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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 1,567 records · Page 87

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NASA NTRS1983

High-speed machining of Space Shuttle External Tank (ET) panels

Potential production rates and project cost savings achieved by converting the conventional machining process in manufacturing shuttle external tank panels to high speed machining (HSM) techniques were studied. Savings were projected from the comparison of current production rates with HSM rates and with rates attainable on new conventional machines. The HSM estimates were also based on rates attainable by retrofitting existing conventional equipment with high speed spindle motors and rates attainable using new state of the art machines designed and built for HSM.

Miller, J. A.↗

NASA NTRS1980

Fabrication and evaluation of brazed titanium-clad Borsic/aluminum compression panels

Processes for brazing Borsic/aluminum composite materials that eliminate diffusion of braze alloy constituents into the aluminum matrix developed. One brazing study led to the development of a hybrid composite which combines high strength Borsic/aluminum and ductile titanium to form a material identified as titanium clad Borsic/aluminum. The titanium foil provides the Borsic/aluminum with a durable outer surface and serves as a diffusion barrier which alleviates fiber and matrix degradation during brazing. Titanium clad Borsic/aluminum skin panels were joined to titanium clad Borsic/aluminum stringers by brazing and were tested in end compression at room and elevated temperatures. The data include failure strength, buckling strength, and the effects of brazing on the material properties. Predicted buckling loads are compared with experimental data.

Royster, D. M.↗

NASA NTRS1983

Thermal Analysis of Antenna Structures. Part 2: Panel Temperature Distribution

This article is the second in a series that analyzes the temperature distribution in microwave antennas. An analytical solution in a series form is obtained for the temperature distribution in a flat plate analogous to an antenna surface panel under arbitrary temperature and boundary conditions. The solution includes the effects of radiation and air convection from the plate. Good agreement is obtained between the numerical and analytical solutions.

Schonfeld, D.↗

NASA NTRS1983

Evaluation of a surface panel method coupled with several boundary layer analyses

Three boundary layer models are interacted with an inviscid panel method to evaluate their capabilities to predict aerodynamic performance characteristics. These boundary layer models include two two-dimensional boundary layer models and one three-dimensional boundary layer model. Previously reported discrepancies between the transpiration and surface displacement inviscid boundary layer simulations are discussed and resolved. Results from each of the models are compared with experimental data.

Kjelgaard, S. O.↗

NASA NTRS1985

Continuous-Filament Isogrid Composite Panel

Damaged panels do not fail catastrophically when fabricated this way. Isogrid stiffener formed in slotted silicon-rubber tool. At grid intersections, slots offset to prevent excessive buildup of composite material and widened to give room for overlapping filaments to spread when compressed. Following total failure of skin, isogrid stiffener still carries 350 kN/m (2,000 1b/in.) and remains intact.

Williams, J. G.↗

NASA NTRS1985

Automated Solar-Panel Fabricator

Automated computer-controlled system based on standard commercial industrial robot takes solar cells and other raw materials and assembles them into completed solar panels.

Hagerty, J. J.↗

NASA NTRS1983

Development of V/STOL methodology based on a higher order panel method

The development of a computational technique to predict the complex flowfields of V/STOL aircraft was initiated in which a number of modules and a potential flow aerodynamic code were combined in a comprehensive computer program. The modules were developed in a building-block approach to assist the user in preparing the geometric input and to compute parameters needed to simulate certain flow phenomena that cannot be handled directly within a potential flow code. The PAN AIR aerodynamic code, which is higher order panel method, forms the nucleus of this program. PAN AIR's extensive capability for allowing generalized boundary conditions allows the modules to interact with the aerodynamic code through the input and output files, thereby requiring no changes to the basic code and easy replacement of updated modules.

Bhateley, I. C.↗

NASA NTRS1983

Metal matrix composite structural panel construction

Lightweight capped honeycomb stiffeners for use in fabricating metal or metal/matrix exterior structural panels on aerospace type vehicles and the process for fabricating same are disclosed. The stiffener stringers are formed in sheets, cut to the desired width and length and brazed in spaced relationship to a skin with the honeycomb material serving directly as the required lightweight stiffeners and not requiring separate metal encasement for the exposed honeycomb cells.

Mcwithey, R. R.↗

NASA NTRS1983

Predicting aerodynamic characteristics of vortical flows on three-dimensional configurations using a surface-singularity panel method

A general low-order surface-singularity panel method is used to predict the aerodynamic characteristics of a problem where a wing-tip vortex from one wing closely interacts with an aft mounted wing in a low Reynolds Number flow; i.e., 125,000. Nonlinear effects due to wake roll-up and the influence of the wings on the vortex path are included in the calculation by using a coupled iterative wake relaxation scheme. The interaction also affects the wing pressures and boundary layer characteristics: these effects are also considered using coupled integral boundary layer codes and preliminary calculations using free vortex sheet separation modelling are included. Calculated results are compared with water tunnel experimental data with generally remarkably good agreement.

Maskew, B.↗

NASA NTRS1983

High speed machining of space shuttle external tank liquid hydrogen barrel panel

Actual and projected optimum High Speed Machining data for producing shuttle external tank liquid hydrogen barrel panels of aluminum alloy 2219-T87 are reported. The data included various machining parameters; e.g., spindle speeds, cutting speed, table feed, chip load, metal removal rate, horsepower, cutting efficiency, cutter wear (lack of) and chip removal methods.

Hankins, J. D.↗

NASA NTRS1984

Skin-stiffener interface stresses in composite stiffened panels

A model and solution method for determining the normal and shear stresses in the interface between the skin and the stiffener attached flange were developed. An efficient, analytical solution procedure was developed and incorporated in a sizing code for stiffened panels. The analysis procedure described provides a means to study the effects of material and geometric design parameters on the interface stresses. These stresses include the normal stress, and the shear stresses in both the longitudinal and the transverse directions. The tendency toward skin/stiffener separation may therefore be minimized by choosing appropriate values for the design variables. The most important design variables include the relative bending stiffnesses of the skin and stiffener attached flange, the bending stiffness of the stiffener web, and the flange width. The longitudinal compressive loads in the flange and skin have significant effects on the interface stresses.

Wang, J. T. S.↗

NASA NTRS1981

PAN AIR: A computer program for predicting subsonic or supersonic linear potential flows about arbitrary configurations using a higher order panel method. Volume 4: Maintenance document (version 1.1)

The Maintenance Document is a guide to the PAN AIR software system, a system which computes the subsonic or supersonic linear potential flow about a body of nearly arbitrary shape, using a higher order panel method. The document describes the over-all system and each program module of the system. Sufficient detail is given for program maintenance, updating and modification. It is assumed that the reader is familiar with programming and CDC (Control Data Corporation) computer systems. The PAN AIR system was written in FORTRAN 4 language except for a few COMPASS language subroutines which exist in the PAN AIR library. Structured programming techniques were used to provide code documentation and maintainability. The operating systems accommodated are NOS 1.2, NOS/BE and SCOPE 2.1.3 on the CDC 6600, 7600 and Cyber 175 computing systems. The system is comprised of a data management system, a program library, an execution control module and nine separate FORTRAN technical modules. Each module calculates part of the posed PAN AIR problem. The data base manager is used to communicate between modules and within modules. The technical modules must be run in a prescribed fashion for each PAN AIR problem. In order to ease the problem of supplying the many JCL cards required to execute the modules, a separate module called MEC (Module Execution Control) was created to automatically supply most of the JCL cards. In addition to the MEC generated JCL, there is an additional set of user supplied JCL cards to initiate the JCL sequence stored on the system.

Baruah, P. K.↗

NASA NTRS1984

The application of a low-order panel method - program VSAERO to powerplant and airframe flow studies

Results from the application of VSAERO, a low-order panel method, to three practical aircraft configurations are presented. The Grumman 698-411 tilt-nacelle V/STOL model is analyzed with particular emphasis on the inlet pressures and the nacelle/fuselage interference effects. Excellent correlation with experiment is reported for the inlet pressure ratio and the inlet operational boundaries. Analysis of an inlet designed for a tilt-rotor/nacelle aircraft is presented. The code was used in a design environment for this configuration to determine an inlet geometry that maintained attached flow for three design flight conditions: hover, hover-transition and cruise. VSAERO is also used to examine the prop-slipstream induced loading for the Langley prop-fan configuration. The versatility and economy of the aerodynamic modeling program, VSAERO, is demonstrated.

Strash, D. J.↗

NASA NTRS1985

Photovoltaic-Panel Laminator

Two-piece unit heats and presses protective layers to form laminate. Rubber diaphragm between upper and lower vacuum chambers alternates between neutral position and one that presses against solar-cell array, supplying distributed force necessary to press layers of laminate together. Encapsulation helps to protect cells from environment and to ensure long panel life while allowing efficient generation of electricity from Sunlight.

Keenan, R.↗

NASA NTRS1981

PAN AIR: A computer program for predicting subsonic or supersonic linear potential flows about arbitrary configurations using a higher order panel method. Volume 3: Case manual (version 1.0)

Numerous applications of the PAN AIR computer program system are presented. PAN AIR is user-oriented tool for analyzing and/or designing aerodynamic configurations in subsonic or supersonic flow using a technique generally referred to as a higher order panel method. Problems solved include simple wings in subsonic and supersonic flow, a wing-body in supersonic flow, wing with deflected flap in subsonic flow, design of two-dimensional and three-dimensional wings, axisymmetric nacelle in supersonic flow, and wing-canard-tail-nacelle-fuselage combination in supersonic flow.

Medan, R. T.↗

NASA NTRS1984

Missions/Planning Panel

A panel discussion was held to develop a viewpoint of space power technology needs and state of readiness for future mission scenarios. Among the points made in the discussion, it was agreed that missions, particularly the far term ones, do serve to drive technology; however, as the missions become nearer term, issues of schedule and cost severely limit the willingness to accept risk. There are, in fact, no rewards to a mission manager for introducing new technology. Mission downscaling is the usual response to technology limitations. All panelists agreed that there exists a serious gap between when technologists feel their job is done and what mission managers need for decision. Typically a two to three year engineering development gap exists. It is essential to take technologies to the engineering model level and conduct a flight demonstration to close this gap. All agreed that increased effort should be made to achieve stronger interactions between planners and technologists and that workshops like the present one are a step in the right direction. Technologists need mission credibility and vice versa.

Fordyce, J. S.↗

NASA NTRS1985

Design procedures for fiber composite structural components: Panels subjected to combined in-plane loads

Step by step procedures are described which can be used to design panels made from fiber composite angleplied laminates and subjected to combined in plane loads. The procedures are set up as a multistep sample design. Steps in the sample design procedure range from selection of the laminate configuration to the subsequent analyses required to check design requirements for: (1) displacement, (2) ply stresses, and (3) buckling. The sample design steps are supplemented with appropriate tabular and graphical data which can be used to expedite the design process.

Chamis, C. C.↗

NASA NTRS1985

Joint design for improved fatigue life of diffusion-bonded box-stiffened panels

Simple photoelastic models were used to identify a cross-section geometry that would eliminate the severe stress concentrations at the bond line between box stiffeners diffusion bonded to a panel skin. Experimental fatigue-test data from titanium test specimens quantified the allowable stress in terms of cycle life for various joint geometries. It is shown that the effect of stress concentration is reduced and an acceptable fatigue life is achieved.

Davis, R. C.↗