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At least 127 records · Page 7

All sources NASA NTRS DOE OSTI

NASA NTRS1992

A computational study of advanced exhaust system transition ducts with experimental validation

The current study is an application of CFD to a 'real' design and analysis environment. A subsonic, three-dimensional parabolized Navier-Stokes (PNS) code is used to construct stall margin design charts for optimum-length advanced exhaust systems' circular-to-rectangular transition ducts. Computer code validation has been conducted to examine the capability of wall static pressure predictions. The comparison of measured and computed wall static pressures indicates a reasonable accuracy of the PNS computer code results. Computations have also been conducted on 15 transition ducts, three area ratios, and five aspect ratios. The three area ratios investigated are constant area ratio of unity, moderate contracting area ratio of 0.8, and highly contracting area ratio of 0.5. The degree of mean flow acceleration is identified as a dominant parameter in establishing the minimum duct length requirement. The effect of increasing aspect ratio in the minimum length transition duct is to increase the length requirement, as well as to increase the mass-averaged total pressure losses. The design guidelines constructed from this investigation may aid in the design and manufacture of advanced exhaust systems for modern fighter aircraft.

Wu, C.↗

NASA NTRS1993

Handling qualities effects of display latency

Display latency is the time delay between aircraft response and the corresponding response of the cockpit displays. Currently, there is no explicit specification for allowable display lags to ensure acceptable aircraft handling qualities in instrument flight conditions. This paper examines the handling qualities effects of display latency between 70 and 400 milliseconds for precision instrument flight tasks of the V-22 Tiltrotor aircraft. Display delay effects on the pilot control loop are analytically predicted through a second order pilot crossover model of the V-22 lateral axis, and handling qualities trends are evaluated through a series of fixed-base piloted simulation tests. The results show that the effects of display latency for flight path tracking tasks are driven by the stability characteristics of the attitude control loop. The data indicate that the loss of control damping due to latency can be simply predicted from knowledge of the aircraft's stability margins, control system lags, and required control bandwidths. Based on the relationship between attitude control damping and handling qualities ratings, latency design guidelines are presented. In addition, this paper presents a design philosophy, supported by simulation data, for using flight director display augmentation to suppress the effects of display latency for delays up to 300 milliseconds.

King, David W.↗

NASA NTRS1995

Structural Damage Prediction and Analysis for Hypervelocity Impact

It is necessary to integrate a wide variety of technical disciplines to provide an analysis of structural damage to a spacecraft due to hypervelocity impact. There are many uncertainties, and more detailed investigation is warranted, in each technical discipline. However, a total picture of the debris and meteoroid hazard is required to support manned spaceflight in general, and the international Space Station in particular. In the performance of this contract, besides producing a handbook, research and development was conducted in several different areas. The contract was broken into six separate tasks. Each task objectives and accomplishments will be reviewed in the following sections. The Handbook and separate task reports are contained as attachments to the final report. The final section summarizes all of the recommendations coming out of this study. The analyses and comments are general design guidelines and not necessarily applicable to final Space Station designs since several configuration and detailed design changes were being made during the course of this contract. Rather, the analyses and comments may indicate either a point-in-time concept analysis, available test data, or desirable protection goals, not hindered by the design and operation constraints faced by Space Station designers.

Elfer, Norman↗

NASA NTRS2012

Modular Integrated Stackable Layers (MISL) 1.1 Design Specification

This document establishes the design guideline of the Modular Instrumentation Data Acquisition (MI‐DAQ) system in utilization of several designs available in EV. The MI‐ DAQ provides the options to the customers depending on their system requirements i.e. a 28V interface power supply, a low power battery operated system, a low power microcontroller, a higher performance microcontroller, a USB interface, a Ethernet interface, a wireless communication, various sensor interfaces, etc. Depending on customer's requirements, the each functional board can be stacked up from a bottom level of power supply to a higher level of stack to provide user interfaces. The stack up of boards are accomplished by a predefined and standardized power bus and data bus connections which are included in this document along with other physical and electrical guidelines. This guideline also provides information for a new design options. This specification is the product of a collaboration between NASA/JSC/EV and Texas A&M University. The goal of the collaboration is to open source the specification and allow outside entities to design, build, and market modules that are compatible with the specification. NASA has designed and is using numerous modules that are compatible to this specification. A limited number of these modules will also be released as open source designs to support the collaboration. The released designs are listed in the Applicable Documents.

Yim, Hester J.↗

NASA NTRS1980

Study to develop improved fire resistant aircraft passenger seat materials

The Phase 3 study of the NASA 'Improved Fire Resistant Aircraft Seat Materials' involved fire tests of improved materials in multilayered combinations representative of cushion configurations. Tests were conducted to determine their thermal, smoke, and fire resistance characteristics. Additionally, a 'Design Guideline' for Fire Resistant Passenger Seats was written outlining general seat design considerations. Finally, a three-abreast 'Tourist Class' passenger seat assembly fabricated from the most advanced fire-resistant materials was delivered.

Duskin, F. E.↗

NASA NTRS1994

Primary battery design and safety guidelines handbook

This handbook provides engineers and safety personnel with guidelines for the safe design or selection and use of primary batteries in spaceflight programs. Types of primary batteries described are silver oxide zinc alkaline, carbon-zinc, zinc-air alkaline, manganese dioxide-zionc alkaline, mercuric oxide-zinc alkaline, and lithium anode cells. Along with typical applications, the discussions of the individual battery types include electrochemistry, construction, capacities and configurations, and appropriate safety measures. A chapter on general battery safety covers hazard sources and controls applicable to all battery types. Guidelines are given for qualification and acceptance testing that should precede space applications. Permissible failure levels for NASA applications are discussed.

Bragg, Bobby J.↗

NASA NTRS2017

Test and Analysis of Buckling-Critical Stiffened Metallic Launch Vehicle Cylinders

A summary of a NASA design analysis and test program on the buckling of large-scale, integrally-stiffened metallic cylinders is presented. The test article designs were developed based on proposed NASA launch vehicle cylinder designs and span a significant portion of the design space. Various loading conditions were applied to the cylinders and include different combinations of axial compression, bending, and internal pressure loads that simulate typical launch vehicle loading scenarios. The data gathered from this test program is being used to develop and validate new analysis-based knockdown factors and design guidelines for these stiffened metallic cylinders. In this paper, the test article designs and fabrication methods are described along with the test facilities and instrumentation. Selected test and finite element analysis results are presented and compared and are used to illustrate the typical response characteristics of the stiffened metallic cylinders considered. Overall, good qualitative agreement is found, however, several discrepancies in the results were identified across several of the tests. The discrepancies were investigated thoroughly and can be attributed to variations in the as-built skin and stiffener geometry, variations in the measured geometric imperfection, and modeling assumptions associated with the boundary conditions, and loading imperfections. Based on these findings, several refinements were made to the finite element models which significantly improved the correlation between the test and analysis results. These modeling refinements are described and the updated analysis results are presented.

Hilburger, Mark W.↗

NASA NTRS1980

Deployable structure design for the science and applications space platform

Basic concepts regarding deployable structures design, including systematic design/classification schemes and a deployability criterion, were proposed for use in synthesis, analysis and evaluation of alternative deployable structure designs. Using design guidelines based on SASP requirements and the basic concepts developed, a variety of designs were synthesized, and these along with previously proposed designs were analyzed and evaluated. Recommendations and conclusions regarding optimal deployable structure design were made.

Stoll, H. W.↗

NASA NTRS1995

Advanced liquid oxygen (LO2) propellant conditioning concept testing

Advanced methods of liquid oxygen (LO2) propellant conditioning were studied as part of an effort for increasing reliability and operability while reducing cost of future heavy lift launch vehicles. The most promising conditioning concept evaluated was no-bleed (passive recirculation) followed by low-bleed, helium injection, and use of a recirculation line. Full-scale cryogenic testing was performed with a sloped feedline test article to validate models of behavior of LO2 in the feedline and to prove no-bleed feasibility. Test data are also intended to help generate design guidelines for the development of a main propulsion system feed duct. A design-of-experiments matrix of over 100 tests was developed to test all four propellant conditioning concepts and the impact of design parameters on the concepts. Liquid nitrogen was used as the test fluid. The work for this project was conducted from October 1992 through January 1994 at the hydrogen cold flow facility of the west test area of MSFC. Test data have shown that satisfactory temperatures are being obtained for the no-bleed conditioning concept.

Perry, G. L. E.↗

NASA NTRS1977

Rotor burst protection program: Experimentation to provide guidelines for the design of turbine rotor burst fragment containment rings

Empirical guidelines for the design of minimum weight turbine rotor disk fragment containment rings made from a monolithic metal were generated by experimentally establishing the relationship between a variable that provides a measure of containment ring capability and several other variables that both characterized the configurational aspects of the rotor fragments and containment ring, and had been found from exploratory testing to have had significant influence on the containment process. Test methodology and data analysis techniques are described. Results are presented in graphs and tables.

Mangano, G. J.↗

NASA NTRS1992

LDEF space optics handbook

There is a need to present design guidelines derived from the Long Duration Exposure Facility (LDEF) space optics experiments to hardware designers. In response to this need, a small study program has been started. The objective is to prepare a top level review of available results on the behavior of certain optical components in the LDEF space experiments. The optics interest centers on optical surfaces and coatings, and fabrication processes for laser windows and mirrors. The program has two main parts: the first phase, consists of identifying and acquiring data from appropriate investigators. The second phase, comprises report preparation as well as selected, prioritized, additional characterization of certain samples, coordinated with the principal investigators. This short paper outlines the program under way.

Champetier, Robert J.↗

NASA NTRS1993

LDEF space optics handbook

There is a need to present design guidelines derived from the Long Duration Exposure Facility (LDEF) space optics experiments to hardware designers. In response to this need a small study program was just started by SAIC and POD Associates for the Phillips Laboratory. The objective is to prepare a top-level review of available results on the behavior of certain optical components in the LDEF space experiments. The optics interest centers on optical surfaces and coatings, and fabrication processes for laser windows and mirrors. The program has two main parts: the first phase, to be completed by the end of 1992, consists of identifying and acquiring data from the appropriate investigators. The second phase, ending in December 1993, comprises report preparation as well as selected, prioritized, additional characterization of certain samples, coordinated with the principal investigators and the Phillips Laboratory. This program is getting under way at the time of the Symposium and does not warrant more than the present summary at this time.

Champetier, Robert J.↗

NASA NTRS2006

Human Factors Considerations for Performance-Based Navigation

A transition toward a performance-based navigation system is currently underway in both the United States and around the world. Performance-based navigation incorporates Area Navigation (RNAV) and Required Navigation Performance (RNP) procedures that do not rely on the location of ground-based navigation aids. These procedures offer significant benefits to both operators and air traffic managers. Under sponsorship from the Federal Aviation Administration (FAA), the National Aeronautics and Space Administration (NASA) has undertaken a project to document human factors issues that have emerged during RNAV and RNP operations and propose areas for further consideration. Issues were found to include aspects of air traffic control and airline procedures, aircraft systems, and procedure design. Major findings suggest the need for human factors-specific instrument procedure design guidelines. Ongoing industry and government activities to address air-ground communication terminology, procedure design improvements, and chart-database commonality are strongly encouraged.

Barhydt, Richard↗

NASA NTRS2007

Design, Qualification, and On Orbit Performance of the CALIPSO Aerosol Lidar Transmitter

The laser transmitter for the CALIPSO aerosol lidar mission has been operating on orbit as planned since June 2006. This document discusses the optical and laser system design and qualification process that led to this success. Space-qualifiable laser design guidelines included the use of mature laser technologies, the use of alignment sensitive resonator designs, the development and practice of stringent contamination control procedures, the operation of all optical components at appropriately derated levels, and the proper budgeting for the space-qualification of the electronics and software.

Hovis, Floyd E.↗

NASA NTRS2014

Design of 3D-Printed Titanium Compliant Mechanisms

This paper describes 3D-printed titanium compliant mechanisms for aerospace applications. It is meant as a primer to help engineers design compliant, multi-axis, printed parts that exhibit high performance. Topics covered include brief introductions to both compliant mechanism design and 3D printing in titanium, material and geometry considerations for 3D printing, modeling techniques, and case studies of both successful and unsuccessful part geometries. Key findings include recommended flexure geometries, minimum thicknesses, and general design guidelines for compliant printed parts that may not be obvious to the first time designer.

Merriam, Ezekiel G.↗

NASA NTRS2015

Analytic Thermoelectric Couple Modeling: Variable Material Properties and Transient Operation

To gain a deeper understanding of the operation of a thermoelectric couple a set of analytic solutions have been derived for a variable material property couple and a transient couple. Using an analytic approach, as opposed to commonly used numerical techniques, results in a set of useful design guidelines. These guidelines can serve as useful starting conditions for further numerical studies, or can serve as design rules for lab built couples. The analytic modeling considers two cases and accounts for 1) material properties which vary with temperature and 2) transient operation of a couple. The variable material property case was handled by means of an asymptotic expansion, which allows for insight into the influence of temperature dependence on different material properties. The variable property work demonstrated the important fact that materials with identical average Figure of Merits can lead to different conversion efficiencies due to temperature dependence of the properties. The transient couple was investigated through a Greens function approach; several transient boundary conditions were investigated. The transient work introduces several new design considerations which are not captured by the classic steady state analysis. The work helps to assist in designing couples for optimal performance, and also helps assist in material selection.

Seebeck Effect↗

NASA NTRS1990

Simultaneous control and structure design for large space structures

The problem of developing design guidelines for the simultaneous selection of control and structural parameters is addressed. One guideline is offered for the case of vibration suppression due to disturbances. The effect of structural design changes is examined by means of a parameterized LQG compensator. It is shown that using the LQG design provides a simple means to evaluate simultaneous control and design changes.

Kosut, Robert L.↗

NASA NTRS2002

Rocket Engine Oscillation Diagnostics

Rocket engine oscillating data can reveal many physical phenomena ranging from unsteady flow and acoustics to rotordynamics and structural dynamics. Because of this, engine diagnostics based on oscillation data should employ both signal analysis and physical modeling. This paper describes an approach to rocket engine oscillation diagnostics, types of problems encountered, and example problems solved. Determination of design guidelines and environments (or loads) from oscillating phenomena is required during initial stages of rocket engine design, while the additional tasks of health monitoring, incipient failure detection, and anomaly diagnostics occur during engine development and operation. Oscillations in rocket engines are typically related to flow driven acoustics, flow excited structures, or rotational forces. Additional sources of oscillatory energy are combustion and cavitation. Included in the example problems is a sampling of signal analysis tools employed in diagnostics. The rocket engine hardware includes combustion devices, valves, turbopumps, and ducts. Simple models of an oscillating fluid system or structure can be constructed to estimate pertinent dynamic parameters governing the unsteady behavior of engine systems or components. In the example problems it is shown that simple physical modeling when combined with signal analysis can be successfully employed to diagnose complex rocket engine oscillatory phenomena.

Nesman, Tom↗