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At least 217 records · Page 12

airborne data analysis/monitor system

An Airborne Data Analysis/Monitor System (ADAMS), a ROLM 1666 computer based system installed onboard test airplanes used during experimental testing is evaluated. In addition to the 1666 computer, the ADAMS hardware includes a DDC System 90 fixed head disk and a Miltape DD400 floppy disk. Boeing designed a DMA interface to the data acquisition system and an intelligent terminal to reduce system overhead and simplify operator commands. The ADAMS software includes RMX/RTOS and both ROLM FORTRAN and assembly language are used. The ADAMS provides real time displays that enable onboard test engineers to make rapid decisions about test conduct thus reducing the cost and time required to certify new model airplanes, and improved the quality of data derived from the test, leading to more rapid development of improvements resulting in quieter, safer, and more efficient airplanes. The availability of airborne data processing removes most of the weather and geographical restrictions imposed by telemetered flight test data systems. A data base is maintained to describe the airplane, the data acquisition system, the type of testing, and the conditions under which the test is performed.

Stephison, D. B.↗

Investigation of mesoscale pre-convective forcing mechanisms

The installation and testing of a numerical mesoscale boundary layer model is discussed. A data analysis is first made using the rawinsonde network which shows a strong baroclinic zone developing in the region where convection was initiated. The observed wind field shows an easterly component developing in opposition to the synoptic flow producing convergence. The numerical boundary layer model is used to diagnose the physical development of the thermal and flow fields. Two physical mechanisms are examined; topography and cloud shading. The results shows that while heated sloping topography alone does create a baroclinic zone and convergence values, cloud shading is a stronger mechanism for producing a thermal field representative of observed conditions

Mcnider, R. T.↗

Second Sailplane Project: The RP-2

Progress has been made on the design fabrication and installation of a tension carry-through linkage between the aft parts of the port and starboard wings to resist forward bending deflection on the RP-2 sailplane. In addition, towhook/release mechanisms, landing gear and wheel brake assembly, compound curved sandwich composite fuselage shells and an enclosed trailer to house and transport the complete disassembled aircraft, have all undergone various stages of design, fabrication, installation and testing.

Source record↗

A method for determining acoustic-liner admittance in ducts with sheared flow in two-cross-sectional directions

A method is developed for determining the acoustic admittance of a test liner installed in the wall of a grazing flow impedance tube. The mean flow is permitted flow gradients in both cross-sectional directions of the tube. The unknown admittance value is obtained by solving an eigenvalue problem. This eigenvalue problem results from the application of the finite-element method to the partial differential equation and boundary conditions governing the acoustic field. The credibility of the method is established by comparing results with exact solutions obtained for a constant mean-flow profile and with previous results for cases involving shear in only one cross-sectional direction. Excellent comparisons are obtained in both cases. The analysis is used in conjunction with a limited amount of experimental data and shows that the flow must be accurately modeled in order to determine the acoustic-liner properties.

Watson, W. R.↗

Structural characterizaiton and gas reactions of small metal particles by high-resolution, in-situ TEM and TED

The existing in-situ transmission electron microscopy (TEM) facility was improved by adding a separately pumped mini-specimen chamber. The chamber contains wire-evaporation sources for three metals and a specimen heater for moderate substrate temperatures. A sample introduction device was constructed, installed, and tested, facilitating rapid introduction of a specimen into the mini-chamber while maintaining the background pressure in that chamber in the 10(-9) millibar range. Small particles and clusters of Pd, grown by deposition from the vapor phase in an in-situ TEM facility on amorphous and crystalline support films of alumina and on ultra-thin carbon films, were analyzed by conventional high-resolution TEM and image analysis in terms of detectability, number density, and size distribution. The smallest particles that could be detected and counted contained no more than 6 atoms; size determinations could be made for particles 1 nm in diameter. The influence of various oxygen plasma treatments, annealing treatments, and of increasing the substrate temperature during deposition was investigated. The TEM technique was employed to demonstrate that under otherwise identica l conditions the lattice parameter of Pd particles in the 1 to 2 nm size range and supported in random orientation on ex-situ prepared mica films is expanded by some 3% when compared to 5 nm size particles. It is believed that this expansion is neither a small-particle diffraction effect nor due to pseudomorphism, but that it is due to a annealing-induced transformation of the small as-deposited particles with predominantly composite crystal structures into larger particles with true f.c.c. structure and thus inherently smaller lattice parameter.

Source record↗

Analysis and modeling of summertime convective cloud and precipitation structure over the southeastern United States

Described is work performed under NASA Grant NAG8-654 for the period 15 March to 15 September 1988. This work entails primarily data analysis and numerical modeling efforts related to the 1986 Satellite Precipitation and Cloud Experiment (SPACE). In the following, the SPACE acronym is used along with the acronym COHMEX, which represents the encompassing Cooperative Huntsville Meteorological Experiment. Progress made during the second half of the first year of the study included: (1) installation and testing of the RAMS numerical Modeling system on the Alabama CRAY X-MP/24; (2) a start on the analysis of the mesoscale convection system (MCS) of 13 July 1986 COHMEX case; and (3) a cursory examination of a small MCS that formed over the COHMEX region on 15 July 1986. Details of each of these individual tasks are given.

Knupp, Kevin R.↗

Personal computers on Ethernet

Many researchers in the Division have projects which require transferring large files between their personal computers (PC) and VAX computers in the Laboratory for Oceans Computing Facility (LOCF). Since Ethernet local area network provides high speed communication channels which make file transfers (among other capabilities) practical, a network plan was assembled to connect IBM and IBM compatible PC's to Ethernet for participating personnel. The design employs ThinWire Ethernet technology. A simplified configuration diagram is shown. A DEC multiport repeater (DEMPR) is used for connection of ThinWire Ethernet segments. One port of DEMPR is connected to a H4000 transceiver and the transceiver is clamped onto the Goddard Ethernet backbonecoaxial cable so that the PC's can be optionally on the SPAN network. All these common elements were successfully installed and tested.

Kao, R.↗

Liquid hydrogen turbopump ALS advanced development program. Volume 1: Hot fire unit

The interface criteria for the Turbopump Test article (TPA) and the Component Test Facility located at NASA, Stennis Space Center is defined by this interface Control Document (ICD). TPA ICD Volume 2 is submitted for the Cold Gas Drive Turbopump Test Article, which is generally similar but incorporates certain changes, particularly in fluid requirements and in instrumentation needs. For the purposes of this ICD, the test article consists of the Hot Fire Drive Turbopump mounted on its test cart, readied for installation in the component test facility. It should be emphasized that the LH2 turbopump program is still in its early concept design phase. Design of the turbopump, test cart, and spools are subject to revisions until successful conclusion of the Detail Design Review (DDR).

Lindley, Bruce↗

Preliminary design of an intermittent smoke flow visualization system

A prototype intermittent smoke flow visualization system for studying the flowfield of an aircraft in flight has been constructed and demonstrated. It provides discrete pulses of dense white smoke suitable for video imaging to determine the unsteady vortex core trajectory of fluid elements in a high angle-of-attack flowfield. Two methods of pulsing the smoke were initially investigated: (1) periodically diverting the smoke between two exit ports and (2) completely blocking the smoke flow for short times. System dynamics have been modeled mathematically, data have been collected in a wind tunnel with blockage times up to 80 milliseconds, and the prototype is currently being flown on a general aviation airplane to collect three-dimensional video data. Three different plenum chamber sizes are available. Data collected so far are consistent and repeatable, though care must be taken to provide adequate contrast levels for accurate video resolution. Camera frame rates of at least 180 frames/second and wide angle lenses for the video cameras are needed to acquire meaningful vortex core velocities and accelerations for the general aviation test aircraft installation.

Ward, D. T.↗

A new thermal vacuum facility at the Martin Marietta Waterton plant

A new thermal-vacuum facility has been recently completed at the Martin Marietta Waterton plant near Denver, Colorado. The facility was designed, fabricated, installed, and tested as a turn-key project by Pitt-Des Moines Inc. and CVI Inc. The chamber has a 5.49 M by 6.10 M (18 ft by 20 ft) flat floor and a half-cylindrical roof with a diameter of 5.49 M (18 ft). Both ends of the chamber have full cross section doors, with one equipped with translating motors for horizontal motion. The chamber is provided with four 0.91 M (36 inches) cryopumps to obtain an ultimate pressure of 9 x 10(exp -8) Torr (Clean-Dry-Empty). The thermal shroud is designed to operate at a maximum of -179 C (-290 F) with an internal heat input of 316 MJ/Hr (300,000 BTU/Hr) using liquid nitrogen. The shroud is also designed to operate at any temperature between -156 C (-250 F) and 121 C (+250 F) using gaseous nitrogen, and heat or cool at a rate of 1.1 C (2 F) per minute.

Watson, Robert N.↗

Experimental Evaluation of a Cooled Radial-inflow Turbine

Two 14.4 inch tip diameter rotors were installed and tested in the Small Engines Component Turbine Facility (SECTF) at NASA Lewis Research Center. The rotors, a solid and a cooled version of a radial-inflow turbine, were tested with a 15 vane stat or over a set of rotational speeds ranging from 80 to 120 percent design speed (17,500 to 21,500 rpm). The total-to-total stage pressure ratios ranged from 2.5 to 5.5. The data obtained at the equivalent conditions using the solid version of the rotor are presented with the cooled rotor data. A Reynolds number of 381,000 was maintained for both rotors, whose stages had a design mass flow of 4.0 Ibm/sec, a design work level of 59.61 Btu/lbm, and a design efficiency of 87 percent. The results include mass flow data, turbine torque, turbine exit flow angles, stage efficiency, and rotor inlet and exit surveys.

Tirres, Lizet↗

Measured acoustic characteristics of ducted supersonic jets at different model scales

A large-scale (about a 25x enlargement) model of the Georgia Tech Research Institute (GTRI) hardware was installed and tested in the Propulsion Systems Laboratory of the NASA Lewis Research Center. Acoustic measurements made in these two facilities are compared and the similarity in acoustic behavior over the scale range under consideration is highlighted. The study provide the acoustic data over a relatively large-scale range which may be used to demonstrate the validity of scaling methods employed in the investigation of this phenomena.

Jones, R. R., III↗

Experimental evaluation of a cooled radial-inflow turbine

Two 14.4 inch tip diameter rotors were installed and tested in the Small Engines Component Turbine Facility (SECTF) at NASA Lewis Research Center. The rotors, a solid and a cooled version of a radial-inflow turbine, were tested with a 15 vane stat or over a set of rotational speeds ranging from 80 to 120 percent design speed (17,500 to 21,500 rpm). The total-to-total stage pressure ratios ranged from 2.5 to 5.5. The data obtained at the equivalent conditions using the solid version of the rotor are presented with the cooled rotor data. A Reynolds number of 381,000 was maintained for both rotors, whose stages had a design mass flow of 4.0 lbm/sec, a design work level of 59.61 Btu/lbm, and a design efficiency of 87 percent. The results include mass flow data, turbine torque, turbine exit flow angles, stage efficiency, and rotor inlet and exit surveys.

Tirres, Lizet↗

Internal performance of Highly Integrated Deployable Exhaust Nozzles

The internal performance characteristics of Highly Integrated Deployable Exhaust Nozzles (HIDEN) applicable to advanced short take-off and vertical landing aircraft have been investigated. Four nozzle concepts, designed for fan and core flow installations, were tested with varying contraction ratio and nozzle exit plane shape. In addition, two offtake duct designs, along with several centerbody and blocker geometries were tested to evaluate their effect on the static thrust and flow performance. This investigation was conducted in the static test facility of the NASA Langley 16-Foot Transonic Tunnel. A six-component strain-gage balance collected force and moment data, and static pressure, total pressure, and total temperature measurements were also made internal to the model. Room temperature, dry high-pressure air was used to simulate jet exhaust. The results indicate that the internal performance of these HIDEN concepts is comparable to previously tested nozzle concepts designed for thrust vectoring about a bearing plane. This report presents the configuration design of the HIDEN concepts and the results of the internal performance testing.

Taylor, John G.↗

Digitally Controlled Acoustic-Testing System

Digital electronic control system developed for use in effecting accurate, real-time, closed-loop control of large acoustic test facility. Installation of system incorporates state-of-the-art technology to optimize shaping of acoustic spectrum and controlling operation of equipment in large reverberant chamber to degree not possible with open-loop manual control.

Shah, K. C.↗

SLR 2000

SLR 2000 is a concept for a totally automated subcentimeter SLR system presently being studied at GSFC. If funding permits, a prototype would be installed and tested at the Goddard Geophysical and Astronomical Observatory (GCAO) in FY98 and a small number of automated stations would be fielded by the year 2000. Unlike present systems, the "SLR 2000" system is being designed to: 1) operate autonomously without the need for onsite operators; 2) present no hazards (i.e., optical, electrical, and/or chemical) to personnel in the vicinity or to overflying aircraft; and 3) have a mean time between failures (MTBF) of at least three months. It is assumed that the systems are located at "friendly" sites where some level of security is provided and where certain low level service functions (e.g. commercial power, communications, heat pump service cleaning, etc.) are available or can be contracted for locally on an as-needed basis. The main system consists of two parts - an optical head and electronics rack. The optical head contains the laser transmitter and power supply, transmit/receive switch, optical telescope, tracking angle sensor (intensified CCD camera), detector and power supply, two angular encoders, azimuth and elevation motors, and a protective dome. The optical head mounts directly to the top of a concrete pier which contains the geodetic monument and forms part of the environmental housing for the hardware and servicing personnel. It is equipped with electronic levels for leveling the mount and monitoring its stability.

Degnan, John J.↗

X-ray transmission microscope development

We are developing a hard x-ray microscope for direct observation of solidification dynamics in metal alloys and metal matrix composites. The Fein-Focus Inc. x-ray source was delivered in September and found to perform better than expected. Confirmed resolution of better than 2 micrometers was obtained and magnifications up to 800X were measured. Nickel beads of 30 micrometer diameter were easily detected through 6mm of aluminum. X-ray metallography was performed on several specimens showing high resolution and clear definition of 3-dimensional structures. Prototype furnace installed and tested.

Kaukler, William F.↗

Development work for a superconducting linear collider

For future linear e(+)e(-) colliders in the TeV range several alternatives are under discussion. The TESLA approach is based on the advantages of superconductivity. High Q values of the accelerator structures give high efficiency for converting RF power into beam power. A low resonance frequency for the RF structures can be chosen to obtain a large number of electrons (positrons) per bunch. For a given luminosity the beam dimensions can be chosen conservatively which leads to relaxed beam emittance and tolerances at the final focus. Each individual superconducting accelerator component (resonator cavity) of this linear collider has to deliver an energy gain of 25 MeV/m to the beam. Today s.c. resonators are in use at CEBAF/USA, at DESY/Germany, Darmstadt/Germany KEK/Japan and CERN/Geneva. They show acceleration gradients between 5 MV/m and 10 MV/m. Encouraging experiments at CEA Saclay and Cornell University showed acceleration gradients of 20 MV/m and 25 MV/m in single and multicell structures. In an activity centered at DESY in Hamburg/Germany the TESLA collaboration is constructing a 500 MeV superconducting accelerator test facility (TTF) to demonstrate that a linear collider based on this technique can be built in a cost effective manner and that the necessary acceleration gradients of more than 15 MeV/m can be reached reproducibly. The test facility built at DESY covers an area of 3.000 m2 and is divided into 3 major activity areas: (1) The testlinac, where the performance ofthe modular components with an electron beam passing the 40 m long acceleration section can be demonstrated. (2) The test area, where all individual resonators are tested before installation into a module. (3) The preparation and assembly area, where assembly of cavities and modules take place. We report here on the design work to reach a reduction of costs compared to actual existing superconducting accelerator structures and on the facility set up to reach high acceleration gradients in a reproducible way.

Matheisen, Axel↗