SEARCH · Engineering Papers

Results for “hinges”

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.

SourceResearch connectionFrom yearThrough year

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

At least 595 records · Page 33

All sources NASA NTRS DOE OSTI

NASA NTRS1979

PEP solar array definition study

The conceptual design of a large, flexible, lightweight solar array is presented focusing on a solar array overview assessment, solar array blanket definition, structural-mechanical systems definition, and launch/reentry blanket protection features. The overview assessment includes a requirements and constraints review, the thermal environment assessment on the design selection, an evaluation of blanket integration sequence, a conceptual blanket/harness design, and a hot spot analysis considering the effects of shadowing and cell failures on overall array reliability. The solar array blanket definition includes the substrate design, hinge designs and blanket/harness flexibility assessment. The structural/mechanical systems definition includes an overall loads and deflection assessment, a frequency analysis of the deployed assembly, a components weights estimate, design of the blanket housing and tensioning mechanism. The launch/reentry blanket protection task includes assessment of solar cell/cover glass cushioning concepts during ascent and reentry flight condition.

Source record↗

NASA NTRS1980

STS-1 operational flight profile. Volume 5: Descent cycle 3. Appendix D: GRTLS six degree of freedom Monte Carlo dispersion analysis

The results of a six degree of freedom (6-DOF) nonlinear Monte Carlo dispersion analysis for the latest glide return to landing site (GRTLS) abort trajectory for the Space Transportation System 1 Flight are presented. For this GRTLS, the number two main engine fails at 262.5 seconds ground elapsed time. Fifty randomly selected simulations, initialized at external tank separation, are analyzed. The initial covariance matrix is a 20 x 20 matrix and includes navigation errors and dispersions in position and velocity, time, accelerometer bias, and inertial platform misalinements. In all 50 samples, speedbrake, rudder, elevon, and body flap hinge moments are acceptable. Transitions to autoland begin before 9,000 feet and there are no tailscrapes. Navigation derived dynamic pressure accuracies exceed the flight control system constraints above Mach 2.5. Three out of 50 landings exceeded tire specification limit speed of 222 knots. Pilot manual landings are expected to reduce landing speed by landing farther downrange.

Montez, M. N.↗

NASA NTRS1980

The dynamics and control of large flexible space structures. Volume 3, part B: The modelling, dynamics, and stability of large Earth pointing orbiting structures

The dynamics and stability of large orbiting flexible beams, and platforms and dish type structures oriented along the local horizontal are treated both analytically and numerically. It is assumed that such structures could be gravitationally stabilized by attaching a rigid light-weight dumbbell at the center of mass by a spring loaded hinge which also could provide viscous damping. For the beam, the small amplitude inplane pitch motion, dumbbell librational motion, and the anti-symmetric elastic modes are all coupled. The three dimensional equations of motion for a circular flat plate and shallow spherical shell in orbit with a two-degree-of freedom gimballed dumbbell are also developed and show that only those elastic modes described by a single nodal diameter line are influenced by the dumbbell motion. Stability criteria are developed for all the examples and a sensitivity study of the system response characteristics to the key system parameters is carried out.

Bainum, P. M.↗

NASA NTRS1980

Material problems in solar sail development

The paper considers the solar sail principle as an effective means of space propulsion. The heliogyro configuration is discussed including the hub structures, the flap-hinge brace assembly, and the blade. The material requirements of the sail film made of metallized polymers, the tendons produced from a polymer-graphite fiber composite, and battens constructed of graphite/epoxy tubings are considered, noting that not all of these materials were readily available. It was concluded that the primary material problems are the environmental degradation of polymer films, the meteoroid hazard, and the production capacity for large polymer film quantities.

Steurer, W. H.↗

NASA NTRS1980

A statistical determination of the shape and position of the geomagnetic neutral sheet

Using 2.5-minute average field values from Imp 6, 7, and 8 magnetic field measurements, the standard magnetotail neutral sheet (MNS) model is examined. The best representation for the MNS is found to be an arched surface which crosses the solar magnetospheric equatorial plane on the flanks of the tail about 18 earth radii (ER) from the tail axis; the surface is anchored to the geomagnetic dipole at a hinging distance of 10.5 ER. In addition, the shape and position of the neutral sheet (NS) do not vary significantly with distance down the tail, but the NS is anchored somewhat closer to the earth during disturbed geomagnetic conditions.

Fairfield, D. H.↗

NASA NTRS1982

Dish Antenna Would Deploy From a Canister

37-tile portable microwave antenna is composed of hexagonal tiles supported by a truss. Skewed connecting struts are hinged at their ends, and rotated during storage and deployment. Proposed microwave antenna would be stored compactly in a canister and deployed onsite.

Finley, L. A.↗

NASA NTRS1980

Feasibility study of using a two-plate model to approximate the TDRSS solar pressure effects

An investigation was performed to determine the feasibility of using a two plate model to approximate the Tracking and Data Relay Satellite (TDRS) in orbit propagation, taking into account the effects of solar radiation pressure. The two plate model comprises one plate which always points to the Earth, and the other which is hinged to an axis normal to the orbital plane and is always rotated so that its normal makes a minimum angle with the direction of the sun. The results indicate that it is sufficient to take three parameters, the areas of the two plates and the reflectivity of the Earth pointing plate, to achieve an accuracy of one meter during a 24 hour orbit propagation.

Chan, F. K.↗

NASA NTRS1978

A computer program to calculate the longitudinal aerodynamic characteristics of upper-surface-blown wing-flap configurations

A user's manual is presented for a computer program in which a vortex-lattice lifting-surface method is used to model the wing and multiple flaps. The engine wake model consists of a series of closely spaced vortex rings with rectangular cross sections. The jet wake is positioned such that the lower boundary of the jet is tangent to the wing and flap upper surfaces. The two potential flow models are used to calculate the wing-flap loading distribution including the influence of the wakes from up to two engines on the semispan. The method is limited to the condition where the flow and geometry of the configurations are symmetric about the vertical plane containing the wing root chord. The results include total configuration forces and moments, individual lifting-surface load distributions, pressure distributions, flap hinge moments, and flow field calculation at arbitrary field points. The use of the program, preparation of input, the output, program listing, and sample cases are described.

Mendenhall, M. R.↗

NASA NTRS1980

A brief analysis and its experiment of the hydraulic-electric loading servosystem

The servosystem is a force simulator. It can be used to simulate the hinge moment of the control surface for aircraft, and still be a stick force generator. According to the experiences of a real system, theoretical analyses of the loading system and its characteristics were performed and the possibility of improving its performances is discussed.

Liango-Fu, M.↗

NASA NTRS1981

Development of the maypole (hoop/column) deployable reflector concept for large space systems application

A review of the NASA supplied mission scenarios for the communications, radiometry and radio astronomy missions. Led to specific hoop/column antenna configurations for each mission. The mission configurations were then evaluated to identify specific technology items requiring further development. The compilation of these technology drivers resulted in a specification of an artificial or point design, the design element around which all design and performance estimates for the rest of the program were made. Mechanisms for deployment and stowing are examined including the cable driven mast and the latch pulley roller. Methods for determining the thermal expansion of candidate materials, the development of the cables, cords, and hinged joints, and surface adjustment are considered.

Montgomery, D. C.↗

NASA NTRS1981

Alleviation of helicopter fuselage-induced rotor unsteady loads through deterministic variation of the individual blade pitch

The effect of fuselage-induced upwash on the flapwise motion of a hinged rotor blade is considered. The typical upwash field is simulated through the flow produced by a moving point source. The resulting blade response is then approximated by its rigid flapping and first bending mode. The perturbation blade pitch variation required to alleviate its response to the upwash in the sense of either reducing the increased hub shear or minimization of the blade overall time averaged deflection, is determined. Calculations are carried out for a model rotor and for the case with increased Lock number. The results are presented in graph form. It is found that the minimum blade deflection criteria suppress the rigid flapping by a large amount and reduce the peak-to-peak value of the blade hub shear by at least 50 percent without causing an additional increase in blade stresses.

Rahnema, M. A.↗

NASA NTRS1981

Wind-tunnel studies of advanced cargo aircraft concepts

Accomplishments in vortex flap research are summarized. A singular feature of the vortex flap is that, throughout the range of angle of attack range, the flow type remains qualitatively unchanged. Accordingly, no large or sudden change in the aerodynamic characteristics, as happens when forcibly maintained attached flow suddenly reverts to separation, will occur with the vortex flap. Typical wind tunnel test data are presented which show the drag reduction potential of the vortex flap concept applied to a supersonic cruise airplane configuration. The new technology offers a means of aerodynamically augmenting roll-control effectiveness on slender wings at higher angles of attack by manipulating the vortex flow generated from leading edge separation. The proposed manipulator takes the form of a flap hinged at or close to the leading edge, normally retracted flush with the wing upper surface to conform to the airfoil shape.

Rao, D. M.↗

NASA NTRS1980

On the dynamics of large orbiting flexible beams and platforms oriented along the local horizontal

The dynamics and stability of large orbiting flexible beams and platforms oriented along the local horizontal are treated both analytically and numerically. It is assumed that such structures could be gravitationally stabilized by attaching a rigid lightweight dumbbell at the center of mass by a spring loaded hinge which also could provide viscous damping. For the beam it is seen that the small amplitude inplane pitch motion, dumbbell librational motion, and the anti-symmetric elastic modes are all coupled. The three dimensional equations of motion for a circular flat plate in orbit with a two-degree-of-freedom gimballed dumbbell are also developed and show that only those elastic modes described by a single nodal diameter line are influenced by the dumbbell motion. Stability criteria are developed for both examples and a parametric study of the least damped mode characteristics together with numerically simulated transient responses are carried out.

Bainum, P. M.↗

NASA NTRS1981

A spacecraft attitude and articulation control system design for the Comet Halley intercept mission

An attitude and articulation control system design for the Comet Halley 1986 intercept mission is presented. A spacecraft dynamics model consisting of five hinge-connected rigid bodies is used to analyze the spacecraft attitude and articulation control system performance. Inertial and optical information are combined to generate scan platform pointing commands. The comprehensive spacecraft model has been developed into a digital computer simulation program, which provides performance characteristics and insight pertaining to the control and dynamics of a Halley Intercept spacecraft. It is shown that scan platform pointing error has a maximum value of 1.8 milliradians during the four minute closest approach interval. It is also shown that the jitter or scan platform pointing rate error would have a maximum value of 2.5 milliradians/second for the nominal 1000 km closest approach distance trajectory and associated environment model.

Key, R. W.↗

NASA NTRS1982

Deployable Reflector for Solar Cells

Unfoldable-membrane-reflector concept leads to mobile photovoltaic generators. Hinged containers swing open for deployment, and counterbalance beam swings into position. Folded reflector membranes are unfolded as deployment mast is extended, until stretched out flat.

Johnson, K. L.↗

NASA NTRS1981

Wind-tunnel investigation of the tail-spoiler concept for stall-prevention on general aviation airplanes

The longitudinal aerodynamic characteristics of a full scale, single engine general aviation airplane equipped with an angle of attack limiting concept which used a tail mounted spoiler for stall prevention were investigated. The tail spoiler was deployed as a nonlinear function of changes in angle of attack in a narrow angle of attack range immediately preceding the stall angle. Spoiler deployment produced a nose down moment which limited the nose up trim capability of the elevator to an angle of attack below the stall angle of the airplane. The tail spoiler system produced significant increases in longitudinal stability and elevator hinge moments near the stall. The effects of power, flaps, and center of gravity position are also studied.

Satran, D. R.↗

NASA NTRS1982

Modular attitude control of a large space platform

The modular attitude control of a large space platform is studied using a three axis five body model of a flexible spacecraft. Three degree of freedom hinges are considered. A three axis four body model of a truss and a three axis ten body model of a space platform are presented. A state variable rotational dynamics model and a multilevel state variable model are shown. A decomposed performance index and decomposed Hamiltonian are also presented. A subproblem hierarchy for hybrid multilevel LQR attitude control of a three axis model is described.

Chichester, F. D.↗

NASA NTRS1982

Design, development and mechanization of a precision deployable truss with optimized structural efficiency for spaceborne applications

A deployable mast concept which meets the weight, size and stability requirements for a feed support structure for offset antennas up to 100 meters in diameter is discussed. A triangulated truss configuration, the use of tapered tubes which exhibit a high strength-to-weight ratio, and low CTE graphite-epoxy material are seen to provide an efficient, lightweight and stable truss suitable for an antenna feed support. A low stowage ratio of 30:1 is achieved through a unique preloaded hinge located at the center of each longeron and an autonomous deployment cage with a drive mechanism. Initial analysis and proof of concept hardware validated the basic mechanism and design assumptions and provided a basis for further investigation. The concept can readily accept variations in member size and thus lends itself to optimization for other potential uses where a stiff, lightweight deployable truss is needed.

Craighead, N. D.↗