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Fatigue Behavior Of A Sic/Sic Composite At 1000⁰C In Air And In Steam, Michael W. Knauf
Fatigue Behavior Of A Sic/Sic Composite At 1000⁰C In Air And In Steam, Michael W. Knauf
Theses and Dissertations
Tension-tension fatigue behavior of a prototype Silicon Carbide/Silicon Carbide (SiC/SiC) ceramic matrix composite (CMC) material was investigated at 1000°C in laboratory air and in steam environments. The material consists of a SiC matrix reinforced with CG NICALON™ fibers woven in an eight harness satin weave (8HSW) and coated with a BN/SiC dual-layer interphase. The composite was manufactured by a Polymer Infiltration and Pyrolysis (PIP) process. A seal coat of SiC and elemental boron was applied to the test specimens after machining. The tensile stress-strain behavior was investigated and the tensile properties were measured at 1000°C. Tension-tension fatigue behavior was studied …
Flow Control Application On A Submerged Inlet Characterized By Three-Component Ldv, Tina H. Reynolds
Flow Control Application On A Submerged Inlet Characterized By Three-Component Ldv, Tina H. Reynolds
Theses and Dissertations
A submerged inlet investigation, using flow control in the form of discrete blowing, examined proximity and jet directionality to improve compressor face uniformity. The flow control locations were at the head of the ramp and part way down the ramp, providing four configurations under examination. Laser Doppler velocimetry (LDV)measurements at the throat determined the effect of the flow control based on the statistical velocity measurements. Blowing at closer proximity to the throat and targeting the largest velocity deficit region provided the best results. The airspeed and inlet velocity simulated takeoff and landing conditions; velocities ranged from Mach 0.1-0.3 at the …
Performance Characterization Of A Three-Axis Hall Effect Thruster, Spencer E. Temkin
Performance Characterization Of A Three-Axis Hall Effect Thruster, Spencer E. Temkin
Theses and Dissertations
No abstract provided.
Effects Of Prior Aging At 274⁰C In Argon On Inelastic Deformation Behavior Of Pmr-15 Polymer At 288⁰C: Experiment And Modeling, Joseph A. Wahlquist
Effects Of Prior Aging At 274⁰C In Argon On Inelastic Deformation Behavior Of Pmr-15 Polymer At 288⁰C: Experiment And Modeling, Joseph A. Wahlquist
Theses and Dissertations
No abstract provided.
Navigation With Limited Prior Information Using Time Difference Of Arrival Measurements From Signals Of Opportunity, Christopher M. Rondeau
Navigation With Limited Prior Information Using Time Difference Of Arrival Measurements From Signals Of Opportunity, Christopher M. Rondeau
Theses and Dissertations
The Global Positioning System (GPS) provides world-wide availability to high-accuracy navigation and positioning information. However, the threats to GPS are increasing, and many limitations of GPS are being encountered. Simultaneously, systems previously considered as viable backups or supplements to GPS are being shut down. This creates the need for system alternatives. Navigation using signals of opportunity (SoOP) exploits any signal that is available in a given area, regardless of whether or not the original intent of the signal was for navigation. Common techniques to compute a position estimate using SoOP include received signal strength, angle of arrival, time of arrival, …
Satellite Capabilities Mapping - Utilizing Small Satellites, David A. Grigsby
Satellite Capabilities Mapping - Utilizing Small Satellites, David A. Grigsby
Theses and Dissertations
The cost and schedule advantages small satellites have over larger legacy systems have been studied, but there has been very little experimentation performed to determine whether small satellites can actually deliver the capabilities of larger spacecraft. To date, a desired operational capability has not been fully realized by a scalable satellite design. Advances in sensor technology have led to significant reductions in size, weight, and power (SWaP) presenting an opportunity to exploit the evolution of space operations by using small satellites to perform specific missions. This paper describes a methodology that maps a specific set of large space vehicle capabilities …
Exploring The Effects Of International Traffic In Arms Regulations Restrictions On Innovation In The U.S. Space Industrial Base, Kalliroi L. Landry
Exploring The Effects Of International Traffic In Arms Regulations Restrictions On Innovation In The U.S. Space Industrial Base, Kalliroi L. Landry
Theses and Dissertations
The International Traffic in Arms Regulations (ITAR) are used to protect United States (U.S.) military technologies. However, changes to ITAR export controls regarding space technologies have had a major impact to the U.S. space industry. The literature mentions a concern for the health of lower-tier firms because they are a major source of innovation, but there is no additional information considering the effects of ITAR on space innovation at those lower tiers. The purpose of this thesis was to explore the implications of continuing the current ITAR restrictions with regard to innovation in the space industry. This research used a …
Orbital Tori Construction Using Trajectory Following Spectral Methods, Ralph E. Bordner Iii
Orbital Tori Construction Using Trajectory Following Spectral Methods, Ralph E. Bordner Iii
Theses and Dissertations
By assuming the motion of a satellite about the earth’s geopotential mimics the known Kolmogorov-Arnold-Moser (KAM) solution of a lightly perturbed integrable Hamiltonian system, this research focused on applying trajectory following spectral methods to estimate orbital tori from sampled orbital data. From an estimated basis frequency set, orbital data was decomposed into multi-periodic Fourier series, essentially compressing ephemerides for long-term use. Real-world Global Positioning System (GPS) orbital tracks were decomposed and reconstructed with error from as low as few kilometers per coordinate axis over a 10-week span to tens of kilometers per coordinate axis over the same time period, depending …
An Integrity Framework For Image-Based Navigation Systems, Craig D. Larson
An Integrity Framework For Image-Based Navigation Systems, Craig D. Larson
Theses and Dissertations
This work first examines fundamental differences between measurement models established for GPS and those of proposed image-based navigation systems. In contrast to single value per satellite GPS pseudorange measurements, image measurements are inherently angle-based and represent pixel coordinate pairs for each mapped target. Thus, in the image-based case, special consideration must be given to the units of the transformations between the states and measurements, and also to the fact that multiple rows of the observation matrix relate to particular error states. An algorithm is developed to instantiate a framework for image-based integrity analogous to that of GPS RAIM. The algorithm …
A Photogrammetry-Based Hybrid System For Dynamic Tracking And Measurement, Daniel P. Magree
A Photogrammetry-Based Hybrid System For Dynamic Tracking And Measurement, Daniel P. Magree
Theses and Dissertations
Noncontact measurements of lightweight flexible aerospace structures present several challenges. Objects are usually mounted on a test stand because current noncontact measurement techniques require that the net motion of the object be zero. However, it is often desirable to take measurements of the object under operational conditions, and in the case of miniature aerial vehicles (MAVs) and deploying space structures, the test article will undergo significant translational motion. This thesis describes a hybrid noncontact measurement system which will enable measurement of structural kinematics of an object freely moving about a volume. By using a real-time videogrammetry system, a set of …
Velocity Plume Profiles For Hall Thrusters Using Laser Diagnostic, Daniel B. Lee
Velocity Plume Profiles For Hall Thrusters Using Laser Diagnostic, Daniel B. Lee
Theses and Dissertations
This research built a non-intrusive laser diagnostic tool using Laser Induced Fluorescence (LIF) and absorption techniques to measure the velocity and density plume profiles of low powered Hall thrusters. This tool was then applied to a Busek 200W Hall thruster to validate the performance against previous research on the same thruster. A laser frequency sweep through 834.72 nm produced LIF signals for ionized xenon –collected at 541.9 nm – in the thruster plume and absorption data outside the plume at a neutral transition at 834.68 nm. The absorption data provided a baseline reference to calculate the axial and radially velocity …
Analysis Of Hybrid-Electric Propulsion System Designs For Small Unmanned Aircraft Systems, Ryan M. Hiserote
Analysis Of Hybrid-Electric Propulsion System Designs For Small Unmanned Aircraft Systems, Ryan M. Hiserote
Theses and Dissertations
Currently fielded electric-powered small unmanned aircraft systems (UAS) lack the endurance desired by warfighters, while their internal combustion engine (ICE) driven counterparts generate mission compromising acoustic and thermal signatures. Parallel hybrid-electric propulsion systems would meet the military’s needs by combining the advantages of hydrocarbon and electric power systems. Three distinct parallel hybrid-electric system designs, each with three unique battery discharging profiles, were analyzed and compared using a constrained static optimization formulation based upon traditional aircraft design equations. Each system combined an ICE sized for cruise speed with an electric motor sized for endurance speed. The nine hybrid variations were compared …
Attitude Control Of A Satellite Simulator Using Reaction Wheels And A Pid Controller, Ryan E. Snider
Attitude Control Of A Satellite Simulator Using Reaction Wheels And A Pid Controller, Ryan E. Snider
Theses and Dissertations
Attitude requirements of a satellite are determined by its mission: telecommunications, optical imagery, and meteorology to name a few. A satellite's ability to orient its mission critical hardware (solar arrays, attitude sensors, etc.), as well as its mission specific payload, is incumbent upon the performance of the satellite's attitude control system (ACS). For a highly accurate ACS and for moderately fast maneuverability, reaction wheels are preferred because they allow continuous and smooth control while inducing the smallest possible disturbance torques. The objective of this research is to design, build, test, and evaluate the performance of a reaction wheel ACS on-board …
Investigation Of A Novel Compact Vibration Isolation System For Space Applications, Steven D. Miller
Investigation Of A Novel Compact Vibration Isolation System For Space Applications, Steven D. Miller
Theses and Dissertations
A novel compact vibration isolation system was designed, built, and tested for the Space Chromotomography Experiment (CTEx) being built by Air Force Institute of Technology (AFIT) researchers. CTEx is a multifunctional experimental imaging chromotomographic spectrometer designed for flight on the International Space Station (ISS) and is sensitive to jitter caused by vibrations both through the support structure as well as those produced on the optical platform by rotating optical components. CTEx demands a compact and lightweight means of vibration isolation and suppression from the ISS structure. Vibration tests conducted on an initial isolator design resulted in changes in the chosen …
Gravity Gradiometry And Map Matching: An Aid To Aircraft Inertial Navigation Systems, Anthony J. Degregoria
Gravity Gradiometry And Map Matching: An Aid To Aircraft Inertial Navigation Systems, Anthony J. Degregoria
Theses and Dissertations
Inertial navigation systems (INS) offer passive, all-weather, and undeniable navigation information, which military customers often view as especially appealing strengths. Unfortunately, Airmen and engineers still struggle with INS’s drifting position errors, and navigation aids generally detract from INS’s strengths. At this year’s Air, Space, and Cyberspace in the 21st Century Conference, the Chief of Staff of the Air Force identified the Global Positioning System (GPS) as a widely-known and exploitable vulnerability, saying that it’s critical the Joint force reduce GPS dependence. Recent advances provide an opportunity for gravity gradient instruments (GGI), which measure spatial derivatives of the gravity vector, to …
Off-Design Analysis Of A High Bypass Turbofan Using A Pulsed Detonation Combustor, Caitlin R. Thorn
Off-Design Analysis Of A High Bypass Turbofan Using A Pulsed Detonation Combustor, Caitlin R. Thorn
Theses and Dissertations
Past research has indicated that implementation of a pulsed detonation combustor (PDC) into a high-bypass turbofan engine yields a more efficient engine at design conditions. It is proposed that performance gains can be made utilizing this hybrid engine off-design. A hybrid high-bypass turbofan engine with a PDC model was evaluated for a range of Mach numbers, altitudes, and fill fractions in the Numerical Propulsion System Simulation (NPSS). Results were compared to a conventional baseline high-bypass turbofan engine that shares the same architecture with the hybrid. The NPSS baseline engine was validated using the Aircraft Engine Design System (AEDsys) program and …
Fatigue Behavior Of An Advanced Sic/Sic Composite With An Oxidation Inhibited Matrix At 1200°C In Air And In Steam, Jacob Delapasse
Fatigue Behavior Of An Advanced Sic/Sic Composite With An Oxidation Inhibited Matrix At 1200°C In Air And In Steam, Jacob Delapasse
Theses and Dissertations
The fatigue behavior of an advanced Silicon Carbide/Silicon Carbide (SiC/SiC) ceramic matrix composite (CMC) with oxidation inhibited matrix was investigated at 1200˚C in laboratory air and in steam environments. The composite consisted of an oxidation inhibited SiC matrix reinforced with Hi-Nicalon fibers coated with pyrolytic carbon (PyC) with a boron carbide overlay woven into eight-harness-satin (8HS) weave plies. Tensile stress-strain behavior and tensile properties were evaluated at 1200˚C. Tension-tension fatigue tests were conducted in both laboratory air and in steam at 1200˚C at frequencies of 0.1 Hz, 1.0 Hz, and 10 Hz. The tension-tension fatigue tests had a ratio of …
Preliminary Electrical Designs For Ctex And Afit Satellite Ground Station, Arthur L. Morse
Preliminary Electrical Designs For Ctex And Afit Satellite Ground Station, Arthur L. Morse
Theses and Dissertations
This thesis outlines the design of the electrical components for the space-based ChromoTomography Experiment (CTEx). CTEx is the next step in the development of high-speed chromotomography at the Air Force Institute of Technology. The electrical design of the system is challenging due to the large amount of data that is acquired by the imager and the limited resources that is inherent with space-based systems. Additional complication to the design is the need to know the angle of a spinning prism that is in the field of view very precisely for each image. Without this precise measurement any scene that is …
Accurate Dynamic Response Predictions Of Pnpsat I, Michael D. Trottier
Accurate Dynamic Response Predictions Of Pnpsat I, Michael D. Trottier
Theses and Dissertations
Researchers at the Air Force Institute of Technology (AFIT) and the Operationally Responsive Space (ORS) Office have conducted extensive vibration testing and structural modeling on the first ORS Plug-and-Play Satellite (PnPSAT I). The intent of this research effort is to evaluate the premise that current post-integration spacecraft environmental test requirements can be reduced or modified using accurately tuned finite element (FE) models. As part of this research, modal testing was conducted on the PnPSAT I structural panels at AFIT. The modal testing was part of a much larger series of experimental trials on various configurations of PnPSAT I at the …
Development Of A Flapping Wing Design Incorporating Shape Memory Alloy Actuation, Jeffrey A. Barrett
Development Of A Flapping Wing Design Incorporating Shape Memory Alloy Actuation, Jeffrey A. Barrett
Theses and Dissertations
This research sought to validate a proof of concept regarding shape memory alloy actuation of a flapping-wing blimp. Specimen wires were subjected to cyclic voltage at increasing frequencies to quantify expected strains. A laser vibrometer captured 2048 sample velocities during single contraction and elongation cycles, and the resulting samples were used to calculate displacements. Displacements were determined ten times for each specimen and frequency to compute averages. Subsequently, a circumventing frame was designed to encase a blimp envelope and provide support for a flapping motion actuation system. Contraction of shape memory wire translated force to the flapping mechanism via bellcranks, …
Disturbance Observer: Design And Flight Test Of A Large Envelope Flight Controller, Donevan A. Rein
Disturbance Observer: Design And Flight Test Of A Large Envelope Flight Controller, Donevan A. Rein
Theses and Dissertations
A new flight controller was evaluated through piloted simulation and flight test conducted at the USAF Test Pilot School. The controller, commonly called a disturbance observer, uses inertial sensor feedback routed through a simple control architecture that acts to force the desired response while rejecting sensor noise and atmospheric disturbances. The investigation included both handling qualities testing in the Octonian simulator at the Air Force Research Laboratories Air Vehicle Directorate, and initial flight test conducted as part of a Test Management Project at the USAF TPS. Simulation produced positive results with desired performance throughout a wide flight envelope. In addition, …
Design Of A Film Cooling Experiment For Rocket Engines, Andrew L. Sincock
Design Of A Film Cooling Experiment For Rocket Engines, Andrew L. Sincock
Theses and Dissertations
The Film Cooling Rig (FCR) is a new test rig at the Air Force Institute of Technology (AFIT) to study film cooling for rocket engine applications. The original researcher designed, built, and then utilized the FCR to study radial curvature effects on film cooling for a non-combustion environment. This effort modified the FCR by adding propane-air combustion. Modular stainless steel test sections were produced to allow study of various curvatures and coolant injection angles. A pre-mixed burner was designed and built to deliver main flow mass flow rates necessary to produce blowing ratios as low as 0.5. A water cooling …
Performance Of A Small Internal Combustion Engine Using N-Heptane And Iso-Octane, Cary W. Wilson
Performance Of A Small Internal Combustion Engine Using N-Heptane And Iso-Octane, Cary W. Wilson
Theses and Dissertations
With the sustained interest in Unmanned Aircraft Systems (UAS) and Micro Air Vehicles (MAV), the military services have a real need for vehicles powered by an internal combustion (IC) engine that can run efficiently on heavy hydrocarbon fuels, especially JP-8 due to established logistics. This thesis concerns the results of running a two horsepower, 4-stroke, spark-ignition engine (FUJI BF34-EI) with both iso-Octane and n-Heptane. Results include the knocking characteristic of this engine with n-Heptane, a comparison of the brake specific fuel consumption (BSFC) of the two fuels in a factory delivered engine configuration with a 17x10 APC propeller loading, a …
Simulation And Application Of Gpops For Trajectory Optimization And Mission Planning Tool, Danielle E. Yaple
Simulation And Application Of Gpops For Trajectory Optimization And Mission Planning Tool, Danielle E. Yaple
Theses and Dissertations
Rapid trajectory generation is crucial to prompt global warfare. To meet the USAF’s objective of Persistent and Responsive Precision Engagement, a rapid mission planning tool is required. This research creates the framework for the mission planning tool and provides a sample optimal trajectory which is solved using the GPOPS software package. GPOPS employs a Gaussian pseudospectral method to solve the non-linear equations of motion with both end conditions and path constraints. By simultaneously solving the entire trajectory based on an initial guess and small number of nodes, this method is ideal for generating rapid solutions. The sample case is a …
Cfd Analysis Of Experimental Wing And Winglet For Falconlaunch 8 And The Exfit Program, Benjamin P. Switzer
Cfd Analysis Of Experimental Wing And Winglet For Falconlaunch 8 And The Exfit Program, Benjamin P. Switzer
Theses and Dissertations
Reusable launch vehicles have many benefits over their expendable counterparts. These benefits range from cost reductions to increased functionality of the vehicles. Further research is required in the development of the technology necessary for reusable launch vehicles to come to fruition. The Air Force Institute of Technology’s future involvement in the ExFIT program will entail designing and testing of a new wing tip mounted vertical stabilizer in the hypersonic regime. One proposed venue for experimentation is to utilize the United States Air Force Academy’s FalconLAUNCH Program which annually designs, builds, and launches a sounding rocket capable of reaching hypersonic speeds. …
Orbit Maneuver For Responsive Coverage Using Electric Propulsion, Timothy S. Hall
Orbit Maneuver For Responsive Coverage Using Electric Propulsion, Timothy S. Hall
Theses and Dissertations
The use of continuous electric propulsion to manipulate a satellite’s orbit offers significant potential for enhancing coverage of a target in ways not previously considered. Elliptical orbits utilizing a very low perigee can facilitate access to the surface and atmosphere of the Earth at sub-ionosphere altitudes while counteracting atmospheric drag forces using continuous electric propulsion. Additionally, in-plane and out-of-plane manipulation of both circular and elliptical orbits can allow for passage of a satellite over a target at a given time. Sustained low perigee orbit was modeled with an initial perigee altitude of 100 km and various apogee altitudes to derive …
Artificial Inhomogeneous Tapered Impedance Sheet Characterization And Applications, Jeffrey P. Massman
Artificial Inhomogeneous Tapered Impedance Sheet Characterization And Applications, Jeffrey P. Massman
Theses and Dissertations
The ability to manipulate a complex impedance sheet about a PEC or general dielectric cylinder of arbitrary diameter to control the overall scattering characteristics at particular angles for shielding or scattering applications is presented. It is shown that with the capability to readily control both the real and imaginary components of a percolated lossy film's effective impedance, specific impedance distributions can be obtained to effectively direct the overall nulls in the bistatic scattering pattern. The exact approach only requires negligible truncation error of the matrix solution and can be applied to cylinders of arbitrary size. This approach relies on general …
Effectsof Prior Aging At 260 °C In Argon On Inelastic Deformation Behavior Of Pmr-15 Polymer At 260 °C: Experiment And Modeling, Bradley K. Diedrick
Effectsof Prior Aging At 260 °C In Argon On Inelastic Deformation Behavior Of Pmr-15 Polymer At 260 °C: Experiment And Modeling, Bradley K. Diedrick
Theses and Dissertations
The purpose of this research was to investigate the inelastic deformation behavior of PMR-15 neat resin, a high-temperature polymer, at 260 °C. The experimental program was designed to explore the influence of strain rate on loading and unloading behaviors. In addition, the effect of prior strain rate on creep, relaxation, and recovery responses was evaluated. The material exhibits positive, nonlinear strain rate sensitivity in monotonic loading. Early failures occur before fully establishing inelastic flow. The creep, relaxation, and recovery responses are significantly influenced by prior strain rate. The experimental results suggest the behavior of PMR-15 at 260 °C can be …
Mission Analysis And Design For Space Based Inter-Satellite Laser Power Beaming, Nicholas M. Keller
Mission Analysis And Design For Space Based Inter-Satellite Laser Power Beaming, Nicholas M. Keller
Theses and Dissertations
This research effort develops an interdisciplinary design tool to optimize an orbit for the purpose of wirelessly beaming power from the International Space Stations (ISS) Japanese Experimental Module Exposed Facility (JEM/EF) to a target satellite. For the purpose of this initiative, the target satellite will be referred to as FalconSAT6, a reference to the proposed follow-on satellite to the U.S. Air Force Academy’s (USAFA) FalconSAT5 program. The USAFA FalconSAT program provides cadets an opportunity to design, analyze, build, test and operate small satellites to conduct Department of Defense (DoD) space missions. The tool developed for this research is designed to …
Estimating Characteristics Of A Maneuvering Reentry Vehicle Observed By Multiple Sensors, Evan M. Brooks
Estimating Characteristics Of A Maneuvering Reentry Vehicle Observed By Multiple Sensors, Evan M. Brooks
Theses and Dissertations
Post flight analysis of ballistic missile reentry vehicles is an area of focus for the U.S. Government, especially for those involved in ballistic missile defense. Typically, this analysis incorporates either a model-driven least squares filter or a data-following Kalman filter. The research performed here developed a filter that attempts to integrate the strengths of both filters. A least squares filter operates on observation data collected during exoatmospheric free flight and a Kalman filter is used to analyze data collected lower in the atmosphere, where potential maneuvers could be performed. Additionally, the filter was written to incorporate data from multiple sensors. …