Comparison Of Novel Heuristic And Integer Programming Schedulers For The Usaf Space Surveillance Network,
2019
Air Force Institute of Technology
Comparison Of Novel Heuristic And Integer Programming Schedulers For The Usaf Space Surveillance Network, Kanit Dararutana
Theses and Dissertations
Space is a highly congested and contested domain begetting the importance of prioritizing the Space Situational Awareness (SSA) mission. With increased dependence on space assets, scheduling and tasking of the Space Surveillance Network (SSN) is vitally important to maintaining space dominance. According to the 2004 USSTRATCOM Strategic Directive 505-1 (SD 505-1) the SSN uses centralized tasking, with decentralized scheduling. Enhancing SSA within available resources is paramount, and the development of a centralized SSN scheduler to maximize performance is crucial. This research develops and compares novel scheduling models to a model reflecting the 2004 SD 505-1. Novel schedulers were developed to …
Simulation And Piloted Simulator Study Of An Automatic Ground Collision Avoidance System For Performance Limited Aircraft,
2019
Air Force Institute of Technology
Simulation And Piloted Simulator Study Of An Automatic Ground Collision Avoidance System For Performance Limited Aircraft, James D. Carpenter
Theses and Dissertations
The F-16 Automatic-Ground Collision Avoidance System (Auto-GCAS) has been a resounding success since implementation in Nov 2014, saving 8 pilots and 7 aircraft from Controlled Flight into Terrain (CFIT). However, there is no implemented Auto- GCAS for "heavy" performance limited aircraft. This research endeavors to expand on the success of F-16 Auto-GCAS to other aircraft in the Air Force inventory such as the C-130, C-17, and B-1. MIL-STD-1797 classifies performance limited aircraft as large, heavy, and low to medium maneuverability. Using a stitched Learjet-25D model (LJ-25D), an Auto-GCAS algorithm was developed to predict multiple escape-maneuver trajectories, compare these paths to …
Direct Numerical Simulation Of Roughness Induced Hypersonic Boundary Layer Transition On A 7° Half-Angle Cone,
2019
Air Force Institute of Technology
Direct Numerical Simulation Of Roughness Induced Hypersonic Boundary Layer Transition On A 7° Half-Angle Cone, Tara E. Crouch
Theses and Dissertations
Direct numerical simulation (DNS) computational fluid dynamic (CFD) calculations were performed on a 30° slice of 7° half-angle cones with increasing nose radii bluntness at Mach 10 while simulating a distributed roughness pattern on the cone surface. These DNS computations were designed to determine if the non-modal transition behavior observed in testing performed at the Arnold Engineering Development Center (AEDC) Hypervelocity Wind Tunnel 9 was induced via distributed surface roughness. When boundary layer transition is dominated by second mode instabilities, an increase in nose radius delays the transition location downstream. However, blunt nose experiments indicated that as the nose radius …
Multi-Path Automatic Ground Collision Avoidance System For Performance Limited Aircraft With Flight Tests: Project Have Medusa,
2019
Air Force Institute of Technology
Multi-Path Automatic Ground Collision Avoidance System For Performance Limited Aircraft With Flight Tests: Project Have Medusa, Kenneth C. Gahan
Theses and Dissertations
A multi-path automatic ground collision avoidance system (Auto-GCAS) for performance limited aircraft was further developed and improved to prevent controlled flight into terrain. This research includes flight test results from the United States Test Pilot School's Test Management Project (TMP) titled Have Multi-Path Escape Decisions Using Sophisticated Algorithms (MEDUSA). Currently, the bomber and mobility air- craft communities lack an Auto-GCAS. The F-16 Auto-GCAS was proven successful for fighter-type aircraft with seven aircraft and eight lives saved from 2014 to 2018. The newly developed and tested Rapidly Selectable Escape Trajectory (RSET) sys- tem included a 5-path implementation which continuously updated at …
Flow Behavior In Radial Rotating Detonation Engines,
2019
Air Force Institute of Technology
Flow Behavior In Radial Rotating Detonation Engines, Scott A. Boller
Theses and Dissertations
Recent progress has been made in demonstrating Radial Rotating Detonation Engine (RRDE) technology for use in a compact Auxiliary Power Unit with a rapid response time. Investigation of RRDEs also suggests an increase in stable operating range, which is hypothesized to be due to the additional degree of freedom in the radial direction which the detonation wave can propagate. This investigation seeks to determine if the detonation wave is in fact changing its radial location. High speed photography was used to capture chemiluminescence of the detonation wave within the channel to examine its radial location, which was found to vary …
Schlieren Imaging And Flow Analysis On A Cone/Flare Model In The Afrl Mach 6 Ludwieg Tube Facility,
2019
Air Force Institute of Technology
Schlieren Imaging And Flow Analysis On A Cone/Flare Model In The Afrl Mach 6 Ludwieg Tube Facility, David A. Labuda
Theses and Dissertations
High-speed Schlieren photography was utilized to visualize flow in the Air Force Research Laboratory Mach 6 Ludwieg tube facility. A 7° half-angle cone/flare model with variable nosetip radius and flare angle options was used in the study. Testing was performed at two driver tube pressures, generating freestream Reynolds numbers of 10.0x106 and 19.8x106 per meter. The variable-angle flare portion of the model provided a method for adjusting the intensity of the adverse pressure gradient at the cone/flare junction. As expected from existing literature, boundary layer separation along the cone frustum occurred further upstream as the magnitude of the …
Sheet Velocity Measurements Using Laser Absorption Spectroscopy In A Xenon Hall Effect Thruster Plume,
2019
Air Force Institute of Technology
Sheet Velocity Measurements Using Laser Absorption Spectroscopy In A Xenon Hall Effect Thruster Plume, Avery W. Leonard
Theses and Dissertations
A new laser absorption spectroscopy (LAS) velocimetry system, designed to obtain 2D planar velocity fields for ionized Xenon in the plume of a Hall effect thruster by probing the transition of Xe II at 834.72 nm, was implemented at the Air Force Institute of Technology (AFIT) Space Propulsion Analysis and System Simulator (SPASS) Lab vacuum chamber. A single horizontal laser sheet was used to probe singly-ionized Xenon in the plume of a Busek BHT-600 Hall thruster and obtain a histogram of estimated axial velocity, to validate the system. Similar velocities to those obtained by an earlier intrusive characterization of the …
Analytical Models And Control Design Approaches For A 6 Dof Motion Test Apparatus,
2019
Air Force Institute of Technology
Analytical Models And Control Design Approaches For A 6 Dof Motion Test Apparatus, Kyra L. Schmidt
Theses and Dissertations
Wind tunnels play an indispensable role in the process of aircraft design, providing a test bed to produce valuable, accurate data that can be extrapolated to actual flight conditions. Historically, time-averaged data has made up the bulk of wind tunnel research, but modern flight design necessitates the use of dynamic wind tunnel testing to provide time-accurate data for high frequency motion. This research explores the use of a 6 degree of freedom (DOF) motion test apparatus (MTA) in the form of a robotic arm to allow models inside a subsonic wind tunnel to track prescribed trajectories to obtain time-accurate force …
Wall Model Large Eddy Simulation Of A Diffusing Serpentine Inlet Duct,
2019
Air Force Institute of Technology
Wall Model Large Eddy Simulation Of A Diffusing Serpentine Inlet Duct, Ryan J. Thompson
Theses and Dissertations
The modeling focus on serpentine inlet ducts (S-duct), as with any inlet, is to quantify the total pressure recovery and ow distortion after the inlet, which directly impacts the performance of a turbine engine fed by the inlet. Accurate prediction of S-duct ow has yet to be achieved amongst the computational fluid dynamics (CFD) community to improve the reliance on modeling reducing costly testing. While direct numerical simulation of the turbulent ow in an S-duct is too cost prohibitive due to grid scaling with Reynolds number, wall-modeled large eddy simulation (WM-LES) serves as a tractable alternative. US3D, a hypersonic research …
Comprehensive Study Of Study Of Optimal Synergetic Skip Entries With Dynamic Thrust Vectoring Control,
2019
Air Force Institute of Technology
Comprehensive Study Of Study Of Optimal Synergetic Skip Entries With Dynamic Thrust Vectoring Control, Jeremiah M. Webb
Theses and Dissertations
The atmospheric skip entry has been studied since London's presentation in 1962 describing a more fuel efficient means of altering the orbital inclination of satellites. Since London, research over the decades since has traversed many aspects of this field with varying degrees of success. The present research employs the use of modern optimal control software, complex dynamics with minor simplifications, and thrust vectoring to re-approach the aerocruise atmospheric skip entry. Using the aerodynamics of the X-34, the aerocruise problem is first compared to the un-powered aeroglide where it is shown that the aerocruise is capable of increasing the inclination change …
Influence Of Leading Edge Oscillatory Blowing On Time-Accurate Dynamic Store Separation,
2019
Air Force Institute of Technology
Influence Of Leading Edge Oscillatory Blowing On Time-Accurate Dynamic Store Separation, Ryan G. Saunders
Theses and Dissertations
The primary objective of this research is to support the static and dynamic characterization and the time-accurate dynamic load data acquisition of store separation from a cavity with leading edge oscillatory blowing. Developing an understanding of, and potentially controlling, pitch bifurcation of a store release is a motivation for this research. The apparatus and data acquisition system was used in a two-part experiment to collect both static and dynamic testing data in the AFIT low speed wind tunnel in speeds of 60, 100, and 120 mph, from Reynolds numbers varying from 5.5x104 to 4.6x105, depending on reference …
A Mixed Integer Programming Framework For The Fuel Optimal Guidance Of Complex Spacecraft Rendezvous And Proximity Operation Missions,
2019
Air Force Institute of Technology
A Mixed Integer Programming Framework For The Fuel Optimal Guidance Of Complex Spacecraft Rendezvous And Proximity Operation Missions, Andrew S. Levalley
Theses and Dissertations
Space is a contested, congested, and competitive environment where space situational awareness (SSA) is a key factor in the long term sustainability of space as a national interest. Space-based SSA conducted by inspector satellites is critical to the detecting, tracking, and attribution of actions in space. Thus, space-based fuel-optimal maneuvers are essential to increasing mission life and improving the capability of inspector satellites working to characterize resident space objects (RSOs) in geosynchronous orbit (GEO). Additionally, on-orbit inspection missions can be characterized by multiple waypoint visits where an inspector is accomplishing a set of proximity operation mission objectives through the visit …
Optimal And Robust Neural Network Controllers For Proximal Spacecraft Maneuvers,
2019
Air Force Institute of Technology
Optimal And Robust Neural Network Controllers For Proximal Spacecraft Maneuvers, Brandon Cole George
Theses and Dissertations
Recent successes in machine learning research, buoyed by advances in computational power, have revitalized interest in neural networks and demonstrated their potential in solving complex controls problems. In this research, the reinforcement learning framework is combined with traditional direct shooting methods to generate optimal proximal spacecraft maneuvers. Open-loop and closed-loop feedback controllers, parameterized by multi-layer feed-forward artificial neural networks, are developed with evolutionary and gradient-based optimization algorithms. Utilizing Clohessy- Wiltshire relative motion dynamics, terminally constrained fixed-time, fuel-optimal trajectories are solved for intercept, rendezvous, and natural motion circumnavigation transfer maneuvers using three different thrust models: impulsive, finite, and continuous. In addition …
Initial Stage Of Fluid-Structure Interaction Of A Celestial Icosahedron Shaped Vacuum Lighter Than Air Vehicle,
2019
Air Force Institute of Technology
Initial Stage Of Fluid-Structure Interaction Of A Celestial Icosahedron Shaped Vacuum Lighter Than Air Vehicle, Dustin P. Graves
Theses and Dissertations
The analysis of a celestial icosahedron geometry is considered as a potential design for a Vacuum Lighter than Air Vehicle (VLTAV). The goal of the analysis is ultimately to understand the initial fluid-structure interaction of the VLTAV and the surrounding airflow. Up to this point, previous research analyzed the celestial icosahedron VLTAV in relation to withstanding a symmetric sea-level pressure applied to the membrane of the structure. This scenario simulates an internal vacuum being applied in the worst-case atmospheric environmental condition. The next step in analysis is to determine the aerodynamic effects of the geometry. The experimental setup for obtaining …
Characterization And Anomalous Diffusion Analysis Of A 100w Low Power Annular Hall Effect Thruster,
2019
Air Force Institute of Technology
Characterization And Anomalous Diffusion Analysis Of A 100w Low Power Annular Hall Effect Thruster, Megan N. Maikell
Theses and Dissertations
A Busek 100W low-power annular Hall effect thruster was characterized to determine the thruster’s best operating parameter range and to study plasma oscillations within the thruster. These experiments were conducted using xenon gas in the Space Propulsion Analysis and System Simulator chamber at the Air Force Institute of Technology on Wright-Patterson Air Force Base. The thruster’s performance characteristics were evaluated at nominal discharge voltages and constant total mass flow rate, solenoid current, and keeper current to determine the operating conditions optimizing divergence angle, beam efficiency, and discharge loss. This was accomplished using a Faraday probe to determine the plume’s current …
Tracking Shock Movement On The Surface Of An Oscillating, Straked Semispan Delta Wing,
2019
Air Force Institute of Technology
Tracking Shock Movement On The Surface Of An Oscillating, Straked Semispan Delta Wing, Justin A. Pung
Theses and Dissertations
A recent research effort, sponsored by the Air Force Office of Scientific Research, numerically investigated the unsteady aerodynamic flow field around an oscillating, straked, delta wing. The study was centered on determining the importance of the unsteady aerodynamic forces acting as a driver for a nonlinear motion known as limit cycle oscillations. The current effort focused on creating a computational model to compare to the results of previous tests and modeling efforts and discover new information regarding the onset of LCO. The computational model was constructed using the Cartesian overset capabilities of the CREATE-AV™ fixed wing fluid dynamics solver Kestrel. …
Verification Of Autonomous Systems: Developmental Test And Evaluation Of An Autonomous Uas Swarming Algorithm Combining Simulation, Formulation And Live Flight,
2019
Air Force Institute of Technology
Verification Of Autonomous Systems: Developmental Test And Evaluation Of An Autonomous Uas Swarming Algorithm Combining Simulation, Formulation And Live Flight, Corey A. Combs
Theses and Dissertations
This research was driven by the increase of autonomous systems in the current millennium and the challenging nature of testing and evaluating their performance. A review of the current literature revealed proposed methods for verifying autonomous systems, but few implementations. It exposed several gaps in the current verification and validation methods and suggested goals for filling them. Through the use of modeling, software in the loop (SITL), and flight test, this research verified an autonomous swarming algorithm for unmanned aerial systems (UAS) and validated an exemplar of a testing framework. Thirteen sets of three-vehicle swarm data produced over two days …
Control Strategies For Multi-Evaporator Vapor Compression Cycles,
2019
Air Force Institute of Technology
Control Strategies For Multi-Evaporator Vapor Compression Cycles, Sunderlin D. Jackson
Theses and Dissertations
Next-generation military aircraft must be able to handle highly transient thermal loads that exceed the ability of current aircraft thermal subsystems. Vapor compression cycle systems are a particular refrigeration technology that is an attractive solution for dealing with this challenge, due primarily to their high efficiency. However, there are several barriers to realizing the benefits of vapor cycles systems for controlling thermal loads in military aircraft. This thesis focuses on addressing the challenge of controlling vapor cycles in the presence of highly transient evaporator heat loads. Specifically, a linear quadratic regulator (LQR) is designed for a simple vapor cycle system, …
Computational Aerothermodynamic Analysis Of Satellite Trans-Atmospheric Skip Entry Survivability,
2019
Air Force Institute of Technology
Computational Aerothermodynamic Analysis Of Satellite Trans-Atmospheric Skip Entry Survivability, John J. Runco
Theses and Dissertations
Computational aerothermodynamic analysis is presented for a spacecraft in low Earth orbit performing an atmospheric skip entry maneuver. Typically, atmospheric reentry is a terminal operation signaling mission end-of-life and, in some instances, executed for spacecraft disposal. A variation on reentry – skip entry – is an aeroassisted trans-atmospheric maneuver in which a spacecraft utilizes the effects of aerodynamic drag in order to reduce energy prior to a terminal entry, pinpoint a targeted entry, or change orbital elements such as inclination. Spacecraft performing a skip entry enable new modes of maneuver to enhance operations in nominal or possibly contested mission environments. …
Search-Based Vs. Task-Based Space Surveillance For Ground-Based Telescopes,
2019
Air Force Institute of Technology
Search-Based Vs. Task-Based Space Surveillance For Ground-Based Telescopes, Fred D. Hertwig
Theses and Dissertations
Persistent Space Situational Awareness (SSA) is one of the top priorities of the DoD. Currently the Space Surveillance Network (SSN) operates using only a task-based method. The goal of this thesis was to compare the current task-based space surveillance performance to a search-based method of space surveillance in the GEO belt region. The performance of a ground telescope network, similar to the Ground-Based Electro-Optical Deep Space Surveillance (GEODSS) network, was modeled and simulated using AGI’s Systems Tool Kit (STK) and Python. The model compared search-based and task-based space surveillance methods by simulating 813 Resident Space Objects (RSOs) on the summer …
