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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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At least 397 records · Page 22

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NASA NTRS1977

Evaluation of structural design concepts for an arrow-wing supersonic cruise aircraft

An analytical study was performed to determine the best structural approach for design of primary wing and fuselage structure of a Mach 2.7 arrow wing supersonic cruise aircraft. Concepts were evaluated considering near term start of design. Emphasis was placed on the complex interactions between thermal stress, static aeroelasticity, flutter, fatigue and fail safe design, static and dynamic loads, and the effects of variations in structural arrangements, concepts and materials on these interactions. Results indicate that a hybrid wing structure incorporating low profile convex beaded and honeycomb sandwich surface panels of titanium alloy 6Al-4V were the most efficient. The substructure includes titanium alloy spar caps reinforced with boron polyimide composites. The fuselage shell consists of hat stiffened skin and frame construction of titanium alloy 6Al-4V. A summary of the study effort is presented, and a discussion of the overall logic, design philosophy and interaction between the analytical methods for supersonic cruise aircraft design are included.

Sakata, I. F.↗

NASA NTRS1977

Study of limitations and attributes of microprocessor testing techniques

All microprocessor units have a similar architecture from which a basic test philosophy can be adopted and used to develop an approach to test each module separately in order to verify the functionality of each module within the device using the input/output pins of the device and its instruction set; test for destructive interaction between functional modules; and verify all timing, status information, and interrupt operations of the device. Block and test flow diagrams are given for the 8080, 8008, 2901, 6800, and 1802 microprocessors. Manufacturers are listed and problems encountered in testing the modules are discussed. Test equipment and methods are described.

Mccaskill, R.↗

NASA NTRS1977

Simulation of a synergistic six-post motion system on the flight simulator for advanced aircraft at NASA-Ames

Motion system drive philosophy and corresponding real-time software have been developed for the purpose of simulating the characteristics of a typical synergistic Six-Post Motion System (SPMS) on the Flight Simulator for Advanced Aircraft (FSAA) at NASA-Ames which is a non-synergistic motion system. This paper gives a brief description of these two types of motion systems and the general methods of producing motion cues of the FSAA. An actuator extension transformation which allows the simulation of a typical SPMS by appropriate drive washout and variable position limiting is described.

Bose, S. C.↗

NASA NTRS1977

Status of the Electroforming Shield Design (ESD) project

The utilization of a digital computer to augment electrodeposition/electroforming processes in which nonconducting shielding controls local cathodic current distribution is reported. The primary underlying philosophy of the physics of electrodeposition was presented. The technical approach taken to analytically simulate electrolytic tank variables was also included. A FORTRAN computer program has been developed and implemented. The program utilized finite element techniques and electrostatic theory to simulate electropotential fields and ionic transport.

Fletcher, R. E.↗

NASA NTRS1977

PLANS; a finite element program for nonlinear analysis of structures. Volume 2: User's manual

The PLANS system, rather than being one comprehensive computer program, is a collection of finite element programs used for the nonlinear analysis of structures. This collection of programs evolved and is based on the organizational philosophy in which classes of analyses are treated individually based on the physical problem class to be analyzed. Each of the independent finite element computer programs of PLANS, with an associated element library, can be individually loaded and used to solve the problem class of interest. A number of programs have been developed for material nonlinear behavior alone and for combined geometric and material nonlinear behavior. The usage, capabilities, and element libraries of the current programs include: (1) plastic analysis of built-up structures where bending and membrane effects are significant, (2) three dimensional elastic-plastic analysis, (3) plastic analysis of bodies of revolution, and (4) material and geometric nonlinear analysis of built-up structures.

Pifko, A.↗

NASA NTRS1975

A brief review of digital image processing

The review is presented with particular reference to Skylab S-192 and Landsat MSS imagery. Attention is given to rectification (calibration) processing with emphasis on geometric correction of image distortions. Image enhancement techniques (e.g., the use of high pass digital filters to eliminate gross shading to allow emphasis of the fine detail) are described along with data analysis and system considerations (software philosophy).

Billingsley, F. C.↗

NASA NTRS1976

Solar astrophysics - Ghettosis from, or symbiosis with, stellar and galactic astrophysics

The purpose of the paper is to show how the solar-stellar symbiotic approach has led to the modeling of a star as a concentration of matter and energy. By 'solar-stellar symbiosis' is meant the philosophy of investigation according to which one asks what change in our general understanding of stellar structure and of stellar spectroscopic diagnostics is required to satisfy both the sun and an unusual star when, for example, some feature of an unusual star is discovered. The evolution of stellar models is traced, from walled, thermodynamic-equilibrium models to de-isolated models featuring transition zones and nonlocal thermodynamic equilibrium.

Pecker, J.-C.↗

NASA NTRS1977

Scramjet exhaust simulation technique for hypersonic aircraft nozzle design and aerodynamic tests

Current design philosophy for scramjet-powered hypersonic aircraft results in configurations with the entire lower fuselage surface utilized as part of the propulsion system. The lower aft-end of the vehicle acts as a high expansion ratio nozzle. Not only must the external nozzle be designed to extract the maximum possible thrust force from the high energy flow at the combustor exit, but the forces produced by the nozzle must be aligned such that they do not unduly affect aerodynamic balance. The strong coupling between the propulsion system and aerodynamics of the aircraft makes imperative at least a partial simulation of the inlet, exhaust, and external flows of the hydrogen-burning scramjet in conventional facilities for both nozzle formulation and aerodynamic-force data acquisition. Aerodynamic testing methods offer no contemporary approach for such vehicle design requirements. NASA-Langley has pursued an extensive scramjet/airframe integration R&D program for several years and has recently developed a promising technique for simulation of the scramjet exhaust flow for hypersonic aircraft. Current results of the research program to develop a scramjet flow simulation technique through the use of substitute gas blends are described in this paper.

Hunt, J. L.↗

NASA NTRS1976

Stabilizing feedback control for dynamical systems with bounded uncertainty

The theories of differential games and generalized dynamic systems are used to deduce stabilizing controllers for quasi-linear systems. Attention is given to a class of dynamic systems subject to parameter and input uncertainty whose values range in a given compact set. Using a worst case design philosophy, a feedback control is derived that assures uniform asymptotic (Liapunov) stability of the origin under all admissible uncertainties.

Gutman, S.↗

NASA NTRS1977

V/STOL shaft propulsion system analytical performance model

Several classes of system performance simulations of V/STOL propulsion systems are presented. A digital simulation approach for a typical system (a propulsion system made up of three engines, shafts and gearbox, and remote lift fan) is given with a description of the general philosophy, solution options and model flexibility.

Sulkoske, R. A.↗

NASA NTRS1977

The sun-tracking control of solar collectors using high-performance step motors

Sun-tracking solar energy-focusing devices involving a central receiver, thermionic conversion, or a distributed solar thermal collector system are described. The Perkins solar collector uses a fixed focal point about which an 18 m-diameter parabolic dish moves on tracks. The elevation axis also moves on a circular track. A microprocessor manipulates sun sensor information and sun ephemeris data to ensure correct placement. Stepper motors are digital devices which provide direct interface with digital electronics and a wide dynamic range, and could easily be associated with the microprocessors. Design philosophy, performance criteria, wind load analysis, and control system requirements are also discussed.

Hughes, R. O.↗

NASA NTRS1977

Ionospheric aerodynamics and space simulation studies utilizing the Shuttle/Spacelab platform

A new philosophy for the second generation of in situ experiments in the area of plasma flows over bodies is discussed. A brief review of the present state of the theory and terrestrial laboratory and in situ studies is given, which points toward the need for further in situ investigations which utilize independently maneuverable test bodies and diagnostic instrument packages on board the Shuttle/Spacelab. The possibility of utilizing the Space Shuttle/Spacelab in the broader context of a general in situ plasma laboratory is considered, as well as the possibility of addressing questions of geo/astrophysical interest if the principle of qualitative scaling is used in conjunction with such a facility.

Samir, U.↗

NASA NTRS1977

Influence of temperature change on optimum laminate design

Results of a laminate optimization study, which includes prescribed temperature change and mechanical loading conditions, are presented. Minimum-weight designs for balanced symmetric laminates are obtained subject to strength, membrane stiffness, and minimum thickness requirements, while including and omitting temperature change effects. Based on a first ply failure design philosophy and employing a linear thermoelastic analysis, it is shown that taking temperature decrease effects into account leads to substantial weight penalties in strength critical fiber composite laminates. Numerical results are presented for representative fiber composite materials based on three commonly used combined stress failure criteria.

Schmit, L. A., Jr.↗

NASA NTRS1977

Designing the L-1011 to minimize rotor failures effects

Design philosophies used in the L-1011 aircraft to provide protection against rotor fragments include: (1) incorporating into the rotor design features that tend to promote small fragments if failure occurs; (2) containing the fragments within the engine shell or greatly reducing the energy content of those fragments that are eventually uncontained; (3) shielding vulnerable elements or systems with heavy structural members that tend to stop or deflect high velocity fragments; and (4) incorporating redundant and/or backup systems into the basic design and separating these systems so as to minimize the probability that more than one system will be damaged by an uncontained rotor fragment. Some of the design features that were incorporated into the Rolls-Royce RB211 engine are discussed, and two in-service experiences are considered in order to illustrate the practical operation of these features.

Wignot, J. E.↗

NASA NTRS1977

Design, construction and testing of the Communications Technology Satellite protection against spacecraft charging

Detailed discussions are presented of the measures taken on the Communications Technology Satellite (CTS or Hermes) which provide protection against the effects of spacecraft charging. These measures include: a comprehensive grounding philosophy and implementation; provision of command and data line transmitters and receivers for transient noise immunity; and a fairly restrictive EMI specification. Ground tests were made on materials and the impact of these tests on the CTS spacecraft is described. Hermes, launched on 17 January 1976 on a 2914 Delta vehicle, has successfully completed 10 months of operations. Anomalies observed are being assessed in relation to spacecraft charging, but no definite correlations have yet been established. A list of conclusions with regard to the CTS experience is given and recommendations for future spacecraft are also listed.

Gore, J. V.↗

NASA NTRS1977

Test techniques for evaluation of indirect effects

Test techniques for evaluation of how well electrical and electronic equipment withstands the indirect effects of lightning were studied. The existing test techniques, and the philosophy behind some of the existing or evolving standards are discussed. Possible avenues of improvement in test techniques are suggested.

Franklin A Fisher↗

NASA NTRS1977

The Feasibility of Establishing Operational Water Hyacinth-Based Systems at the Treatment Facilities of Existing Cities

The wastewater treatment facilities of three communities in southern Florida and two in southern Texas areas having populations of 20,000 or fewer persons were surveyed to determine: (1) their performance characteristics and the nature of their customers; (2) facility upgrading requirements needed to meet current and future EPA and State standards; (3) their adaptability to water hyacinth utilization and harvested plant disposal; and (4) the level of community support. Guidelines for site selection were established and applied to five cities in Texas and four in Florida. An evaluation of the prospective sites reveals that the Florida locations are generally unsuitable for implementation of water hyacinth based systems because of regulatory philosophy. All five Texas sites have excellent potential.

Source record↗

NASA NTRS1973

Feasibility study of an Integrated Program for Aerospace-vehicle Design (IPAD) system. Volume 6: Implementation schedule, development costs, operational costs, benefit assessment, impact on company organization, spin-off assessment, phase 1, tasks 3 to 8

A baseline implementation plan, including alternative implementation approaches for critical software elements and variants to the plan, was developed. The basic philosophy was aimed at: (1) a progressive release of capability for three major computing systems, (2) an end product that was a working tool, (3) giving participation to industry, government agencies, and universities, and (4) emphasizing the development of critical elements of the IPAD framework software. The results of these tasks indicate an IPAD first release capability 45 months after go-ahead, a five year total implementation schedule, and a total developmental cost of 2027 man-months and 1074 computer hours. Several areas of operational cost increases were identified mainly due to the impact of additional equipment needed and additional computer overhead. The benefits of an IPAD system were related mainly to potential savings in engineering man-hours, reduction of design-cycle calendar time, and indirect upgrading of product quality and performance.

Garrocq, C. A.↗