Underactuated Attitude Control Of A Cubesat Using Cold Gas Thrusters And Nonlinear Control Methods,
2022
Air Force Institute of Technology
Underactuated Attitude Control Of A Cubesat Using Cold Gas Thrusters And Nonlinear Control Methods, Adam S. Cottrell
Theses and Dissertations
Impulsive thrusters on small satellites, such as CubeSats, are typically used for attitude control. However, to become more agile, small CubeSats must also look to propulsion systems utilizing impulsive thrusters, such as cold-gas, for translational maneuvers. The combined thrust vector is often misaligned with the system's center of mass resulting in a disturbance torque. This must be counteracted by either an attitude determination and control system (ADCS), additional thrusters, or a control method to keep the satellite's attitude at or near equilibrium. Nonlinearities generated by the impulsive maneuvers are overcome via control techniques explored in this research to include on-off …
Design And Application Of Compact Combustors In Small-Scale Jetcat Engines,
2022
Air Force Institute of Technology
Design And Application Of Compact Combustors In Small-Scale Jetcat Engines, Nathan A. Clark
Theses and Dissertations
Ultra-compact combustors (UCC) are an innovative approach to improving overall engine efficiency and thrust-to-weight ratio by reducing the axial length and weight of the engine. Previous efforts looked at integrating a UCC into a small-scale JetCat P90 engine utilizing gaseous propane fuel. The current investigation aimed to utilize the previous compact combustor design and switch fuels to liquid kerosene. Based on the results from testing, a new combustor was designed equipped with a different flame holding mechanism at the larger P400-scale while maintaining a length savings of 20%. Testing of the P400 compact combustors was performed within a newly designed …
Design And Testing Of A Composite Compressor Rotor,
2022
Air Force Institute of Technology
Design And Testing Of A Composite Compressor Rotor, Mauro Noel V. De Leon
Theses and Dissertations
Additive manufacturing (AM) and molding are manufacturing methods known for building representations or replicas of conceptualized engine components, but was considered impractical for manufacturing operating engine components. More recent technology has rendered composite materials (combining high-temperature polymers and fiber reinforcement) capable of withstanding the temperature and structural requirements to compete with conventional turbomachinery metals. This study explores the application of several high-temperature polymers (ULTEM 9085, Onyx-Carbon fiber, and Epoxy-Carbon fiber) and their survivability in the operating conditions of a P400 Engine compressor. The tests conducted for this study determined their viability as compressor materials. This study required conducting tensile specimen …
Design Of An Electro-Thermal Nanosatellite Propulsion System,
2022
Air Force Institute of Technology
Design Of An Electro-Thermal Nanosatellite Propulsion System, James H. Founds
Theses and Dissertations
This research focused on designing an arcjet system with water as the propellant. Previous research developed a compact, reliable, and safe propellant storage and feed system. The goal is to combine the arcjet with the previous tank to achieve thrust and specific impulse characteristics greater than cold gas or resistojet system. This platform features a 1 U, non-hazardous, and sub-kilowatt powered propulsion system for nanosatellites. A simplified analysis of the design predicts thrust and specific impulse greater than can be achieved by cold gas or resistojet thrusters. Testing resulted in oxidation of the electrodes raising concerns about the longevity of …
Manufacturing Of A Ceramic Turbine Rotor For A Compact Jet Engine,
2022
Air Force Institute of Technology
Manufacturing Of A Ceramic Turbine Rotor For A Compact Jet Engine, Bryan T. Leicht
Theses and Dissertations
The primary goal of this study was to develop a low-cost, timely, scalable manufacturing method that produced a ceramic turbine that can be tested as a drop-in replacement on a JetCat P400 small scale gas turbine engine. This research compared two processes for manufacturing a ceramic turbine utilizing a pour casting method and 3D printing using stereolithography ceramic manufacturing (SLCM). The pour casting method used Silicon Nitride to create a cast turbine using a sacrificial 3D printed mold. The SLCM method evaluated producing an alumina turbine using an ADMATEC Admaflex 300 SLCM printer to directly print a ceramic turbine. This …
Characterizing Wake Roll-Up And Vortex Structure For Delta Wing Configuations Featuring Flow Control Devices At Low Reynolds Number,
2022
Air Force Institute of Technology
Characterizing Wake Roll-Up And Vortex Structure For Delta Wing Configuations Featuring Flow Control Devices At Low Reynolds Number, Jeffrey M. Layng
Theses and Dissertations
Various configurations of a cropped delta wing featuring a NACA 0012 wing-section were evaluated experimentally at a Reynolds number of 5.0 x 105 in the Air Force Institute of Technology Low-Speed Wind Tunnel facility. The effects of active flow control (AFC) and passive boundary-layer fences (BLF) were shown to improve high angle of attack delta wing performance. The AFC BLFs were shown to replicate the performance enhancements found in passive BLFs without incurring a drag penalty. An experimental characterization of the wake region is presented to compare the wake roll-up and leading edge vortices for these baseline, passive BLF, …
Effects Of Cone Tip Changes On Wall-Cooled Hypersonic Boundary Layer Transition And Turbulence,
2022
Air Force Institute of Technology
Effects Of Cone Tip Changes On Wall-Cooled Hypersonic Boundary Layer Transition And Turbulence, Mathew M. Major
Theses and Dissertations
Boundary layer measurements took place at Air Force Research Lab’s (AFRL) Mach-6 Ludwieg tube hypersonic wind tunnel on a 7-degree half angle spherically blunted nose cone with a 1.5 mm radius to study the effects of a cooled surface on the transition process. Experiments compared uncooled and cooled flow conditions on the blunt-nosed model, and then compared to past data for a sharp-tipped cone of similar geometry. Cooling the surface delayed the onset of transition on the blunt nose model. Combining the effects of nose blunting and cooling further increased transition delay than each acting individually compared to the sharp-tipped …
Development Of Minimum Delta-V Trajectories To Service Geo Assets From Cislunar Space,
2022
Air Force Institute of Technology
Development Of Minimum Delta-V Trajectories To Service Geo Assets From Cislunar Space, Alexander C. Urban
Theses and Dissertations
Orbits around Earth are becoming increasingly congested and contested, posing potential future threats to space assets. Cislunar space may offer an effective solution to these problems by offering storage for servicing and replacement vehicles. This investigation explores how to minimize the dV costs required of a network of service vehicles traveling from cislunar space to GEO using in-situ resource utilization. In this investigation the arc costs of an event-driven generalized multicommodity network flow are generated for creation of a model to be used to develop a dynamic scheduler. High-thrust trajectories between various inclinations of GEO, an Earth-Moon L1 Lyapunov orbit …
Synthetic Aperture Sillouette Imaging For Space Domain Awareness,
2022
Air Force Institute of Technology
Synthetic Aperture Sillouette Imaging For Space Domain Awareness, Lester L. Tuck Iv
Theses and Dissertations
A gap exists in imaging capabilities necessary for Space Domain Awareness, at Geostationary Equatorial Orbit (GEO) distances and beyond. Synthetic Aperture Silhouette Imaging (SASI), which resolves a space object's silhouette with measurements of the diffraction pattern cast by the object's occultation of a distant star, provides a new method that may be used to characterize these satellites. This research analyzes the reconstruction of satellite silhouettes using data from a scaled benchtop experiment to evaluate the distance and resolution limitations of SASI at distances equal to and beyond GEO. Diffraction patterns of two satellite silhouette targets are captured at various scaled …
Applied Agile Digital Mission Engineering For Cislunar Space Domain Awareness,
2022
Air Force Institute of Technology
Applied Agile Digital Mission Engineering For Cislunar Space Domain Awareness, Benjamin R. Williams
Theses and Dissertations
In the backdrop of an expansion into cislunar space and a digital transformation, the author synthesizes a methodology from agile system development, DE, ME, and MBSE processes, methods, and tools to develop a basic RA and DT for cislunar SDA mission and system design. The Agile DME methodology is used to conduct basic requirements analysis, develop a concept, understand cislunar physics, study scenario geometries, and perform analyses and the DT implements, executes, and accelerates research by integrating a descriptive tool with analytical and simulation tools. This research demonstrates the value of automated Modeling, Simulation, and Analysis (MSA) work flows and …
Surrogate Modeling Of Computational Aerodynamic Responses For A Generic Hypersonic Vehicle,
2022
Air Force Institute of Technology
Surrogate Modeling Of Computational Aerodynamic Responses For A Generic Hypersonic Vehicle, Jacob R. Johanik
Theses and Dissertations
In the field of multidisciplinary hypersonic vehicle design, striking the balance between the accuracy and efficiency of a predictive aerodynamic response model is a significant challenge. In response to this challenge, the objective of this thesis is to evaluate the aerodynamic performance of a Generic Hypersonic Vehicle (GHV) using the technique of surrogate modeling Computational Fluid Dynamic data points across a large range of flight conditions. To accomplish this, the full CFD process was conducted by preparing the vehicle geometry, generating a grid, computing the flow, and post-processing the data. A three-dimensional, quasi-random distribution of 1000 points defined the design …
Pedagogical Approaches For Facilitating Engineering Leadership Development,
2022
Missouri University of Science and Technology
Pedagogical Approaches For Facilitating Engineering Leadership Development, Teresa J. Didiano, Annie E. Simpson, David J. Bayless
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This article describes transformative, impactful pedagogical practices that engage students in the process of leadership development. We share practical examples of instructional strategies and facilitation techniques from curricular and co-curricular initiatives.
Coupled Orbit-Attitude Dynamics And Control Of A Cubesat Equipped With A Robotic Manipulator,
2022
Air Force Institute of Technology
Coupled Orbit-Attitude Dynamics And Control Of A Cubesat Equipped With A Robotic Manipulator, Charles M. Carr
Theses and Dissertations
This research investigates the utility and expected performance of a robotic servicing CubeSat. The coupled orbit-attitude dynamics of a 6U CubeSat equipped with a four-link serial manipulator are derived. A proportional-integral-derivative controller is implemented to guide the robot through a series of orbital scenarios, including rendezvous and docking following ejection from a chief spacecraft, repositioning the end effector to a desired location, and tracing a desired path with the end effector. Various techniques involving path planning and inverse differential kinematics are leveraged. Simulation results are presented and performance metrics such as settling time, state errors, control use, and system robustness …
Covariance Analysis For Multi-Source Navigation Architecture,
2022
Air Force Institute of Technology
Covariance Analysis For Multi-Source Navigation Architecture, Tristan T. Williams
Theses and Dissertations
Currently, analysis on navigation systems can be slow and computationally expensive using Monte Carlo approaches. Covariance analysis is a tool that can return trade space analysis results promptly and can be computationally reasonable. This research aims to create a covariance analysis tool in a new navigation framework architecture, PntOS. The creation of this covariance tool is explained in coordination with the tool being used in a few different navigation scenarios with the results. These scenarios include a Doppler LiDAR velocity sensor and magnetic anomaly navigation.
Satellite Tt&C For Cubesats With Applications For Grissom-1,
2022
Air Force Institute of Technology
Satellite Tt&C For Cubesats With Applications For Grissom-1, Michael J. Bittle
Theses and Dissertations
This thesis describes the assessment and analysis performed to characterize the communication subsystem used for command and telemetry transmission in support of the Grissom-1 Mission (GM1). The GM1 is unique in that it represents the pathfinder for a standardized 6U bus that serves as the basis for future CubeSat missions to host a variety of technical and scientific payloads, as prioritized by the Department of Defense, requiring flight demonstration or access to the orbital environment. Lab-based testing within an anechoic chamber provided link margin data required to characterize the command and telemetry links of the GM1. Experimental data describing the …
Leveraging Xgeo Orbits For Cislunar Space Domain Awareness,
2022
Air Force Institute of Technology
Leveraging Xgeo Orbits For Cislunar Space Domain Awareness, Jay Laone
Theses and Dissertations
With recent interest in using cislunar orbits for a variety of missions, it is more important than ever to also have cislunar space domain awareness. This thesis aims to bridge the gap between traditional LEO/GEO architectures and the new cislunar orbit architectures with orbits higher than GEO but still within the Earth sphere of influence, called xGEO. This research effort first explores the feasibility of xGEO orbits by examining the errors that the two-body assumption builds over time. Findings suggest that the two body assumption can be used to varying degrees depending on the orbit radius. This study has found …
Effects Of A Nitrogen And Hydrogen Build Atmosphere On The Properties Of Additively Manufactured Tungsten,
2022
Air Force Institute of Technology
Effects Of A Nitrogen And Hydrogen Build Atmosphere On The Properties Of Additively Manufactured Tungsten, Dana C. Madsen
Theses and Dissertations
Additively manufactured tungsten was printed in pure nitrogen, nitrogen-2.5% hydrogen, and nitrogen-5% hydrogen atmospheres as part of a 2^3 full factorial designed experiment and subjected to room temperature and high-temperature three-point-bend testing, chemical analysis, hardness testing, and microstructural imaging techniques. The pure nitrogen specimens exhibited the highest strength and ductility at both high temperature and room temperature. Chemical analysis showed a 2-8x reduction in compositional oxygen relative to unprocessed powder. Hardness values for all samples was between 306.8 and 361.5 HV1. It is proposed that adding hydrogen into the build atmosphere reduced the available energy density for tungsten melting by …
Thermal Relaxation Of Shot Peen Induced Residual Stresses In A Nickel-Base Superalloy,
2022
Air Force Institute of Technology
Thermal Relaxation Of Shot Peen Induced Residual Stresses In A Nickel-Base Superalloy, Bryce E. Van Velson
Theses and Dissertations
Shot peening induces compressive residual stresses in components that positively influence fatigue life. Thermal and mechanical loading causes those residual stresses to relax. The hole drilling method and xray diffraction is used to measure the thermal relaxation of residual stresses in the nickel-base superalloy ME3.
Double Cone Flow Field Reconstruction Between Mach 4 And 12 Using Machine Learning Techniques,
2022
Air Force Institute of Technology
Double Cone Flow Field Reconstruction Between Mach 4 And 12 Using Machine Learning Techniques, Trevor A. Toros
Theses and Dissertations
No abstract provided.
Experimental Study Of Turbulent Flow Heat Transfer And Pressure Loss Over Surfaces With Dense Micro-Depth Dimples Under Viscous Sublayer,
2022
Institute of Turbomachinery, Shanghai Jiao Tong University
Experimental Study Of Turbulent Flow Heat Transfer And Pressure Loss Over Surfaces With Dense Micro-Depth Dimples Under Viscous Sublayer, Peng Zhang, Yu Rao, Phillip M. Ligrani
PRC-Affiliated Research
Presented are experimentally-measured heat transfer and pressure loss characteristics for dimpled surfaces, placed along one surface of a channel, with different ratios of dimple depth to channel height δ/H, and for Reynolds numbers ranging from 10,000 to 70,000. With the same relative dimple spacing to dimple print diameter, and the same ratio of dimple depth to dimple print diameter of δ/d = 0.20, experimental results for arrays of spherical indentation dimples with micro depths of δ = 0.6 and 1.0 mm (δ/H = 0.03 and 0.05) are compared with thermal characteristics for arrays of larger dimples with δ = 4.0 …
