Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Pathfinder”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

NTF model pressure measurements

Pressure measurements on the National Transonic Facility models will be made using electronically scanned pressure instrumentation. The system consists of pressure modules, a pressure calibration standard, and a system controller. The pressure modules, which must be operated above -18 C, will be housed in model-integrated designed thermally controlled containers. The Pathfinder 1 192-channel pressure package is described. Recent and planned developments to reduce the pressure module's volume per channel ratio are discussed, including the 48-channel module and a proposed 32-channel module that would be 2.54 by 2.54 by 8.13 cm. Pressure transducers capable of operating at cryogenic temperatures for dynamic and static pressure measurements are discussed.

Kern, F. A.↗
NASA NTRS1983

Plasma diagnostics package assessment of the STS-3 orbiter environment and systems for science

Primary objectives of the Plasma Diagnostics Package (PDP) on STS-3 as part of the OSS-1 'Pathfinder' payload were to measure aspects of the Orbiter's induced environment and to utilize Orbiter crew and subsystems in the conduct of scientific investigations. Instrumentation temperatures were found to be within predicted limits, payload bay pressure varied from ambient up to 0.001 torr with thruster firings, EMI levels were found to be below worst case estimates, and V x B motional potentials were observed to vary + or - 5 V with respect to Orbiter ground. These parameters exhibited orbit-period modulation. Payload bay plasma varied in density and composition from ambient to a rarefied mixture with Orbiter-produced H2O(+). Energetic electrons and ions with energies up to 10's of eV were observed occasionally. Primary and vernier thrusters induce a momentary perturbation to the electron density, to the pressure and to the electric field with low energy ions and electrons occasionally produced. With the PDP on the RMS, both automode and manual modes were used to seek sources of EMI, to characterize the Orbiter's plasma wake and to measure beam-plasma phenomena.

Shawhan, S. D.↗
NASA NTRS1984

Fracture temperature and flaw growth in nitronic 40 at cryogenic temperatures

The fracture resistance and fatigue response of Armco Nitronic 40 austenitic stainless steel were evaluated under cryogenic conditions. Tensile, fracture toughness and fatigue crack growth properties were measured at -275 F. The tensile yield strength was approximately 120 ksi and the fracture toughness was estimated to be 350 ksi-in /2 on the basis of fracture toughness measurements. Testing was conducted to evaluate the behavior of a simulated section of the wing of the Pathfinder 1 model subject to a load and temperature history typical of that for testing in the National Transonic Facility. The wing section model incorporated a proposed brazing technique for pressure-transducer attachment. The simulated wing section performed satisfactorily at stress levels of nearly 60 percent of the material yield strength. The brazing technique proved to be an effective method of transducer attachment under conditions of high stress levels and large temperature excursions.

Domack, M. S.↗
NASA NTRS1985

Comet flyby sample return

The results of a joint JPL/CSFC feasability study of a low-cost comet sample return flyby mission are presented. It is shown that the mission could be undertaken using current earth orbiter spacecraft technology in conjunction with pathfinder or beacon spacrcraft. Detailed scenarios of missions to the comets Honda-Mrkos-Pajdusakova (HMP), comet Kopff, and comet Giacobini-Zinner (GZ) are given, and some crossectional diagrams of the spacecraft designs are provided.

Tsou, P.↗
NASA NTRS1985

The US National Transonic Facility, part 2

The construction of the National Transonic Facility was completed in September 1982, and checkout operations started the following month with the maximum Reynolds number being obtained in May 1983. Afterwards, effort was primarily devoted to installing the model access housings and adjusting or altering various tunnel hardware systems. In May 1984, the aerodynamic calibration started and was performed in parallel with checkout of the tunnel systems. In August 1984, the final operation readiness review was conducted and the facility declared operational for research testing. The facility has been operated in both air and nitrogen modes covering a Mach number range of 0.2 to 1.22 at pressures up to 8.5 atm and at temperatures doen to 100K. A limited amount of tunnel circuit performance information has been obtained and is presented in this paper. An aerodynamic calibration plan has been outlined, and the first part of the steady-state calibration has been completed, of which some results are presented in this paper. The first aerodynamic vehicle, Pathfinder I, was installed in December 1984 for checkout of instrumentation systems, and a status report and some results are presented.

Bruce, W. E., Jr.↗
NASA NTRS1985

Cognitive network organization and cockpit automation

Attention is given to a technique for the derivation of pilot cognitive networks from empirical data, which has been successfully used to guide the redesign of the Control Display Unit that serves as the primary interface of the complex flight management system being developed by NASA's Advanced Concepts Flight Simulator program. The 'pathfinder' algorithm of Schvaneveldt et al. (1985) is used to obtain the conceptual organization of four pilots by generating a family of link-weighted networks from a set of psychological distance data derived through similarity ratings. The degree of conceptual agreement between pilots is assessed, and the means of translating a cognitive network into a menu structure are noted.

Roske-Hofstrand, R. J.↗
NASA NTRS1986

Status and projections of the NAS program

NASA's Numerical Aerodynamic Simulation (NAS) Program has completed development of the initial operating configuration of the NAS Processing System Network (NPSN). This is the first milestone in the continuing and pathfinding effort to provide state-of-the-art supercomputing for aeronautics research and development. The NPSN, available to a nation-wide community of remote users, provides a uniform UNIX environment over a network of host computers ranging from the Cray-2 supercomputer to advanced scientific workstations. This system, coupled with a vendor-independent base of common user interface and network software, presents a new paradigm for supercomputing environments. Background leading to the NAS program, its programmatic goals and strategies, technical goals and objectives, and the development activities leading to the current NPSN configuration are presented. Program status, near-term plans, and plans for the next major milestone, the extended operating configuration, are also discussed.

Bailey, Frank R.↗
NASA NTRS1987

NAS-current status and future plans

The Numerical Aerodynamic Simulation (NAS) has met its first major milestone, the NAS Processing System Network (NPSN) Initial Operating Configuration (IOC). The program has met its goal of providing a national supercomputer facility capable of greatly enhancing the Nation's research and development efforts. Furthermore, the program is fulfilling its pathfinder role by defining and implementing a paradigm for supercomputing system environments. The IOC is only the begining and the NAS Program will aggressively continue to develop and implement emerging supercomputer, communications, storage, and software technologies to strengthen computations as a critical element in supporting the Nation's leadership role in aeronautics.

Bailey, F. R.↗
NASA NTRS1987

NASA's technology plans - Will technology be ready when we are

Recent low NASA science and technology budgets impacted unfavorably on trade balances of aerospace products and lags in several technological areas impinged on other areas already in application which could not be exploited or did not achieve desired performance levels. NASA has formed a Civil Space Technology Initiative, for 1988 start, to foster research on safe and efficient access to space, earth orbiting operations, and science support technologies. R&D programs for fully reusable launch systems, aerobraking concepts, and a multi-arm, highly autonomous capability for space-based remote assembly, repair and servicing of space vehicles are described. Regarding science, emphasis will be placed on large flexible structures and the associated control programs, sensors and data handling and analysis equipment and programs. Finally, technologies common to human activities in regions beyond the Space Station are to be explored in the second phase of the NASA initiative, Pathfinder.

Colladay, Raymond S.↗
NASA NTRS1986

Status and projections of the NAS Program

NASA's Numerical Aerodynamic Simulation (NAS) Program has completed development of the initial operating configuration of the NAS Processing System Network (NPSN). This is the first milestone in the continuing and pathfinding effort to provide state-of-the-art supercomputing for aeronautics research and development. The NPSN, available to a nation-wide community of remote users, provides a uniform UNIX environment over a network of host computers ranging from the new Cray-2 supercomputer to advanced scientific workstations. This system, coupled with a vendor-independent base of common user interface and network software, presents a new paradigm for supercomputing environments. Presented here is the background leading to the NAS Program, its programmatic goals and strategies, technical goals and objectives, and the development activities leading to the current NPSN configuration. Program status, near-term plans and plans for the next major milestone, the extended operating configuration, are also discussed.

Bailey, F. R.↗
NASA NTRS1986

Comparison of two models of total electron content at three midlatitude stations

TEC values calculated with the Bent model were used instead of actual data for the Madrid Deep Space Communications Complex during most of the Voyager Uranus approach and encounter. These values were used from December 1, 1985 to January 16, 1986 for Voyager Uranus, and for March 1986 to support the Pathfinder mission; thus, the Halley flybys of Vega 1 and 2 and Giotto were included. Provided sunspot numbers are below 130, the Bent model can be used with confidence to calculate TEC values for midlatitude stations when actual TEC data or monthly averages are not available.

Royden, H. N.↗
NASA NTRS1986

Preliminary calibration and test results from the National Transonic Facility

The National Transonic Facility (NTF) was operated to design condition of 120 million Reynolds number at a Mach number of 1.0. All systems were checked out except plenum isolation valves; modifications are being made to heaters on the actuators. Initial steady-state calibration indicates excellent steady flow characteristics. The first test of the Pathfinder 1 model indicated significant Reynolds number effects. Some effect of temperature on instrumentation were obtained. The cause of these effects is being evaluated.

Mckinney, Linwood W.↗
NASA NTRS1988

NAS: The first year

Discussed are the capabilities of NASA's Numerical Aerodynamic Simulation (NAS) Program and its application as an advanced supercomputing system for computational fluid dynamics (CFD) research. First, the paper describes the NAS computational system, called the NAS Processing System Network, and the advanced computational capabilities it offers as a consequence of carrying out the NAS pathfinder objective. Second, it presents examples of pioneering CFD research accomplished during NAS's first operational year. Examples are included which illustrate CFD applications for predicting fluid phenomena, complementing and supplementing experimentation, and aiding in design. Finally, pacing elements and future directions for CFD and NAS are discussed.

Bailey, F. R.↗
NASA NTRS1988

Advanced photovoltaic power system technology for lunar base applications

Advanced photovoltaic/electrochemical (batteries or regenerative fuel cells for storage) power system options for a lunar base are discussed and compared. Estimated system masses are compared with those projected for the SP-100 nuclear system. The results of the comparison are quantified in terms of the mass saved in a scenario which assembles the initial base elements in Low Earth Orbit (LEO) and launches from there to the lunar surface. A brief summary is given of advances in photovoltaic/electrochemical power system technologies currently under development in the NASA/OAST program. A description of the planned focussed technology program for surface power in the new Pathfinder initiative is also provided.

Brinker, David J.↗
NASA NTRS1988

Space Station - A focus for the development of structural dynamics scale model technology for large flexible space structures

The paper discusses the scale model technology being developed at the NASA Langley Research Center in support of the development of structural dynamic prediction methods for large flexible space structures. Space Station is used as a focus. The Dynamic Scale Model Technology (DSMT) Program is described; results of the effect of scaling Space Station components are presented; and supporting scale model technology development activities are described and results presented. The conceptual design of a hybrid-scale Pathfinder model for developing test techniques and suspension methods is also discussed, and a summary of the broad application of the scale model technology being developed is presented.

Letchworth, Robert↗
NASA NTRS1988

Heating requirements and nonadiabatic surface effects for a model in the NTF cryogenic wind tunnel

A theoretical study has been made of the severity of nonadiabatic surface conditions arising from internal heat sources within a model in a cryogenic wind tunnel. Local surface heating is recognized as having an effect on the development of the boundary layer, which can introduce changes in the flow about the model and affect the wind tunnel data. The geometry was based on the NTF Pathfinder I wind tunnel model. A finite element heat transfer computer code was developed and used to compute the steady state temperature distribution within the body of the model, from which the surface temperature distribution was extracted. Particular three dimensional characteristics of the model were represented with various axisymmetric approximations of the geometry. This analysis identified regions on the surface of the model susceptible to surface heating and the magnitude of the respective surface temperatures. It was found that severe surface heating may occur in particular instances, but could be alleviated with adequate insulating material. The heat flux through the surface of the model was integrated to determine the net heat required to maintain the instrumentation cavity at the prescribed temperature. The influence of the nonadiabatic condition on boundary layer properties and on the validity of the wind tunnel simulation was also investigated.

Macha, J. M.↗
NASA NTRS1988

Space power technologies

Information is given in viewgraph form on space power technologies. Energy conversion, the role of nuclear power in space, lunar and Mars bases, and the Pathfinder program are covered.

Sovie, Ronald J.↗
NASA NTRS1988

Physical/chemical closed-loop life support

Information on physical/chemical closed-loop life support systems are given in viewgraph form. Information is given on program objectives, the elements of a life support system, and Pathfinder program elements.

Lawless, James G.↗