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Articles 121 - 138 of 138
Full-Text Articles in Aerospace Engineering
Takeoff And Landing Distance Measurement: An Evaluation Of Laser Altimetry For The Collection Of Absolute Aircraft Altitude, Christopher John Kennedy
Takeoff And Landing Distance Measurement: An Evaluation Of Laser Altimetry For The Collection Of Absolute Aircraft Altitude, Christopher John Kennedy
Theses and Dissertations
The measurement of takeoff and landing distance during flight testing of general aviation aircraft requires the accurate measurement of aircraft position over the ground and altitude up to 50 feet above surface elevation. Current methods of evaluating takeoff and landing distances include cinetheodolites, laser and radar trackers, and Differential Global Positioning Systems (DGPS). The use of laser altimetry to range altitude above the ground originated with military and agricultural aircraft. The AgLaser laser module was an infrared laser ranging unit designed for agricultural aircraft to gauge optimal spray height above a field. The AgLaser system has a stated accuracy of …
Single Waypoint Zem/Zev Based Closed-Loop Controller Design For Rendezvous With A Rotating Target, Armando Alvarez Rolins
Single Waypoint Zem/Zev Based Closed-Loop Controller Design For Rendezvous With A Rotating Target, Armando Alvarez Rolins
Theses and Dissertations
The research presented in this thesis addresses a very specific kind of autonomous rendezvous procedure between two spacecraft in close proximity, namely that in which the chaser object is attempting to dock at a location on a rotating target which is tracing a circle perpendicular to the axis of rotation. The approaches that have been mentioned in literature which focus on this specific condition make use of offline optimization algorithms to plot the trajectory of the chaser and use closed-loop control to follow that trajectory. This method is computationally demanding and does not allow for feedback in the desired boundary …
Effect Of The Wake Structure On Drag Coefficient For A Thin Flexible Wire, Harika Gurram
Effect Of The Wake Structure On Drag Coefficient For A Thin Flexible Wire, Harika Gurram
Theses and Dissertations
The present research work focuses on investigating the effect of wake structure on the drag coefficient of a thin flexible wire. Previous researchers have investigated the flow characteristics around the cylinder and estimated the drag coefficient for different Reynold’s number range. The flow transition characteristics in the boundary layer and its effect on the drag coefficient were described. These studies were performed on a non-deformable cylinder. The present work focuses on the drag characteristics of thin flexible cylinders whose diameter is on the order of microns. The results showed up to 30% lower value than reported literature drag coefficient values …
Modeling And Analysis Of A Novel Imbedded Organic Thermal Cycle, Joel Maker Faure
Modeling And Analysis Of A Novel Imbedded Organic Thermal Cycle, Joel Maker Faure
Theses and Dissertations
A thermal cycle is a device that converts thermal energy into work energy. There is a strong need in the United States and the world for a cycle that can have viable performances with low-grade temperature heat sources to increase the supply of power generation. There are many cycles with different configurations, however most do not involve mixing. Generally speaking this is due to modeling difficulties with multiple constituents, phases, and the technology available that lose performance under these mixed conditions. The gap in technology for mixed flow and phase components is getting smaller due to the need. Current cycles …
Flight Test Evaluation And Analysis Of The Wingbug: A Miniature Air Data Computer And Inertial Measurement Unit, Matthew Knight Rhoney
Flight Test Evaluation And Analysis Of The Wingbug: A Miniature Air Data Computer And Inertial Measurement Unit, Matthew Knight Rhoney
Theses and Dissertations
The prototype WingBug was an innovative concept by Straight & Level Technologies to measure airspeed, altitude, temperature, Euler angles, angular rates, and acceleration information. The unit was portable, self-powered, streamed data via WiFi to any tablet or smart phone in the cockpit, and cost less than $1000. It measured 8”x3”x3”, weighed 6 ounces, and used a GoPro mount to attach externally to any aircraft. This thesis covers results from the initial flight test program flown at the Florida Institute of Technology in 2016. The WingBug was flown on a Piper Warrior. Data from the WingBug were compared to “truth” data …
Cooling Performance Of Reciprocating Aircraft Engines: A Quantitative Analysis Of 14 Cfr Part 23 Certification Requirements, Kevin Andrew Stuth
Cooling Performance Of Reciprocating Aircraft Engines: A Quantitative Analysis Of 14 Cfr Part 23 Certification Requirements, Kevin Andrew Stuth
Theses and Dissertations
An analysis of the Federal Aviation Administration (FAA) aircraft certification requirements has revealed a potential error in the temperature correction formula the FAA requires aircraft manufacturers to use to process engine cooling performance data for compliance with Part 23 of Title 14 of the Code of Federal Regulations (14 CFR Part 23). The FAA engine cooling performance temperature correction formula, which predicts the critical temperature of engine components, was quantitatively evaluated using data acquired with a single-engine aircraft powered by a normally-aspirated, air-cooled, reciprocating engine. Previous research has failed to analyze the effect ambient air temperature has on oil temperature …
The Kinematics And X-Ray Emission Mechanism Of The Large-Scale Jet Of 3c 111, Devon Clautice
The Kinematics And X-Ray Emission Mechanism Of The Large-Scale Jet Of 3c 111, Devon Clautice
Theses and Dissertations
Relativistic jets are the most energetic manifestation of the active galactic nucleus (AGN) phenomenon. AGN jets are observed from the radio through gamma rays and carry copious amounts of matter and energy from the sub-parsec central regions out to the kiloparsec and often megaparsec scale galaxy and cluster environs. While most spatially-resolved jets are seen in the radio, an increasing number have been discovered to emit in the optical/near-IR and/or X-ray bands. Here we discuss a spectacular example of this class, the 3C 111 jet, housed in one of the nearest, double-lobed FR II radio galaxies known. We discuss new, …
Dynamics And Control Of Three-Dimensional Perching Maneuver Under Dynamic Stall Influence, Mir Alikhan Bin Mohammad Feroskhan
Dynamics And Control Of Three-Dimensional Perching Maneuver Under Dynamic Stall Influence, Mir Alikhan Bin Mohammad Feroskhan
Theses and Dissertations
Perching is a type of aggressive maneuver performed by the class ‘Aves’ species to attain precision point landing with a generally short landing distance. Perching capability is desirable on unmanned aerial vehicles (UAVs) due to its efficient deceleration process that potentially expands the functionality and flight envelope of the aircraft. This dissertation extends the previous works on perching, which is mostly limited to two-dimensional (2D) cases, to its state-of-the-art three-dimensional (3D) variety. This dissertation presents the aerodynamic modeling and optimization framework adopted to generate unprecedented variants of the 3D perching maneuver that include the sideslip perching trajectory, which ameliorates the …
A Maximum Entropy Approach To Identifying Important Statistical Moments To Best-Represent Spray Distribution Data, Cheng Chen
Theses and Dissertations
To obtain accurate spray droplet size and velocity distributions, higher-order statistical moments are needed. The Maximum Entropy formalism has been successfully used to predict the motion of spray flow in different models. This work is mainly focused on the use of the fourth-order moment combinations to calculate droplet probability density functions using the Maximum Entropy Formalism. Beginning with the second-order moment combinations, Lagrange multipliers have been calculated subject to given moment constraints, defining the probability density function. All lower moments are included when calculating the possible different higher-order moment combinations. From the results, each moment combination generated a set of …
Flight Test Investigation On The Effects Of Aircraft Flap Configuration Change On Longitudinal Trim, Tiziano Bernard
Flight Test Investigation On The Effects Of Aircraft Flap Configuration Change On Longitudinal Trim, Tiziano Bernard
Theses and Dissertations
Loss of Control (LOC) in general aviation has been a topic of extensive study and analysis in the United States and the European Union due to a long series of aircraft accidents in the past decades. The National Transportation Safety Board (NTSB) has identified over 1500 accidents in the traffic pattern involving LOC in general aviation aircraft between 1982 and 2015. LOC has often been attributed to deficiencies in pilot training, and the typical recommendation to reduce the number of accidents is to provide further training in stalls and spins. The European Aviation Safety Agency (EASA) has performed research that …
Experimental, Numerical, And Analytical Slosh Dynamics Of Water And Liquid Nitrogen In A Spherical Tank, Jedediah Morse Storey
Experimental, Numerical, And Analytical Slosh Dynamics Of Water And Liquid Nitrogen In A Spherical Tank, Jedediah Morse Storey
Theses and Dissertations
Understanding, predicting, and controlling fluid slosh dynamics is critical to safety and improving performance of space missions when a significant percentage of the spacecraft’s mass is a liquid. Computational fluid dynamics simulations can be used to predict the dynamics of slosh, but these programs require extensive validation. Many experimental and numerical studies of water slosh have been conducted. However, slosh data for cryogenic liquids is lacking. Water and cryogenic liquid nitrogen are used in various ground-based tests with a spherical tank to characterize damping, slosh mode frequencies, and slosh forces. A single ring baffle is installed in the tank for …
The Rapidly Reconfigurable Research Cockpit, Richard Joyce
The Rapidly Reconfigurable Research Cockpit, Richard Joyce
Link Foundation Modeling, Simulation and Training Fellowship Reports
The goal of the Rapidly Reconfigurable Research Cockpit (R3C) project is to create and evaluate a novel approach for aviation simulators. Our concept combines a virtual reality visual environment with the tactile feedback typically found in early stage mockups. A low cost, easily modified, yet geometrically accurate cockpit panel (fabricated using 3D printing, for example) can be used while the pilot/operator wears a head-mounted display providing the visual overlay of the simulator.
Self-Organization Of Protein Fibers In Weightlessness, Dylan Bell
Self-Organization Of Protein Fibers In Weightlessness, Dylan Bell
Theses and Dissertations
It is currently hypothesized and widely believed that the growth of self aggregating protein chains such as amyloid fibers has a direct effect on the function of the human brain. We hypothesized creating self-assembling protein in weightlessness would allow the aggregation to continue for a longer period of time in solution without sedimentation. When protein de-natures and self-organizes into amyloid fibers the effect can be detrimental. Some neurodegenerative diseases, such as Alzheimer’s and Dementia, are believed to be caused by the collection of these fibers made from proteins such as tau and amyloid-β. For the purpose of this experiment, lysozyme …
Characterization Of Sinusoidal Vibration Induced Fluid Motion In Spherical Elastomeric Diaphragm Tanks, Cody Ambrose Harris
Characterization Of Sinusoidal Vibration Induced Fluid Motion In Spherical Elastomeric Diaphragm Tanks, Cody Ambrose Harris
Theses and Dissertations
Elastomeric diaphragm tanks are commonly used in spacecraft applications to incite positive expulsion of hydrazine monopropellant. The diaphragm exhibits low flexural rigidity, causing it to easily fold under its own weight at low fill levels. If the tank is sinusoidally oscillated under standard gravity, such as during ground transportation or launch pad winding, these folds will result in rubbing, eventually wearing down the thin material to the point of failure. The ability to accurately predict the presence of folds, rubs, and center of gravity shifts for a given tank design and frequency excitation is thus of critical importance to mission …
Flexible Slosh Diaphragm Modeling And Simulation In Propellant Tanks, Darren Vaughn Levine
Flexible Slosh Diaphragm Modeling And Simulation In Propellant Tanks, Darren Vaughn Levine
Theses and Dissertations
iquid sloshing and propellant distribution is an important field of research for aerospace applications such as launch vehicles and spacecraft. The propellant mass behavior can greatly influence vehicle dynamics, altering trajectories and structural loading distributions. In order to combat these concerns some propellant tanks employ thin elastomeric diaphragms to separate the fuel from the gas volumes and restrict the fluid's motion. The diaphragm’s flexible behavior is generally highly nonlinear, and various propellant fill levels and acceleration conditions can cause large deflections resulting in complex buckling and folding patterns. When complex and non-uniform deformations occur, there is potential for diaphragm wear …
Robust Decentralized Formation Flight Control, Weihua Zhao, Tiauw Hiong Go
Robust Decentralized Formation Flight Control, Weihua Zhao, Tiauw Hiong Go
Aerospace, Physics, and Space Science Faculty Publications
Motivated by the idea of multiplexed model predictive control (MMPC), this paper introduces a new framework for unmanned aerial vehicles (UAVs) formation flight and coordination. Formulated using MMPC approach, the whole centralized formation flight system is considered as a linear periodic system with control inputs of each UAV subsystem as its periodic inputs. Divided into decentralized subsystems, the whole formation flight system is guaranteed stable if proper terminal cost and terminal constraints are added to each decentralized MPC formulation of the UAV subsystem. The decentralized robust MPC formulation for each UAV subsystem with bounded input disturbances and model uncertainties is …
Quantitative Characterization Of Resistive Defects In Thick Composites Using Step Heating Thermography, Adel A. Badghaish, David C. Fleming
Quantitative Characterization Of Resistive Defects In Thick Composites Using Step Heating Thermography, Adel A. Badghaish, David C. Fleming
Aerospace, Physics, and Space Science Faculty Publications
Inspection of thick composite structures, such as Reinforced Thermosetting Resin (RTR) pipes used in the petroleum industry, using infrared thermography is difficult. This paper investigates the use of step heating thermography to increase the maximum detectable defect depth and describes techniques to quantitatively characterize defect depth and severity in thick composites. A procedure to simultaneously determine defect depth and thermal resistance from the early time surface temperature is described. The procedure is based on fitting the early time surface temperature profile over a defect to a one-dimensional three-layer analytical model. Experimental testing demonstrates the accuracy of the procedure.
Vortex Generated Rotor Wake Model For Real-Time Simulation, Kenneth S. Graham
Vortex Generated Rotor Wake Model For Real-Time Simulation, Kenneth S. Graham
Link Foundation Modeling, Simulation and Training Fellowship Reports
The University of Alabama Flight Dynamics Laboratory (UA FDL) has been simulating helicopters since 1981. The real-time, man-in-the-loop, simulator was developed locally and is continuously being upgraded. The hardware, software, architecture and math models are all developed in-house by a team of faculty and graduate students. Since 1994, the UA rotor model has been Bladehelo [2] - a true blade model that numerically integrates the flapping motion of individual blades and the shaft rotation. The approach is physically based. Discrepancies are studied until they are understood. Bladehelo played a key role in the discovery of residual bending [3], [4]. Bladehe!o …