Aerospace Engineering Commons^™

Closed-Loop Propulsive Control For Very Low Perigee Orbit Energy Management And Stabilization, Tyler J. Gardner

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Within the past decade, the United States Air Force has begun exploring options for using smaller satellites, known as SmallSats and CubeSats, to decrease the time it takes to design and build new satellites. If used properly, a rapid development environment for satellites could improve the Air Force's ability to respond to new technologies and threats. Other organizations such as NASA and universities have been using SmallSats and CubeSats for research and development missions.

While smaller satellites are usually much cheaper to develop and require less time to create, limited volume strictly constrains the size of instrumentation and avionics that …

Analytic Guidance Strategies For Passively Safe Rendezvous And Proximity Operations, Simon Shuster

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A safety ellipse is a type of relative motion trajectory that is commonly used for unmanned rendezvous and proximity operations. As the name suggests, safety ellipses are passively safe relative motion trajectories, which means that their natural motion inherently maintains a low collision risk. The focus of this dissertation is the derivation, analysis, and application of guidance strategies that reconfigure, establish, and exit a safety ellipse. The guidance strategies consist of a set of ∆v vectors and impulse times, all written in closed form. Through applications of optimal control theory and parameter optimization, it is shown that these maneuver …

Test And Evaluation Of An Artec Leo 3d Scanner, Chelsea Alexis Reichard

Theses and Dissertations

With new and innovative technologies, companies have begun utilizing 3-Dimensional Scanners to reverse engineer objects of virtually any size or complexity. These scanners increase efficiency, allowing companies to import physical items into the computer without the hassle of modeling it themselves in Computer Aided Design (CAD) software. Although these highly advanced devices can be very fast and effective, we will be studying the surfaces that are incompatible to these scanners. The study performed in this research will test the limitations of a new, highly advanced, wireless 3D Scanner; The Artec Leo. For many scanners, including the one used in this …

Measuring Pilot Control Force In General Aviation: Strain Gauges And Load Cell, Benjamin David Wyma

Theses and Dissertations

Flight test requires a variety of sensors and data systems to accurately read variables on an aircraft during testing. One of these important variables is the pilots control force. Control force is used in many tests in flight test to ensure the aircraft being tested meets the required FAA standards. One essential test is stick free longitudinal stability where control force is needed to calculate the stick free neutral points of the aircraft [1]. The objective of the project was to explore two methods of electronically measuring control force and determining which method is best suited for Florida Institute of …

Existence Of Ballistic Capture Transfer Trajectories From Trans-Lunar Injection To Lunar Polar Orbit For All Lunar Phases At Time Of Departure, Anthony Lawrence Genova

Theses and Dissertations

This dissertation reveals several families of trajectories that can reduce the change in velocity(ΔV) required to transfer from trans-lunar injection (TLI) to a lunar polar circular orbit with 100 km altitude by up to 26.5% compared to conventional transfers. The primary hypothesis states that such trajectories, termed lunar polar ballistic capture (LPBC) transfers, exist for all lunar phases at the time of lunar departure (i.e., initial lunar flyby).The existence of LPBC transfers for all lunar phases can enable missions with ride-share restrictions (CubeSat), limited propellant capability (small spacecraft), and/or payloads that are not time sensitive (cargo).Evidence to support the primary …

Attitude Determination And Control Of Arksat-1, Jared Gilliam

Mechanical Engineering Undergraduate Honors Theses

ARKSAT-1 is a nanosatellite developed at the University of Arkansas as part of NASA’s CubeSat Launch Initiative (CSLI). The goal of ARKSAT-1 is to utilize an LED emitter paired with a ground-based tracking system to perform measurements of the composition of the atmosphere using spectroscopy. As part of its function, it is imperative that the satellite is able to control its orientation so that the emitter is aligned as closely as possible with the ground tracker. To do this, the attitude control system of ARKSAT-1 uses magnetic actuators to create a torque on the satellite by interacting with Earth’s magnetic …

Development Of A Single Emitter Ionic Liquid Ion Source Research Platform, Thomas V. Kerber

Masters Theses

A single emitter ionic liquid ion source using porous borosilicate glass was developed. Two emitters with different radii of curvatures were tested using 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF₄). I-V curves of the currents on the extractor electrode and a collector plate were obtained for potential differences between the emitter and the extractor ranging from 0 V to 3500 V. For the first emitter chip, extraction began near 2400 V. The highest emission current measured on the first chip was 80 µA at 3500 V with an interception current on the extractor of 4.86 µA. An new collector plate was used …

Conical Orbital Mechanics: A Rework Of Classic Orbit Transfer Mechanics, Cian Anthony Branco

Mechanical & Aerospace Engineering Theses & Dissertations

Simple orbital maneuvers obeying Kepler’s Laws, when taken with respect to Newton’s framework, require considerable time and effort to interpret and understand. Instead of a purely mathematical approach relying on the governing relations, a graphical geometric conceptual representation provides a useful alternative to the physical realities of orbits. Conic sections utilized within the full scope of a modified cone (frustum) were employed to demonstrate and develop a geometric approach to elliptical orbit transformations. The geometric model in-question utilizes the rotation of a plane intersecting the orbital frustum at some angle β (and the change in this angle) in a novel …

Parallelization Of The Advancing Front Local Reconnection Mesh Generation Software Using A Pseudo-Constrained Parallel Data Refinement Method, Kevin Mark Garner Jr.

Computer Science Theses & Dissertations

Preliminary results of a long-term project entailing the parallelization of an industrial strength sequential mesh generator, called Advancing Front Local Reconnection (AFLR), are presented. AFLR has been under development for the last 25 years at the NSF/ERC center at Mississippi State University. The parallel procedure that is presented is called Pseudo-constrained (PsC) Parallel Data Refinement (PDR) and consists of the following steps: (i) use an octree data-decomposition scheme to divide the original geometry into subdomains (octree leaves), (ii) refine each subdomain with the proper adjustments of its neighbors using the given refinement code, and (iii) combine all subdomain data into …

The Effect Of Compaction Temperature And Pressure On Mechanical Properties Of 3d Printed Short Glass Fiber Composites, Pushpashree Jain Ajith Kumar Jain

Mechanical & Aerospace Engineering Theses & Dissertations

Among many thermoplastics that are used in engineering, polyamide 6 (nylon 6) is an extremely versatile engineering thermoplastic. Nylon filled with glass fibers has higher mechanical strength and high wear resistance than general purpose nylon. 3D printed composites, based on fused filament modeling, typically suffer from poor bead-to-bead bonding and relatively high void content, limiting their mechanical properties

This thesis explores the effect of compaction pressure and temperature on improving the mechanical properties of 3D printed composites. Engineering moduli in the printing and transverse to printing direction, as well as ultimate strength were measured using the tensile testing with Digital …

Space-Based Countermeasure For Hypersonic Glide Vehicle, Robert Joseph Fowler Iv

Mechanical & Aerospace Engineering Theses & Dissertations

The purpose of this thesis is to investigate the effectiveness of a space-based laser weapon system for countering a hypersonic glide vehicle. Hypersonic glide vehicles are an emerging type of weapon system which combine the range of ballistic missiles with the maneuverability of cruise missiles. These systems pose a unique threat to military assets not only for their expanded capabilities but also for the lack of an effective defensive countermeasure. Space-based laser weapon systems may offer a solution to this problem. The dynamics of a space-based laser system defending against a hypersonic glide vehicle are modeled first. The governing equations …

Specifying Space Defense Operator Interfaces Through The Application Of Cognitive Systems Engineering And Prototyping, Justin E. Oryschak

Theses and Dissertations

The Department of Defense needs better tools to support its operators as they strive to defend its space assets. The growing sophistication of anti-satellite weapons increasingly challenges the nation’s orbital communications and surveillance infrastructure. Operators face difficulties gathering useful information and dealing with the complexity of potential enemy actions. This research applied cognitive systems engineering and ecological interface design (EID) methodologies to create a prototype space mission management tool that enhances operator situation awareness and decision-making ability. Applied cognitive task analysis interviews were used to document space operator decision-making in their domain. Model-based systems engineering was applied to integrate work …

Hexakis Icosahedron Frame-Skin Vacuum Lighter Than Air Vehicle, Brian Cranston, Anthony N. Palazotto

AFIT Patents

A vacuum lighter than air vehicle (VLTAV) includes a rigid frame of rods connected together to form a hexakis icosahedron. A membrane skin covers the rigid frame and defines therewith a vessel configured to hold an internal vacuum that allows the vessel to float in the air. The plurality of rods and membrane skin have weights and dimensions that result in a neutral and/or positive buoyancy for the vessel while preventing geometric instability.

Advanced Concepts For Multiengine Airplane Flying, Nihad E. Daidzic

Aviation Department Publications

FAA Safety Webinar (GL15102159) held online at 9:00 CST on Saturday, November 21, 2020.

An Investigative Study Of Combustion And Emissions With Noise And Vibrations Of Synthetic Fuels Within An Aero-Gas Turbine, Camille J. Phillips

Honors College Theses

The pollution from the aerospace transportation is rapidly becoming the largest source of greenhouse gas (GHG) emissions. The FAA expects aviation emissions to almost triple by 2050, making the aerospace industry responsible for the release of approximately 25% of the global carbon dioxide budget. These aviation emissions, including CO2 and NOx, as well as other GHGs, contribute to the destruction of ozone layer. Carbon dioxide emissions have a particularly negative effect on humans, leading to airway diseases especially in children and elderly. To combat the addition of further GHG emissions into the atmosphere, it is necessary to minimize the usage …

A Ranking Method To Prioritize Vfr Airports To Be Provided With Instrument Approach Procedures, Marcelo Soares Leao, Gustavo A.M. Ortegal Leal, Fabio Rodrigues Paukoski Fernandes

Graduate Student Works

The primary purpose of this work is to investigate the necessity of a more comprehensive and systematic method to prioritize airports to be provided with instrument approach and landing procedures in the Brazilian air transportation landscape. An overview of the main contributors to risks associated with the approach and landing phases is provided, covering the most important aspects of unstable approaches and CFIT events. Considering the emergence of Terrain Awareness and Alerting Systems (TAWS), the role of its contribution to safety is discussed, as well as the certification context related to the design, installation, and operation of those systems. A …

Effect Of Cold Work Expansion On The Fatigue Life Of Pre-Cracked Al 2024-T3, Christopher Leirer

Doctoral Dissertations and Master's Theses

No abstract provided.

Geomagnetic Aided Dead-Reckoning Navigation, Andrei Cuenca

Doctoral Dissertations and Master's Theses

The dependence of modern navigation methods on global positioning systems has led to developing alternative algorithms for localization, capable of providing reliable and robust estimations. Global position system is commonly used in a vast majority of the world’s devices, and it can supply real time position and velocity information. However, its accuracy can be compromised by external operational effects such as signal availability, cyber-attacks or weather conditions. This thesis investigates an alternative approach to enhance navigation in GPS-denied environments. Particularly, it develops an integrated navigation architecture based on geomagnetic referencing models capable of dead reckoning at GPS denied intervals. A …

Efficient Yield Estimation Of Multiband Patch Antennas By Polynomial Chaos-Based Kriging, Leifur Leifsson, Xiaosong Du, Slawomir Koziel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Yield estimation of antenna systems is important to check their robustness with respect to the uncertain sources. Since direct Monte Carlo sampling of accurate physics-based models can be computationally intensive, this work proposes the use of the polynomial chaos–Kriging (PC-Kriging) metamodeling method for fast yield estimation of multiband patch antennas. PC-Kriging integrates the polynomial chaos expansion (PCE) as the trend function of Kriging metamodel since the PCE is good at capturing the function tendency and Kriging is good at matching the observations at training points. The PC-Kriging method is demonstrated on two analytical cases and two multiband patch antenna cases …

Model Based Systems Engineering For A Venture Class Launch Facility, Walter Mcgee Taraila

Mechanical & Aerospace Engineering Theses & Dissertations

A study of Model-Based Systems Engineering (MBSE) applied to a small-lift launch facility is presented. The research uses Systems Modeling Language (SysML) products and functional diagrams to document the structure, controls, electrical power, hydraulic, safety mechanisms, software, and fluid ground systems on a launch pad. The research is motivated by the need to design complex systems with an unambiguous understanding that improves communication, quality, productivity, and reduces risk. A model is developed following the ISO/IEC-15288 technical process framework. The stakeholder requirements are defined and analyzed to provide traceability to individual systems and subsystems. An architectural design is realized and implemented …