Open Access. Powered by Scholars. Published by Universities.®

Aerospace Engineering Commons

Open Access. Powered by Scholars. Published by Universities.®

5,808 Full-Text Articles 7,205 Authors 2,171,447 Downloads 121 Institutions

All Articles in Aerospace Engineering

Faceted Search

5,808 full-text articles. Page 192 of 199.

Reducing Orbit Covariance For Continuous Thrust Spacecraft Transfers, Scott Zimmer, Oscar Ocampo, Robert H. Bishop 2010 Marquette University

Reducing Orbit Covariance For Continuous Thrust Spacecraft Transfers, Scott Zimmer, Oscar Ocampo, Robert H. Bishop

Mechanical Engineering Faculty Research and Publications

The calculus of variations is used to develop the necessary theory and derive the optimality conditions for a spacecraft to transfer between a set of initial and final conditions, while minimizing a combination of fuel consumption and a function of the estimation error covariance matrix associated with the spacecraft state. The theory is developed in a general manner that allows for multiple observers, moving observers, covariance associated with an arbitrary frame, a wide variety of observation types, multiple gravity bodies, and uncertainties in the spacecraft equations of motion based on the thrusting status of the engine. A series of example ...


Efficient Models For The Evaluation And Estimation Of The Gravity Field, Brandon Allan Jones 2010 University of Colorado, Boulder

Efficient Models For The Evaluation And Estimation Of The Gravity Field, Brandon Allan Jones

Aerospace Engineering Sciences Graduate Theses & Dissertations

Current astrodynamics applications require a rapid evaluation of the gravity field and an efficient approach to gravity estimation. The commonly used spherical harmonic model does not meet either of these needs. To address these issues, this research considers two new gravity representations: the cubed-sphere and the MRQSphere models. Offering a means for rapid evaluation, the cubed-sphere model yields an effectively constant computation time for any degree of the modeled gravity field. Analyzing the model's performance in a series of Monte-Carlo-like tests characterizes its effects on both orbit propagation and determination. When compared to the spherical harmonic gravity model, the ...


Inter Spem Et Metum, Fiat Lux, Michael A. Mota 2010 Rhode Island College

Inter Spem Et Metum, Fiat Lux, Michael A. Mota

Honors Projects Overview

Explores the design and development of a simple, 3D flight simulator. The resulting application allows users to pilot an abstract human avatar and to create free-hand strokes and physically-based explosions onto the environment through a ball discharge meta-game feature. Uses the C++ language, and the ancillary programming API libraries, OpenGL, GLEW, and Win32.


High Order Finite Elements For Lagrangian Computational Fluid Dynamics, Truman Everett Ellis 2010 California Polytechnic State University - San Luis Obispo

High Order Finite Elements For Lagrangian Computational Fluid Dynamics, Truman Everett Ellis

Master's Theses and Project Reports

A general finite element method is presented to solve the Euler equations in a Lagrangian reference frame. This FEM framework allows for separate arbitrarily high order representation of kinematic and thermodynamic variables. An accompanying hydrodynamics code written in Matlab is presented as a test-bed to experiment with various basis function choices. A wide range of basis function pairs are postulated and a few choices are developed further, including the bi-quadratic Q2-Q1d and Q2-Q2d elements. These are compared with a corresponding pair of low order bi-linear elements, traditional Q1-Q0 and sub-zonal pressure Q1-Q1d. Several test problems are considered including static convergence ...


Assessing The V2-F Turbulence Models For Circulation Control Applications, Travis M. Storm 2010 California Polytechnic State University – San Luis Obispo

Assessing The V2-F Turbulence Models For Circulation Control Applications, Travis M. Storm

Master's Theses and Project Reports

In recent years, airports have experienced increasing airport congestion, partially due to the hub-and-spoke model on which airline operations are based. Current airline operations utilize large airports, focusing traffic to a small number of airports. One way to relieve such congestion is to transition to a more accessible and efficient point-to-point operation, which utilizes a large web of smaller airports. This expansion to regional airports propagates the need for next-generation low-noise aircraft with short take-off and landing capabilities. NASA has attacked this problem with a high-lift, low-noise concept dubbed the Cruise Efficient Short Take-Off and Landing (CESTOL) aircraft. The goal ...


Stability Of Fully Nonlinear Stokes Waves On Deep Water: Part 1. Perturbation Theory, Shahrdad Sajjadi, David L. Ross 2010 Embry-Riddle Aeronautical University

Stability Of Fully Nonlinear Stokes Waves On Deep Water: Part 1. Perturbation Theory, Shahrdad Sajjadi, David L. Ross

Publications

We consider a full set of harmonics for the Stokes wave in deep water in the absence of viscosity, and examine the role that higher harmonics play in modifying the classical Benjamin-Feir instability. Using a representation of the wave coefficients due to Wilton, a perturbation analysis shows that the Stokes wave may become unbounded due to interactions between the Nth harmonic of the primary wave train and a set of harmonics of a disturbance. If the frequency of the nth harmonic is denoted n = Ꙍ(1 ± ꭉ) then instability will occur if

√2 k nn sn ...


Analysis Of Helicopter Downwash/Frigate Airwake Interaction Using Statistically Designed Experiments, Yavuz Nacakli 2010 Old Dominion University

Analysis Of Helicopter Downwash/Frigate Airwake Interaction Using Statistically Designed Experiments, Yavuz Nacakli

Mechanical & Aerospace Engineering Theses & Dissertations

A research program to investigate helicopter downwash/frigate airwake interaction has been initiated using a statistically robust experimental program featuring Design of Experiments. Engineering analysis of the helicopter/frigate interface is complicated by the fact that two flowfields become inherently coupled as separation distance decreases. The final objective of this work is to develop experimental methods to determine when computer simulations need to include the effects of a coupled flowfield versus using a simplified representation by superposing the velocity fields of the individual flowfields. The work presented was performed in the Old Dominion University Low Speed Wind Tunnel using a ...


Hybrid Intelligent Optimization Methods For Engineering Problems, Yasin Volkan Pehlivanoglu 2010 Old Dominion University

Hybrid Intelligent Optimization Methods For Engineering Problems, Yasin Volkan Pehlivanoglu

Mechanical & Aerospace Engineering Theses & Dissertations

The purpose of optimization is to obtain the best solution under certain conditions. There are numerous optimization methods because different problems need different solution methodologies; therefore, it is difficult to construct patterns. Also mathematical modeling of a natural phenomenon is almost based on differentials. Differential equations are constructed with relative increments among the factors related to yield. Therefore, the gradients of these increments are essential to search the yield space. However, the landscape of yield is not a simple one and mostly multi-modal. Another issue is differentiability. Engineering design problems are usually nonlinear and they sometimes exhibit discontinuous derivatives for ...


Flight Tracking And Messaging Systems, Steven Heindel 2010 Messiah College

Flight Tracking And Messaging Systems, Steven Heindel

Honors Projects and Presentations: Undergraduate

The Flight Tracking and Messaging Systems (FTMS) project seeks to meet the tracking and messaging needs of small aircraft operated by missionary pilots. FTMS has built upon the work of several previous senior projects at Messiah College, and has adapted and upgraded an existing but obsolete flight tracking system known as AFFS to serve UIM. At the end of the 2009/2010 school year, the modified system has been partially prototyped, including the pilot interface.


Reducing Orbit Covariance For Continuous Thrust Spacecraft Transfers, Robert Bishop 2010 Marquette University

Reducing Orbit Covariance For Continuous Thrust Spacecraft Transfers, Robert Bishop

Robert H Bishop

No abstract provided.


Follow Up Nucleate Boiling On-Flight Experiment, Andrew Fassmann 2010 Utah State University

Follow Up Nucleate Boiling On-Flight Experiment, Andrew Fassmann

Presentations

No abstract provided.


Compression Testing Of Composite Laminated Foam Under Thermal Loading And With Central Holes, Dominic Surano, Jonathan Russo, Daniel Leighton 2010 California Polytechnic State University - San Luis Obispo

Compression Testing Of Composite Laminated Foam Under Thermal Loading And With Central Holes, Dominic Surano, Jonathan Russo, Daniel Leighton

Aerospace Engineering

A study was conducted to investigate the effect of heat on composite sandwich plates, fabricated with the vacuum resin infusion process, with center holes of varying diameters. The study involved conventional notched specimens and notched specimens with shear keys, both of which were subjected to monotonic inplane compression loading. Hole diameter was be varied from one to four inches in one inch increments. Loading rate was applied using the Instron machine at one millimeter per minute. The diameter of the shear key around the holes varied from one inch to four inches in one inch increments. The specimens were placed ...


Disturbance Observer: Design And Flight Test Of A Large Envelope Flight Controller, Donevan A. Rein 2010 Air Force Institute of Technology

Disturbance Observer: Design And Flight Test Of A Large Envelope Flight Controller, Donevan A. Rein

Theses and Dissertations

A new flight controller was evaluated through piloted simulation and flight test conducted at the USAF Test Pilot School. The controller, commonly called a disturbance observer, uses inertial sensor feedback routed through a simple control architecture that acts to force the desired response while rejecting sensor noise and atmospheric disturbances. The investigation included both handling qualities testing in the Octonian simulator at the Air Force Research Laboratories Air Vehicle Directorate, and initial flight test conducted as part of a Test Management Project at the USAF TPS. Simulation produced positive results with desired performance throughout a wide flight envelope. In addition ...


Verification Of Kam Theory On Earth Orbiting Satellites, Christian L. Bisher 2010 Air Force Institute of Technology

Verification Of Kam Theory On Earth Orbiting Satellites, Christian L. Bisher

Theses and Dissertations

This paper uses KAM torus theory and Simplified General Perturbations 4 (SGP4) orbit prediction techniques compiled by Dr. William Wiesel and compares it to Analytical Graphics ® Incorporated (AGI) Satellite Toolkit ® (STK) orbit data. The goal of this paper is to verify KAM torus theory can be used to describe and propagate an Earth satellite orbit with similar accuracy to existing general perturbation techniques. Using SGP4 code including only truncated geopotential effects, KAM torus generating code, and other utilities were used to describe a particular satellite orbit as a torus and then propagate the satellite using traditional and KAM torus techniques ...


Numerical Investigation Of Pre-Detonator Geometries For Pde Applications, Robert T. Fievisohn 2010 Air Force Institute of Technology

Numerical Investigation Of Pre-Detonator Geometries For Pde Applications, Robert T. Fievisohn

Theses and Dissertations

A parametric study was performed to determine optimal geometries to allow the successful transition of a detonation from a pre-detonator into the thrust tube of a pulse detonation engine. The study was performed using a two-dimensional Euler solver with progress variables to model the chemistry. The geometrical configurations for the simulations look at the effect of shock reflections, flow obstructions, and detonation diffraction to determine successful geometries. It was observed that there are success and failure rates associated with pre-detonators. These success rates appear to be determined by the transverse wave structure of a stably propagating detonation wave and must ...


A Structural Dynamic Analysis Of A Manduca Sexta Forewing, Travis W. Sims 2010 Air Force Institute of Technology

A Structural Dynamic Analysis Of A Manduca Sexta Forewing, Travis W. Sims

Theses and Dissertations

Micro air vehicles (MAVs) are intended for future intelligence, surveillance, and reconnaissance use. To adequately fulfill a clandestine capacity, MAVs must operate in close proximity to their intended target without eliciting counter-observation. This objective, along with DARPA’s constraint of a sub-15 centimeter span, requires future MAVs to mimic insect appearance and flight characteristics. This thesis describes an experimental method for conducting a structural analysis of a Manduca Sexta (hawkmoth) forewing. Geometry is captured via computed tomography (CT), and frequency data is collected using laser vibrometry in air and vacuum. A finite element (FE) model is constructed using quadratic beams ...


Consideration Of Wear Rates At High Velocities, Stephen P. Meador 2010 Air Force Institute of Technology

Consideration Of Wear Rates At High Velocities, Stephen P. Meador

Theses and Dissertations

The goal of this research is to study sliding contact wear of test sled slippers at high velocities. Experimentation representative of the slippers is infeasible, so numerical studies are used. An Eulerian-Lagrangian hydrocode called CTH is used to study mechanical wear. Failure criteria have been established to evaluate the stresses and strains resulting from the hydrocode simulation of a single asperity collision. The results from the hydrocode simulations are scaled to account for slipper bounce and multiple asperities, and these results produce total wear values that are approximately 90% of total experimental wear. Slipper thermodynamics have also been evaluated. The ...


Part Count: Monolithic Part Effects On Manufacturing Labor Cost, An Aircraft Applied Model, Aaron M. Lemke 2010 Air Force Institute of Technology

Part Count: Monolithic Part Effects On Manufacturing Labor Cost, An Aircraft Applied Model, Aaron M. Lemke

Theses and Dissertations

There are significantly different manufacturing processes and part counts associated with composites that are not currently addressed within the aircraft procurement and life cycle management processes in the Department of Defense (DoD). A series of affordability initiatives have culminated in significant evidence over the last decade to better quantify the impact of primarily composite structures in aircraft. An Air Force Research Laboratory program, Advanced Composite Cargo Aircraft (ACCA), provides substantial support for the impact of part size on life cycle cost for payload aircraft. This research evaluates select methods used and seeks to introduce modifications to the projected manufacturing hours ...


Mechanical Properties Characterization And Business Case Analysis Of The Fiber Metal Laminate Glare-3 For Use As Secondary Aircraft Structure, Benjamin O. Elton 2010 Air Force Institute of Technology

Mechanical Properties Characterization And Business Case Analysis Of The Fiber Metal Laminate Glare-3 For Use As Secondary Aircraft Structure, Benjamin O. Elton

Theses and Dissertations

This effort explored the mechanical characteristics and economic feasibility of using the fiber metal laminate, GLARE-3, as a secondary aircraft structure; specifically, the cargo floor of a C-130. The mechanical properties were determined through static four-point bending and tensile testing and dynamic impact testing. Aggregate behavior of the constituent materials was predicted using a model which consisted of Mass Volume Fraction (MVF) and Classical Laminated Plate Theory (CLPT) methods using known values for the constituents. Static testing was conducted on coupon-level specimens using standardized testing procedures. Static tensile tests were conducted on specimens with four different fiber orientations, 0°, 22 ...


Development Of Morphing Aircraft Using Smp, Soo-Chan Jee 2010 Air Force Institute of Technology

Development Of Morphing Aircraft Using Smp, Soo-Chan Jee

Theses and Dissertations

The U.S Air Force needs new aircraft which provide longer flight time, less fuel consumption, better aerodynamics in order to perform Air Force missions successfully as the mission environment changes rapidly. A morphing wing aircraft is considered as a potential new aircraft for those missions. This thesis explores Shape Memory Polymer (SMP) properties test results and its application for morphing wing skin. Several SMP composite laminates were considered for investigating shape changing characteristics required for morphing skin. The braided composite preforms used in making SMP composites were explored in morphing wing operating system based on the results of property ...


Digital Commons powered by bepress