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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 649 records · Page 36

All sources NASA NTRS DOE OSTI

NASA NTRS1986

Design and fabrication of the 20 km/10 kV electromechanical tether for TSS-1 using high impact conductor (Hiwire)

The development of a 20-km electromechanical tether for the tethered satellite system (TSS) is described. The basic design requirements for electromagnetic cables and for conductors in cables subject to stresses and cyclic loading are discussed. The tether fabricatioon procedures involve: (1) conductor twisting around the core, (2) insulation extrusion, (3) strength member braiding, and (4) protective jacket braiding.

Scala, E.↗

NASA NTRS1986

General equilibrium characteristics of a dual-lift helicopter system

The equilibrium characteristics of a dual-lift helicopter system are examined. The system consists of the cargo attached by cables to the endpoints of a spreader bar which is suspended by cables below two helicopters. Results are given for the orientation angles of the suspension system and its internal forces, and for the helicopter thrust vector requirements under general circumstances, including nonidentical helicopters, any accelerating or static equilibrium reference flight condition, any system heading relative to the flight direction, and any distribution of the load to the two helicopters. Optimum tether angles which minimize the sum of the required thrust magnitudes are also determined. The analysis does not consider the attitude degrees of freedom of the load and helicopters in detail, but assumes that these bodies are stable, and that their aerodynamic forces in equilibrium flight can be determined independently as functions of the reference trajectory. The ranges of these forces for sample helicopters and loads are examined and their effects on the equilibrium characteristics are given parametrically in the results.

Cicolani, L. S.↗

NASA NTRS1986

High frequency power distribution system

The objective of this project was to provide the technology of high frequency, high power transmission lines to the 100 kW power range at 20 kHz frequency. In addition to the necessary design studies, a 150 m long, 600 V, 60 A transmission line was built, tested and delivered for full vacuum tests. The configuration analysis on five alternative configurations resulted in the final selection of the three parallel Litz straps configuration, which gave a virtually concentric design in the electromagnetic sense. Low inductance, low EMI and flexibility in handling are the key features of this configuration. The final design was made after a parametric study to minimize the losses, weight and inductance. The construction of the cable was completed with no major difficulties. The R,L,C parameters measured on the cable agreed well with the calculated values. The corona tests on insulation samples showed a safety factor of 3.

Patel, Mikund R.↗

NASA NTRS1989

Interface For Fault-Tolerant Control System

Interface unit and controller emulator developed for research on electronic helicopter-flight-control systems equipped with artificial intelligence. Interface unit interrupt-driven system designed to link microprocessor-based, quadruply-redundant, asynchronous, ultra-reliable, fault-tolerant control system (controller) with electronic servocontrol unit that controls set of hydraulic actuators. Receives digital feedforward messages from, and transmits digital feedback messages to, controller through differential signal lines or fiber-optic cables (thus far only differential signal lines have been used). Analog signals transmitted to and from servocontrol unit via coaxial cables.

Shaver, Charles↗

NASA NTRS1989

Compliant Prosthetic Or Robotic Joint

Rotation partly free and partly restrained by resilience and damping. Joint includes U-shaped x- and y-axis frames joined by cables that cross in at center piece. The y-axis frame rotates about y-axis on roller bearing within predetermined angular range. The y-axis frame rotates slightly farther when arm strikes stop, because cables can twist. This mimics compliant resistance of knee joint reaching limit of its forward or backward motion. Used in prosthetic device to replace diseased or damage human joint, or in robot linkage to limit movement and cushion overloads.

Kerley, James J.↗

NASA NTRS1988

Successful expert systems for space shuttle payload integration

Expert systems are successfully applied to solve recurring NASA Space Shuttle orbiter payload integration problems. Recurrence of these problems is the result of each Space Shuttle mission being unique. The NASA Space Shuttle orbiter was designed to be extremely flexible in its ability to handle many types and combinations of satellites and experiments. This flexibility results in different and unique engineering resource requirements for each of the payload satellites and experiments. The first successful expert system to be applied to these problems was the Orbiter Payload Bay Cabling Expert System (EXCABL), developed at Rockwell International Space Transportation Systems Division. The operational version of EXCABL was delivered in 1986 and successfully solved the payload electrical support services cabling layout problem. As a result of this success, a second expert system, Expert Drawing Matching System (EXMATCH), was developed to generate a list of the reusable installation drawings available for each EXCABL solution. EXMATCH went operational in 1987. As a result of these initial successes, the need for a third expert system was defined and is awaiting development. This new Expert System, called Technical Order Listing Expert System (EXTOL), will generate a list of all the applicable reusable installation drawings available to support the total payload bay mission provisioning and installation effort. This paper describes these expert systems, the individual problems that they were designed to solve, their individual solutions, and the degree of success achieved. These expert systems' instantiate the applicability of this technology to the solution of real-world Space Shuttle payload integration problems.

Morris, Keith↗

NASA NTRS1988

Simulation and control of a 20 kHz spacecraft power system

A detailed computer representation of four Mapham inverters connected in a series, parallel arrangement has been implemented. System performance is illustrated by computer traces for the four Mapham inverters connected to a Litz cable with parallel resistance and dc receiver loads at the receiving end of the transmission cable. Methods of voltage control and load sharing between the inverters are demonstrated. Also, the detailed computer representation is used to design and to demonstrate the advantages of a feed-forward voltage control strategy. It is illustrated that with a computer simulation of this type, the performance and control of spacecraft power systems may be investigated with relative ease and facility.

Wasynczuk, O.↗

NASA NTRS1988

Spectral transmissometer and radiometer - Design and initial results

A new solid-state spectral transmissometer and radiometer is described. The radiometer measures upwelling radiance, downwelling irradiance, and beam transmittance from 390 to 750 nm with channel widths of 2.35 nm. The spectrometer consists of a 256 element CCD linear array collecting light dispersed by a reflection grating in a modified Littrow configuration. The spectrometer is time and space-shared among the three signal types. The instrument has been deployed as a free-drifting buoy and in the profiling mode, with data stored internally on a magnetic bubble memory or sent up a conducting cable as desired. Power can be supplied either by a detachable external battery pack or through conducting cable. The instrument has been deployed in the oligotrophic North Pacific Central Gyre and in the eutrophic Straits of Juan de Fuca, and preliminary results for each region are discussed.

Carder, Kendall L.↗

NASA NTRS1990

Tester Detects Steady-Short Or Intermittent-Open Circuits

Momentary open circuits or steady short circuits trigger buzzer. Simple, portable, lightweight testing circuit sounds long-duration alarm when it detects steady short circuit or momentary open circuit in coaxial cable or other two-conductor transmission line. Tester sensitive to discontinuities lasting 10 microseconds or longer. Used extensively for detecting intermittent open shorts in accelerometer and extensometer cables. Also used as ordinary buzzer-type continuity checker to detect steady short or open circuits.

Anderson, Bobby L.↗

NASA NTRS1990

Borescope With Large Depth Of Focus

Modification of commercial borescope yields clear, glare-free images of defects on inside of tube. Used to examine diverging wall of tube. Wall illuminated by light from fiber distinct from fused-fiber cable used for viewing. Viewing cable holds right-angle mirror at tip so it can look sideways. Image appears, magnified, on monitor. Instrument offers large depth of focus and therefore used in tubes of varying inside diameter.

Guirguis, Kamal S.↗

NASA NTRS1990

Mobile Centers For Secondary Power Distribution

Concept for distribution of 60-Hz ac power in large building devoted to assembly and testing of equipment improves safety, reduces number of outlets and lengthy cables, and readily accommodates frequent changes in operations and configuration. Power from floor recess fed via unobtrusive cable to portable power management center. A cart containing variety of outlets and circuit breakers, wheeled to convenient location near equipment to be assembled or tested. Power distribution system presents larger range of operational configurations than fixed location. Meets tighter standards to feed computers and delicate instruments. Industrial-grade power suitable for power tools and other hardware. Three-phase and single-phase outlets available from each.

Mears, Robert L.↗

NASA NTRS1990

Mobile Uninterruptible Power Supply

Proposed mobile unit provides 20 kVA of uninterruptible power. Used with mobile secondary power-distribution centers to provide power to test equipment with minimal cabling, hazards, and obstacles. Wheeled close to test equipment and system being tested so only short cable connections needed. Quickly moved and set up in new location. Uninterruptible power supply intended for tests which data lost or equipment damaged during even transient power failure.

Mears, Robert L.↗

NASA NTRS1990

Helmet-Mounted Visual Display For Flight Simulation

Helmet-mounted visual display system provides pilot with broad range of visual information for flight simulation. Offers nearly unlimited field of regard. Optical fibers transmit wide-angle images in response to motions of head. Two "pancake" lenses mounted on lightweight helmet. Cable of optical fibers carries images to each lens. "Light-valve" projectors deliver computer-generated binocular images to cables.

Cook, Anthony M.↗

NASA NTRS1990

Positioning X-Ray Film By Balloon

Film rolled around deflated balloon before being inserted in duct. Clamped at end of segmented flexible cable and fed with balloon into duct to predetermined point where inspection made, as indicated by length of cable paid out. Inflated balloon holds x-ray film against inside wall of duct for radiographic inspection. Ensures film positioned in contact with welded joint far along duct from opening through which inserted, so clear x-ray image of joint obtained.

Windbiel, Frederich↗

NASA NTRS1989

Flight set 360T004 (STS-30) field joint protection system, volume 7

The Redesigned Solid Rocket Motors (RSRM) of the Space Transportation System have three field joints that are protected by the Joint Protection Systems (JPS). The igniter heater was mounted on the igniter flange. This report documents the performance of the JPS and igniter heaters on the pad and the post-flight condition of the JPS components. All observations that were written up as Squawks and/or Problem Reports are also discussed. The primary heaters performed satisfactorily and maintained the field joint temperatures within the required temperature range. A secondary heater failed Dielectric Withstanding Voltage (DWV) test during the joint closeout prior to launch. This heater was not used, however, since the primary heater functioned properly. Post-test inspection revealed that pin A of the heater power cable was shorted to the connector shell. Design changes have been implemented to resolve the heater power cable problem. All field joint assemblies met all of the performance requirements.

Hale, Elgie↗

NASA NTRS1989

Considerations in the design of a communication network for an autonomously managed power system

The considerations involved in designing a communication network for an autonomously managed power system intended for use in space vehicles are examined. An overview of the design and implementation of a communication network implemented in a breadboard power system is presented. An assumption that the monitoring and control devices are distributed but physically close leads to the selection of a multidrop cable communication system. The assumption of a high-quality communication cable in which few messages are lost resulted in a simple recovery procedure consisting of a time out and retransmit process.

Mckee, J. W.↗

NASA NTRS1991

Low-Frequency Suspension System For Large Space Structures

Simple system enables vibration testing of space structures on ground. Suspension system includes number of suspension stations attached by cables to space structure (such as truss beam) along its length. Suspension stations fixed to ceiling or other rigid support. Disk and cable adjustments lower frequency of oscillatory motion of suspension system to enable accurate measurements of frequencies of vibration of space structure. Designed to alleviate coupling between suspension system and torsional vibrational modes of structure.

Reed, Wilmer H., III↗

NASA NTRS1991

Servo Reduces Friction In Flexure Bearing

Proposed servocontrol device reduces such resistive torques as stiction, friction, ripple, and cogging in flexure bearing described in LAR-14348, "Flexure Bearing Reduces Startup Friction". Reduces frictional "bump" torque encountered when bearing ball runs into buildup of grease on bearing race. Also used as cable follower to reduce torque caused by cable and hoses when they bend because of motion of bearing. New device includes torquer across ball race. Torquer controlled by servo striving to keep flexure at null, removing torque to outer ring. In effect, device is inner control loop reducing friction, but does not control platforms or any outer-control-loop functions.

Clingman, W. Dean↗