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

Aerospace Engineering Commons™

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

PDF

1992

Discipline
Institution
Keyword
Publication
Publication Type

Articles 1 - 30 of 67

Full-Text Articles in Aerospace Engineering

Utilizing Instructional Design Constructs To Enhance Computer-Based Instruction In Air Traffic Controller Training, Theodore Scott Rhoads Dec 1992

Utilizing Instructional Design Constructs To Enhance Computer-Based Instruction In Air Traffic Controller Training, Theodore Scott Rhoads

Master's Theses - Daytona Beach

This study demonstrates that a computer-based instructional design format is appropriate for novice air traffic control (ATC) training. The computer presents the student with small amounts of information in tutorial and drill and practice sequences that necessitate student interactivity. The student is then periodically audit tested to ascertain mastery of the subject matter. The result of these mid-lesson evaluations serve as a self-check so that the student can assess his/her progress in the learning cycle. The systematic design of instruction and interactive approach to learning, enhances student motivation, improves learning and retention, while placing the responsibility of achieving specific learning …

Go to article

Thermally Induced Vibration Of A Cross-Ply Laminated Plate With Hygrothermal Effects (Exact Solution), Stephen Jerry Maerz Dec 1992

Thermally Induced Vibration Of A Cross-Ply Laminated Plate With Hygrothermal Effects (Exact Solution), Stephen Jerry Maerz

Master's Theses - Daytona Beach

Of increasing importance in structural design is the use of fiber-reinforced polymeric composite material, notably in advanced aircraft and projectiles. These applications expose the materials to varied environmental conditions, therefore the material performance under these conditions is of great interest. One aspect of this is the solution of the dynamic response of a composite structure under elevated temperature and moisture conditions. An exact solution is formulated which describes the hygrothermal effects due to heating and moisture diffusion on one surface of a symmetric cross-ply plate made of AS/3501 graphite epoxy with simply-supported boundary conditions.

Go to article

Isolating Failure Mechanisms In A Fiberglass/Epoxy Tensile Test Specimen Using Acoustic Emission Signal Parameters, Michael Kouvarakos Dec 1992

Isolating Failure Mechanisms In A Fiberglass/Epoxy Tensile Test Specimen Using Acoustic Emission Signal Parameters, Michael Kouvarakos

Master's Theses - Daytona Beach

This study used acoustic emission (AE) signal parameters to isolate the failure mechanisms in a 0° unidirectional, fiberglass/epoxy tensile test specimen. Since several failure mechanisms were known to be present, the lack of any distinctly identifiable bands in the original amplitude distribution indicated that there was considerable overlap between the AE signals of the various failure mechanisms. In order to separate the amplitude bands associated with each mechanism, it was necessary to sort on the duration of the AE signal. Two additional plots, counts versus amplitude and hits versus counts, were used to verify that the amplitude distributions were comprised …

Go to article

Total Hemispherical Emittance Of Niobium-1% Zirconium Fuel Cladding For The Sp-100 Space Reactor, John E. Thomason Iii Dec 1992

Total Hemispherical Emittance Of Niobium-1% Zirconium Fuel Cladding For The Sp-100 Space Reactor, John E. Thomason Iii

Theses and Dissertations

Total hemispherical emittance was measured for the SP-100 reactor fuel cladding alloy (Nb-l% Zr). Based on a standard test method (ASTM C 835-82), experiments were conducted on a reference sample of oxidized stainless steel and then on a sample of actual cladding. The sample is heated in a vacuum by passing DC current through it until reaching equilibrium. Measurements are made of the electrical power dissipated in the sample and of the surface temperature. Using the Stefan-Boltzmann Law and some key assumptions concerning conductive and radiative heat transfer, the measured quantities are used to calculate emittance. Calculated values for unoxidized …

Go to article

A Model Of Global Positioning System (Gps) Master Control Station (Mcs) Operations, David N. Koster Dec 1992

A Model Of Global Positioning System (Gps) Master Control Station (Mcs) Operations, David N. Koster

Theses and Dissertations

The United States Air Force's Navstar Global Positioning System (GPS) provides high-accuracy space-based navigation and time distribution to suitably- equipped military and civilian users. The system consists of earth-orbiting satellites and a world-wide network of ground stations. A single operational control center, the GPS Master Control Station (MCS) monitors, maintains, and commands the GPS satellite constellation. The on-going deployment of the complete satellite constellation and recent changes in the operational crew structure may invalidate previously used planning and management paradigms. There is currently no analytical method for predicting the impact of these and other environmental changes on system parameters and …

Go to article

Effect Of Transverse Vibration On The Capillary Limit Of A Wrapped Screen Wick Copper/Water Heat Pipe, Mark C. Charlton Dec 1992

Effect Of Transverse Vibration On The Capillary Limit Of A Wrapped Screen Wick Copper/Water Heat Pipe, Mark C. Charlton

Theses and Dissertations

The effect of transverse vibration on the capillary limit of a copper/water heat pipe with a tightly wrapped screen wick was investigated. The capillary limit was measured over a range of operating temperatures under static conditions. A bench-top shaker was used to provide vibration normal to the longitudinal axis of the pipe, and the capillary limit was measured at vibration frequencies of 30, 250, and 1000 Hz. At each of these frequencies, tests were run at vibration levels of 1.0, 2.5, and 5.0 G. The pipe was maintained at a zero degree inclination angle and power throughput was increased until …

Go to article

An Experimental Determination Of The Effects Of Blending Collocated And Non-Collocated Sensor Measurements To Control A Flexible Structure, Richard G. Cobb Dec 1992

An Experimental Determination Of The Effects Of Blending Collocated And Non-Collocated Sensor Measurements To Control A Flexible Structure, Richard G. Cobb

Theses and Dissertations

An experimental investigation was performed controlling a cantilevered beam in bending using proportional feedback on a blend of collocated and non-collocated sensor measurements using a single actuator. Exact transfer functions between the control input and the measurements were developed and compared to the finite element method. By analyzing the open loop pole-zero locations as a function of the measurement blending, insight into the closed loop behavior is obtained. Minimum phase behavior can be maintained for a range of the blending ratio. Results using blended control were compared to both proportional collocated feedback and compensated collocated feedback using LQG methods. The …

Go to article

Nonlinear Large Displacement And Moderate Rotational Characteristics Of Composite Beams Incorporating Transverse Shear Strain, Stephen G. Creaghan Dec 1992

Nonlinear Large Displacement And Moderate Rotational Characteristics Of Composite Beams Incorporating Transverse Shear Strain, Stephen G. Creaghan

Theses and Dissertations

This research was directed toward the investigation of nonlinear large displacements and moderate rotations of composite beam structures considering a finite element potential energy approach incorporating through the thickness shear strain as an analytical function. This approach was compared to large rotation theories. Test cases were run to evaluate numerical algorithms Riks method and displacement imposed techniques were employed. The limitations and advantages of both methods were considered. Loading arrangements included concentrated forces as well as moments.

Go to article

Extended Lyapunov Exponents For Second Order Systems, Janice M. Horn Dec 1992

Extended Lyapunov Exponents For Second Order Systems, Janice M. Horn

Theses and Dissertations

It is shown that the concept of the Lyapunov exponent can be extended to include an imaginary part. A numerical technique used to calculate these extended Lyapunov exponents for second order systems is presented. There are two requirements to make this extension possible: the definition of a coordinate frame on the tangent space of the differential equation, and an extension of the classical limit, called the limit of the mean. An application of the technique to the van der Pol equation for the constant coefficient and periodic coefficient cases is given. The extended Lyapunov exponents found using this technique totally …

Go to article

An Approximate Solution For The Linearized Spinup Dynamics Of A Dual-Spin Spacecraft, David L. Kinney Dec 1992

An Approximate Solution For The Linearized Spinup Dynamics Of A Dual-Spin Spacecraft, David L. Kinney

Theses and Dissertations

An approximate solution is obtained for the linearized equations of motion for the spinup dynamics of a dual-spin spacecraft. The approximation is obtained from the WKB (Wentzel, Kramers, and Brillouin) method, which usually generates a divergent series. Comparison between the WKB solution and the numerically integrated solution are used to study the effects of spinup torque magnitude and the number of WKB terms used on the accuracy of the approximation. The WKB method generates accurate approximations for small spinup torques using as few as two terms in the series when no singularities are present in the WKB terms during the …

Go to article

An Electromagnetically-Controlled Precision Orbital Tracking Vehicle (Potv), Richard E. Lawrence Jr. Dec 1992

An Electromagnetically-Controlled Precision Orbital Tracking Vehicle (Potv), Richard E. Lawrence Jr.

Theses and Dissertations

A propulsion configuration it defined for a precision orbital tracking vehicle (POTV) that employs electrodynamic forces to control vehicle attitude and position with respect to another spacecraft. A pair of electrically powered thrusters assist the POTV in position control. The vehicle can maintain continuous standoff at close range from another spacecraft in any direction, has docking capability, and has gross orbital transfer capability. These capabilities and the specific design derived for the POTV have been defined by the requirements of a postulated space facility (ASSET) that salvages structural aluminum from the external fuel tank of the space shuttle. Precision control …

Go to article

Canonical Floquet Perturbation Theory, David J. Pohlen Dec 1992

Canonical Floquet Perturbation Theory, David J. Pohlen

Theses and Dissertations

Classical Floquet theory is examined in order to generate a canonical transformation to modal variables for periodic system This transformation is considered canonical if the periodic matrix of eigenvectors is symplectic at the initial time. Approaches for symplectic normalization of the eigenvectors had to be examined for each of the different Poincare eigenvalue cases. Particular attention was required in the degenerate case, which depended on the solution of a generalized eigenvector. Transformation techniques to ensure real modal variables and real periodic eigenvectors were also needed. Periodic trajectories in the restricted three-body case were then evaluated using the canonical Floquet solution. …

Go to article

Passive Damping Of A Solar Array, Mark A. Scharpen Dec 1992

Passive Damping Of A Solar Array, Mark A. Scharpen

Theses and Dissertations

This study was an attempt to conceptualize, design, build, and test a constrained layer damping device that uses mechanical advantage for the purpose of increasing the damping of transient vibration of a five-bay planar truss. The aluminum truss was clamped to a fixed support and simulated a solar array. A conventional constrained layer treatment was designed, built, and tested to serve as a benchmark for comparison. For the conventional treatment, Plunkett and Lee's segmented constraining layer technique was used. The improved device, two three-layer sandwich beams spanning the two bays nearest the built-in end, were supported several inches away from …

Go to article

Data Reduction With Least Squares Differential Correction Using Equinoctial Elements, Michael S. Wasson Dec 1992

Data Reduction With Least Squares Differential Correction Using Equinoctial Elements, Michael S. Wasson

Theses and Dissertations

This study investigates earth satellite orbit estimation on a track of range, azimuth, and elevation data from a single tracking station. The estimation routine is a least squares batch filter based solely on two-body orbital motion. Using equinoctial elements for the reference orbit avoids the numerical difficulties of the classical elements at eccentricities near zero and inclinations near zero or 90 degrees. Orbits for Mir, DMSP, Explorer, Cosmos, and GPS are investigated. The goal of this study is to reduce orbit information from observations (range, azimuth, and elevation) to an element set and a covariance matrix without considering perturbation effects. …

Go to article

Nozzle/Cowl Optimization For A Hypersonic Vehicle On A Typical Trajectory, Michael J. Bonaparte Dec 1992

Nozzle/Cowl Optimization For A Hypersonic Vehicle On A Typical Trajectory, Michael J. Bonaparte

Theses and Dissertations

An investigation of the effects of simultaneous variation of the nozzle attachment and cowl deflection angle on the performance of a two- dimensional nozzle used on a hypersonic vehicle such as the National Aero-Space Plane (NASP) was performed using a two parameter optimization procedure. Total thrust optimization was accomplished using a Flux-Difference-Split (FDS) cods, a RAMJET Performance Analysis program, and an oblique shock wave solver program, at sixteen points on a 1000 psf dynamic pressure trajectory for Mach numbers from 10.0 to 25.0. A single parameter optimization of the total thrust using a variable nozzle attachment angle was accomplished first …

Go to article

Characterization Of Stall Inception In High-Speed Single-Stage Compressors, Keith M. Boyer Dec 1992

Characterization Of Stall Inception In High-Speed Single-Stage Compressors, Keith M. Boyer

Theses and Dissertations

Two single-stage, transonic compressor designs were tested under various undistorted operating conditions to characterize the process leading up to aerodynamic stall. The rig case was instrumented with eight high-response static pressure transducers equally spaced around the annulus for stall development detection. High-response measurements were low-pass filtered and both spatially and temporally analyzed using discrete Fourier techniques. At all speeds tested for both designs, stall inception was characterized by growth of a small amplitude' rotating wave. The waves did not grow significantly until just prior to the instability, when exponential growth into fully-developed rotating stall occurred very rapidly, within 6-10 rotor …

Go to article

Experimental Investigation Of The Aerodynamics Of Independently Rotating Cylindrical Shells, Walter C. Howerton Dec 1992

Experimental Investigation Of The Aerodynamics Of Independently Rotating Cylindrical Shells, Walter C. Howerton

Theses and Dissertations

The purpose of this thesis was to investigate experimentally the aerodynamic forces on two adjacent, independently rotating cylinders in a cross- flow. This investigation involved a force measurement setup which had the two cylinders mounted on a common support shaft, extending beyond the span of the wind tunnel test section, and supported by spoke rings with strain gages in the vertical and horizontal directions. This setup proved capable of measuring aerodynamic forces. The lift on the independently rotating cylinders was found to increase as one cylinder's angular speed increased while the other's remained constant, and decrease as the relative angular …

Go to article

Improvements To Lqgi/Ltr Methodology For Plants With Lightly Damped Or Low Frequency Poles, An-Chi Ju Dec 1992

Improvements To Lqgi/Ltr Methodology For Plants With Lightly Damped Or Low Frequency Poles, An-Chi Ju

Theses and Dissertations

LQG/LTR design has a tendency to invert the plant's dynamics, which is undesirable if there are plant poles near the imaginary axis. In this study, Static Output Feedback (SOF) is applied to reassign plant poles before LQG/LTR is applied. Alternatively, Robust Eigenstructure Assignment (REA) was used to design the target loop transfer function with an ideal eigenstructure to avoid the undesirable cancellations. Both methods were applied to several aircraft design problems. Results showed that the methods can be effectively used so that the LQG/LTR design has improved stability and performance; however, it was found that each method had strengths and …

Go to article

Development Of An Engine/Airframe Performance Matching Scheme For Jet Engine Retrofit, Alan Lach Dec 1992

Development Of An Engine/Airframe Performance Matching Scheme For Jet Engine Retrofit, Alan Lach

Theses and Dissertations

This investigation developed a procedure and new analysis tools for identifying retrofit engine designs for use in existing airframes. The goal was to find a replacement engine for the air-to-air fighter, AAF, developed in the textbook Aircraft Engine Design. This paper introduced the ideas of solution surfaces, constraint/thrust diagrams, quality measures and linear regression analysis for the engine design problem. It considered the application of the jet engine design software ACSYS, MISS, and ONX along with statistical analysis software, SAS. Modeling techniques and linear regression analysis were used to minimize iteration while searching a wide range of design variables. Improvements …

Go to article

Vibration Suppression In Large Flexible Space Structures Using Active Control Techniques, Chad T. Matheson Dec 1992

Vibration Suppression In Large Flexible Space Structures Using Active Control Techniques, Chad T. Matheson

Theses and Dissertations

This report investigates the use of active vibration control techniques applied to the PACOSS Dynamic Test Article as an experimental structure. In the course of the research, a mathematical model of the lightly damped experimental structure was created based on experimental data. This model was used in the design of two classes of controllers. The first class is pure rate feedback of the structure's measured states such that global stability is insured. The second type of controller investigated was an optimal controller (LQG) that was created using the truncated mathematical model. The rate feedback controller showed significant improvements in the …

Go to article

The Influence Of Structural Optimization On The Aeroelastic Properties Of A Vertical Tail, David G. Miller Dec 1992

The Influence Of Structural Optimization On The Aeroelastic Properties Of A Vertical Tail, David G. Miller

Theses and Dissertations

The purpose of this thesis is to investigate the influence of structural optimization parameters on the structural and aeroelastic behavior of a vertical tail. The outside geometry of the tail is assumed fixed. The objective of the optimization is to reduce the structural member sizes so that the overall weight of the tail is minimized. The influence that design loads, design constraints, design variable linking has on the optimal design is observed examining several design cases. The static aeroelastic properties a flutter speeds of the various design cases are then compared. The doublet lattice method is used to calculate the …

Go to article

The Effects Of Viscosity On A Conically Derived Waverider, James A. Mundy Dec 1992

The Effects Of Viscosity On A Conically Derived Waverider, James A. Mundy

Theses and Dissertations

This study investigated the effects of the interaction between the viscous boundary layer and the shock wave produced by a Mach 10 inviscid optimized waverider. An implicit, Roe flux-splitting algorithm, developed by WL/FIMM, was used to solve the flow field. A validation for the inviscid version of the CFD algorithm was accomplished by comparing the numerical -data produced by the CFD code to the analytic results derived by Rasmussen, and by comparison to results of the explicit version of the same Roe flux-splitting code. The computational results compared favorably. The inviscid case studied using the implicit code produced results identical, …

Go to article

A Wind Tunnel Study Of Magnus Effects On A Differentially Rotating Missile, Karen A. Naselius Dec 1992

A Wind Tunnel Study Of Magnus Effects On A Differentially Rotating Missile, Karen A. Naselius

Theses and Dissertations

This study investigates magnus effects on a non-firmed missile model which had three axially rotating sections that span at different rates. Five spin cases are examined; the mid section spinning only; the front and rear sections spinning only; all section spinning at the same speed; all sections spinning in the same direction with the mid section spinning at an additional ten revolutions per second; and all sections spinning with the mid sections spinning the opposite direction at an additional ten revolutions per second. These five cases are tested at three different spin rates for two different wind tunnel velocities. Since …

Go to article

Application Of The Program Profile For The Design Of Low-Speed, Low- Observable Configuration Airfoils, Gregory A. Sharp Dec 1992

Application Of The Program Profile For The Design Of Low-Speed, Low- Observable Configuration Airfoils, Gregory A. Sharp

Theses and Dissertations

This study investigated-the use of the program PROFILE for the design of low-speed, low-observable configuration airfoils. For our purposes, low- observable configuration is defined as being characterized by a small leading- edge radius of less than 1.18 percent chord and a thickness-to-chord ratio of 2. 5 to 5.5 percent. A methodology was developed whereby the input parameters to prescribe the velocity distribution over the airfoil could be determined by a power law relationship. This relationship enables the designer to develop symmetric airfoils with the desired thickness-to-chord and leading-edge radius within the stated constraints. The resulting symmetric airfoils compared very well …

Go to article

Helicopter Flight Control System Design Using The Linear Quadratic Regulator For Robust Eigenstructure Assignment, Dempsey D. Solomon Dec 1992

Helicopter Flight Control System Design Using The Linear Quadratic Regulator For Robust Eigenstructure Assignment, Dempsey D. Solomon

Theses and Dissertations

This thesis applied modern, multi-variable control design techniques, via a FORTRAN computer algorithm, to U.S. Army helicopter models in hovering flight conditions. Eigenstructure assignment and Linear Quadratic Regulator (LQR) theory are used to achieve enhanced closed loop performance and stability characteristics with full state feedback. The addition of cross coupling weights to the standard LQR performance index is specifically addressed. A desired eigenstructure is chosen with a goal of reduced pilot workload via performance qualities requirements. Cross coupling weighting is shown to provide greater flexibility in achieving a desired closed loop eigenstructure. While the addition of cross coupling weighting is …

Go to article

An Experimental Investigation Of A Finite Circulation Control Wing, John M. Tallarovic Dec 1992

An Experimental Investigation Of A Finite Circulation Control Wing, John M. Tallarovic

Theses and Dissertations

This wind tunnel investigation examined the lift, drag, and pitching moment of a 20% thick, 8.5% camber, partial elliptical cross-section, single blowing slot, rectangular, circulation control wing. The aspect ratios tested were 3.71 and 3.99. Variables included three differently shaped trailing edge Coanda surfaces and steady blowing and pulsed blowing. The test Reynolds number, based on the chord was 500,000. The-angle of attack was varied from minus 6 degrees to the inception of stall. The maximum lift coefficient measured was 3. 17 with an equivalent drag coefficient of 1.85. Results also show a limit to increasing lift by increasing the …

Go to article

A Comparison Of Computational Fluid Dynamics Computer Programs For Hypersonic Propulsive Nozzle Flowfields, Kennedy B. Wilson Jr. Dec 1992

A Comparison Of Computational Fluid Dynamics Computer Programs For Hypersonic Propulsive Nozzle Flowfields, Kennedy B. Wilson Jr.

Theses and Dissertations

This study compared the results of two computer programs, a flux- difference-splitting (FDS) Godunov-based scheme and the SCPAMjet Hypersonic Nozzle (SCHNOZ) paraobolized Navier-Stoke's code using MacCormack's method, applied to a hypersonic nozzle flowfield. Two different nozzle geometries were investigated at three Mach numbers along a typical hypersonic flight trajectory. A direct compariosn between the SCHNOZ and FDS programs was made by numerically solving the steady Euler equations using a frozen flow assumption in the nozzle. The frozen flow SCHNOZ code is currently 6 to 10 times more efficient in terms of computational time than the FDS frozen flow code. The …

Go to article

A Synthetic Environment For Satellite Modeling And Satellite Orbital Motion, David L. Pond Dec 1992

A Synthetic Environment For Satellite Modeling And Satellite Orbital Motion, David L. Pond

Theses and Dissertations

Analysts tasked to study satellites moving in space must often rely on photographs to conduct their analysis. Often these photographs do not adequately represent how satellites move in space, their spatial relationships, or their interaction with other satellites. What analysts need is a three- dimensional synthetic environment that depicts satellites as they actually move and interact in space. This thesis addresses the early development of the Satellite Modeler (SM), a system that allows analysts to study, satellite motion and maneuvering of computer aided design (CAD) models of those satellites in a three-dimensional orbit. The system contains equipment that allows analysts …

Go to article

Analysis Of Titan Iv Launch Responsiveness, Michael T. Dunn Dec 1992

Analysis Of Titan Iv Launch Responsiveness, Michael T. Dunn

Theses and Dissertations

This research investigates the feasibility of developing responsive space systems through responsive launch operations with the Titan IV, the only expendable heavy-lift launch vehicle in the United States inventory. A definition for responsive launch has not been firmly established by Air Force Space Command for this launch vehicle. For benchmark purposes, this study uses the responsive launch definition contained in the proposal request for the Medium Launch Vehicle Ill: launch vehicle ignition within 60 days of mission need notification. Titan IV launch processing at Cape Canaveral Air Force Station (CCAFS), Florida currently requires in excess of six months, rendering Titan …

Go to article

Strategies For Optimal Control Design Of Normal Acceleration Command Following On The F-16, James C. Baird Dec 1992

Strategies For Optimal Control Design Of Normal Acceleration Command Following On The F-16, James C. Baird

Theses and Dissertations

Weight shapes and locations are investigated for H2, H∞, and the general mixed H2/H infinity optimization methodologies. The design model is normal acceleration command following for the F-16 (SISO) at Mach 0.6 and Sea Level, which yields a nonminimum phase and unstable plant. H2 design types include LQG, LQG/Sensitivity, and LQG/Tracking. Robustness and tracking are the objectives of the central H infinity process. Both H∞ optimal and suboptimal controllers are examined, with the suboptimal controller shown as the practical choice for this plant. The mixed H2/H∞ setup allows the tradeoff between …

Go to article

Next Last