Aerospace Engineering Commons^™

Hall Effect Thruster Characterization Through Potential, Magnetic, And Optical Measurements, Nicholas L. Hyatt

Theses and Dissertations

Electric propulsion is a promising method for providing ΔV to spacecraft on orbit. In general, much higher I_SPS are obtained compared to their chemical counterparts. Hall thrusters are a subset of electric propulsion with moderately high specific impulse and thrust when compared to other forms of electric propulsion. Even though Hall thrusters have an extensive flight legacy around the world, there are still many unknowns associated with their operation. Experimental research was conducted in AFIT’s Space Propulsion Application Simulation System (SPASS) laboratory, to measure Hall current, plasma potential and visible emission from the 600W Hall thruster in a …

Modeling And Computation Of The Maximum Braking Energy Speed For Transport Category Airplanes, Nihad E. Daidzic

Journal of Aviation Technology and Engineering

Transport-category or FAR/CS 25 certified airplanes may occasionally become braking energy capacity limited. Such limitation may exist when heavy airplanes are departing airports at high-density altitudes, on relatively long runways, and/or possibly with some tailwind component. A maximum braking energy VMBE speed exists which may limit the maximum allowable takeoff decision/action speed V1. The ever-existing possibility of high-speed rejected takeoff in such conditions may also limit the airplane gross weight for declared available distances. To gain deeper insights and acquire better understanding of the topic, a theoretical model of the maximum braking energy and the related VMBE speed for T-category …

P26. Global Exponential Stabilization On So(3), Soulaimane Berkane

Western Research Forum

Global Exponential Stabilization on SO(3)

Collision Avoidance And Navigation Of Uas Using Vision-Based Proportional Navigation, Matthew J. Clark

Doctoral Dissertations and Master's Theses

Electro-optical devices have received considerable interest due to their light weight, low cost, and low algorithm requirements with respect to computational power. In this thesis, vision-based guidance laws are developed to provide sense and avoid capabilities for unmanned aerial vehicles (UAVs) operating in complex environments with multiple static and dynamic collision threats. These collision avoidance guidance laws are based on the principle of proportional navigation (Pro-Nav), which states that a UAV is on a collision course with another vehicle or object if the line-of-sight (LOS) angles to the object remain constant. The guidance laws are designed for use with monocular …

The Collisional Evolution Of Orbital Debris In Geopotential Wells And Disposal Orbits, Benjamin Polzine

Master's Theses

This thesis investigates the orbital debris evolution in the geosynchronous disposal orbit regime and within geosynchronous orbits effected by the geopotential wells. A propagator is developed for the accurate simulation of GEO specific orbits and the required perturbations are determined and described. Collisions are then simulated in the selected regimes using a low velocity breakup model derived from the NASA EVOLVE breakup model. The simulations described in this thesis consider a set of perturbations including the geopotential, solar and lunar gravity, and solar radiation pressure forces. This thesis is based on a prior paper and additionally seeks to address an …

Orbital Determination Feasibility Of Leo Nanosatellites Using Small Aperture Telescopes, Michael R. Strange

Master's Theses

This thesis is directed toward the feasibility of observing satellites on the nano scale and determining an accurate propagated orbit using a Meade LX600-ACF 14” diameter aperture telescope currently located on the California Polytechnic State University campus. The optical telescope is fitted with an f/6.3 focal reducer, SBIG ST-10XME CCD camera and Optec TCF-S Focuser. This instrumentation allowed for a 22’ X 15’ arcminute FOV in order to accurately image passing LEO satellites. Through the use of the Double-r and Gauss Initial Orbit Determination methods as well as Least Squared Differential Correction and Extended Kalman Filter Orbit Determination methods, an …

Decibel Notes, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A class notes on "Decibel Notes" created by Professor Bob Twiggs on February 27, 2017.

Phonon Interference In Crystalline And Amorphous Confined Nanoscopic Films, Zhi Liang, Thomas E. Wilson, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Using Molecular Dynamics Phonon Wave Packet Simulations, We Study Phonon Transmission Across Hexagonal (H)-BN and Amorphous Silica (A-SiO₂) Nanoscopic Thin Films Sandwiched by Two Crystalline Leads. Due to the Phonon Interference Effect, the Frequency-Dependent Phonon Transmission Coefficient in the Case of the Crystalline Film (Si|h-BN|Al Heterostructure) Exhibits a Strongly Oscillatory Behavior. in the Case of the Amorphous Film (Si|a-SiO₂|Al and Si|a-SiO₂|Si Heterostructures), in Spite of Structural Disorder, the Phonon Transmission Coefficient Also Exhibits Oscillatory Behavior at Low Frequencies (Up to ∼1.2 THz), with a Period of Oscillation Consistent with the Prediction from the Two-Beam …

Surrogate Modeling Of Ultrasonic Simulations Using Data-Driven Methods, Xiaosong Du, Robert Grandin, Leifur Leifsson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Ultrasonic testing (UT) is used to detect internal flaws in materials and to characterize material properties. In many applications, computational simulations are an important part of the inspection-design and analysis processes. Having fast surrogate models for UT simulations is key for enabling efficient inverse analysis and model-assisted probability of detection (MAPOD). In many cases, it is impractical to perform the aforementioned tasks in a timely manner using current simulation models directly. Fast surrogate models can make these processes computationally tractable. This paper presents investigations of using surrogate modeling techniques to create fast approximate models of UT simulator responses. In particular, …

In-House Fabrication Of Temperature Sensitive Paint For Turbine Cooling Research, Mayur D. Patel, Mark A. Ricklick

Beyond: Undergraduate Research Journal

The Temperature Sensitive Paint (TSP) is a widely used method in measuring and visualizing flow separation and heat transfer. Compared to the cost and time consumption needed for methods such as pitot tubes, temperature sensitive paint is a cheaper alternative. Due to high usage in College of Engineering research projects, it was determined that in house fabrication of temperature sensitive paint would reduce time and cost limitations. For initial stages, literature research was performed to determine the recipe of intensity based TSP with luminophore and polymer binder that operated optimum at temperatures from 0-100°C. Europium III thenoyltrifluoroacetonate was determined to …

Method And Apparatus For Singularity Avoidance For Control Moment Gyroscope (Cmg) Systems Without Using Null Motion, Brij N. Agrawal, Jae Jun Kim, Timothy Andrew Sands

AFIT Patents

A method is described for avoiding gyroscopic singularities during attitude correction to a system, such as a spacecraft having a CMG array. The method receives a corrective torque vector μ and gimbal angle values δ for each of at least three gimbals within the CMG array. The method generates a Jacobian matrix A as a function of gimbal angle values δ. The method calculates a determinant D of Jacobian matrix A. If the determinant is not equal to zero, it is not singular, and the method calculates a gimbal rate {dot over (δ)} using a pseudo-inverse steering law equation. If …

Determining Power For A Cubesat, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Determining Power for a CubeSat" from February 3, 2017.

The Effect Of Biocomposite Material In A Composite Structure Under Compression Loading, Benjamin Andrew Sweeney

Master's Theses

While composite structures exhibit exceptional strength and weight saving possibilities for engineering applications, sometimes their overall cost and/or material performance can limit their usage when compared to conventional structural materials. Meanwhile ‘biocomposites’, composite structures consisting of natural fibers (i.e. bamboo fibers), display higher cost efficiency and unique structural benefits such as ‘sustainability’. This analysis will determine if the integration of these two different types of composites are beneficial to the overall structure. Specifically, the structure will consist of a one internal bamboo veneer biocomposite ply; and two external carbon fiber weave composite plies surrounding the bamboo biocomposite. To acquire results …

Professional Pilot Commercial Off-The-Shelf (Cots) Efb Usage, Policies And Reliability, Tyler A. Babb

International Journal of Aviation, Aeronautics, and Aerospace

Electronic Flight Bags (EFBs) have flooded the aviation industry. Commercial off-the-shelf (COTS) tablets are now commonly used by pilots as EFBs. Operators use EFBs for ease of use, faster access to information, to remove weight from the aircraft, and to increase pilots’ quality of life. Identifying trends in EFB usage among professional pilots could benefit operators and universities with flight training programs. EFB policies and procedures may vary among operators but achieve FAA compliance. This study identified these policies and procedures. The types of devices and software vary, and identifying these devices and software could be useful. This research used …

The Effects Of Using Noise Reduction Turbofan Engine Nozzle Designs On A Turbojet Engine, Donald Bartlett

Journal of Applied Sciences and Arts

Abstract

Aircraft noise is a complex topic which is projected to increase with the increasing number of aircraft and size of the engines. Turbine-powered aircraft produce sounds that are considered pollutants at certain decibel levels. Turbofan engines are inherently quieter than turbojet engines for a given level of thrust. The purpose of this research is to determine if current turbofan noise reduction nozzles could reduce the amount of noise for turbojet engines at two different thrust levels. Three turbofan engine nozzles were designed and tested on a turbojet engine. Decibel levels of 30 frequencies for each of the nozzles were …

An Archival Analysis Of Stall Warning System Effectiveness During Airborne Icing Encounters, John Michael Maris

Doctoral Dissertations and Master's Theses

An archival study was conducted to determine the influence of stall warning system performance on aircrew decision-making outcomes during airborne icing encounters. A Conservative Icing Response Bias (CIRB) model was developed to explain the historical variability in aircrew performance in the face of airframe icing. The model combined Bayes’ Theorem with Signal Detection Theory (SDT) concepts to yield testable predictions that were evaluated using a Binary Logistic Regression (BLR) multivariate technique applied to two archives: the NASA Aviation Safety Reporting System (ASRS) incident database, and the National Transportation Safety Board (NTSB) accident databases, both covering the period January 1, 1988 …

Reference Slides, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation of "Reference Slides" created by Professor Bob Twiggs from January 18, 2017.

An Exciting Opportunity To Advance Stem Education With Femto-Satellites, Dale Nash

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Dale Nash titled "An Exciting Opportunity to Advance STEM Education with Femto-satellites" from January 16, 2017.

Tu-Pod: Launched From The International Space Station, Amin Djamshidpour, Bob Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs and Amin Djamshidpour titled "TU-POD: Launched from the International Space Station" from January 16, 2017.

Image And Information Fusion Experiments With A Software-Defined Multi-Spectral Imaging System For Aviation And Marine Sensor Networks, Sam B. Siewert, Matthew Demi Vis, Ryan Claus, Ramnarayan Krishnamurthy, Surjith B. Singh, Akshay K. Singh, Shivasankar Gunasekaran

Publications

The availability of Internet, line-of-sight and satellite identification and surveillance information as well as low-power, low-cost embedded systems-on-a-chip and a wide range of visible to long-wave infrared cameras prompted Embry Riddle Aeronautical University to collaborate with the University of Alaska Arctic Domain Awareness Center (ADAC) in summer 2016 to prototype a camera system we call the SDMSI (Software-Defined Multi-spectral Imager). The concept for the camera system from the start has been to build a sensor node that is drop-in-place for simple roof, marine, pole-mount, or buoy-mounts. After several years of component testing, the integrated SDMSI is now being tested, first …

Rans Simulations Of Aerodynamic Performance Of Naca 0015 Flapped Airfoil, Sohaib Obeid, Ratneshwar Jha, Goodarz Ahmadi

Henry M. Rowan College of Engineering Departmental Research

An analysis of 2D subsonic flow over an NACA 0015 airfoil with a 30% trailing edge flap at a constant Reynolds number of 106 for various incidence angles and a range of flap deflections is presented. The steady-state governing equations of continuity and momentum conservation are solved combined with the realizable k-ε turbulence model using the ANSYS-Fluent code (Version 13.7, ANSYS, Inc., Canonsburg, PA, USA). The primary objective of the study is to provide a comprehensive understanding of flow characteristics around the NACA 0015 airfoil as a function of the angle of attack and flap deflection at Re = 106 …

Multi-Stage Nozzle-Shape Optimization For Pulsed Hydrogen-Air Detonation Combustor, Francesco Ornano, James Braun, Bayindir H. Saracoglu, Guillermo Paniagua

School of Aeronautics and Astronautics Faculty Publications

hermal engines based on pressure gain combustion offer new opportunities to generate thrust with enhanced efficiency and relatively simple machinery. The sudden expansion of detonation products from a single-opening tube yields thrust, although this is suboptimal. In this article, we present the complete design optimization strategy for nozzles exposed to detonation pulses, combining unsteady Reynolds-averaged Navier-Stokes solvers with the accurate modeling of the combustion process. The parameterized shape of the nozzle is optimized using a differential evolution algorithm to maxi­ mize the force at the nozzle exhaust. The design of experiments begins with a first optimization considering steady-flow conditions, subsequently …

Multi-Stage Axial Compressor With Counter-Rotation, Vinod Gehlot, Magdy S. Attia, Divyam Garg

Publications

A multi-stage axial compressor incorporating a counter-rotational movement is provided with a series of rotors mounted along and driven by a driveshaft, and a geared counter-rotating outer casing. A planetary gear system is assembled along a static casing, which can be assembled as a forward or aft casing for the compressor. The bearings of the planetary gear system typically will be aligned concentrically with a center rotor drum assembly mounted along the single driveshaft. The counter-rotating drum assembly will be assembled over the rotor drum assembly and will be engaged by the forward and aft casings so as to provide …

A Multiscale Model For Damage Progression And Detection In Piezo/Pyroelectric Composite Laminates, Yehia Bahei-El-Din, Amany Micheal

Centre for Advanced Materials

Assessment of damage initiation and progression in composite structures reinforced with electrically active filaments is modelled in a multiscale analysis. The analysis developed is a two-tier, interactive analysis, which involves two length scales; macroscopic, and microscopic. The proposed multiscale analysis provides seamless integration of the mechanics at the two length scales, including piezoelectric and pyroelectric coupling effects and damage under overall thermomechanical loads and an electric field applied to electroactive fibers. The macromechanical analysis is performed for multidirectional, fibrous laminates using the lamination theory, including bending, and the micromechanical analysis is performed using a two-phase model and a periodic array …

The Gettysburg Economic Review, Volume 10, Spring 2017

Gettysburg Economic Review

No abstract provided.

Detecting Laminate Damage Using Embedded Electrically Active Plies – An Analytical Approach, Amany Micheal, Yehia Bahei-El-Din

Centre for Advanced Materials

Assessment of damage initiation and progression in composite laminates with embedded electrically active plies is modeled. Utilizing electrically active layers embedded in composite laminates as damage sensors is proposed by several researchers and is mainly assessed experimentally. Sensing damage using embedded electrically active plies is generally preferred over the use of surface mounted PZT wafers since the range of the latter is limited to a very narrow area underneath the surface, while multiple damage mechanisms can generally be found in several plies of the laminate. The solution presented invokes two levels of analysis. Firstly, on the laminate level, applied membrane …

The Effects Of Airline Behavior On Aircraft Accidents, Anneliese S. Brown

Gettysburg Economic Review

The purpose of this paper is to study the effects of specific airline business decisions on aircraft accident propensity. Airline safety affects everyone and has large regulatory and policy implications. Existing research has focused largely on three areas: airline financial health, safety and the resulting effects of accidents. I use both Poisson and Negative Binomial models to study two different airline features: low-cost carriers and flight length, and how they relate to the probability of an aircraft accident. Based on results using a Generalized Negative Binomial model, I find statistically significant evidence at the 99% confidence level that a 1-unit …

Utilizing Ground-Based Lidar Measurements To Aid Autonomous Airdrop Systems, Martin Cacan, Edward Scheuermann, Michael Ward, Mark Costello, Nathan Slegers

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Uncertainty in atmospheric winds represents one of the primary sources of landing error in airdrop systems. In this work, a ground-based LIDAR system samples the wind field at discrete points above the target and transmits real-time data to approaching autonomous airdrop systems. In simulation and experimentation, the inclusion of a light detection and ranging (LIDAR) system showed a maximum of 40% improvement over unaided autonomous airdrop systems. Wind information nearest ground level has the largest impact on improving accuracy.

Vtol Hybrids: Tiltrotors Are Gaining Acceptance, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

Optimal Trajectory Determination And Mission Design For Asteroid/Deep-Space Exploration Via Multibody Gravity Assist Maneuvers, Sean Fritz, Kamran Turkoglu

Faculty Publications

This paper discusses the creation of a genetic algorithm to locate and optimize interplanetary trajectories using gravity assist maneuvers to improve fuel efficiency of the mission. The algorithm is implemented on two cases: (i) a Centaur-class target close to the ecliptic plane and (ii) a Centaur-class target with a high inclination to the ecliptic plane. Cases for multiple numbers of flybys (up to three) are discussed and compared. It is shown that, for the targets considered here, a single flyby of Jupiter is the most efficient trajectory to either target with the conditions and limitations discussed in this paper. In …