Orbit Determination Using Vinti's Solution,
2016
Air Force Institute of Technology
Orbit Determination Using Vinti's Solution, Steven P. Wright
Theses and Dissertations
Orbital altitudes congested with spacecraft and debris combined with recent collisions have all but negated the Big Sky Theory. As the sheer number of orbital objects to track grows unbounded so does interest in prediction methods that are rapid and minimally computational. Claimed as the \other solvable solution, the recently completed solution too orbital motion about the earth, based on Vinti's method and including the major effects of the equatorial bulge, opens up the prospect of much more accurate analytical models for space situational awareness. A preliminary examination of this solution is presented. A numerical state transition matrix is found …
Cavity Geometric Features And Entrainment Characterization Resulting From A Ballistically Induced Hydrodynamic Ram Event,
2016
Air Force Institute of Technology
Cavity Geometric Features And Entrainment Characterization Resulting From A Ballistically Induced Hydrodynamic Ram Event, Andrew J. Lingenfelter
Theses and Dissertations
Hydrodynamic Ram can cause damage to industrial and aircraft systems. The resulting transient spray increases the probability of fire. To better understand the driving mechanisms behind transient spray, internal, and external measurements of the cavity geometry, and entrained flow field were accomplished. Research determined cavity contraction and separation are pre-cursors to the initiation of the transient spray phases. The entrained flow measurement required development of a new and novel technique using a continuous wave laser and atomized water particles. The peak mass flow correlated well with cavity geometric features, such as cavity contraction. Using the mass flow, cavity diameter at …
The Scaling Of Loss Pathways And Heat Transfer In Small Scale Internal Combustion Engines,
2016
Air Force Institute of Technology
The Scaling Of Loss Pathways And Heat Transfer In Small Scale Internal Combustion Engines, Joseph K. Ausserer
Theses and Dissertations
Prior literature indicates fuel conversion efficiency and normalized power deteriorate increasingly rapidly with decreasing displacement, but does not fully reveal the driving losses. The literature also suggested that increasing losses relax the required fuel anti-knock index (AKI), but offered conflicting conclusions on the performance impact. This comprehensive experimental study of three, 28 cm3 to 85 cm3 displacement, commercial-off-the-shelf (COTS), two-stroke ICEs identified short-circuiting as having the most deleterious impact on COTS engine performance in this size range. Heat transfer losses were comparable to larger engines for displaced volumes greater than 10 cm3. An engine friction model was developed that uses …
Optimal Control Of An Uninhabited Loyal Wingman,
2016
Air Force Institute of Technology
Optimal Control Of An Uninhabited Loyal Wingman, Clay J. Humphreys
Theses and Dissertations
As researchers strive to achieve autonomy in systems, many believe the goal is not that machines should attain full autonomy, but rather to obtain the right level of autonomy for an appropriate man-machine interaction. A common phrase for this interaction is manned-unmanned teaming (MUM-T), a subset of which, for unmanned aerial vehicles, is the concept of the loyal wingman. This work demonstrates the use of optimal control and stochastic estimation techniques as an autonomous near real-time dynamic route planner for the DoD concept of the loyal wingman. First, the optimal control problem is formulated for a static threat environment and …
Adaptive Estimation And Heuristic Optimization Of Nonlinear Spacecraft Attitude Dynamics,
2016
Air Force Institute of Technology
Adaptive Estimation And Heuristic Optimization Of Nonlinear Spacecraft Attitude Dynamics, Joshuah A. Hess
Theses and Dissertations
For spacecraft conducting on-orbit operations, changes to the structure of the spacecraft are not uncommon. These planned or unanticipated changes in inertia properties couple with the spacecraft's attitude dynamics and typically require estimation. For systems with time-varying inertia parameters, multiple model adaptive estimation (MMAE) routines can be utilized for parameter and state estimates. MMAE algorithms involve constructing a bank of recursive estimators, each assuming a different hypothesis for the systems dynamics. This research has three distinct, but related, contributions to satellite attitude dynamics and estimation. In the first part of this research, MMAE routines employing parallel banks of unscented attitude …
Improving Real-World Performance Of Vision Aided Navigation In A Flight Environment,
2016
Air Force Institute of Technology
Improving Real-World Performance Of Vision Aided Navigation In A Flight Environment, Donald T. Venable
Theses and Dissertations
The motivation of this research is to fuse information from an airborne imaging sensor with information extracted from satellite imagery in order to provide accurate position when GPS is unavailable for an extended duration. A corpus of existing geo-referenced satellite imagery is used to create a key point database. A novel algorithm for recovering coarse pose using by comparing key points extracted from the airborne imagery to the reference database is developed. This coarse position is used to bootstrap a local-area geo-registration algorithm, which provides GPS-level position estimates. This research derives optimizations for existing local-area methods for operation in flight …
Mechanical Properties And Fatigue Behavior Of Unitized Composite Airframe Structures At Elevated Temperature,
2016
Air Force Institute of Technology
Mechanical Properties And Fatigue Behavior Of Unitized Composite Airframe Structures At Elevated Temperature, Mohamed Noomen
Theses and Dissertations
The tension-tension fatigue behavior of a newly developed unitized composite material system was investigated. The unitized composite consisted of a polymer matrix composite (PMC) co-cured with a ceramic matrix composite (CMC). The PMC portion consisted of an NRPE high-temperature polyimide matrix reinforced with carbon fibers woven in an eight harness satin weave (8HSW). The CMC layer is a single-ply non-crimp 3D orthogonal weave composite consisting of ceramic matrix reinforced with glass fibers. In order to assess the performance and suitability of this composite for use in aerospace components designed to contain high-temperature environments, mechanical tests were performed under temperature conditions …
From Xst To F-117a,
2016
Embry-Riddle Aeronautical University
From Xst To F-117a, Alan Brown
ERAU Prescott Aviation History Program
Learn the remarkable story of stealth technology from the man often referred to as “Mr. Stealth.” From 1975-1989 Alan Brown was a member of Lockheed “Skunk Works”, becoming program manager & chief engineer for the F-117A Stealth Fighter from initial concept until the first production aircraft was built, 1978 to 1982. Hear the inside story of the many challenges faced by the stealth program and how they were solved.
Pocketcubes/Cubesats On Antares,
2016
Morehead State University
Pocketcubes/Cubesats On Antares, Robert J. Twiggs, Walter Holemans, Michael Bitzer
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint Presentation created by Professor Bob Twiggs, Walter Holmans, and Michael Bitzer titled "PocketCubes/CubeSats on Antares" from September 6, 2016.
Experimentation Of Mode I And Mode Ii Fracture Of Uni-Directional Composites And Finite Element Analysis Of Mode I Fracture Using Cohesive Contact,
2016
California Polytechnic State University, San Luis Obispo
Experimentation Of Mode I And Mode Ii Fracture Of Uni-Directional Composites And Finite Element Analysis Of Mode I Fracture Using Cohesive Contact, Joseph Daniel Garrett
Master's Theses
As the use of fiber-reinforced composites has increased over the decades, so has the need to understand the complexity of their failure mechanisms as engineers seek to improve the damage tolerance of composite laminated structures. One of the most prevalent and limiting mode of failure within composite laminates is delamination, since it not only reduces a structures stiffness and strength, but can be very difficult to detect without the use of special non-destructive equipment. Industry testing organizations have utilized several fracture tests in order to characterize the fracture toughness of composite materials under different loading conditions. For this research, ASTM …
High-Frequency Instabilities Of Stationary Crossflow Vortices In A Hypersonic Boundary Layer,
2016
Missouri University of Science and Technology
High-Frequency Instabilities Of Stationary Crossflow Vortices In A Hypersonic Boundary Layer, Fei Li, Meelan Choudhari, Pedro Paredes-Gonzalez, Lian Duan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Hypersonic boundary layer flows over a circular cone at moderate incidence angle can support strong crossflow instability in between the windward and leeward rays on the plane of symmetry. Due to more efficient excitation of stationary crossflow vortices by surface roughness, such boundary layer flows may transition to turbulence via rapid amplification of the high-frequency secondary instabilities of finite-amplitude stationary crossflow vortices. The amplification characteristics of these secondary instabilities are investigated for crossflow vortices generated by an azimuthally periodic array of roughness elements over a 7° half-angle circular cone in a Mach 6 free stream. The analysis is based on …
Experimental And Numerical Investigations Of Dust Effects On Surface Charging In Plasma,
2016
Missouri University of Science and Technology
Experimental And Numerical Investigations Of Dust Effects On Surface Charging In Plasma, Kevin Chou, Daoru Frank Han, Joseph J. Wang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A series of 3-D, fully kinetic particle-in-cell (PIC) simulations were performed to simulate mesothermal plasma flow self-consistently with surface charging. Simulation results of plasma charging of a conducting surface covered by a thin dust layer in a plasma of cold ions and thermal electrons are presented. The surface potentials and potentials inside the dust layer are compared with experimental results. Results show that a layer of dust over a conducting surface creates a capacitance, which drives the surface more negative with respect to the ambient plasma.
Numerical Modeling Of Dust Dynamics Around Small Asteroids,
2016
Missouri University of Science and Technology
Numerical Modeling Of Dust Dynamics Around Small Asteroids, William Yu, Joseph J. Wang, Daoru Frank Han
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Dynamics of dust transport around an airless body has been a focused area of research in recent years, however, various challenging aspects still remain to be addressed. This paper presents an investigation of charged dust transport and distribution around small asteroids utilizing a full particle Particle-in-Cell (PIC) model to simulate plasma flow around an asteroid and calculate surface charging self-consistently from charge deposition on asteroid. Material properties of asteroid are also explicitly included in the simulation. PIC simulation results are fed into a 3D dust dynamics model to simulate charged dust levitation, transport and distribution. In addition to electrostatic and …
Experimental Investigation On Flow Characteristics Of A Four-Wing Micro Air Vehicle,
2016
Department of Mechanical Engineering
Experimental Investigation On Flow Characteristics Of A Four-Wing Micro Air Vehicle, Lisong Shi, Chunkit Uy, Shih K. Huang, Zifeng Yang, George P.G. Huang, Chihyung Wen
Mechanical and Materials Engineering Faculty Publications
The aim of current research work on micro air vehicles is to realize their autonomous control, i.e. building a library for a lookup table that would apply to micro electronics. In doing so, comprehensive flight tests need to be carried out. In this study, a four-wing flapping MAV is built and a multi-discipline approach is used to design the MAV model. Precision manufacturing technology is introduced here. The finished micro air vehicle has a weight of 8 g and is tested for flight by remote control. The micro air vehicle can perform both hovering and forward flight with high maneuverability. …
Propulsion Theory Of Flapping Airfoils, Comparison With Computational Fluid Dynamics,
2016
Utah State University
Propulsion Theory Of Flapping Airfoils, Comparison With Computational Fluid Dynamics, Doug F. Hunsaker, W. F. Phillips
Mechanical and Aerospace Engineering Faculty Publications
It is shown that the time-dependent aerodynamic forces acting on a flapping airfoil in forward flight are functions of both axial and normal reduced frequencies. The axial reduced frequency is based on the chord length, and the normal reduced frequency is based on the plunging amplitude. Furthermore, the time-dependent aerodynamic forces are related to two Fourier coefficients, which are evaluated here from computational results. Correlation equations for these Fourier coefficients are obtained from a large number of grid- and time-step-resolved inviscid computational-fluid-dynamics solutions, conducted over a range of both axial and normal reduced frequencies. The correlation results can be used …
A Hybrid Optimization Technique Applied To The Intermediate-Target Optimal Control Problem,
2016
Air Force Institute of Technology
A Hybrid Optimization Technique Applied To The Intermediate-Target Optimal Control Problem, Clay J. Humphreys, Richard G. Cobb, David R. Jacques, Jonah A. Reeger
Faculty Publications
The DoD has introduced the concept of Manned-Unmanned Teaming, a subset of which is the loyal wingman. Optimal control techniques have been proposed as a method for rapidly solving the intermediate-target (mid-point constraint) optimal control problem. Initial results using direct orthogonal collocation and a gradient-based method for solving the resulting nonlinear program reveals a tendency to converge to or to get `stuck’ in locally optimal solutions. The literature suggested a hybrid technique in which a particle swarm optimization is used to quickly find a neighborhood of a more globally minimal solution, at which point the algorithm switches to a gradient-based …
Citizensatellite: Low Cost Missions For The Unordinary Innovator,
2016
Morehead State University
Citizensatellite: Low Cost Missions For The Unordinary Innovator, Robert J. Twiggs, Amin Djamshidpour, Ted Tagami, Tony So
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint presentation created by Robert Twiggs, Amin Djamshidpour, Ted Tagami, and Tony Sotitled "CitizenSatellite: Low Cost Missions for the Unordinary Innovator" from August 19, 2016.
Secondary Launch Opportunities Orbital Atk,
2016
Morehead State University
Secondary Launch Opportunities Orbital Atk, Robert J. Twiggs
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint Presentation created by Professor Bob Twiggs titled "Secondary Launch Opportunities Orbital ATK" from August 17, 2016.
On Event-Triggered Adaptive Architectures For Decentralized And Distributed Control Of Large-Scale Modular Systems,
2016
Missouri University of Science and Technology
On Event-Triggered Adaptive Architectures For Decentralized And Distributed Control Of Large-Scale Modular Systems, Ali Albattat, Benjamin C. Gruenwald, Tansel Yucelen
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The last decade has witnessed an increased interest in physical systems controlled over wireless networks (networked control systems). These systems allow the computation of control signals via processors that are not attached to the physical systems, and the feedback loops are closed over wireless networks. The contribution of this paper is to design and analyze event-triggered decentralized and distributed adaptive control architectures for uncertain networked large-scale modular systems; that is, systems consist of physically interconnected modules controlled over wireless networks. Specifically, the proposed adaptive architectures guarantee overall system stability while reducing wireless network utilization and achieving a given system performance …
Experimental Study Of Simulated Geophysical Buoyancy-Driven Vortical Flow,
2016
Western Michigan University
Experimental Study Of Simulated Geophysical Buoyancy-Driven Vortical Flow, Mohammad Hady Makhmalbaf
Dissertations
This paper describes an experimental study on the flow within a rotating cylinder with a counter-rotating disk located below to mimic certain aspects of the unique flow structures of the Great Red Spot (GRS) in Jupiter using a simple laboratory setup. The special design of this setup makes it capable of spinning the side wall of a vertical cylinder in both directions as well as rotating the bottom of the cylinder independently, where both can rotate in wide ranges of spin rates. Also, different thermal conditions can be applied on the bottom of the disk. All of these conditions provide …
