Using A Gatling-Gun Configured Micro Pulsed Plasma Thruster As A Means To Control Micro Satellites With Extreme Precision,
2011
Air Force Institute of Technology
Using A Gatling-Gun Configured Micro Pulsed Plasma Thruster As A Means To Control Micro Satellites With Extreme Precision, Lee I. Watson
Theses and Dissertations
Micro-Pulsed Plasma Thrusters (µPPT) are becoming increasingly attractive for their low power consumption and moderately high specific impulse in the range of 800-1200s. The Gatling Gun micro-Pulsed Plasma Thruster (GG-µPPT) is a new device offering reduced mass and higher thrust than single µPPTs and solid application in precise pointing and orbit maintenance applications. The performance of µPPTs depends on frequency and applied voltage/power levels. Variation of these input parameters and effects on operation and performance of this thruster system were the focus of this research. Contamination aspects were also considered and discussed, since the buildup of carbon results in decreased …
Stochastic Orbit Prediction Using Kam Tori,
2011
Air Force Institute of Technology
Stochastic Orbit Prediction Using Kam Tori, Max W. Yates
Theses and Dissertations
Kolmogorov-Arnold-Moser (KAM) Theory states that a lightly perturbed, conservative, dynamical system will exhibit lasting quasi-periodic motion on an invariant torus. Its application to purely deterministic orbits has revealed exquisite accuracy limited only by machine precision. The theory is extended with new mathematical techniques for determining and predicting stochastic orbits for Earth satellite systems. The linearized equations of motion are developed and a least squares estimating environment is pioneered to fit observation data from the International Space Station to a phase space trajectory that exhibits drifting toroidal motion over a dense continuum of adjacent tori. The dynamics near the reference torus …
Kernelized Locality-Sensitive Hashing For Fast Image Landmark Association,
2011
Air Force Institute of Technology
Kernelized Locality-Sensitive Hashing For Fast Image Landmark Association, Mark A. Weems
Theses and Dissertations
As the concept of war has evolved, navigation in urban environments where GPS may be degraded is increasingly becoming more important. Two existing solutions are vision-aided navigation and vision-based Simultaneous Localization and Mapping (SLAM). The problem, however, is that vision-based navigation techniques can require excessive amounts of memory and increased computational complexity resulting in a decrease in speed. This research focuses on techniques to improve such issues by speeding up and optimizing the data association process in vision-based SLAM. Specifically, this work studies the current methods that algorithms use to associate a current robot pose to that of one previously …
Airborne Pseudolites In A Global Positioning System Degraded,
2011
Air Force Institute of Technology
Airborne Pseudolites In A Global Positioning System Degraded, Halit Oktay
Theses and Dissertations
The high accuracy of the Global Positioning System allows for precision navigation in support of current and future military operations. However, generating a three-dimensional position using GPS requires a clear line-of-sight between the user and at least four GPS satellites, and so the GPS service can be denied in scenarios such as a street surrounded by tall buildings. Therefore, there is a need for augmentation in these environments. Pseudolites, which transmit GPS-like ranging signals, can be deployed in order to improve the geometry and provide additional ranging signals. Users can then receive and process both GPS and pseudolite signals simultaneously …
Creep Performance Of Oxide Ceramic Fiber Materials At Elevated Temperature In Air And In Steam,
2011
Air Force Institute of Technology
Creep Performance Of Oxide Ceramic Fiber Materials At Elevated Temperature In Air And In Steam, Clinton J. Armani
Theses and Dissertations
The effects of steam on the creep performance for several ceramic materials were investigated at temperatures in the 1100-1300 deg. C range. Experimental programs were designed to explore both tensile and compressive creep behaviors as well as the response in monotonic tension. Subcritical crack growth was determined to be the dominant failure mechanism in ceramic fibers at elevated temperatures in steam. The creep life prediction analysis of ceramic fiber tows was performed using linear elastic fracture mechanics and a power-law crack velocity model. Additionally, the effects of steam at 1300 deg. C on creep performance of high-purity polycrystalline yttrium aluminum …
An Experimental Characterization Of Damping Properties Of Thermal Barrier Coatings At Elevated Temperatures,
2011
Air Force Institute of Technology
An Experimental Characterization Of Damping Properties Of Thermal Barrier Coatings At Elevated Temperatures, Oliver T. Easterday
Theses and Dissertations
This research program developed the apparatus and associated techniques to mechanically characterize the complex modulus of hard coatings across a temperature range from about 70 deg F to 900 deg F. Major effort in designing, analyzing, and experimentally validating the chamber were performed to establish that it isothermally heated a beam specimen, accomplished modal detuning, and achieved a near free-free boundary condition, and that the chamber was characterized for its forcing excitation. Novel aspects of the chamber include non-contact for the excitation, nearly non-contacted boundary conditions, and measurement of the field variables within the specimen using a hybrid experimental-numerical approach. …
Architecture Based Workload Analysis Of Uas Multi-Aircraft Control: Implications Of Implementation On Mq-1b Predator,
2011
Air Force Institute of Technology
Architecture Based Workload Analysis Of Uas Multi-Aircraft Control: Implications Of Implementation On Mq-1b Predator, Jason D. Mcgrogan, Michael F. Schneider
Theses and Dissertations
An increased demand for use of Unmanned Aircraft Systems (UASs) without commensurate increases in pilot manpower has prompted proposals for simultaneous control of multiple aircraft by a single pilot or Multi-Aircraft Control (MAC). To understand the potential effects of MAC, an IMPRINT Pro, Multi-Resource Theory, pilot workload model was developed from pedigreed system architecture. Feedback from active UAS pilots was used to validate the model and establish a workload saturation threshold value of 60, above which pilots may experience performance degradation over extended periods of time. The model predicts that pilots experience low workload when operating one or two UASs …
Airborne Wind Energy: Implementation And Design For The U.S. Air Force,
2011
Air Force Institute of Technology
Airborne Wind Energy: Implementation And Design For The U.S. Air Force, Troy L. Cahoon
Theses and Dissertations
Excitement among researchers about Airborne Wind Energy (AWE) technology matches DoD aims to advance and employ renewable energy. AWE seeks to cost-effectively tap the vast supply of wind energy available at altitudes high above the reach of conventional, ground-based wind turbines (e.g. 500-12,000m). This paper explores viability and implementation of AWE technology for fulfilling USAF energy needs. Characteristics, potential, and developmental status of the AWE resource are presented. A design tool for a rotor-based AWE system is developed, facilitating the analysis of blade performance to simplify design and provide the best efficiencies for a range of conditions. USAF bases are …
Ch-47d Rotating System Fault Sensing For Condition Based Maintenance,
2011
Air Force Institute of Technology
Ch-47d Rotating System Fault Sensing For Condition Based Maintenance, Stephen M. Dickerson
Theses and Dissertations
The Department of Defense (DoD) has mandated the use of maintenance practices based on component condition rather than component time in service or age. This new practice is known as Condition Based Maintenance, and it relies on accurate detection and identification of material deficiencies in system components. Rotor system components in rotary-wing aircraft can be difficult to monitor due to the rotational environment experienced by the sensors and the difficulty of signal transmission. Current methods are able to detect the existence of a fault in the rotor system but cannot link the vibrations experienced in the airframe to a specific …
Cubesat Packaged Electrospray Thruster Evaluation For Enhanced Operationally Responsive Space Capabilities,
2011
Air Force Institute of Technology
Cubesat Packaged Electrospray Thruster Evaluation For Enhanced Operationally Responsive Space Capabilities, Scott T. Ober
Theses and Dissertations
A new specialized electrospray thruster with a potential to be used with a 3-U CubeSat was operated. The key difference in this thruster from traditional colloid thrusters is the porous stainless steel surface used for the emission sites. With this porous surface the actual location and number of the Taylor cones formations vary with changing fuel flow. The understanding of these formations is discussed with low, moderate, and high flow rates. The limitations of the experiment and observed system response are discussed. Due to these limitations, the colloid thruster was only able to operate in the low mass flow rate …
Experimental Measurements Of Store Separation Using Dry Ice Models In A Subsonic Flow,
2011
Air Force Institute of Technology
Experimental Measurements Of Store Separation Using Dry Ice Models In A Subsonic Flow, Michael C. Paul
Theses and Dissertations
Testing free-drop store separation from a cavity in wind tunnels proves a difficult task because the models are typically destroyed during the test. Furthermore, there is potential for damage to wind tunnel components. Prior work has shown that small dry ice models released within the test section do not cause damage to the AFIT pressure-vacuum wind tunnel components or vacuum chamber. Rather, the dry ice models break apart and sublimate harmlessly into gaseous carbon dioxide. Therefore, this study was undertaken to determine whether dry ice models might prove useful in free-drop store separation testing. A generic aircraft cavity was constructed …
Effect Of Atmospheric Pressure And Temperature On A Small Spark Ignition Internal Combustion Engine's Performance,
2011
Air Force Institute of Technology
Effect Of Atmospheric Pressure And Temperature On A Small Spark Ignition Internal Combustion Engine's Performance, Peter J. Schmick
Theses and Dissertations
The ever increasing use of man portable unmanned aerial vehicles, UAV, by the US military in a wide array of environmental conditions calls for the investigation of engine performance under these conditions. Previous research has focused on individual changes in pressure or temperature conditions of the air stream entering the engine. The need was seen for a facility capable of providing an environment representative of various simulated altitude conditions. A mobile test facility was developed to test small internal combustion engines with peak powers less than 10 hp. A representative engine was tested over a range of speeds from 2000 …
Vision-Aided Autonomous Precision Weapon Terminal Guidance Using A Tightly-Coupled Ins And Predictive Rendering Techniques,
2011
Air Force Institute of Technology
Vision-Aided Autonomous Precision Weapon Terminal Guidance Using A Tightly-Coupled Ins And Predictive Rendering Techniques, Jonathan W. Beich
Theses and Dissertations
This thesis documents the development of the Vision-Aided Navigation using Statistical Predictive Rendering (VANSPR) algorithm which seeks to enhance the endgame navigation solution possible by inertial measurements alone. The eventual goal is a precision weapon that does not rely on GPS, functions autonomously, thrives in complex 3-D environments, and is impervious to jamming. The predictive rendering is performed by viewpoint manipulation of computer-generated of target objects. A navigation solution is determined by an Unscented Kalman Filter (UKF) which corrects positional errors by comparing camera images with a collection of statistically significant virtual images. Results indicate that the test algorithm is …
Multiple Integrated Navigation Sensors For Improving Occupancy Grid Fastslam,
2011
Air Force Institute of Technology
Multiple Integrated Navigation Sensors For Improving Occupancy Grid Fastslam, Christopher P. Weyers
Theses and Dissertations
An autonomous vehicle must accurately observe its location within the environment to interact with objects and accomplish its mission. When its environment is unknown, the vehicle must construct a map detailing its surroundings while using it to maintain an accurate location. Such a vehicle is faced with the circularly defined Simultaneous Localization and Mapping (SLAM) problem. However difficult, SLAM is a critical component of autonomous vehicle exploration with applications to search and rescue. To current knowledge, this research presents the first SLAM solution to integrate stereo cameras, inertial measurements, and vehicle odometry into a Multiple Integrated Navigation Sensor (MINS) path. …
Time Resolved Filtered Rayleigh Scattering Measurement Of A Centrifugally Loaded Buoyant Jet,
2011
Air Force Institute of Technology
Time Resolved Filtered Rayleigh Scattering Measurement Of A Centrifugally Loaded Buoyant Jet, Firas Benhassen
Theses and Dissertations
The combustion process within the Ultra-Compact Combustor (UCC) occurs in the circumferential direction. The presence of variable flow density within the circumferential cavity introduces significant buoyancy issues. On the other hand, G-loading caused by the presence of centrifugal forces, ensures the circulation of the flow in the circumferential cavity and enhances the completion of the combustion process before allowing the exit of the hot gases to the main flow. The coupling between buoyancy and high G-loading is what predominately influences the behavior of the flow within the UCC. In order to better understand the combustion process within the UCC, three …
Kam Torus Frequency Generation From Two-Line Element Sets,
2011
Air Force Institute of Technology
Kam Torus Frequency Generation From Two-Line Element Sets, Gregory R. Frey
Theses and Dissertations
The Kolmogorov Arnold and Moser (KAM) theorem states that a lightly perturbed Hamiltonian system will have solutions which lie on a torus. Earlier work by the second author has shown that most Earth satellite orbits perturbed by the geopotential lie on KAM tori. The problem then arises as to how to convert the current satellite tracking orbits to KAM tori. A KAM torus is characterized by three frequencies and three phase angles. The frequencies are essentially the rates of change of the mean anomaly, the longitude of the ascending node, and the argument of perigee. In this paper we explore …
Implementation Of A Rule-Based Open-Loop Control Strategy For A Hybrid-Electric Propulsions System On A Small Rpa,
2011
Air Force Institute of Technology
Implementation Of A Rule-Based Open-Loop Control Strategy For A Hybrid-Electric Propulsions System On A Small Rpa, Collin Greiser
Theses and Dissertations
Currently fielded electric-powered small remotely-piloted aircraft (RPA) lack endurance desired by warfighters, and internal combustion engine (ICE) RPAs generate undesirable acoustic and thermal signatures. Hybrid-electric (HE) propulsion systems would combine both electric power for endurance and ICE power for cruise and climb modes. Use of HE systems would eliminate undesirable signatures in addition to providing considerable fuel savings over time. Five components were used in this HE system: the ICE, electric motor (EM), electromagnetic clutch, battery pack, and a propeller. Control of such a system in a small RPA has never been attempted before. A rulebased controller was developed to …
Optimized Dual Expander Aerospike Rocket,
2011
Air Force Institute of Technology
Optimized Dual Expander Aerospike Rocket, Joshua N. Hall
Theses and Dissertations
Research at the Air Force Institute of Technology (AFIT) focused on designing a cryogenic dual-expander aerospike nozzle (DEAN) upper stage rocket engine to produce 50,000 pounds-force (222.4 kilo-Newtons) vacuum thrust, 464 seconds of vacuum specific impulse and a thrust-to-weight ratio of 106.5. The use of dual expander cycles improves engine reliability, maximizes efficiency, and eliminates some catastrophic failure modes. An upper stage engine with an aerospike nozzle is shorter and lighter than an equivalent performing conventional bell nozzle upper stage engine. Previous research focused on first developing a feasible closed DEAN design model and secondly expanding the model to support …
X-Hale: The Development Of A Research Platform For The Validation Of Nonlinear Aeroelastic Codes,
2011
Air Force Institute of Technology
X-Hale: The Development Of A Research Platform For The Validation Of Nonlinear Aeroelastic Codes, Alexander A. Kaszynski
Theses and Dissertations
In conjunction with the Air Force Institute of Technology (AFIT) and the Air Force Research Laboratory (AFRL), the University of Michigan has designed and is currently building a remotely piloted aircraft (RPA) experimental high altitude long endurance (X-HALE) aircraft to collect non-linear aeroelastic data to validate HALE aircraft design codes developed by academia, industry, and the federal government. While X-HALE is representative of HALE aircraft, the manufacturing and evaluation techniques are applicable to larger full size HALE aircraft such as the concepts being developed under Defense Advanced Research Projects Agency's (DARPA's) Vulture program. This paper documents the development of the …
Optimization Of Hybrid-Electric Propulsion Systems For Small Remotely-Piloted Aircraft,
2011
Air Force Institute of Technology
Optimization Of Hybrid-Electric Propulsion Systems For Small Remotely-Piloted Aircraft, Todd A. Rotramel
Theses and Dissertations
Small electric-powered remotely-piloted aircraft (RPA) used by today's warfighters for intelligence, surveillance, and reconnaissance (ISR) missions lack desired endurance and loiter times, while the acoustics and thermal signatures of those configured with internal combustion engines (ICE) may make them unpractical for ISR. Outfitting RPA with parallel hybrid-electric propulsion systems (H-EPS) would meet the military's needs by combining the advantages of both systems while reducing fuel consumption and environmental impacts. An analysis tool was created, using constrained static optimization, to size the H-EPS components. Based on the RPA's required power and velocity for the endurance phase, an electric motor (EM) can …
