Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Rolling”

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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Analysis of electrical contact occurrences between rolling surface with application to elastohydrodynamic lubrication

A mathematical model enabling the relation of electrical contact occurrences between rolling surfaces to the mean thickness of an elastohydrodynamic lubricant film is discussed. A previous development by other authors is shown to contain an error invalidating their results. Some potentially useful approximations are developed for the case when the lubricant film is large with respect to the surface roughness. Complete solutions that are valid for all film thicknesses are not yet available.

Sidik, S. M.↗
NASA NTRS1973

On the inviscid rolled-up structure of lift generated vortices

A simple form is presented of the relationships for the inviscid, fully developed structure of lift-generated vortices behind aircraft wings. The method is then extended to arbitrary span-load distributions by inferring guidelines for the selection of rollup centers for the vortex sheet, along with rules for calculating the fully developed structure of the resulting multiple vortices. These techniques yield realistic estimates of the rolled-up structure of vortices produced by a wider variety of span-load distributions than possible with the original form of the theory.

Rossow, V. J.↗
NASA NTRS1972

Design and development of LH2 cooled rolling element radial bearings for the NERVA engine turbopump. Volume 3: Phase 2: Tests on build-ups 16, 17, and 18 at NRDS, Jackass Flats, Nevada, December 1971 - March 1972

The use of liquid hydrogen to cool the rolling element radial bearings in the nuclear engine for rocket vehicles is discussed. The fifteen hour service life goal was obtained during the tests. The increase in bearing life was also considered to be produced by: (1) improvements in bearing material, (2) bearing retainer configuration and manufacturing changes, and (3) better control of operating parameters.

Accinelli, J. B.↗
NASA NTRS1973

Low mass rolling element for bearings

Low mass rolling elements for bearings having a high fatigue strength and high resistance to flexure fatigue are reported. The elements have a lightweight core with a hollow center or is made of a low density material. The core is plated to provide a hard surface.

Parker, R. J.↗
NASA NTRS1973

High speed hybrid bearing comprising a fluid bearing and a rolling bearing convected in series

A description is given of an antifriction bearing and a process by which its fatigue life may be extended. The method involves a rotating shaft supported by a fluid bearing and a rolling element bearing coupled in series. Each bearing turns at a fraction of the rotational speed of the shaft. The fluid bearing is preferably conical, thereby providing thrust and radial load support in a single bearing structure.

Anderson, W. J.↗
NASA NTRS1973

Theoretical study of lift generated vortex sheets designed to avoid roll up

The random motions of the vortex elements behind a wing that sheds a disturbed, translating array of vortices are analyzed. The analysis indicates that the wake would diffuse and decay rapidly when viscosity is present and would produce small rolling moments on encountering aircraft. It was found that comparable results could also be achieved with an array consisting of vortices that are equal in magnitude but which alternate in sign. This observation indicates that random motion can probably be achieved with a variety of stepped loadings.

Rossow, V. J.↗
NASA NTRS1973

RUSAP: A computer program for the calculation of Roll-Up Solar Array Performance characteristics

RUSAP is a FORTRAN 4 computer program designed to determine the performance characteristics (power-to-weight ratio, blanket tension, structural member section dimensions, and resonant frequencies) of large-area, roll-up solar arrays of the single-boom, tensioned-substrate design. The program includes the determination of the size and weight of the base structure supporting the boom and blanket and the determination of the blanket tension and deployable boom stiffness needed to achieve the minimum-weight design for a specified frequency for the first mode of vibration. A complete listing of the program, a description of the theoretical background, and all information necessary to use the program are provided.

Ross, R. G., Jr.↗
NASA NTRS1973

Rolling-element bearings: A review of the state of the art

Some of the research conducted which has brought rolling-element technology to its present state is discussed. Areas touched upon are material effects, processing variables, operating variables, design optimization, lubricant effects and lubrication methods. Finally, problem areas are discussed in relation to the present state-of-the-art and anticipated requirements.

Anderson, W. J.↗
NASA NTRS1973

A roll-pitch interaction simulator and a control position command encoder for remote piloting of spin-entry research models

The Langley Research Center uses radio-controlled, scaled aircraft models to study the spin-entry characteristics of aircraft. Recent spin-entry studies required the use of an electronic proportional-control system for manipulating model control surfaces. In order to meet control system requirements, a special-purpose analog computer was designed to simulate the coupling between roll and pitch controls. A digital encoder was designed to encode the voltage analogs of control-surface position into a special pulse format for transmission to the model. This paper describes the two special developments and their relationship to the functions of the overall control system.

Meissner, C. W., Jr.↗
NASA NTRS1974

Roll plane analysis of on-aircraft antennas

Roll plane radiation patterns of on-aircraft antennas are analyzed using high frequency solutions. Aircraft-antenna pattern performance in which the aircraft is modelled in its most basic form is presented. The fuselage is assumed to be a perfectly conducting elliptic cylinder with the antennas mounted near the top or bottom. The wings are simulated by arbitrarily many sided flat plates and the engines by circular cylinders. The patterns in each case are verified by measured results taken on simple models as well as scale models of actual aircraft.

Burnside, W. D.↗
NASA NTRS1973

Hollow rolling element bearings

A low mass rolling element with a lightweight core and hollow center was developed for use in bearings. The core is plated so as to provide a hard surface and increase the life and reliability of the high speed ball bearings.

Parker, R. J.↗
NASA NTRS1974

Roll plane analysis of on-aircraft antennas

The roll plane radiation patterns of on-aircraft antennas are analyzed using high frequency solutions. This is a basic study of aircraft-antenna pattern performance in which the aircraft is modelled in its most basic form. The fuselage is assumed to be a perfectly conducting elliptic cylinder with the antennas mounted near the top or bottom. The wings are simulated by arbitrarily many sided flat plates and the engines by circular cylinders. The patterns in each case verified by measured results taken on simple models as well as scale models of actual aircraft.

Burnside, W. D.↗
NASA NTRS1973

Rolling-element bearings - A review of the state of the art

Some of the research conducted which has brough rolling-element technology to its present state is discussed. Areas touched upon are material effects, processing variables, operating variables, design optimization, lubricant effects and lubrication methods. Finally, problem areas are discussed in relation to the present state-of-the-art and anticipated requirements.

Anderson, W. J.↗
NASA NTRS1973

On the inviscid rolled-up structure of lift-generated vortices

A simple form is presented of the relationships derived by Betz for the inviscid, fully developed structure of lift-generated vortices behind aircraft. An extension is then made to arbitrary span-load distributions by inferring guidelines for the selection of rollup centers for the vortex sheet. These techniques are easier to use and yield more realistic estimates of the rolled-up structure of vortices than the original form of Betz' theory when the span loading differs appreciably from elliptic loading.

Rossow, V. J.↗
NASA NTRS1974

Spoilers for roll control of light airplanes

The paper presents an overview of the state-of-the-art of roll control spoilers for light airplanes. Reasons for using spoilers on light airplanes are presented. Several classical objections to the use of spoilers of such airplanes are critically examined. It is shown that mechanically driven spoiler systems can be designed. Flight test results of a new mechanically driven spoiler on the Redhawk airplane are discussed. Tunnel data of spoilers on the new general aviation airfoil GA(W)-1 are presented. Finally, a bibliography on spoiler data is included.

Roskam, J.↗
NASA NTRS1973

An experimental study of the motorcycle roll stabilization task

The work of Sharp represents the most complete theoretical analysis of the uncontrolled motorcycle presently available, and serves as a theoretical basis for the study described. Sharp's analysis included roll, yaw, lateral translation, and steering degrees of freedom, and the resulting equations are linear with constant coefficients. Tire aligning moments due to tire sideslip were added to Sharp's equations. Experimental results are presented, and related to the theoretical studies of Sharp and Weir.

Eaton, D. J.↗
NASA NTRS1974

The viscous lubrication of rolling and sliding rigid cylinders

The viscous lubrication of rolling and sliding cylinders is studied both independently and with the aid of much of the previous work done by other investigators. Building upon the specialized results of others, a problem formulation is obtained which encompasses the general viscous fluid as well as the linear viscous fluid. A uniform solution technique is derived which is adequate for the general problem formulation. Results obtained for three special classes of viscosity functions are presented.

Carlson, S. F.↗