Unmanned lunar roving vehicle elevation determination analysis
Elevation determination methods for unmanned lunar roving vehicle, considering instruments, orbiter tracking, etc
Martin, R. V.↗
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CoMET: Cost and Mass Evaluation Tool for Spacecraft and Mission Design
New technology in space exploration is often developed without a complete knowledge of its impact. While the immediate benefits of a new technology are obvious, it is harder to understand its indirect consequences, which ripple through the entire system. COMET is a technology evaluation tool designed to illuminate how specific technology choices affect a mission at each system level. COMET uses simplified models for mass, power, and cost to analyze performance parameters of technologies of interest. The sensitivity analysis that CoMET provides shows whether developing a certain technology will greatly benefit the project or not. CoMET is an ongoing project approaching a web-based implementation phase. This year, development focused on the models for planetary daughter craft, such as atmospheric probes, blimps and balloons, and landers. These models are developed through research into historical data, well established rules of thumb, and engineering judgment of experts at JPL. The model is validated by corroboration with JpL advanced mission studies. Other enhancements to COMET include adding launch vehicle analysis and integrating an updated cost model. When completed, COMET will allow technological development to be focused on areas that will most drastically improve spacecraft performance.
Bieber, Ben S.↗
Airbreathing hypersonic vehicle design and analysis methods
The design, analysis, and optimization of airbreathing hypersonic vehicles requires analyses involving many highly coupled disciplines at levels of accuracy exceeding those traditionally considered in a conceptual or preliminary-level design. Discipline analysis methods including propulsion, structures, thermal management, geometry, aerodynamics, performance, synthesis, sizing, closure, and cost are discussed. Also, the on-going integration of these methods into a working environment, known as HOLIST, is described.
Lockwood, Mary Kae↗
Simulink-Based Simulation Architecture for Evaluating Controls for Aerospace Vehicles (SAREC-ASV)
The Simulation Architecture for Evaluating Controls for Aerospace Vehicles (SAREC-ASV) is a Simulink-based approach to providing an engineering quality desktop simulation capability for finding trim solutions, extracting linear models for vehicle analysis and control law development, and generating open-loop and closed-loop time history responses for control system evaluation. It represents a useful level of maturity rather than a finished product. The layout is hierarchical and supports concurrent component development and validation, with support from the Concurrent Versions System (CVS) software management tool. Real Time Workshop (RTW) is used to generate pre-compiled code for substantial component modules, and templates permit switching seamlessly between original Simulink and code compiled for various platforms. Two previous limitations are addressed. Turn around time for incorporating tabular model components was improved through auto-generation of required Simulink diagrams based on data received in XML format. The layout was modified to exploit a Simulink "compile once, evaluate multiple times" capability for zero elapsed time for use in trimming and linearizing. Trim is achieved through a Graphical User Interface (GUI) with a narrow, script definable interface to the vehicle model which facilitates incorporating new models.
Christhilf, David m.↗
Procedure for Efficiently Generating, Checking, and Displaying NASTRAN Input and Output Data for Analysis of Aerospace Vehicle Structures
Auxiliary computer routines for generating, checking, and displaying NASTRAN input and output data for analysis of aerospace vehicle structures
Giles, G. L.↗
Characterization of Deposits on Glass Substrate as a Tool in Failure Analysis: The Orbiter Vehicle Columbia Case Study
In connection with the accident investigation of the space shuttle Columbia, an analysis methodology utilizing well established microscopic and spectroscopic techniques was implemented for evaluating the environment to which the exterior fused silica glass was exposed. Through the implementation of optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, and electron diffraction, details emerged regarding the manner in which a charred metallic deposited layer formed on top of the exposed glass. Due to nature of the substrate and the materials deposited, the methodology proved to allow for a more detailed analysis of the vehicle breakup. By contrast, similar analytical methodologies on metallic substrates have proven to be challenging due to strong potential for error resulting from substrate contamination. This information proved to be valuable to not only those involved in investigating the break up of Columbia, but also provides a potential guide for investigating future high altitude and high energy accidents.
Olivas, J. D.↗
An Upgrade of the Aeroheating Software "MINIVER"
Many software packages assist engineers with performing flight vehicle analysis, but some of these packages have gone many years without updates or significant improvements to their workflows. One such software, known as MINIVER, is a powerful yet lightweight tool that is used for aeroheating analyses. However, it is an aging program that has not seen major improvements within the past decade. As part of a collaborative effort with Florida Institute of Technology, MINIVER has received a major user interface overhaul, a change in program language, and will be continually receiving updates to improve its capabilities. The user interface update includes a migration from a command-line interface to that of a graphical user interface supported in the Windows operating system. The organizational structure of the preprocessor has been transformed to clearly defined categories to provide ease of data entry. Helpful tools have been incorporated, including the ability to copy sections of cases as well as a generalized importer which aids in bulk data entry. A visual trajectory editor has been included, as well as a CAD Editor which allows the user to input simplified geometries in order to generate MINIVER cases in bulk. To demonstrate its continued effectiveness, a case involving the JAXA OREX flight vehicle will be included, providing comparisons to captured flight data as well as other computational solutions. The most recent upgrade effort incorporated the use of the CAD Editor, and current efforts are investigating methods to link MINIVER projects with SINDA/Fluint and Thermal Desktop.
Louderback, Pierce M.↗
A Upgrade of the Aeroheating Software "MINIVER"
Many software packages assist engineers with performing flight vehicle analysis, but some of these packages have gone many years without updates or significant improvements to their workflows. One such software package, known as MINIVER, is a powerful yet lightweight tool used for aeroheating analyses. However, it is an aging program that has not seen major improvements within the past decade. As part of a collaborative effort with the Florida Institute of Technology, MINIVER has received a major user interface overhaul, a change in program language, and will be continually receiving updates to improve its capabilities. The user interface update includes a migration from a command-line interface to that of a graphical user interface supported in the Windows operating system. The organizational structure of the pre-processor has been transformed to clearly defined categories to provide ease of data entry. Helpful tools have been incorporated, including the ability to copy sections of cases as well as a generalized importer which aids in bulk data entry. A visual trajectory editor has been included, as well as a CAD Editor which allows the user to input simplified geometries in order to generate MINIVER cases in bulk. To demonstrate its continued effectiveness, a case involving the JAXA OREX flight vehicle will be included, providing comparisons to captured flight data as well as other computational solutions. The most recent upgrade effort incorporated the use of the CAD Editor, and current efforts are investigating methods to link MINIVER projects with SINDA/Fluint and Thermal Desktop.
Louderback, Pierce↗
A Passive Gravitational Attitude Control System for Satellites
It is shown how the gravity-gradient effect may be utilized to design a long-lived, earth-pointing satellite attitude control system which requires no fuel supplies, attitude sensors or active control equipment. This two-body system is provided with a magnetic hysteresis damper which effectively damps out oscillations (librations) about the local vertical. The long rods, which must be extended in space from coiled up metal tapes, provide the required large moments of inertia and possess adequate rigidity and sufficient strength to endure the rigors of the extension process. The system is compatible with the requirements of multiple satellite launchings from a single last-stage vehicle. Analysis indicates that the gravitational torques are sufficient to keep the disturbing effects of solar radiation pressure, residual magnetic dipole moments, orbit eccentricity, rod curvature, eddy currents, and meteorite impacts within tolerable limits. It is believed that the high-performance, earth-pointing system described and analyzed in this paper represents an essential step in the development of high-capacity communications satellites requiring long life.
GRAVITY↗
Experimental investigation to determine utility of tension shell concept
Utility of tension shell concept for application to entry vehicles - analysis by linear membrane theory
PLANETARY ENTRY↗
Early orbit determination scheme for the Juno space vehicle
The present status (1959-60) of the ABMA early orbit determination scheme for the Juno space vehicle is described. The design of the scheme was essentially influenced by three factors: its origin centered around postflight vehicle analysis, the flexibility required for accepting varied kinds of data, and the potential of highspeed computers concentrated in ABMA's Computation Laboratory. The scheme is outlined, the tracking stations participating are shortly described, and the physical layout and computational equipment are briefly mentioned. The evaluation techniques used for the various steps of the orbit determination are discussed in detail. Appendices describe briefly the principal coordinate systems used and characteristics of the digital computer programs.
Fletcher Kurtz↗
Time Domain Identification of an Optimal Control Pilot Model with Emphasis on the Objective Function
A method for the identification of the pilot's control compensation using time domain techniques is proposed. From this information we hope to infer a quadratic cost function, supported by the data, that represents a reasonable expression for the pilot's control objective in the task being performed, or an inferred piloting strategy. The objectives for this method are: (1) obtain a better understanding of the fundamental piloting techniques in complex tasks, such as landing approach; (2) the development of a metric measurable in simulations and flight test that correlate with subjective pilot opinion; and (3) to further validate pilot models and pilot vehicle analysis methods.
Schmidt, D. K.↗
A study of flight control requirements for advanced, winged, earth-to-orbit vehicles with far-aft center-of-gravity locations
Control requirements of Controlled Configured Design Approach vehicles with far-aft center of gravity locations are studied. The baseline system investigated is a fully reusable vertical takeoff/horizontal landing single stage-to-orbit vehicle with mission requirements similar to that of the space shuttle vehicle. Evaluations were made to determine dynamic stability boundaries, time responses, trim control, operational center-of-gravity limits, and flight control subsystem design requirements. Study tasks included a baseline vehicle analysis, an aft center of gravity study, a payload size study, and a technology assessment.
Hepler, A. K.↗
System requirements specification for SMART structures mode
Specified here are the functional and informational requirements for software modules which address the geometric and data modeling needs of the aerospace structural engineer. The modules are to be included as part of the Solid Modeling Aerospace Research Tool (SMART) package developed for the Vehicle Analysis Branch (VAB) at the NASA Langley Research Center (LaRC). The purpose is to precisely state what the SMART Structures modules will do, without consideration of how it will be done. Each requirement is numbered for reference in development and testing.
Source record↗
Geometric modeling for computer aided design
Over the past several years, it has been the primary goal of this grant to design and implement software to be used in the conceptual design of aerospace vehicles. The work carried out under this grant was performed jointly with members of the Vehicle Analysis Branch (VAB) of NASA LaRC, Computer Sciences Corp., and Vigyan Corp. This has resulted in the development of several packages and design studies. Primary among these are the interactive geometric modeling tool, the Solid Modeling Aerospace Research Tool (smart), and the integration and execution tools provided by the Environment for Application Software Integration and Execution (EASIE). In addition, it is the purpose of the personnel of this grant to provide consultation in the areas of structural design, algorithm development, and software development and implementation, particularly in the areas of computer aided design, geometric surface representation, and parallel algorithms.
Schwing, James L.↗
Risks and reliability of manufacturing processes as related to composite materials for spacecraft structures
Fabricating primary aircraft and spacecraft structures using advanced composite materials entail both benefits and risks. The benefits come from much improved strength-to-weight ratios and stiffness-to-weight ratios, potential for less part count, ability to tailor properties, chemical and solvent resistance, and superior thermal properties. On the other hand, the risks involved include high material costs, lack of processing experience, expensive labor, poor reproducibility, high toxicity for some composites, and a variety of space induced risks. The purpose of this project is to generate a manufacturing database for a selected number of materials with potential for space applications, and to rely on this database to develop quantitative approaches to screen candidate materials and processes for space applications on the basis of their manufacturing risks including costs. So far, the following materials have been included in the database: epoxies, polycyanates, bismalemides, PMR-15, polyphenylene sulfides, polyetherimides, polyetheretherketone, and aluminum lithium. The first four materials are thermoset composites; the next three are thermoplastic composites, and the last one is is a metal. The emphasis of this database is on factors affecting manufacturing such as cost of raw material, handling aspects which include working life and shelf life of resins, process temperature, chemical/solvent resistance, moisture resistance, damage tolerance, toxicity, outgassing, thermal cycling, and void content, nature or type of process, associate tooling, and in-process quality assurance. Based on industry experience and published literature, a relative ranking was established for each of the factors affecting manufacturing as listed above. Potential applications of this database include the determination of a delta cost factor for specific structures with a given process plan and a general methodology to screen materials and processes for incorporation into the current conceptual design optimization of future spacecrafts as being coordinated by the Vehicle Analysis Branch where this research is being conducted.
Bao, Han P.↗
Flight Performance of a Spin-Stabilized 20-Inch-Diameter Solid-Propellant Spherical Rocket Motor
A successful flight test of a spin-stabilized 20-inch-diameter solid-propellant rocket motor having a propellant mass fraction of 0.92 has been made. The motor was fired at altitude after being boosted by a three-stage test vehicle. Analysis of the data indicates that a total impulse of 44,243 pound-second with a propellant specific impulse of approximately 185 was achieved over a total action time of about 12 seconds. These results are shown to be in excellent agreement with data from ground static firing tests of these motors. The spherical rocket motor with an 11-pound payload attained a velocity of 15,620 feet per second (m = 16.7) with an incremental velocity increase for the spherical motor stage of 12,120 feet per second.
Levine, Jack↗
Real-Time Simulation of the X-33 Aerospace Engine
This paper discusses the development and performance of the X-33 Aerospike Engine RealTime Model. This model was developed for the purposes of control law development, six degree-of-freedom trajectory analysis, vehicle system integration testing, and hardware-in-the loop controller verification. The Real-Time Model uses time-step marching solution of non-linear differential equations representing the physical processes involved in the operation of a liquid propellant rocket engine, albeit in a simplified form. These processes include heat transfer, fluid dynamics, combustion, and turbomachine performance. Two engine models are typically employed in order to accurately model maneuvering and the powerpack-out condition where the power section of one engine is used to supply propellants to both engines if one engine malfunctions. The X-33 Real-Time Model is compared to actual hot fire test data and is been found to be in good agreement.
Aguilar, Robert↗