Dynamics And Control Of Satellite Relative Motion In Proximity Operations,
2012
Old Dominion University
Dynamics And Control Of Satellite Relative Motion In Proximity Operations, Mohamed Elsayed Aly Abd Elaziz Okasha
Mechanical & Aerospace Engineering Theses & Dissertations
In this dissertation, the development of relative navigation, guidance, and control algorithms of an autonomous space rendezvous and docking system are presented. These algorithms are based on innovative formulations of the relative motion equations that are completely explicit in time. The navigation system uses an extended Kalman filter based on these formulations to estimate the relative position and velocity of the chaser vehicle with respect to the target vehicle and the chaser attitude and gyro biases. This filter uses the range and angle measurements of the target relative to the chaser from a simulated LIDAR system, along with the star …
A Nanoporous Silicon Nitride Membrane Using A Two-Step Lift-Off Pattern Transfer With Thermal Nanoimprint Lithography,
2012
Missouri University of Science and Technology
A Nanoporous Silicon Nitride Membrane Using A Two-Step Lift-Off Pattern Transfer With Thermal Nanoimprint Lithography, Bhargav P. Nabar, Zeynep Çelik-Butler, Brian H. Dennis, Richard E. Billo
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Nanoimprint lithography is emerging as a viable contender for fabrication of large-scale arrays of 5500 nm features. A fabrication process for the realization of thin nanoporous membranes using thermal nanoimprint lithography is presented. Suspended silicon nitride membranes were fabricated by low-pressure chemical vapor deposition (LPCVD) in conjunction with a potassium hydroxide-based bulk micromachining process. Nanoscale features were imprinted into a commercially available thermoplastic polymer resist using a prefabricated silicon mold. The pattern was reversed and transferred to a thin aluminum oxide layer by means of a novel two-stage lift-off technique. The patterned aluminum oxide was used as an etch mask …
Increasing Reliability Of A Small 2-Stroke Internal Combustion Engine For Dynamically Changing Attitudes,
2012
Air Force Institute of Technology
Increasing Reliability Of A Small 2-Stroke Internal Combustion Engine For Dynamically Changing Attitudes, Steven C. Crosbie
Theses and Dissertations
Remotely Piloted Aircraft (RPA) typically utilize commercial internal combustion engines (ICE) as their power sources. These engines are designed to run at sea level, but these aircraft are often pressed into service at higher altitudes where the performance characteristics deteriorate. A Brison 95cc two-stroke engine's performance characteristics at altitude are investigated using a test facility that can measure these characteristics over a range of pressures and temperatures. With its stock carburetor at sea level static (SLS) conditions, the engine makes 5.5 peak horsepower (hp) and brake specific fuel consumption (BSFC) ranged from 1.2-4.0 lb/(hp-hr). At 10,000 feet conditions, the peak …
Evaluation Of The Thorax Of Manduca Sexta For Flapping-Wing Micro Air Vehicle Applications,
2012
Air Force Institute of Technology
Evaluation Of The Thorax Of Manduca Sexta For Flapping-Wing Micro Air Vehicle Applications, Alex C. Hollenbeck
Theses and Dissertations
The tobacco hornworm hawkmoth (Manduca sexta) provides an excellent model from which to garner knowledge pertaining to the development of a Flapping Wing Micro Air Vehicle (FWMAV). Insect-sized FWMAVs will be used by the future warfighter for reconnaissance, nuclear/chemical/biological hazard sensing, and targeting. One of the major challenges facing FWMAV developers is the energetically demanding nature of low Reynolds flapping flight. Investigating the Manduca sexta thorax/wing flapping mechanism as a mechanical system will provide insight into its inherent efficiency. This thesis examined the energetics of the thorax under static loading and dynamic loading using an innovative load-application technique. It was …
Material Characterization For Composite Materials In Load Bearing Wave Guides,
2012
Air Force Institute of Technology
Material Characterization For Composite Materials In Load Bearing Wave Guides, Gabriel Almodovar
Theses and Dissertations
This study will establish a methodology to examine samples of composite material for application in a load bearing waveguide. The composite material will operate in a specific frequency range for applications in small RPAs. A graphite epoxy stiffening component will be primarily considered. Different nickel, graphene, and carbon nanotube (CNT) coatings and films will be applied to the graphite epoxy. Tests will determine the material's radio frequency (RF) performance for application as an antenna/waveguide component. The study will use scattering (S) parameters determined from a network analyzer to collect these data. The S parameters will then be used to resolve …
Satellite Relative Motion Control For Mit's Spheres Program,
2012
Air Force Institute of Technology
Satellite Relative Motion Control For Mit's Spheres Program, Samuel P. Barbaro
Theses and Dissertations
Autonomous formation flight concepts and algorithms have great potential to revolutionize spacecraft operations enabling missions to perform autonomous docking, in-space refueling, in-space robotic assembly, and space debris removal. Such tasks require the implementation of speed and path control algorithms to maneuver satellites along relative paths with specified rates along those paths. This thesis uses MATLAB® and SIMULINK® to design and simulate a control algorithm capable of providing relative speed and path control between satellites with a pointing error of less than two degrees, a position error of less than two millimeters, and a millimeter per second of velocity error. The …
Integration, Testing And Validation, Of A Small Hybrid-Electric Remotely-Piloted Aircraft,
2012
Air Force Institute of Technology
Integration, Testing And Validation, Of A Small Hybrid-Electric Remotely-Piloted Aircraft, Joseph K. Ausserer
Theses and Dissertations
Parallel hybrid-electric technology offers a wide variety of new mission capabilities including low-observable loiter operations and increased fuel efficiency for small remotely-piloted aircraft. This research focused on the integration, validation, and testing of a hybrid-electric propulsion system consisting of commercially available components to fabricate a small remotely-piloted aircraft capable of extended low-observable operation. Three novel aspects contributed to the success of the design: optimization of the propulsive components to the integrated system, torque control of the components for additive power, and a one-way bearing/ pulley mechanism (patent pending) mechanically linking the hybrid system components. To the knowledge of the author …
Enhanced Image-Aided Navigation Algorithm With Automatic Calibration And Affine Distortion Prediction,
2012
Air Force Institute of Technology
Enhanced Image-Aided Navigation Algorithm With Automatic Calibration And Affine Distortion Prediction, Juan D. Jurado
Theses and Dissertations
This research aims at improving two key steps within the image aided navigation process: camera calibration and landmark tracking. The camera calibration step is improved by automating the point correspondence calculation within the standard camera calibration algorithm, thereby reducing the required time for calibration while maintaining the output model accuracy. The feature landmark tracking step is improved by digitally simulating affine distortions on input images in order to calculate more accurate feature descriptors for improved feature matching in high relative viewpoint change. These techniques are experimentally demonstrated in an outdoor environment with a consumer-grade inertial sensor and three imaging sensors, …
Cubesat Attitude Determination And Helmholtz Cage Design,
2012
Air Force Institute of Technology
Cubesat Attitude Determination And Helmholtz Cage Design, Megan R. Brewer
Theses and Dissertations
A method of 3-axis satellite attitude determination utilizing six body-fixed light sensors and a 3-axis magnetometer is analyzed. A Helmholtz cage is designed, built, and tested to provide a dynamic, 3-axis, uniform magnetic field to cancel the Earth's magnetic field and create an environment similar to the geomagnetic field a satellite would experience on-orbit. A CubeSat is provided the inertial magnetic vector and Sun vector, which are combined with data from the light sensors and magnetometer in a CubeSat. Attitude is estimated on-board the CubeSat via the optimal fast quaternion estimation algorithm. The capabilities of the Helmholtz cage, including the …
Conceptual Layout Of Wing Structure Using Topology Optimization For Morphing Micro Air Vehicles In A Perching Maneuver,
2012
Air Force Institute of Technology
Conceptual Layout Of Wing Structure Using Topology Optimization For Morphing Micro Air Vehicles In A Perching Maneuver, James R. Elgersma
Theses and Dissertations
A topology optimization model for conceptual wing structure layouts of morphing micro air vehicles (MAVs) has been developed and implemented in MATLAB. Specifically, a six degree-of-freedom finite element (FE) model with a general quadrilateral discretization scheme was created by superposition of a known simple linear plane membrane element and a Kirchhoff plate bending element derived herein. The purpose of the six degree-offreedom model was to accommodate in-plane and out-of-plane aerodynamic loading combinations. The FE model was validated and the MATLAB implementation was verified with classical beam and plate solutions. A compliance minimization optimization objective was then formulated with the Solid …
Accurate Modeling Of Stability And Control Properties For Fighter Aircraft From Cfd,
2012
Air Force Institute of Technology
Accurate Modeling Of Stability And Control Properties For Fighter Aircraft From Cfd, Jedediah H. Butler
Theses and Dissertations
Difficulties in obtaining accurate Stability and Control (S&C) data for nonlinear regions in the flight envelope early in the design phase often lead to costly fixes late in the acquisition process. Work examined herein addresses this problem by utilizing recent advances in Computational Fluid Dynamics (CFD) to create a high-fidelity database before any parts have to be physically produced. In combination with CFD, System Identification (SID) is used to characterize the S&C characteristics of aircraft by some Reduced Order Model (ROM). The method of obtaining enough data in the right places, via some optimized maneuver, to create an accurate ROM …
Hybrid Solution Of Stochastic Optimal Control Problems Using Gauss Pseudospectral Method And Generalized Polynomial Chaos Algorithms,
2012
Air Force Institute of Technology
Hybrid Solution Of Stochastic Optimal Control Problems Using Gauss Pseudospectral Method And Generalized Polynomial Chaos Algorithms, Gerald C. Cottrill
Theses and Dissertations
Two numerical methods, Gauss Pseudospectral Method and Generalized Polynomial Chaos Algorithm, were combined to form a hybrid algorithm for solving nonlinear optimal control and optimal path planning problems with uncertain parameters. The algorithm was applied to two concept demonstration problems: a nonlinear optimal control problem with multiplicative uncertain elements and a mission planning problem sponsored by USSTRATCOM. The mission planning scenario was constructed to find the path that minimizes the probability of being killed by lethal threats whose locations are uncertain to statistically quantify the effects those uncertainties have on the flight path solution, and to use the statistical properties …
Determination Of Effective Crossover Location And Dimensions For Branched Detonation In A Pulsed Detonation Engine,
2012
Air Force Institute of Technology
Determination Of Effective Crossover Location And Dimensions For Branched Detonation In A Pulsed Detonation Engine, Louis A. Camardo Ii
Theses and Dissertations
A study is presented of the optimal crossover duct location and width to obtain consistent branched detonation transition from one detonation tube to another. On a Pulsed Detonation Engine (PDE) with detonation branching, the duct location at which the detonation crosses from one (primary) tube to a branched (secondary) tube impacts the number of successful detonations. In this paper, a comparison is made of the effects of the location and width of the crossover duct for hydrogen, ethylene and an n-alkane. The crossover location is varied from the aft end of the detonation tube to the middle of the detonation …
Computational Analysis And Characterization Of Rc-135 External Aerodynamics,
2012
Air Force Institute of Technology
Computational Analysis And Characterization Of Rc-135 External Aerodynamics, Michael G. Chenery
Theses and Dissertations
Both the RC-135V/W Rivet Joint (RJ) and the RC-135U Combat Sent (CS) aircraft are United States Air Force (USAF) electronics reconnaissance platforms. The RJ is the USAF's standard airborne signals intelligence (SIGINT) gathering platform, while the CS is designed to collect technical intelligence on adversary radar emitter systems. Both aircraft are extensively modified C-135's characterized by protruding cheek fairings along the sides of the fuselage forward of the wings as well as the addition of numerous antennas along the top and bottom of the fuselage. The major distinguishing feature between the two variants is the nose radome, wherein the RJ …
Cooling Requirements For The Ultra Compact Combuster,
2012
Air Force Institute of Technology
Cooling Requirements For The Ultra Compact Combuster, Donald D. Johnson
Theses and Dissertations
Over the past several years, AFIT and the Air Force Research Laboratory have collaboratively investigated a novel combustor system that is compact in design and has potential use in an inter-turbine burner system. The ultra-compact combustor (UCC) design wraps the combustion section circumferentially around the axial core flow and exploits the use of high-g combustion. The combustor's volume and weight are reduced by integrating the exit compressor vane and the turbine inlet vane. This creates a new hybrid vane that resides directly below the circumferential combustor. Recently, a computational effort to understand the fundamental aspects of the UCC on a …
Applications Of Aerodynamic Forces For Spacecraft Orbit Maneuverability In Operationally Responsive Space And Space Reconstitution Needs,
2012
Air Force Institute of Technology
Applications Of Aerodynamic Forces For Spacecraft Orbit Maneuverability In Operationally Responsive Space And Space Reconstitution Needs, Matthew N. Goodson
Theses and Dissertations
Each year multiple satellites are launched to provide end users key pieces of information. This information ranges from remote sensing data for military or civilian purposes (e.g., weather forecasting, troop movements, agricultural production, etc.) to large bandwidth telecommunications sensors. No matter the type of information needed, society is demanding more. Because of this continual rise in information needs, the current model of launching one satellite for one mission is not sustainable. To satisfy the information needs of nations across the globe, a means for satellites to transition from one mission type to another must be developed. One means of transitioning …
Validation Of The Chemistry Module For The Euler Solver In Unified Flow Solver,
2012
Air Force Institute of Technology
Validation Of The Chemistry Module For The Euler Solver In Unified Flow Solver, William C. Humphrey Jr.
Theses and Dissertations
In the world of computational fluid dynamics (CFD), three main types of flow regimes exist: continuum, rarified, and free molecular. Of these regimes, the rarified regime is the most difficult to model because the continuum equations don't apply and using the Boltzmann equation is too computationally expensive to use. The Unified Flow Solver (UFS) is currently being developed to solve this problem by using the kinetic continuum Euler equations where valid, and only using the Boltzmann equation where necessary, thus reducing the computational cost. The use of the kinetic Euler equations helps to aid in the coupling of the Euler …
Gravitational Lens: Deep Space Probe Design,
2012
Air Force Institute of Technology
Gravitational Lens: Deep Space Probe Design, Berkley R. Davis
Theses and Dissertations
A number of interstellar precursor missions have been designed, but they have all made use of unproven future technologies. This research focuses on designing an interstellar precursor mission to the gravitational lens that can be manufactured solely with today's technology. The design includes an examination of trip time and trajectory, a system trade between subsystems, a launch vehicle analysis and an overall spacecraft performance analysis. The trip time was found to be approximately 108 years using the NEXT thruster and GPHS power source. The GPHS provided approximately 4 kW of power at BOL. The communications subsystem relied on a 12 …
Impact Of Trench And Ramp Film Cooling Designs To Reduce Heat Release Effects In A Reacting Flow,
2012
Air Force Institute of Technology
Impact Of Trench And Ramp Film Cooling Designs To Reduce Heat Release Effects In A Reacting Flow, Michael R. Delallo
Theses and Dissertations
Increasing combustor fuel-air ratios are a recent area of concern in gas turbine film cooling due to the potential for heat release on the surface of film-cooled components. This investigation compared four different cooling designs on their heat release potential: namely fanned, normal and radial trenched, and ramped. Measurements of heat flux to the downstream surface, when subjected to a reacting mainstream flow, provide a qualitative comparison between the four tested configurations. Furthermore, this work studied the effect of multiple injection points in series along the surface of a flat plate. An upstream set of normal holes and an upstream …
Methane Dual Expander Aerospike Nozzle Rocket Engine,
2012
Air Force Institute of Technology
Methane Dual Expander Aerospike Nozzle Rocket Engine, Michael D. Moen
Theses and Dissertations
The Air Force Institute of Technology (AFIT), working to meet requirements set by the Air Force Research Laboratory's Next Generation Engine (NGE) initiative, is developing upper stage rocket models. The current path of investigation focuses on combining a dual expander cycle with an aerospike nozzle, or the Dual Expander Aerospike Nozzle (DEAN) using methane fuel. The design process will rely heavily on AFIT's previous work, which focused on the development of tools for and the optimization of a hydrogen/oxygen DEAN engine. The work outlined in this paper expands the existing research by substituting methane for hydrogen. The targets derived from …
