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Articles 5671 - 5695 of 5695
Full-Text Articles in Engineering
Numerical Analysis Of Critical Inclinations About The Planet Mars, Kenneth J. Hyatt
Numerical Analysis Of Critical Inclinations About The Planet Mars, Kenneth J. Hyatt
Theses and Dissertations
This study investigated critical inclinations about the planet Mars. Averaged equations of motion were numerically integrated over a time span of ten Earth years for various inclinations, eccentricities, and perigee heights. Each orbit (i.e. set of initial conditions) produced a standard deviation of the variations in eccentricity (SDE) and inclination (SDI). These were calculated using a polynomial approximation to the variations. Surface plots of SDI and SDE vs the initial conditions are then examined to ascertain the critical inclinations.
Minimum Orbits About The Planet Venus, Jeffrey J. Smith
Minimum Orbits About The Planet Venus, Jeffrey J. Smith
Theses and Dissertations
An investigation is conducted into low orbiting satellites around the planet Venus with drag limited lifetimes. It is possible to specify combinations of orbital elements which result in orbital lifetimes in excess of some desired value. These combinations can be assembled into Critical Curves and Critical surfaces. Critical Curves and Surfaces are defined as curves and surfaces in orbital element space above which initial element sets will result in orbits that meet or exceed lifetime requirements. A numerical method is implemented for finding these combinations, and three Critical Surfaces are examined. A decay threshold is selected for bounding satellite lifetime. …
Dynamic Analysis Of A Combat Aircraft With Control Surface Failure, Marc Roy
Dynamic Analysis Of A Combat Aircraft With Control Surface Failure, Marc Roy
Theses and Dissertations
An investigation was performed to analyze the dynamic stability characteristic of an aircraft which has sustained damage to a primary control surface. The analysis was performed using the existing functional form of actual wind tunnel data taken on an F-16 model. Two control schemes are used for trimming an F-16 that has sustained damage to its rudder. The first control scheme represent the basic aircraft, while the second allowed the horizontal tail ailerons to move independently from the flaperons. The investigation was conducted for one flight condition representative of the aircraft at cruise speed. Region in α/β (angle of attack)/(sideslip …
Analysis Of Parking Orbits For A Sts External Tank In Low Earth Orbit, James E. Cross
Analysis Of Parking Orbits For A Sts External Tank In Low Earth Orbit, James E. Cross
Theses and Dissertations
A study was conducted of a single external tank in low earth orbit. Criteria for a parking orbit are then defined. Various orbits are then selected by varying the semi-major axis, eccentricity, and inclination. The resulting equations of motion for each of the above orbits (including atmospheric drag and a 2x0 gravity model) are numerically integrated over a time span of 90 earth days. An examination was made of the lowest initial altitudes which allowed the external tank to remain in the orbit window.
Specification And Equivalence Verification Of Sequential Circuits Via Vhdl, Richard L. Miller
Specification And Equivalence Verification Of Sequential Circuits Via Vhdl, Richard L. Miller
Theses and Dissertations
This research presents a merger of the specification and design capabilities of the Very High Speed Integrated Circuit (VHSIC) Hardware Description Language (VHDL) with a known verification method (UC Berkeley's verify software) in order to solve the design and verification problem of sequential circuits. The fruits of this research are a behavioral VHDL model for sequential circuit specification, a structural VHDL model for sequential circuit design, and a method for comparing two circuits described using these VHDL models in order to demonstrate circuit equivalence. The behavioral and structural VHDL models were developed and tested within the Intermetric's VHDL software support …
On The Maximum Range Of Flying Wings, Peter J. Torvik
On The Maximum Range Of Flying Wings, Peter J. Torvik
AFIT Documents
The classical equations for determining the maximum range of aircraft with propeller and jet propulsion systems are reviewed, along with previous work conducted to determine the optimal division of aircraft volume between fuselage and wing components. That the jet powered flying wing configuration produces optimal range only for limited geometries is confirmed. The optimal range of aircraft employing high bypass jet engines is explored, and found to lead to a broader range of design parameters for which the flying wing design produces maximum range than is the case when a pure jet system is used.
Monte Carlo Simulation Of Atmospheric Neutron Transport At High Altitudes Using Mcnp, Donald R. Culp, David L. Monti, James R. Shoemaker, David Wesley, Kirk A. Mathews
Monte Carlo Simulation Of Atmospheric Neutron Transport At High Altitudes Using Mcnp, Donald R. Culp, David L. Monti, James R. Shoemaker, David Wesley, Kirk A. Mathews
AFIT Documents
Neutron transport calculations were performed using the Monte Carol code, MCNP. The transport problem considered has a point source at high altitude (40 km). Since atmospheric density decreases with altitude, two-dimensional effects (cylindrical coordinates) can be important. Results were compared to those obtained with the SMAUG-II computer code, which performs mass-integral scaling of approximate fits to one-dimensional spherical discrete ordinates solutions. These comparisons show the importance of two-dimensional computations. The report discusses practical issues of applying MCNP to this problem, without code modifications and includes example input files for MCNP and for SMAUG-II. Computational modelling of neutron transport in the …
Pronated Escape System For Fighter Aircraft, Allen D. Disselkoen Jr., Robert F. Gargiulo, James E. Haywood, Keith H. Heise, Darrell H. Holcombe, Stuart C. Kramer, Gregory R. Miller, Jeffrey S. Nicholson, Curtis H. Spenny
Pronated Escape System For Fighter Aircraft, Allen D. Disselkoen Jr., Robert F. Gargiulo, James E. Haywood, Keith H. Heise, Darrell H. Holcombe, Stuart C. Kramer, Gregory R. Miller, Jeffrey S. Nicholson, Curtis H. Spenny
AFIT Patents
An improved aircraft ejection seat system is described which embodies a forward leaning position for an occupant of the aircraft providing enhanced acceleration tolerance for an occupant during ejection from the cockpit, comprising a platform supporting at a rearward end thereof a seat having a seat back and seat pan sized and configured for accommodating the occupant, a forwardly disposed cowling integral with and faired to the platform for providing windblast protection to the occupant, a solid or cushioned upright wall member disposed centrally of the platform and extending between the seat and cowling and supporting an inclined chest plate …
System For Boundary Layer Control Through Pulsed Heating Of A Strip Heater, Milton E. Franke, Lawrence Kudelka
System For Boundary Layer Control Through Pulsed Heating Of A Strip Heater, Milton E. Franke, Lawrence Kudelka
AFIT Patents
A system is described for controlling the transition of laminar/turbulent flow at a surface which comprises a thin narrow strip heater disposed adjacent the surface and extending substantially transversely of the flow of the air stream thereacross, the heater being resiliently held in tension on or in closely spaced relationship to the surface, and a power source operatively connected to the heater for applying pulsed voltage of preselected amplitude and frequency to the heater.
Synthetic Aperture Multi-Telescope Tracker Apparatus, Richard A. Carreras, Salvatore J. Cusumano, Morton B. Jenks, Robert I. Suizu
Synthetic Aperture Multi-Telescope Tracker Apparatus, Richard A. Carreras, Salvatore J. Cusumano, Morton B. Jenks, Robert I. Suizu
AFIT Patents
A plurality of telescopes provide output return signals which are applied both directly and in sampled form to a photo-detector cell. The detected signals from the photo-detector will represent the constant and transient errors of the telescope system. A low pass filter insures that the tracker provides only the constant or D.C. component of the error, while a high pass filter insures that the existing measuring devices for each telescope beam provide only the transient or A.C. component of the error. The A.C. and D.C. error signals are summed together with the appropriate applied gains on each channel such that …
Optically Phased Laser Transmitter, Janet S. Fender, Salvatore J. Cusumano, Robert R. Butts, Christopher R. Dehainaut
Optically Phased Laser Transmitter, Janet S. Fender, Salvatore J. Cusumano, Robert R. Butts, Christopher R. Dehainaut
AFIT Patents
An apparatus and technique are described for phasing the outputs of a multiplier telescope array used as a laser transmitter. The technique uses samples of the transmitted beams to control optical path lengths through the separate telescopes so that the beams add coherently at the receiver. The phasing concept is applicable both to systems which provide inputs to the multiple telescopes by dividing a single laser beam and to systems in which the inputs to the telescopes and multiple, phase-locked laser beams. The approach is also compatible with single line and multi-line lasers, and it does not entail stringent alignment …
Multiple Jet Blowing Around The Blunt Trailing Edge Of A Circulation Controlled Airfoil, John K. Harvell, Milton E. Franke
Multiple Jet Blowing Around The Blunt Trailing Edge Of A Circulation Controlled Airfoil, John K. Harvell, Milton E. Franke
AFIT Patents
A circulation controlled airfoil has a body structure with leading and trailing ends and upper and lower surfaces extending therebetween, and a cylindrical member disposed along the trailing end of the body structure between the upper and lower surfaces thereof so as to form a rounded, blunt trailing edge surface on the airfoil. A first blowing jet slot is defined between the outer surface of the cylindrical member and the trailing end of the body structure adjacent its upper surface. A second blowing jet slot is defined in a tubular wall of the cylindrical member. The latter member can be …
High Discharge Rate Characteristics Of Nickel-Cadmium Batteries For Pulse Load Filtering, Gregory M. Gearing, Michael B. Cimino, David H. Fritts, John F. Leonard, Anthony J. Terzuoli Jr.
High Discharge Rate Characteristics Of Nickel-Cadmium Batteries For Pulse Load Filtering, Gregory M. Gearing, Michael B. Cimino, David H. Fritts, John F. Leonard, Anthony J. Terzuoli Jr.
Faculty Publications
Several tests of specially fabricated nickel-cadmium batteries having circular disk type electrodes were considered. These batteries were evaluated as filter elements between a constant current power supply and a five hertz pulsed load demanding approximately twice the power supply current during the load on portion of the cycle. Short tests lasting 10,000 cycles were conducted at up to a 21 C rate and an equivalent energy density of over 40 Joules per pound. In addition, two batteries were subjected to 107 charge/discharge cycles, one at a 6.5 C rate and the other at a 13 C rate. Assuming an …
Study Of Longitudinal Landing Flying Qualities Evaluation Using Pilot Model Theory, Eric D. Didomenico
Study Of Longitudinal Landing Flying Qualities Evaluation Using Pilot Model Theory, Eric D. Didomenico
Theses and Dissertations
Control Anticipation Parameter (CAP), used in MIL-SPEC-8785C as a longitudinal handling qualities criterion does not adequately distinguish between different flight phases. Recent flight test data from the Landing Approach Higher Order Systems (LAHOS) study further indicate the inadequacy of the second order approximations for higher order longitudinal landing flying qualities. Nine Aircraft that fall within the Level 1 boundary reveal pilot ratings ranging from 1.5 to 10 (Cooper/Harper). These nine aircraft are studied by combining their longitudinal dynamics with pilot modelling to examine a better method of landing flying quality prediction and evaluation. Pilot model theory (cross-over pilot model) is …
Solution To Eigenvalue Problems Of Antisymmetric Cross-Ply And Antisymmetric Angle-Ply Laminated Plates Using Affine Transformations, Zaffir A. Chaudry
Solution To Eigenvalue Problems Of Antisymmetric Cross-Ply And Antisymmetric Angle-Ply Laminated Plates Using Affine Transformations, Zaffir A. Chaudry
Theses and Dissertations
Using affine transformations and suitably recasting the buckling vibration differential equations, the eigenvalue problem of anti-symmetric cross-ply and antisymmetric angle-ply laminated rectangular plates has been reduced to a function of two strong material constants, the generalized rigidity ratio, whose range is in the closed interval from 0 to 1, and the ratio of principal lamina stiffness. With the reduction in number of constants an exhaustive parameter study of buckling and vibration solution trends, is possible. The buckling coefficients decrease with decreasing value of generalized rigidity ratio for both antisymmetric cross-ply and antisymmetric angle-ply laminates. For a given aspect ratio, and …
Measurement Of Air Force Fire Department Productivity: An Evaluation Of Efficiency/Effectiveness, Timothy A. Byers, Susanne M. Waylette
Measurement Of Air Force Fire Department Productivity: An Evaluation Of Efficiency/Effectiveness, Timothy A. Byers, Susanne M. Waylette
Theses and Dissertations
This research was sponsored to develop a method of evaluating the productivity of Air Force Fire Departments. Using the tasks developed by the Fire Department Workshop, input and output measures were defined and used in a new model of efficiency called Constrained Facet Analysis (CFA). The advantage of this methodology over others considered was that it can simultaneously evaluate multiple inputs and multiple outputs using empirical data with no a priori weighting. The results of the analysis provided an efficiency rating for each fire department and information about marginal rates of substitution and marginal rates of productivity for inefficient units …
Planning For The On-Orbit Servicing Of Military Spacecraft, Michael E. Russell, Robert M. Tayloe
Planning For The On-Orbit Servicing Of Military Spacecraft, Michael E. Russell, Robert M. Tayloe
Theses and Dissertations
On-orbit spacecraft servicing for military programs is examined. The military community appears to be somewhat reticent to embrace or, in some cases, to even consider on-orbit servicing. The civilian community appears enthusiastic about the potential of on-orbit servicing and the majority of economic studies of civilian missions show servicing strategies to be an attractive alternative to most expendable spacecraft strategies. A model called SATSERV is presented. This model can be used to conduct economic comparisons from an overall standpoint between expendable and servicing strategies. The model is implemented in a microcomputer spreadsheet format for rapid implementation and application along with …
Axisymmetric Thrust Augmenting Ejector With Discrete Primary Air Slot Nozzles, Steven G. Reznick, Milton E. Franke
Axisymmetric Thrust Augmenting Ejector With Discrete Primary Air Slot Nozzles, Steven G. Reznick, Milton E. Franke
AFIT Patents
A circular thrust augmenting ejector has an annular wall which defines a central passageway and a convergent contoured inlet section, a constant area cylindrical mixing section and a divergent conical diffuser outlet section. The inlet, mixing and outlet sections merge one into the next in axisymmetric serial relationship. The ejector also has a plurality of discrete primary nozzles arranged about the periphery of the annular wall at the entrance to the inlet section thereof for injecting a primary flow of high velocity air into the inlet section and thereby entraining a secondary flow of ambient air into the central passageway …
Stochastic Estimation Applied To The Land Speed Of Sound Record Attempt By A Rocket Car, David A. Reinholz
Stochastic Estimation Applied To The Land Speed Of Sound Record Attempt By A Rocket Car, David A. Reinholz
Theses and Dissertations
Optimal linear smoothing theory is applied to the data from the Speed of Sound record attempt of a three-wheeled rocket car on 17 December 1979. A forward-backward estimation method is used which employs a seven state forward-running extended Kalman filter and a Meditch-form backward recursive 'fixed-interval' smoothing algorithm. Data for this analysis is supplied by a longitudinal accelerometer mounted on the vehicle and tracking radar measurements of range, azimuth, and elevation. States of interest include two components of vehicle position and velocity, accelerometer time-correlated error, and radar range and azimuth bias errors. Two iterations of the forward-backward smoothing algorithm provide …
Modal Control Of An Unstable Periodic Orbit, William Wiesel, William Shelton
Modal Control Of An Unstable Periodic Orbit, William Wiesel, William Shelton
Faculty Publications
We apply Floquet theory to the problem of designing a control system for a satellite in an unstable periodic orbit. Expansion about a periodic orbit produces a time periodic linear system, which is augmented by a time periodic control term. We show that this can be done such that a) the application of control produces only inertial accelerations, b) positive real Poincare exponents are shifted into the left half-plane, and c) the shift of the exponent is linear with control gain. We apply these developments to an unstable orbit near the Earth-Moon L3 point perturbed by the Sun. Finally, …
A Study Of A Wind Tunnel Measurement System For Unsteady Pressures Using Pneumatic Transmission Lines, Mohammed Javed Khan
A Study Of A Wind Tunnel Measurement System For Unsteady Pressures Using Pneumatic Transmission Lines, Mohammed Javed Khan
Theses and Dissertations
The application of pneumatic transmission lines theory to a tube-scanning valve system for unsteady pressure measurements in the AFIT 5-foot wind tunnel is investigated. Transfer gains of various tube-scanning valve configurations were experimentally measured and the validity of a theoretical model verified for a frequency range of 20 Hz to 140 Hz. The selected system having a 0.0625-in. ID flexible tube of 84 in. length connected to a scanning valve was installed in the wind tunnel. Unsteady pressures introduced over an 18 percent airfoil at zero angle of attack were measured with this system. Data were collected for 0, 40, …
Faa/Dod Liaison In Management Of The National Aviation System, Ronald S. Brooks, Jerry L. Beatty
Faa/Dod Liaison In Management Of The National Aviation System, Ronald S. Brooks, Jerry L. Beatty
Theses and Dissertations
This study describes and analyzes military and FAA liaison efforts which impact on the management of the National Aviation System. It begins with the historical development of the National Airspace System (NAS), The system is evolutionary in nature and most innovations have come from user demands and outside sources, Long term government responsibility to manage the system has been secondary to the operation and maintenance functions, There has been duplication of effort due to poor coordination on developing common goals, The military has been the leader in developing technology that led to improvement of the system.
Software Simulation Of The D17b Computer, Bruce Chatterton
Software Simulation Of The D17b Computer, Bruce Chatterton
Theses and Dissertations
A software program has been written which simulates the functions of the Minuteman D17B computer at the register transfer level. The simulation program is written in the FORTRAN Extended language to be used on the Intercom System (teletype) of a CDC 6600 computer system. The simulation program consists of a main program and eight subroutines. A programming language for the D17B simulation was formed which contains numbers and load codes, switches, and miscellaneous commands. Example programs run on the simulated computer have been included to show the types of output available.
Investigation Of The Platinum-Rich Portion Of The Platinum-Tantalum Phase Diagram, Bob Dean Browning
Investigation Of The Platinum-Rich Portion Of The Platinum-Tantalum Phase Diagram, Bob Dean Browning
Theses and Dissertations
The Pt-Ta binary system was investigated at two isotherms;1000°C and 1500°C, and at eleven alloy compositions in the range of 50 to 100 atomic percent platinum. The alloys were examined by x-ray diffraction and metallography. Three intermetallic compounds, Pt2Ta, Pt3Ta, and Pt4Ta were found to exist in this composition range. The Pt4Ta intermetallic appeared only at the 1500°C isotherm. Platinum dissolved tantalum substitutionally to 90 atomic percent at 1500 °C and to approximately 80 atomic percent at 1000 °C.
Air Corp Engineering School, Wright Field - 1935 Catalog, Air Corps Engineering School, A. W. Robins
Air Corp Engineering School, Wright Field - 1935 Catalog, Air Corps Engineering School, A. W. Robins
AFIT Documents
This publication is issued to fill the need on the part of the Air Corps in general for a more detailed description of the curriculum of the Air Corps Engineering School. This description will serve as a guide to the accepted applicant in his preliminary preparation and a standard by which the individual Air Corps officer can arrive at an intelligent decision as to whether his own enthusiasm and preparation will be sufficient to warrant making application for the course. Entrance requirements are definitely stated herein. For those who do not contemplate intensive aeronautical engineering training, this publication may be …