Aerospace Engineering Commons^™

Control Laws For Autonomous Landing On Pitching Decks, Kendrick Buchala

Theses and Dissertations

This thesis addresses the problem of landing a quadcopter onto the pitching deck of a ship, as a partial simulation of a shipboard landing during high seas. The deck is modeled to pitch with a sinusoidal motion. While shipboard landing consists of many stages, only the final landing is simulated in this research. Other ship motions, such as roll and heave, are likewise not considered. The goal is to land the quadcopter in the center of the deck with minimal position and pitch error, where position error measures how far fore or aft of the center of the landing pad …

A Computational Analysis Of The Aerodynamics And Aeroacoustics Of Jets With Fluid Injection, Marco Coderoni

Doctoral Dissertations and Master's Theses

A detailed numerical analysis of fluidic injection as a tool to reduce noise emission is presented here. The noise reduction strategy, developed at the Pennsylvania State University, is based on injectors that blow air into the diverging section of the nozzle to emulate the effect of interior corrugation on the jet plume. The advantage is that the injection can be activated during takeoff and turned o_ during other phases of flight so that performance is not affected. Numerical simulations are performed on a military-style nozzle based on the GE F400-series engines, with a design Mach number of 1:65, for over-expanded …

Aerothermodynamic Analysis Of A Mars Sample Return Earth-Entry Vehicle, Daniel A. Boyd

Mechanical & Aerospace Engineering Theses & Dissertations

Because of the severe quarantine constraints that must be imposed on any returned extraterrestrial samples, the Mars sample return Earth-entry vehicle must remain intact through sample recovery. Vehicles returning on a Mars-Earth trajectory will attain velocities exceeding any that have been experienced by prior space exploration missions, with velocities approaching 14 km/s. Velocities as high as these will encounter significant heating during atmospheric re-entry to Earth.

The purpose of this study has been to systematically investigate the aerothermodynamic challenges that will result from a Mars sample return, Earth-entry vehicle design. The goal was to enable efficient estimation of maximum stagnation …

Dynamics Of Spacecraft Orbital Refueling, Casey Clark

Theses and Dissertations

A quantitative collation of relevant parameters for successfully completed experimental on-orbit fluid transfers and anticipated orbital refueling future missions is performed. The dynamics of connected satellites sustaining fuel transfer are derived by treating the connected spacecraft as a rigid body and including an internal mass flow rate. An orbital refueling results in a time-varying local center of mass related to the connected spacecraft. This is accounted for by incorporating a constant mass flow rate in the inertia tensor. Simulations of the equations of motion are performed using the values of the parameters of authentic missions in an endeavor to provide …

Simulation Of Radiation Flux From Thermal Fluid In Origami Tubes, Robert R. Bebeau

USF Tampa Graduate Theses and Dissertations

Spacecraft in orbit experience temperature swings close to 240 K as the craft passes from the shadow of the Earth into direct sunlight. To regulate the craft’s internal energy, large radiators eject unwanted energy into space using radiation transfer. The amount of radiation emitted is directly related to the topology of the radiator design. Deformable structures such as those made with origami tessellation patterns offer a mechanism to control the quantity of energy being emitted by varying the radiator shape. Three such patterns, the Waterbomb, Huffman Waterbomb, and Huffman Stars-Triangles, can be folded into tubes. Origami tubes offer greater control …

Static Performance Results Of Propellers Used On Nano, Micro, And Mini Quadrotors, Robert W. Deters, D. Dantsker, S.C. Kleinke, Narcrisha Norman, Michael S. Selig

Publications

An increase in the number of small quadrotors has created the interest in having performance data on the propellers used by these aircraft. With an aircraft size less than 5 in and propellers diameters less than 3 in, these quadrotors are typically referred to mini, micro, or nano by hobbyists and manufacturers. The size of the propellers used on these aircraft operate at low Reynolds numbers that are typically less than 50,000 for diameters up to 3 in and less than 20,000 for diameters up to 2 in. Static performance testing of the propellers used on 11 small quadrotors was …

Book Review: Fundamentals Of International Aviation, Alan Bender

International Journal of Aviation, Aeronautics, and Aerospace

Not applicable.

Creep Of Hi-Nicalon™ S Ceramic Fiber Tows At 1100°C In Air And In Silicic Acid-Saturated Steam, Logan M. Gumucio

Theses and Dissertations

Innovations in SiC based ceramic matrix composites (CMCs) have yielded exceptional high-temperature properties and performance in aggressive oxidizing environments. These material characteristics provide potential avenues for future advancements in many applications where current metallic alloys perform near their operating temperature limits in a harsh environment. As steam (typically present in these environments) enters through cracks in the matrix of a SiC/SiC composite, it leaches Si and becomes saturated with silicic acid, Si(OH)₄, prior to attacking the reinforcing SiC fibers. Therefore, it is paramount that a thorough understanding of the performance and durability of SiC fibers be obtained under …

Mitigating Interference With Knowledge-Aided Subarray Pattern Synthesis And Space Time Adaptive Processing, Yongjun Yoon

Theses and Dissertations

Phased arrays are essential to airborne ground moving target indication (GMTI), as they measure the spatial angle-of-arrival of the target, clutter, and interference signals. The spatial and Doppler (temporal) frequency is utilized by space-time adaptive processing (STAP) to separate and filter out the interference from the moving target returns. Achieving acceptable airborne GMTI performance often requires fairly large arrays, but the size, weight and power (SWAP) requirements, cost and complexity considerations often result in the use of subarrays. This yields an acceptable balance between cost and performance while lowering the system’s robustness to interference. This thesis proposes the use of …

Competitiveness Of Hybrid Electric Aircraft On Short Range Scheduled Flights, Johannes Anton, Hans-Joachim K. Ruff-Stahl

International Journal of Aviation, Aeronautics, and Aerospace

Hybrid electric aircraft are expected to enter the small regional aircraft market within the next two decades. The aim of this study was to investigate if a hybrid electric passenger aircraft with 50 seats can be competitive against the established 100 seat aircraft on short range scheduled flights. The Embraer EMB 145 and EMB 190 regional jets were chosen as benchmarks for that market. A hypothetical hybrid version of the EMB 145 with increased fuel efficiency was tested on a cost per available seat mile (CASM) basis. The t tests confirmed significant (p < 0.05) competitiveness of the hybrid version, while in contrast the conventional 50-seater was significantly more expensive compared to the 100seat aircraft. This indicates that hybrid aircraft could enter the short haul market with a competitive advantage, even against the established 100 seat regional jets.

The Pocketqube Standard: Issue 1, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A report titled "The PocketQube Standard Issue 1" published on June 7, 2018.

An Evaluation Of Ultrasonic Shot Peening And Abrasive Flow Machining As Surface Finishing Processes For Selective Laser Melted 316l, Rhys Gilmore

Master's Theses

Additive Manufacturing, and specifically powder bed fusion processes, have advanced rapidly in recent years. Selective Laser Melting in particular has been adopted in a variety of industries from biomedical to aerospace because of its capability to produce complex components with numerous alloys, including stainless steels, nickel superalloys, and titanium alloys. Post-processing is required to treat or solve metallurgical issues such as porosity, residual stresses, and surface roughness. Because of the geometric complexity of SLM produced parts, the reduction of surface roughness with conventional processing has proven especially challenging. In this Thesis, two processes, abrasive flow machining and ultrasonic shot peening, …

Orbital Constellation Design And Analysis Using Spherical Trigonometry And Genetic Algorithms: A Mission Level Design Tool For Single Point Coverage On Any Planet, Joseph R. Gagliano

Master's Theses

Recent interest surrounding large scale satellite constellations has increased analysis efforts to create the most efficient designs. Multiple studies have successfully optimized constellation patterns using equations of motion propagation methods and genetic algorithms to arrive at optimal solutions. However, these approaches are computationally expensive for large scale constellations, making them impractical for quick iterative design analysis. Therefore, a minimalist algorithm and efficient computational method could be used to improve solution times. This thesis will provide a tool for single target constellation optimization using spherical trigonometry propagation, and an evolutionary genetic algorithm based on a multi-objective optimization function. Each constellation will …

Investigating Forward Flight Multirotor Wind Tunnel Testing In A 3-By 4-Foot Wind Tunnel, Reed Danis

Master's Theses

Investigation of complex multirotor aerodynamic phenomena via wind tunnel experimentation is becoming extremely important with the rapid progress in advanced distributed propulsion VTOL concepts. Much of this experimentation is being performed in large, highly advanced tunnels. However, the proliferation of this class of vehicles extends to small aircraft used by small businesses, universities, and hobbyists without ready access to this level of test facility. Therefore, there is a need to investigate whether multirotor vehicles can be adequately tested in smaller wind tunnel facilities. A test rig for a 2.82-pound quadcopter was developed to perform powered testing in the Cal Poly …

Use Of Manifolds In The Insertion Of Ballistic Cycler Trajectories, Oliver K. Morrison

Master's Theses

Today, Mars is one of the most interesting and important destinations for humankind and copious methods have been proposed to accomplish these future missions. One of the more fascinating methods is the Earth-Mars cycler trajectory which is a trajectory that accomplishes repeat access to Earth and Mars with little to no fuel-burning maneuvers. This would allow fast travel to and from Mars, as well as grant the possibility of multiple missions using the same main vehicle.

Insertion from Earth-orbit onto the cycler trajectory has not been thoroughly ex- plored and the only existing method so far is a Hohmann-esque transfer …

Electrode Geometry Effects In An Electrothermal Plasma Microthruster, Harrison Raymond King

Master's Theses

Nanosatellites, such as Cubesats, are a rapidly growing sector of the space industry. Their popularity stems from their low development cost, short development cycle, and the widespread availability of COTS subsystems. Budget-conscious spacecraft designers are working to expand the range of missions that can be accomplished with nanosatellites, and a key area of development fueling this expansion is the creation of micropropulsion systems. One such system, originally developed at the Australian National University (ANU), is an electrothermal plasma thruster known as Pocket Rocket (PR). This device heats neutral propellant gas by exposing it to a Capacitively Coupled Plasma (CCP), then …

Development Of A Vortex Particle Code For The Modeling Of Wake Interaction In Distributed Propulsion, Eduardo Alvarez, Andrew Ning

Faculty Publications

Recent developments in electric aircraft technology have enabled the use of distributed propulsion for the next generation of vertical lift vehicles. However, the ability to rapidly assess the performance of these design concepts, with sufficient fidelity, is a current weakness of this nascent industry. This paper explores the capacity of the viscous Vortex Particle Method (VPM) to model wake interactions found in distributed propulsion. The elements of the vortex particle method are summarized, and a new approach for the calculation of vortex stretching through the complex-step derivative approximation is presented. Preliminary validation is performed on vortex ring cases resembling the …

Interplanetary Transfer Trajectories Using The Invariant Manifolds Of Halo Orbits, Megan S. Rund

Master's Theses

Throughout the history of interplanetary space travel, the Newtonian dynamics of the two-body problem have been used to design orbital trajectories to traverse the solar system. That is, that a spacecraft orbits only one large celestial body at a time. These dynamics have produced impressive interplanetary trajectories utilizing numerous gravity assists, such as those of Voyager, Cassini, Rosetta and countless others. But these missions required large amounts of delta-v for their maneuvers and therefore large amounts of fuel mass. As we desire to travel farther and more extensively in space, these two-body dynamics lead to impossibly high delta-v values, and …

Modification Of A Ground Based Atomic Oxygen Simulation Apparatus To Accommodate Three Dimensional Specimens, Charles Ward

Master's Theses

The space environment presents various challenges when designing systems and selecting materials for applications beyond Earth’s atmosphere. For mission success, these challenges must be considered. One of the detrimental aspects of the space en- vironment is Atomic Oxygen, AO. Only present in harmful quantities in Lower Earth Orbit, LEO, AO causes significant damage to materials by breaking molecular bonds. California Polytechnic State University’s, Cal Poly’s, space environments laboratory features an apparatus capable of simulating this environment. Very thin or short samples were tested to observe the mass loss due to erosion of the sample material. Recent modifications to the system …

The Effects Of Varying Composition And Build Direction On Direct Metal Deposition Fabricated Inconel 718, Abigail P. Nilan, Jessica M. Fordham

Materials Engineering

Inconel 718 (IN718) is a popular wrought superalloy, and is currently being investigated for additive manufacturing (AM) applications in the aerospace industry. However, overaging and the presence of microcracks have caused a significant reduction in properties. The purpose of this study is to meet or exceed the mechanical properties of wrought IN718 by varying the composition and build direction of the AM alloy. Alternative compositions were selected with Oerlilon Metco’s Rapid Alloy Development (RAD) software, and differ in niobium content, which increases the fraction of the primary strengthening phase (γʺ). Direct metal deposition (DMD) was used to fabricate the samples, …