Aerospace Engineering Commons^™

A Panel Data Regression Model For Defense Merger And Acquisition Activity, Corey D. Mack, Clay Koschnick, Michael Brown, Jonathan D. Ritschel, Brandon M. Lucas

Faculty Publications

Excerpt: This paper examines the relationship between a prime contractor's financial health and its mergers and acquisitions (M&A) spending in the defense industry. It aims to provide models that give the United States Department of Defense (DoD) indications of future M&A activity, informing decision-makers and contributing to ensuring competitive markets that benefit the consumer.

The results show a significant relationship between efficiency and M&A spending, indicating that companies with lower efficiency tend to spend more on M&As. However, there was no significant relationship between M&A spending and a company's profitability or solvency. These results were consistent with previous research and …

Guidance, Navigation, And Control For Multi-Agent Inspection Of An Unknown Space Object, Mark R. Mercier

Theses and Dissertations

On-orbit inspection is a rapidly growing mission that enables extending the life of aging legacy space systems through refueling, replacing, or upgrading components. For an inspection operation, multiple agents taking observations simultaneously can more quickly map an RSO and assure an inspection is complete regardless of RSO dynamics. A multi-agent guidance, navigation, and control (GNC) scheme must be designed with cooperation in mind to achieve inspection objectives, while leveraging the unique capabilities of a distributed inspection system. This work splits the GNC system into two parts composed of an offline guidance scheme for translational reference trajectory generation and an online …

Heuristic Design Of Cislunar Space Situational Awareness Architectures, Jacob A. Dahlke

Theses and Dissertations

The growing interest in the cislunar domain, which encompasses geosynchronous Earth orbit (GEO), the Moon, and the region where Earth-Moon gravitational effects are the primary influence, necessitates the development of tools to ensure safe and successful exploration. Space situational awareness (SSA) involves monitoring an environment to detect, track, identify, and catalog space objects. While most SSA experience comes from near-Earth operations, expanding into the cislunar domain presents significant challenges due to its vast expanse—greater than 10 times the radius of GEO—and the unique dynamics governed by the Circular Restricted Three-Body Problem (CR3BP) influenced by both Earth and Moon gravitational forces. …

Optimal Placement Of Artificial Hair-Cell Airflow Sensors For Bioinspired Flight-By-Feel, Alex C. Hollenbeck

Theses and Dissertations

The Sparse Sensor Placement Optimization for Prediction (SSPOP) algorithm reduces highdimensional airflow data to a low-dimensional sparse approximation to identify an optimal placement for any number of sensors on airfoil or wing models of arbitrary shape and size, and outperforms conventional optimization techniques in accuracy and speed. For 2D flow this algorithm found a sensor placement solution (design point, or DP) which predicts AoA to within 0.10 degrees and ranks within the top 1 percent of the design space. On 3D wing models SSPOP found four-sensor DPs ranked well within the top 0.10 percent. Experimental validation with velocity and pressure …

Enhancing Crossflow Dynamics Through The Gas Injection From Multiple Cylinders, Sahrish B. Naqvi, Sadia Siddiqa, Maciej Matyka, Rama S. R. Gorla, Md. Mamum Molla

Faculty Publications

We investigate unsteady, two-dimensional laminar fluid flow around cylinders, focusing on understanding the impact of injecting methane gas through two diametrically opposite arcs on the cylinder in the crossflow of the second fluid. This study encompasses applications in mixing and dispersion, which are crucial in various technological and natural processes. Our analysis addresses velocity field’s contribution to the spatiotemporal distribution of transported quantities. We observed that mixing induces a transition from laminar to turbulent flow. Depending on the injected-to-crossflow velocity ratios, the wake vortices downstream of cylinder arrays separate from or connect to the injected gas. This phenomenon significantly impacts …

Magnetic Sensor Compensation Utilizing Factor Graph Estimation, Frederic W. Lathrop, Clark N. Taylor, Aaron Nielsen

Faculty Publications

Recently, there has been significant interest in the ability to navigate without GPS using the magnetic anomaly field of the Earth (magnav). One of the key technical bottlenecks to achieving magnav is obtaining an accurate magnetic sensor calibration, taking into account own-ship and sensor effects. The Tolles-Lawson magnetic calibration method continues to be the industry standard and was developed when airborne magnetic survey aircraft were first employed over 70 years ago. In this paper, we present a magnetic calibration algorithm based on a factor graph optimization using inertial measurements as well as inputs from both a vector and scalar magnetometer. …

Tension–Compression Fatigue Of A Hybrid Polymer-Matrix/Ceramic-Matrix Composite At Elevated Temperature, Marina B. Ruggles-Wrenn, Joshua Schmidt

Faculty Publications

Fully reversed tension–compression fatigue of a hybrid material comprising polymer matrix composite (PMC) co-cured with a ceramic matrix composite (CMC) was investigated. The PMC portion had a polyimide matrix reinforced with 15 plies of carbon fibers woven in an eight-harness satin weave (8HSW). The CMC portion had three plies of a quartz-fiber 8HSW fabric in a zirconia-based ceramic matrix. The hybrid PMC/CMC was developed for use in aerospace thermal protection systems (TPS). Hence, the experimental setup aimed to simulate the TPS service environment—the CMC side was kept at 329 °C, whereas the PMC side was open to laboratory air. Compression …

An Integrated Space Test Lexicon: A Taxonomy For The Integrated Test And Evaluation Of Space Systems, Stephen K. Tullino, Andrew S. Keys, Robert A. Bettinger, Amy M. Cox, David R. Jacques

Faculty Publications

The proposed Integrated Space Test Lexicon is intended to amalgamate the numerous definitions of integrated (IT or IT&E), development test (DT or DT&E), and operational test (OT or OT&E) into unified, service-wide definitions, aligned with the Space Test Enterprise Vision. Refining such definitions will help distill the core characteristics of these fundamental test types to first identify space system activities composing what is traditionally known as DT and OT, then to provide a means of how these activities fit into the IT paradigm and support space system development. In forging a common understanding of how DT and OT support space …

Disk Engine With Circumferential Swirl Radial Combustor, Brian T. Bohan, Marc D. Polanka, Bennett Staton

AFIT Patents

A disk engine and system configured to provide high power at a reduced axial length is disclosed herein. The disk engine includes a radial compressor, a compressor discharge manifold positioned circumferentially about compressor, a combustion chamber positioned within the discharge manifold and a radial turbine positioned radially inward of the combustion chamber.

Turbine Cooling System With Energy Separation, James L. Rutledge, Matthew N. Fuqua, Carol M. Bryant

AFIT Patents

A method and system for cooling an engine and/or vehicle using energy separation is disclosed herein. An energy separation device is operable for separating a compressed gaseous coolant stream into a first relatively cooler coolant flow stream and a second relatively hotter coolant flow stream. The relative cooler coolant flow stream is directed to a first region requiring increased cooling and the relative hotter coolant flow stream is directed to a second region requiring lower cooling than the first region in the engine or vehicle.

Disposal And Earth-Moon Escape From Cislunar Orbits Using Non-Linear Programming Techniques, Sam T. Loeffler

Theses and Dissertations

This thesis involves theoretical and numerical analysis of trajectories off of cislunar orbits to determine the reachability and escape of various impulsive Δ^→v. The research will propagate trajectories using three body dynamics from various orbit families around the Earth-Moon Lagrange points and find low energy transfers that escape the Earth-Moon system. In order to achieve this, various different nonlinear programming solvers in MATLAB will be used to explore low energy impulsive escape transfers from common cislunar orbit families given long periods of computation time. After many points on cislunar orbits are analyzed, the data will be analyzed to …

Developing A Lean Spacecraft Test And Evaluation Architecture For A Contested Space Domain, Stephen K. Tullino

Theses and Dissertations

The US Space Force (USSF) is currently investigating possible opportunities to improve the testing paradigm of spacecraft in order to get assets on-orbit faster, while maintaining suitable quality to meet mission needs in a contested space environment. To support this goal, USSF’s approach to test and evaluation (T&E) is centered around the concept of integrated test. In this research, the space text lexicon is defined, addressing the ambiguities on exactly what integrated test is with respect to spacecraft systems development and on-orbit mission assurance. This research considered any statistical trends in categorical discrepancies (i.e., anomalies) during prelaunch integration and test …

Relative Vectoring Using Dual Object Detection For Autonomous Aerial Refueling, Derek B. Worth, Jeffrey L. Choate, James Lynch, Scott L. Nykl, Clark N. Taylor

Faculty Publications

Once realized, autonomous aerial refueling will revolutionize unmanned aviation by removing current range and endurance limitations. Previous attempts at establishing vision-based solutions have come close but rely heavily on near perfect extrinsic camera calibrations that often change midflight. In this paper, we propose dual object detection, a technique that overcomes such requirement by transforming aerial refueling imagery directly into receiver aircraft reference frame probe-to-drogue vectors regardless of camera position and orientation. These vectors are precisely what autonomous agents need to successfully maneuver the tanker and receiver aircraft in synchronous flight during refueling operations. Our method follows a common 4-stage process …

Random Forests For Detecting Weak Signals And Extracting Physical Information: A Case Study Of Magnetic Navigation, Mohammadamin Moradi, Zheng-Meng Zhai, Aaron Nielsen, Ying-Cheng Lai, Aaron P. Nielsen

Faculty Publications

It has been recently demonstrated that two machine-learning architectures, reservoir computing and time-delayed feed-forward neural networks, can be exploited for detecting the Earth’s anomaly magnetic field immersed in overwhelming complex signals for magnetic navigation in a GPS-denied environment. The accuracy of the detected anomaly field corresponds to a positioning accuracy in the range of 10–40 m. To increase the accuracy and reduce the uncertainty of weak signal detection as well as to directly obtain the position information, we exploit the machine-learning model of random forests that combines the output of multiple decision trees to give optimal values of the physical …

Investigation Of The Effect Of Internal Reynolds Number And Advective Capacity Ratio On Gas Turbine Film Cooling Parameters, John P. Di Lella

Theses and Dissertations

The desire for more powerful engines drives higher turbine inlet temperatures and a greater need to cool them. Experimentalists attempt to match cooling effectiveness between two conditions by matching several non-dimensional parameters, one of which is the coolant warming factor. The first investigation of this study examines the effect of the internal Reynolds number and the advective capacity ratio on the coolant warming factor by making use of a computational model and four different gases. It indicates the non-negligible and opposing effects of external convection and solid conduction on the coolant warming factor at matched internal Reynolds number and advective …

Trajectory Optimization Via Direct Collocation Methods Of Boost-Glide Vehicle With Newtonian Aerodynamic Model, Andrew Bonavita

Theses and Dissertations

In this work, a Newtonian aerodynamic model was developed for an elliptic cone glide geometry at a variety of angles of attack, and a functional relationship between an input angle of attack and the vehicle lift and drag coefficients was developed. This model was used in a direct orthogonal collocation framework to simulate a series of boost-glide trajectories, with objectives of minimum distance to target, minimum time to target, and maximum velocity to target. The optimal control problem was then expanded into a reachability study, considering a wide range of additional scenarios, along with studies on the vehicle range capabilities. …

Influence Of Environmental Barrier Coatings On The Overall Effectiveness Of A Film Cooled Ceramic Matrix Composite Plate, Shane P. Lindsay

Theses and Dissertations

Silicon carbide ceramic matrix composites, a promising new potential upgrade over the conventional metals currently used for jet engine turbine blades, have a propensity to oxidize in a combustion environment. Engine manufacturers often apply environmental barrier coatings to prevent the composites from oxidizing. What is unclear, however, is how environmental barrier coatings effect underlying composite temperatures. This research examined the coatings’ effects by first characterizing the influence of environmental barrier coatings on the underlying temperature of a protected ceramic, then evaluating the significance of lateral conduction for cooling a coated ceramic, and finally comparing cooling results for coated and uncoated …

Positioning, Navigation, And Timing (Pnt) Study For Select Multibody Environments, Kaitlin R. Roberts

Theses and Dissertations

In the renewed 21st-century race to the Moon, the demand for heightened mission capabilities in the cislunar region, lunar surface, and beyond is imperative. With an escalating number and complexity of lunar missions, persistent positioning, navigation, and timing (PNT) capabilities are becoming paramount. This thesis presents innovative lunar PNT architectures designed to provide continuous coverage of the lunar South Pole, near-continuous coverage of the entire lunar surface, and coverage of the Earth-Moon Corridor. As space faring countries advance from lunar exploration to Mars, similar assets are essential for astronaut exploration in this extraterrestrial environment. Additionally, this thesis introduces and meticulously …

A Nonlinear Least Squarees Approach To Orbit Determination In Near-Earth Orbits, Ryan M. Vorst

Theses and Dissertations

This work explores relevant scenarios to implement a Frequency on Arrival method using nonlinear least squares to determine a transmitting satellite’s orbit based only on measurements of the received radio frequency. Multiple relevant collection geometries, such as a target in prograde low earth orbit, in retrograde low earth orbit, in sun synchronous orbit, in near-perigee highly elliptical orbit, in near-apogee highly elliptical orbit, and in geosynchronous orbit, are simulated to collect theoretical received frequency data. Once data collection has been simulated, the theoretical apparent frequencies recorded are used in a nonlinear least squares method with differential correction to find a …

Statistical Reliability Estimation Of Space Launch Vehicles, Brooke N. Wagenblast

Theses and Dissertations

Space launch vehicle reliability is imperative to understand since launch vehicles are crucial in getting payloads into space for a hopefully successful mission. This thesis examines the reliability of commercial, civil, and military space launch vehicles through trend analysis and a variety of statistical methods. Data sets obtained from the Seradata database are analyzed for trends by looking at data subsets including launch date, launch country, final mission orbit, section (commercial, civil or military), launch vehicle family and failed subsystem. First-level Bayesian analysis and mean success rates are performed, primarily split up by launch vehicle family and total launches, and …

Characterization Of Additively Manufactured Ti-6al-4v Yield Behavior And The Influence Of Varied Build Layer Heights, Joseph Puglisi

Theses and Dissertations

This study evaluates the yield behavior of additively manufactured Ti-6-4 specimens in combined loading. Specimens were probed for yield across multiple load combinations along a given yield surface, holding pin one mode while applying load increments in the other mode until yield was detected. In combined loading, the yield surfaces across varied print parameters showed statistically significant, but negligible differences. This research sought to characterize the yield behavior across print parameters with the goal of increasing manufacturability. Ultimately, the benefits of the smaller print powder did not outweigh the increased manufacturing time. Furthermore, the comparison of material behavior in subsequent …

Discerning Satellite Subsystem Costs To Improve Cost Estimation, Ryan A. Candella

Theses and Dissertations

The race for supremacy in the space environment is accelerating, with the United States taking a significant step by establishing its dedicated military branch for space operations. Achieving dominance in this realm relies on efficiently managing costs and securing rapid funding to initiate new programs. One step towards accomplishing this goal is to comprehend the cost distribution across the primary components of a Space Vehicle Bus and to delve into lower-level Work Breakdown Structure (WBS) elements for more precise and expeditious cost estimations. To achieve this, descriptive statistics for a variety of Bus subsystem WBS elements are provided in this …

Preliminary Assessment Of Cislunar Disposal Orbits, Ryan M. Sargent

Theses and Dissertations

This thesis investigates the disposal of end-of-life spacecraft from key orbits with a focus on minimizing delta-v expenditure and preventing debris propagation. Simulated Lyapunov and halo orbits around the L2 Lagrange point are analyzed for disposal feasibility. Both impulsive and continuous thrust methods are explored to achieve disposal trajectories. Continuous thrust will be modeled after a Hall thruster utilizing electric propulsion. Leveraging the Circular Restricted Three Body Problem framework, low delta-v cost trajectories are computed, with a multi-level correction algorithm optimizing total delta-v via heteroclinic connections. The study assesses various delta-v amounts for Earth-Moon system escape and evaluates the potential …

Computational Modeling Of Single Shear Bolted Joints In Hybrid Composite Laminates With And Without Film Adhesive, Cameron S. Mcmahan

Theses and Dissertations

This research explores the effectiveness of predicting composite failure subject to quasi-static loading conditions using computational methods. FEA models were created using Abaqus and were employed to predict composite yield and initial failure behavior. Boundary conditions are generated to replicate the loading scenario seen in the experimental tests. Computationally predicted structural response of the composite range in accuracy from a 2% difference compared to experimental values to a maximum of 63%.

Preliminary Architecture Assessment Of Lunar Surface Sensors For Cislunar Ssa, Clint J. Spesard

Theses and Dissertations

The exploration of the lunar and cislunar realm is becoming increasingly active as several entities, private and public, foreign and domestic, set their sights beyond traditional Earth-centered space operations. Along with this renewed activity is a growing need for comprehensive Space Situational Awareness (SSA) and Space Traffic Management (STM) in the inherently chaotic cislunar system. This thesis seeks to embolden the study of cislunar SSA by considering the lunar-surface as a platform from which to conduct optical SSA. In this thesis, a lunar-based SSA system is heuristically optimized via a genetic algorithm through three separate implementations. All surface locations considered …

Development Of Cost Factors For Satellite Rechargeable Batteries, Katelyn A. Clements

Theses and Dissertations

Factors are often used by the cost estimating profession to predict costs of future projects or project components. Cost factors can be useful when little to no cost data is available from which to build an initial estimate or as an easy-to-use cross check of a primary estimate. Specific to satellites, previous studies have examined cost factors at higher Work Breakdown Structure (WBS) levels (e.g., Level 2 or Level 3), while this research analyzes cost factors developed using data specific to rechargeable batteries at USCM WBS Level 4 and its parent, the Electrical Power System (EPS) at Level 3. Within …

Standardization Of Risk Classifications For Unmanned Space Vehicle Missions, Collin A. Gwaltney

Theses and Dissertations

This paper seeks to model risk classification levels (A-D) for 122 Space Vehicle programs. Models include multinomial logistic regression as well as random forest, a machine learning technique based on decision trees. We use independent variables (IVs) which are theoretically correlated to risk class for the regression and one random forest model. We then include all IVs and allow the random forest technique to use those which provide the most information on risk class before paring down the number of IVs to only 7. We show that the accuracy of predictions increases from 62% to 87% by using random forest …

Hardware-In-The-Loop Autonomous Trajectory Generations For On-Orbit Rendezvous And Proximity Operations, Connor Slattery

Theses and Dissertations

Utilizing the C++ version of GPOPS within a robotic operating system to assess efficacy on flight-ready hardware is a vital interest of the space industry today. The findings in this paper show the ability of employing GPOPS in C++ on flight-ready hardware, leveraging optimal control as the main driver to creating a control pipleline to allow a robotic platform to generate and follow an optimized trajectory with minimal user input.

Computational Analysis Of Transverse Jet Interactions On A Cone In Mach 3.9 Crossflow, Tia Massa

Theses and Dissertations

The objective of this investigation was to analyze jet interactions using numerical simulations, which was compared to experimental data. A sharp cone with a 7-degree half-angle was modeled, along with the wind tunnel, using a 1:1 scale. Analysis of the data found the flow characteristics of the jet, including the bow shock and recirculation regions, were captured nicely in the CFD simulations, as well as the oblique shock off the nose of the cone. CFD simulations of the cone in a freestream environment depict shock-shock interactions not captured by experimental schlieren images. This research provides a rare glimpse into CFD …

Origami Application And Attitude Control Investigation Of Space-Based Mirror System, David J. Garcia

Theses and Dissertations

Imaging and inspecting Resident Space Objects (RSO) have gained increasing importance in Space Situational Awareness (SSA) missions. These missions are driven by the necessity to perform satellite repairs, refueling, de-orbiting, and orbital debris reduction. However, the challenging lighting conditions in space often hinder these tasks. To overcome this challenge, a novel concept has been proposed—deploying mirrors from servicer satellites. These mirrors would harness solar energy to illuminate dimly-lit RSOs, enabling imaging, inspection, repair, and refueling operations. In this context, servicer satellites play a pivotal role in controlling the reflected light beam and precisely positioning themselves to illuminate RSOs effectively. Notably, …