Apollo spacecraft systems analysis program. Preliminary LR reflectivity model
Preliminary lunar reflectivity graphs
Dickerson, E. T.↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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High tip speed fan inlet noise reduction using treated inlet splitters and accelerating inlets (quiet engine program fan C scale model)
A series of inlet suppression tests were run on a supersonic tip speed fan which employed an acoustically treated cowl wall, treated splitters and elevated average throat Mach numbers in various combinations. Results show appreciable fan noise reductions at high fan speeds; 15-18 PNdB. On the basis of inlet total pressure recovery loss per PNdb of noise reduction, an inlet with no splitters produced the most efficient design. However, greater reduction in noise was achieved with one splitter in the inlet. It was also noted that moderate increases in inlet Mach number increased noise in the acoustically treated inlets and that Mach numbers in excess of 0.65 were required before net noise reduction was realized.
Kazin, S. B.↗
USDA Application Test System (ATS) session: Resource modelling, a reality for program cost analysis
There are no author-identified significant results in this report.
Fouts, L.↗
A system safety model for developmental aircraft programs
Basic tenets of safety as applied to developmental aircraft programs are presented. The integration of safety into the project management aspects of planning, organizing, directing and controlling is illustrated by examples. The basis for project management use of safety and the relationship of these management functions to 'real-world' situations is presented. The rationale which led to the safety-related project decision and the lessons learned as they may apply to future projects are presented.
Amberboy, E. J.↗
UH-60A Black Hawk engineering simulation program. Volume 1: Mathematical model
A nonlinear mathematical model of the UR-60A Black Hawk helicopter was developed. This mathematical model, which was based on the Sikorsky General Helicopter (Gen Hel) Flight Dynamics Simulation, provides NASA with an engineering simulation for performance and handling qualities evaluations. This mathematical model is total systems definition of the Black Hawk helicopter represented at a uniform level of sophistication considered necessary for handling qualities evaluations. The model is a total force, large angle representation in six rigid body degrees of freedom. Rotor blade flapping, lagging, and hub rotational degrees of freedom are also represented. In addition to the basic helicopter modules, supportive modules were defined for the landing interface, power unit, ground effects, and gust penetration. Information defining the cockpit environment relevant to pilot in the loop simulation is presented.
Howlett, J. J.↗
Modelling high data rate communication network access protocol
Modeling of high data rate communication systems is different from the low data rate systems. Three simulations were built during the development phase of Carrier Sensed Multiple Access/Ring Network (CSMA/RN) modeling. The first was a model using SIMCRIPT based upon the determination and processing of each event at each node. The second simulation was developed in C based upon isolating the distinct object that can be identified as the ring, the message, the node, and the set of critical events. The third model further identified the basic network functionality by creating a single object, the node which includes the set of critical events which occur at the node. The ring structure is implicit in the node structure. This model was also built in C. Each model is discussed and their features compared. It should be stated that the language used was mainly selected by the model developer because of his past familiarity. Further the models were not built with the intent to compare either structure or language but because the complexity of the problem and initial results contained obvious errors, so alternative models were built to isolate, determine, and correct programming and modeling errors. The CSMA/RN protocol is discussed in sufficient detail to understand modeling complexities. Each model is described along with its features and problems. The models are compared and concluding observations and remarks are presented.
Khanna, S.↗
C-Language Integrated Production System, Version 5.1
CLIPS 5.1 provides cohesive software tool for handling wide variety of knowledge with support for three different programming paradigms: rule-based, object-oriented, and procedural. Rule-based programming provides representation of knowledge by use of heuristics. Object-oriented programming enables modeling of complex systems as modular components. Procedural programming enables CLIPS to represent knowledge in ways similar to those allowed in such languages as C, Pascal, Ada, and LISP. Working with CLIPS 5.1, one can develop expert-system software by use of rule-based programming only, object-oriented programming only, procedural programming only, or combinations of the three.
Riley, Gary↗
Simulation and model reduction for the AFW program
The simulation methodology used in the Active Flexible Wing wind-tunnel test program is described. An overview of the aeroservoelastic modeling used in building the required batch and hot-bench simulations is presented. Successful hot-bench implementation required that the full mathematical model be significantly reduced while assuring that accuracy be maintained for all combinations of 10 inputs and 56 outputs. The reduction was accomplished by using a method based on internally balanced realizations and focussing on the linear, aeroelastic portion of the full mathematical model. The error-bound properties of the internally balanced realization significantly contribute to its utility in the model reduction process. The reduction method and the results achieved are described.
Buttrill, Carey↗
ASTEC and MODEL: Controls software development at Goddard Space Flight Center
The ASTEC (Analysis and Simulation Tools for Engineering Controls) software is under development at the Goddard Space Flight Center (GSFC). The design goal is to provide a wide selection of controls analysis tools at the personal computer level, as well as the capability to upload compute-intensive jobs to a mainframe or supercomputer. In the last three years the ASTEC (Analysis and Simulation Tools for Engineering Controls) software has been under development. ASTEC is meant to be an integrated collection of controls analysis tools for use at the desktop level. MODEL (Multi-Optimal Differential Equation Language) is a translator that converts programs written in the MODEL language to FORTRAN. An upgraded version of the MODEL program will be merged into ASTEC. MODEL has not been modified since 1981 and has not kept with changes in computers or user interface techniques. This paper describes the changes made to MODEL in order to make it useful in the 90's and how it relates to ASTEC.
Downing, John P.↗
FNAS/summer faculty fellowship research continuation program. Task 6: Integrated model development for liquid fueled rocket propulsion systems. Task 9: Aspects of model-based rocket engine condition monitoring and control
The objective of Phase I of this research effort was to develop an advanced mathematical-empirical model of SSME steady-state performance. Task 6 of Phase I is to develop component specific modification strategy for baseline case influence coefficient matrices. This report describes the background of SSME performance characteristics and provides a description of the control variable basis of three different gains models. The procedure used to establish influence coefficients for each of these three models is also described. Gains model analysis results are compared to Rocketdyne's power balance model (PBM).
Santi, L. Michael↗
Applications of Data Assimilation to Analysis of the Ocean on Large Scales
It is commonplace to begin talks on this topic by noting that oceanographic data are too scarce and sparse to provide complete initial and boundary conditions for large-scale ocean models. Even considering the availability of remotely-sensed data such as radar altimetry from the TOPEX and ERS-1 satellites, a glance at a map of available subsurface data should convince most observers that this is still the case. Data are still too sparse for comprehensive treatment of interannual to interdecadal climate change through the use of models, since the new data sets have not been around for very long. In view of the dearth of data, we must note that the overall picture is changing rapidly. Recently, there have been a number of large scale ocean analysis and prediction efforts, some of which now run on an operational or at least quasi-operational basis, most notably the model based analyses of the tropical oceans. These programs are modeled on numerical weather prediction. Aside from the success of the global tide models, assimilation of data in the tropics, in support of prediction and analysis of seasonal to interannual climate change, is probably the area of large scale ocean modeling and data assimilation in which the most progress has been made. Climate change is a problem which is particularly suited to advanced data assimilation methods. Linear models are useful, and the linear theory can be exploited. For the most part, the data are sufficiently sparse that implementation of advanced methods is worthwhile. As an example of a large scale data assimilation experiment with a recent extensive data set, we present results of a tropical ocean experiment in which the Kalman filter was used to assimilate three years of altimetric data from Geosat into a coarsely resolved linearized long wave shallow water model. Since nonlinear processes dominate the local dynamic signal outside the tropics, subsurface dynamical quantities cannot be reliably inferred from surface height anomalies. Because of its potential for large scale synoptic coverage of the deep ocean, acoustic travel time data should be a natural complement to satellite altimetry. Satellite data give us vertical integrals associated with thermodynamic and dynamic processes.
Miller, Robert N.↗
NASA's Management and Utilization of the Small Business Innovative Research (SBIR) Program
The United Space Congress established the SBIR program in 1982 for the following purposes: ( 1) Stimulate technological innovation (2) Increase private-sector commercialization derived from federal R&D (3) Use small business to meet federal R&D needs (4) Foster and encourage participation by disadvantaged persons and women in technological innovation The STTR program was established in 1992 with the additional requirement of having a small business partner with a research institution (usually a university) for the purpose of transferring intellectual property from the research institution to the small business concern for enabling a government technical need and furthering the technological development for the purpose of developing commercial products. The government of Japan has established a program that models portions of the U.S. SBIR and STTR programs. They are very interested in how NASA has been so successful in fulfilling the Congressional objectives of these programs. In particular, they want to understand the management practices and incentives that are provided to enable partnerships between business enterprises, academia and government. The speech will also focus on some of the many successful technologies (on a conceptual level) that have been developed through NASA s SBIR and STTR programs and mechanisms used to promote cooperation between small businesses, large businesses, academia and government agencies within the United States. The speech is on a conceptual level, focusing on U.S. and NASA policies and management implementation practices. No enabling technical discussion will be held.
Mexcur, Winfield Paul↗
Effects of Low Activity Solar Cycle on Orbital Debris Lifetime
Long duration of low solar activity in the last solar minimum has an undesirable consequence of extending the lifetime of orbital debris. The AFRL TacSat-2 satellite decommissioned in 2008 has finally re-entered into the atmosphere on February 5th after more than one year overdue. Concerning its demise we have monitored its orbital decay and monthly forecasted Tacsat-2 re-entry since September 2010 by using the Orbital Element Prediction (OEP) model developed by the AFRL Orbital Drag Environment program. The model combines estimates of future solar activity with neutral density models, drag coefficient models, and an orbit propagator to predict satellite lifetime. We run the OEP model with solar indices forecast by the NASA Marshall Solar Activity Future Estimation model, and neutral density forecast by the MSIS-00 neutral density model. Based on the two line elements in 2010 up to mid September, we estimated at a 50% confidence level TacSat-2's re-entry time to be in early February 2011, which turned out to be in good agreement with Tacsat-2's actual re-entry date. The potential space weather effects of the coming low activity solar cycle on satellite lifetime and orbital debris population are examined. The NASA long-term orbital debris evolutionary model, LEGEND, is used to quantify the effects of solar flux on the orbital debris population in the 200-600 km altitude environment. The results are discussed for developing satellite orbital drag application product.
Cable, Samual B.↗
Reduced Pressure Cabin Testing of the Orion Atmosphere Revitalization Technology
An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Atmosphere Revitalization System for moderate duration missions of the Orion Multipurpose Crew Vehicle. In previous years at this conference, reports were presented on extensive Johnson Space Center testing of this technology in a sea-level pressure environment with simulated and actual human metabolic loads in both open and closed-loop configurations. In 2011, the technology was tested in an open cabin-loop configuration at ambient and two sub-ambient pressures to compare the performance of the system to the results of previous tests at ambient pressure. The testing used a human metabolic simulator with a different type of water vapor generation than previously used, which added some unique challenges in the data analysis. This paper summarizes the results of: baseline and some matrix testing at all three cabin pressures, increased vacuum regeneration line pressure with a high metabolic load, a set of tests studying CO2 and water vapor co-adsorption effects relative to model-predicted performance, and validation tests of flight program computer model predictions with specific operating conditions.
Button, Amy↗
Reduced Pressure Cabin Testing of the Orion Atmosphere Revitalization Technology
An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Atmosphere Revitalization System for moderate duration missions of the Orion Multipurpose Crew Vehicle. In previous years at this conference, reports were presented on extensive Johnson Space Center testing of this technology in a sea-level pressure environment with simulated and actual human metabolic loads in both open and closed-loop configurations. In 2011, the technology was tested in an open cabin-loop configuration at ambient and two sub-ambient pressures to compare the performance of the system to the results of previous tests at ambient pressure. The testing used a human metabolic simulator with a different type of water vapor generation than previously used, which added some unique challenges in the data analysis. This paper summarizes the results of: baseline and some matrix testing at all three cabin pressures, increased vacuum regeneration line pressure with a high metabolic load, a set of tests studying CO2 and water vapor co-adsorption effects relative to model-predicted performance, and validation tests of flight program computer model predictions with specific operating conditions.
Button, Amy↗
The NASA Commercial Crew Program (CCP) Shared Assurance Model for Safety
This presentation describes the CCP SMA approach to assuring the approved verifications of hazard controls are in place.
Risk Based Assessment↗
Contributions of the ARM Program to Radiative Transfer Modeling for Climate and Weather Applications
Accurate climate and weather simulations must account for all relevant physical processes and their complex interactions. Each of these atmospheric, ocean, and land processes must be considered on an appropriate spatial and temporal scale, which leads these simulations to require a substantial computational burden. One especially critical physical process is the flow of solar and thermal radiant energy through the atmosphere, which controls planetary heating and cooling and drives the large-scale dynamics that moves energy from the tropics toward the poles. Radiation calculations are therefore essential for climate and weather simulations, but are themselves quite complex even without considering the effects of variable and inhomogeneous clouds. Clear-sky radiative transfer calculations have to account for thousands of absorption lines due to water vapor, carbon dioxide, and other gases, which are irregularly distributed across the spectrum and have shapes dependent on pressure and temperature. The line-by-line (LBL) codes that treat these details have a far greater computational cost than can be afforded by global models. Therefore, the crucial requirement for accurate radiation calculations in climate and weather prediction models must be satisfied by fast solar and thermal radiation parameterizations with a high level of accuracy that has been demonstrated through extensive comparisons with LBL codes. See attachment for continuation.
climatology↗
Space Technology Mission Directorate - Game Changing Development Program: FY22 Entry Systems Modeling Annual Review Presentation
Explore the source record for details and available documents.
Entry systems↗