designed to anticipate future standards on flying the UAS in civil airspace that the U.S. Federal Aviation Administration (FAA) will adopt. Our SAA solution includes a LADAR system that is cued by EO cameras; data from a LADAR system is fused with the existing EO system. The main role of the LADAR system is to confirm the existence of a possible target, thus decreasing the false alarm rate. The LADAR system will also provide an accurate range to the target and track the target to determine its course. The key aspects of this design include a telescope, transmitter/receiver switch, and beam scanner. The telescope consists of two lenses and is used for both transmission and reception of the laser signal. The transmitter/receiver switch provides detection for a long range signal and consists of an avalanche photodiode detector (APD) coupled with a time-to-digital (TDC) converter and a fiber laser. The accuracy of the LADAR system depends on the accuracy of both the beam scanner and the gimbal the system will be placed in. Our system is designed to have less than 1 foot accuracy at ranges approaching 10 km. Each component was tested and the system performance was validated with outdoor experiments to almost 8 km.1

Committee:

Joseph Haus, Ph.D. (Advisor); Cong Deng, Ph.D. (Committee Member); Edward Hovenac, M.S. (Committee Member)

Subjects:

Electrical Engineering; Optics

Keywords:

LADAR; Sense and Avoid; Mono-static System; Unmanned Aircraft Systems (UAS); Laser Range and Detection

Sinnamon, Ryan R.Analysis of a Fuel Cell Combustor in a Solid Oxide Fuel Cell Hybrid Gas Turbine Power System for Aerospace Application
Master of Science in Engineering (MSEgr), Wright State University, 2014, Mechanical Engineering
Over the last few years, fuel cell technology has significantly advanced and has become a mode of clean power generation for many engineering applications. Currently the dominant application for fuel cell technology is with stationary power generation. Very little has been published for applications on mobile platforms, such as unmanned aerial vehicles. With unmanned aerial vehicles being used more frequently for national defense and reconnaissance, there is a need for a more efficiency, longer endurance power system that can support the increased electrical loads onboard. It has already been proven by others that fuel cell gas turbine hybrid systems can achieve higher system efficiencies at maximum power. The integration of a solid oxide fuel cell combustor with a gas turbine engine has the potential to significantly increase system efficiency at off-design conditions and have a higher energy density compared to traditional heat based systems. This results in abilities to support larger onboard electrical loads and longer mission durations. The majority of unmanned air vehicle mission time is spent during loiter, at part load operation. Increasing part load efficiency significantly increases mission duration and decreases operational costs. These hybrid systems can potentially have lower power degradation at higher altitudes compared to traditional heat based propulsion systems. The purpose of this research was to analyze the performance of a solid oxide fuel cell combustor hybrid gas turbine power system at design and off-design operating conditions at various altitudes. A system level MATLAB/Simulink model has been created to analyze the performance of such a system. The hybrid propulsion system was modeled as an anode-supported solid oxide fuel cell integrated with a commercially-available gas turbine engine used for remote control aircraft. The design point operation of the system was for maximum power at sea-level. A steady-state part load performance analysis was conducted for various loads ranging from 10 = L = 100 percent design load at varying altitudes ranging from 0 = Y = 20,000 feet. This analysis was conducted for four different fuel types: humidified hydrogen, propane, methane, and JP-8 jet fuel. The analysis showed that maximum system efficiency was achieved at loads of 40 = L = 60 percent design load at each altitude and fuel type. The system utilizing methane fuel, internally-steam reformed within the fuel cell, proved to have the highest system efficiency of 46.8 percent (LHV) at a part load of L = 60 percent and an altitude of Y = 20,000 feet.

Committee:

Rory Roberts, Ph.D. (Advisor); Scott Thomas, Ph.D. (Committee Member); Hong Huang, Ph.D. (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

SOFC; Fuel Cell; Aerospace; UAV; Hybrid Power System; Unmanned Aircraft;