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At least 433 records · Page 24

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NASA NTRS1992

The NASA/Industry Design Analysis Methods for Vibrations (DAMVIBS) Program - A government overview

An overview is presented of government contributions to the program called Design Analysis Methods for Vibrations (DAMV) which attempted to develop finite-element-based analyses of rotorcraft vibrations. NASA initiated the program with a finite-element modeling program for the CH-47D tandem-rotor helicopter. The DAMV program emphasized four areas including: airframe finite-element modeling, difficult components studies, coupled rotor-airframe vibrations, and airframe structural optimization. Key accomplishments of the program include industrywide standards for modeling metal and composite airframes, improved industrial designs for vibrations, and the identification of critical structural contributors to airframe vibratory responses. The program also demonstrated the value of incorporating secondary modeling details to improving correlation, and the findings provide the basis for an improved finite-element-based dynamics design-analysis capability.

Kvaternik, Raymond G.↗

NASA NTRS1992

Overview of the manufacturing sequence of the Advanced Solid Rocket Motor

The manufacturing sequence of NASA's new Advanced Solid Rocket Motor, developed as a replacement of the Space Shuttle's existing Redesigned Solid Rocket Motor, is overviewed. Special attention is given to the case preparation, the propellant mix/cast, the nondestructuve evaluation, the motor finishing, and the refurbishment. The fabrication sequences of the case, the nozzle, and the igniter are described.

Chapman, John S.↗

NASA NTRS1992

Overview of the NASA/Marshall Space Flight Center (MSFC) CFD Consortium for Applications in Propulsion Technology

This paper presents an overview of the NASA/Marshall Space Flight Center (MSFC) Computational Fluid Dynamics (CFD) Consortium for Applications in Propulsion Technology (CAPT). The objectives of this consortium are discussed, as is the approach of managing resources and technology to achieve these objectives. Significant results by the three CFD CAPT teams (Turbine, Pump, and Combustion) are briefly highlighted with respect to the advancement of CFD applications, the development and evaluation of advanced hardware concepts, and the integration of these results and CFD as a design tool to support Space Transportation Main Engine and National Launch System development.

Mcconnaughey, P. K.↗

NASA NTRS1991

Degradation of materials properties in space-overview of LDEF (Long Duration Exposure Facility)

This paper presents an overview of the initial observations of the Long Duration Exposure Facility and, in particular, the degradation of the onboard materials. The LDEF was retrieved from space on January 12, 1990, during the Space Shuttle STS Mission 32 after having remained in space for almost 6 years. Ongoing studies of this retrieved hardware are providing a wealth of basic science data on the environments of near-earth space and the synergistic effects of these space environments on a large array of typical spacecraft materials and systems.

Kinard, William H.↗

NASA NTRS1992

An overview of in-flight plume diagnostics for rocket engines

An overview and progress report of the work performed or sponsored by LeRC toward the development of in-flight plume spectroscopy technology for health and performance monitoring of liquid propellant rocket engines are presented. The primary objective of this effort is to develop technology that can be utilized on any flight engine. This technology will be validated by a hardware demonstration of a system capable of being retrofitted onto the Space Shuttle Main Engines for spectroscopic measurements during flight. The philosophy on system definition and status on the development of instrumentation, optics, and signal processing with respect to implementation on a flight engine are discussed.

Madzsar, G. C.↗

NASA NTRS1992

Space Exploration Initiative - Overview, current status, near term plans

An overview is presented of the Space Exploration Initiative (SEI) describing current activities, accomplishemnts, and directions. The program is considered in terms of activities relevant to the three phases which are: manned robotic/precursor missions, manned lunar missions, and manned Mars missions. SEI is shown to be in the First Lunar Outpost (FLO) mission phase which is based on an early manned lunar return, and development is described of earth-to-orbit (ETO) vehicles, a translunar injection stage, and a lunar surface habitat. Two ETO vehicles are considered, and the translunar injection stage is illustrated. The FLO mission is also considered as an initiation of the design activity for the Mars mission so that the requirements and preliminary designs could be defined. The FLO program demonstrates the feasibility of a manned return to the moon as an initiation of subsequent SEI activities.

Adams, Alan M.↗

NASA NTRS1992

A history of the Lonar crater, India: An overview

The origin of the circular structure at Lonar, India, described variously as cauldron, pit, hollow, depression, and crater, has been a controversial subject since the early nineteenth century. A history of its origin and other aspects from 1823 to 1990 are overviewed. The structure in the Deccan Trap Basalt is nearly circular with a breach in the northeast, 1830 m in diameter, 150 m deep, with a saline lake in the crater floor. Over the years, the origin of the Lonar structure has risen from volcanism, subsidence, and cryptovolcanism to an authentic meteorite impact crater. Lonar is unique because it is probably the only terrestrial crater in basalt and is the closest analog with the Moon's craters. Some unresolved questions are suggested. The proposal is made that the young Lonar impact crater, which is less than 50,000 years old, should be considered as the best crater laboratory analogous to those of the Moon, be treated as a global monument, and preserved for scientists to comprehend more about the mysteries of nature and impact cratering, which is now emerging as a fundamental ubiquitous geological process in the evolution of the planets.

Nayak, V. K.↗

NASA NTRS1992

Overview of high performance aircraft propulsion research

The overall scope of the NASA Lewis High Performance Aircraft Propulsion Research Program is presented. High performance fighter aircraft of interest include supersonic flights with such capabilities as short take off and vertical landing (STOVL) and/or high maneuverability. The NASA Lewis effort involving STOVL propulsion systems is focused primarily on component-level experimental and analytical research. The high-maneuverability portion of this effort, called the High Alpha Technology Program (HATP), is part of a cooperative program among NASA's Lewis, Langley, Ames, and Dryden facilities. The overall objective of the NASA Inlet Experiments portion of the HATP, which NASA Lewis leads, is to develop and enhance inlet technology that will ensure high performance and stability of the propulsion system during aircraft maneuvers at high angles of attack. To accomplish this objective, both wind-tunnel and flight experiments are used to obtain steady-state and dynamic data, and computational fluid dynamics (CFD) codes are used for analyses. This overview of the High Performance Aircraft Propulsion Research Program includes a sampling of the results obtained thus far and plans for the future.

Biesiadny, Thomas J.↗

NASA NTRS1992

LDEF materials: An overview of the interim findings

The flight and retrieval of the National Aeronautics and Space Administration's Long Duration Exposure Facility (LDEF) provided an opportunity for the study of the low-Earth orbit (LEO) environment and long-duration space environmental effect (SEE) on materials that are unparalleled in the history of the U.S. space program. The 5.8-year flight of LDEF greatly enhanced the potential value of materials data from LDEF to the international SEE community, compared to that of the original 1-year flight plan. The remarkable flight attitude stability of LDEF enables specific analyses of various individual and combined effects of LEO environmental parameters on identical materials of the same space vehicle. NASA recognized the potential by forming the LDEF Space Environmental Effects on Materials Special Investigation Group (MSIG) to address the greatly expanded materials and LEO space environment parameter analysis opportunities available in the LDEF structure, experiment trays, and corollary measurements, so that the combined value of all LDEF materials data to current and future space missions will be assessed and documented. This paper provides an overview of the interim LDEF materials findings of the Principal Investigators and the Materials Special Investigation Group. These revelations are based on observations of LEO environmental effects on materials made in-space during LDEF retrieval and during LDEF tray deintegration at the Kennedy Space Center, and on findings of approximately 1.5 years of laboratory analyses of LDEF materials by the LDEF materials scientists. These findings were extensively reviewed and discussed at the MSIG-sponsored LDEF Materials Workshop '91. The results are presented in a format which categorizes the revelations as 'clear findings' or 'confusing/unexplained findings' and resultant needs for new space materials developments and ground simulation testing/analytical modeling in seven categories: environmental parameters and data bases; LDEF contamination; thermal control coatings and protective treatments; polymers and films; polymer-matrix composites; metals, ceramics, and optical materials; and systems-related materials. General outlines of findings of the other LDEF Special Investigation Groups (Ionizing Radiation, Meteoroid and Debris, and Systems) are also included. The utilization of LDEF materials data for future low-earth orbit missions is also discussed, concentrating on Space Station Freedom. Some directions for continuing studies of LDEF materials are outlined. In general, the LDEF data is remarkable consistent; LDEF will provide a 'benchmark' for materials design data bases for satellites in low-Earth orbit. Some materials were identified to be encouragingly resistant to LEO SEE for 5.8-years; other 'space qualified' materials displayed significant environmental degradation. Molecular contamination was widespread; LDEF offers an unprecedented opportunity to provide a unified perspective of unmanned LEO spacecraft contamination mechanisms. New material development requirements for long-term LEO missions have been identified and current ground simulation testing methods/data for new, durable materials concepts can be validated with LDEF results. LDEF findings are already being integrated into the design of Space Station Freedom.

Stein, Bland A.↗

NASA NTRS1992

A brief overview of NASA Langley's research program in formal methods

An overview of NASA Langley's research program in formal methods is presented. The major goal of this work is to bring formal methods technology to a sufficiently mature level for use by the United States aerospace industry. Towards this goal, work is underway to design and formally verify a fault-tolerant computing platform suitable for advanced flight control applications. Also, several direct technology transfer efforts have been initiated that apply formal methods to critical subsystems of real aerospace computer systems. The research team consists of six NASA civil servants and contractors from Boeing Military Aircraft Company, Computational Logic Inc., Odyssey Research Associates, SRI International, University of California at Davis, and Vigyan Inc.

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NASA NTRS1991

Solar System Exploration Division Strategic Plan, volume 1. Executive summary and overview

This first document is the first of a six-volume series presenting the Solar System Exploration Division's Strategic Plan for the 10-year period FY 1994 to FY 2003. The overall strategy is characterized by five fundamental precepts: (1) execute the current program; (2) improve the vitality of the program and the planetary science community; (3) initiate innovative, small, low-cost planetary missions; (4) initiate new major and moderate missions; and (5) prepare for the next generation of missions. This Strategic Plan describes in detail our proposed approach to accomplish these goals. Volume 1 provides first an Executive Summary of highlights of each of the six volumes, and then goes on to present an overview of the plan, including a discussion of the planning context and strategic approach. Volumes 2, 3, 4, and 5 describe in detail the initiatives proposed. An integral part of each of these volumes is a set of responses to the mission selection criteria questions developed by the Space and Earth Science Advisory Committee. Volume 2, Mission From Planet Earth, describes a strategy for exploring the Moon and Mars and sets forth proposed moderate missions--Lunar Observer and a Mars lander network. Volume 3, Pluto Flyby/Neptune Orbiter, discusses our proposed major new start candidate for the FY 1994 to FY 1998 time frame. Volume 4, Discovery, describes the Near-Earth Asteroid Rendezvous, as well as other candidates for this program of low-cost planetary missions. Volume 5, Toward Other Planetary Systems, describes a major research and analysis augmentation that focuses on extrasolar planet detection and the study of planetary system processes. Finally, Volume 6 summarizes the technology program that the division has structured around these four initiatives.

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NASA NTRS1992

An overview of reliability growth models and their potential use for NASA applications

An overview is provided of reliability growth literature over the past 25 years. This includes a thorough literature review of different areas of the application of reliability growth such as design, prediction, tracking/management, and demonstration. Various reliability growth models use different bases on how they characterize growth. Different models are discussed. Also, the use is addressed of reliability growth models to NASA applications. This includes the application of these models to the space shuttle main engine. For potential NASA applications, we classify growth models in two groups, which are characterized.

Taneja, V. S.↗

NASA NTRS1992

Space resources. Overview

Space resources must be used to support life on the Moon and in the exploration of Mars. Just as the pioneers applied the tools they brought with them to resources they found along the way rather than trying to haul all their needs over a long supply line, so too must space travelers apply their high technology tools to local resources. This overview describes the findings of a study on the use of space resources in the development of future space activities and defines the necessary research and development that must precede the practical utilization of these resources. Space resources considered included lunar soil, oxygen derived from lunar soil, material retrieved from near-Earth asteroids, abundant sunlight, low gravity, and high vacuum. The study participants analyzed the direct use of these resources, the potential demand for products from them, the techniques for retrieving and processing space resources, the necessary infrastructure, and the economic tradeoffs.

Mckay, Mary Fae↗

NASA NTRS1992

An interim overview of LDEF materials findings

Stein, Brad A.↗

NASA NTRS1992

Initial overview of disconnection events in Halley's Comet 1986

We present an initial overview of the disconnection events (DE's) in Comet Halley in 1986. Although disconnection events are arguably the most spectacular of all dynamic comet phenomena, the mechanisms by which they occur are not fully understood. It is generally believed that the solar wind plays a major role in determining when disconnection events occur, but the details of the solar wind/cometary interactions responsible for initiating the tail disconnection are still under debate. The three most widely accepted models are: (1) high speed streams in the solar wind cause the tail to disconnect due to pressure effects; (2) decreased production of cometary ions in a high speed stream allows magnetic field to slip away from the comet; and (3) the tail disconnects after frontside reconnection of the interplanetary magnetic field (IMF) as the comet crosses a magnetic field sector boundary. We find that the front-side magnetic reconnection model is the best explanation for the DE's we have considered.

Brandt, John C.↗

NASA NTRS1993

An overview of European activities on microgravity combustion

The global objective of the European efforts in microgravity combustion is to combine theoretical and experimental work, both under normal and reduced gravity, to progress in the basic understanding of gravity dependent phenomena in various combustion situations. The first phase of the European activities on microgravity combustion has been summarized in refs. 1, 2, and 3. This overview will summarize the more recent developments. The focus will be on new experimental facilities, new research topics, and new collaborative efforts.

Goekalp, Iskender↗

NASA NTRS1993

The NASA/industry Design Analysis Methods for Vibrations (DAMVIBS) program: A government overview

NASA-Langley, under the Design Analysis Methods for Vibrations (DAMVIBS) Program, set out in 1984 to establish the technology base needed by the rotorcraft industry for developing an advanced finite-element-based dynamics design analysis capability for vibrations. Considerable work has been done by the industry participants in the program since that time. Because the DAMVIBS Program is being phased out, a government/industry assessment of the program has been made to identify those accomplishments and contributions which may be ascribed to the program. The purpose of this paper is to provide an overview of the program and its accomplishments and contributions from the perspective of the government sponsoring organization.

Kvaternik, Raymond G.↗

NASA NTRS1991

Soviet automated rendezvous and docking system overview

The Soviets have been performing automated rendezvous and docking for many years. This paper will present an overview and brief history of the Soviet AR&D system, based on the open literature and publicly available sources.

Hinman, Elaine M.↗