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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 199 records · Page 11

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NASA NTRS1973

Fleet retrofit report

Flight tests are evaluated of an avionics system which aids the pilot in making two-segment approaches for noise abatement. The implications are discussed of equipping United's fleet of Boeing 727-200 aircraft with two-segment avionics for use down to Category 2 weather operating minima. The experience is reported of incorporating two-segment approach avionics systems on two different aircraft. The cost of installing dual two-segment approach systems is estimated to be $37,015 per aircraft, including parts, labor, and spares. This is based on the assumption that incremental out-of-service and training costs could be minimized by incorporating the system at airframe overhaul cycle and including training in regular recurrent training. Accelerating the modification schedule could add up to 50 percent to the modification costs. Recurring costs of maintenance of the installation are estimated to be of about the same magnitude as the potential recurrent financial benefits due to fuel savings.

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NASA NTRS1975

Strapdown cost trend study and forecast

The potential cost advantages offered by advanced strapdown inertial technology in future commercial short-haul aircraft are summarized. The initial procurement cost and six year cost-of-ownership, which includes spares and direct maintenance cost were calculated for kinematic and inertial navigation systems such that traditional and strapdown mechanization costs could be compared. Cost results for the inertial navigation systems showed that initial costs and the cost of ownership for traditional triple redundant gimbaled inertial navigators are three times the cost of the equivalent skewed redundant strapdown inertial navigator. The net cost advantage for the strapdown kinematic system is directly attributable to the reduction in sensor count for strapdown. The strapdown kinematic system has the added advantage of providing a fail-operational inertial navigation capability for no additional cost due to the use of inertial grade sensors and attitude reference computers.

Eberlein, A. J.↗

NASA NTRS1973

The effect of communications and traffic situation displays on pilots awareness of traffic in the terminal area

The Air Traffic Control (ATC) system is evolving under a general plan specified by the Federal Aviation Administration. Among the developments being considered is the Discrete Address Beacon System (DABS). The use of this system, although relieving congestion on the communications frequencies, would eliminate information about other aircraft because the party line communications now in use would be lost. One alternative to restore this lost information is an Airborne Traffic Situation Display (TSD). Experienced airline and military pilots participated in a factorial design to evaluate two types of communication (discrete address, party line) and two types of displays (TSD, no TSD). A stop-action quiz was used to evaluate their knowledge of other aircrafts' position, altitude, speed, heading, rate of climb, identity, and landing sequence number. Significant differences between conditions were detected, primarily in the position variables. Workload, as measured by a spare capacity side-task, showed a main effect of displays and a significant interaction between displays and communications. The data are summarized by plotting each display/communication condition configuration in the plane defined by information and workload index. A limited number of blunders by other aircraft were included in the simulations with a significant, but not entirely satisfactory, improvement in blunder detection attributed to the TSD.

Melanson, D.↗

NASA NTRS1975

Computation-based reliability analysis

The structural and functional complexity of man-made systems is reported, showing the reliability analysis task becoming much more complex. Quantative methods are discussed for analyzing system quality. The reliability equations that are developed for systems employing modular redundancy and sparing are discussed to illustrate the need for computation-based reliability analysis.

Meyer, J. F.↗

NASA NTRS1974

Space satellite power system

The concept of a satellite solar power station was studied. It is shown that it offers the potential to meet a significant portion of future energy needs, is pollution free, and is sparing of irreplaceable earth resources. Solar energy is converted by photovoltaic solar cell arrays to dc energy which in turn is converted into microwave energy in a large active phased array. The microwave energy is beamed to earth with little attenuation and is converted back to dc energy on the earth. Economic factors are considered.

Glaser, P. E.↗

NASA NTRS1974

Repair of major system elements on Skylab

In-flight maintenance, as conceived and preplanned for the Skylab mission was limited to simple scheduled and unscheduled replacement tasks and minor contingency repairs. Tools and spares were provided accordingly. However, failures during the mission dictated complicated and sophisticated repairs to major systems so that the mission could continue. These repairs included the release of a large structure that failed to deploy, the assembly and deployment of large mechanical devices, the installation and checkout of precision electronic equipment, troubleshooting and repair of precision electromechanical equipment, and tapping into and recharging a cooling system. The repairs were conducted both inside the spacecraft and during extravehicular activities. Some of the repair tasks required team effort on the part of the crewmen including close procedural coordination between internal and extravehicular crewmen. The Skylab experience indicates that crewmen can, with adequate training, make major system repairs in space using standard or special tools. Design of future spacecraft systems should acknowledge this capability and provide for more extensive in-flight repair and maintenance.

Pace, R. E., Jr.↗

NASA NTRS1975

A leading edge heating array and a flat surface heating array - operation, maintenance and repair manual

A general description of the leading edge/flat surface heating array is presented along with its components, assembly instructions, installation instructions, operation procedures, maintenance instructions, repair procedures, schematics, spare parts lists, engineering drawings of the array, and functional acceptance test log sheets. The proper replacement of components, correct torque values, step-by-step maintenance instructions, and pretest checkouts are described.

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NASA NTRS1974

Architectural concepts and redundancy techniques in fault-tolerant computers

This paper presents a description of redundancy techniques employed in the design of fault-tolerant computers, and a discussion of the effects of functional requirements, technology constraints, and cost considerations which enter into the choice of these techniques. The STAR computer, developed at the Jet Propulsion Laboratory for long-duration planetary spacecraft missions, is discussed along with several later fault-tolerant computer designs. The class of computers described in this paper employs dynamic redundancy, i.e., the machine is divided into a set of submodules, each with standby spares; a special hard core monitor unit detects and diagnoses faults, and effects automated recovery by replacing failed parts.

Rennels, D. A.↗

NASA NTRS1976

An engineering treatise on the CARE II dual mode and coverage models

A mathematical model used to calculate the reliability of any dual-mode, spare-switching computer system was described, and some illustrative examples were presented. The possibility of extending the resultant computer program further was also examined, enabling it, in particular, to accommodate computer configurations involving more than two modes of operation.

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NASA NTRS1975

Life-support systems for interplanetary spacecraft and space stations for long-term use

Integrated regenerative life support systems in which the by-products of one system become useful material for another are considered. Regeneration or reclamation of water and the principal atmospheric gases, and elimination or disposition of waste products are the principal functions of such systems. A modular system concept is described. Features of this system include: commonality (for spares reduction), maintainability, overall computer-monitored functioning, and onboard repair and replacement tasks in the event of failure.

Jones, W. L.↗

NASA NTRS1975

LST refurbishment and support

The Large Space Telescope (LST) is a Space Shuttle payload with relatively high reliability, but it will require maintenance support in order to meet the operational life requirement of 15 years. It was determined that it would be efficient and economical to support LST by having four limited inflight maintenance (IFM) missions and three ground refurbishments. The IFM missions would include replacement of the four items with a limited operating life. The LST program would provide for a ground refurbishment every four years at a central payload depot. It was recommended that the depot should be located at MSFC and be manned by a permanent party which would be augmented on a temporary basis during LST refurbishments by engineering personnel from the LST contractors. Required spare parts would be acquired incrementally for the depot based on maximum refurbishment of repairable items.

Henschke, J.↗

NASA NTRS1975

LST power system long life design techniques

The LST mission of up to 15 years plus about two years allotment for ground return maintenance could stretch the LST operation to the end of the century. This extended mission life, combined with the large power requirements of the telescope and the scientific instruments, imposes stringent requirements on the electrical power subsystem. The use of an onboard microprocessor for individual battery cell control and monitoring offers a technique that could improve the battery cycle life dramatically. The battery configuration includes spare battery cells which can be switched by the microprocessor to replace failed cells. The microprocessor can also be used for inflight reconditioning of the batteries to increase performance and verify ampere-hour capacity. The Flexible Roll-Up Solar Array (FRUSA) system offers a solar array at an acceptable cost that can stay within weight and volume constraints.

Smith, O. B.↗

NASA NTRS1975

Large Space Telescope - Orbital crew EV maintenance operations

The paper shows that orbital EV maintenance by the crew has a tremendous impact on several areas of the program, including operations, Shuttle interfaces, support equipment rendezvous and berthing, checkout and verification, levels of servicing achievable, logistics and spares and scientific instruments in order to permit changeout and possible future refurbishment. To achieve on-orbit EV maintenance, such challenges as designing for suited-astronaut access to all subsystem equipment elements, minimization for contamination, handling of extremely sensitive instruments, development of translation techniques, and use of existing GFE and hardware must be faced early in the preliminary design and operations analysis phases. All studies to date indicate that on-orbit EV manned maintenance of the LST (Large Space Telescope) is not only feasible but can be designed to be readily within the capability of the EV functioning astronaut. Both 1-g and neutral buoyancy man-in-the-loop simulations further support this point.

Fisher, H. T.↗

NASA NTRS1976

Implementation of an experimental fault-tolerant memory system

The experimental fault-tolerant memory system described in this paper has been designed to enable the modular addition of spares, to validate the theoretical fault-secure and self-testing properties of the translator/corrector, to provide a basis for experiments using the new testing and correction processes for recovery, and to determine the practicality of such systems. The hardware design and implementation are described, together with methods of fault insertion. The hardware/software interface, including a restricted single error correction/double error detection (SEC/DED) code, is specified. Procedures are carefully described which, (1) test for specified physical faults, (2) ensure that single error corrections are not miscorrections due to triple faults, and (3) enable recovery from double errors.

Carter, W. C.↗

NASA NTRS1977

Return Beam Vidicon (RBV) panchromatic two-camera subsystem for LANDSAT-C

A two-inch Return Beam Vidicon (RBV) panchromatic two camera Subsystem, together with spare components was designed and fabricated for the LANDSAT-C Satellite; the basis for the design was the Landsat 1&2 RBV Camera System. The purpose of the RBV Subsystem is to acquire high resolution pictures of the Earth for a mapping application. Where possible, residual LANDSAT 1 and 2 equipment was utilized.

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NASA NTRS1977

Flight control electronics reliability/maintenance study

Collection and analysis of data are reported that concern the reliability and maintenance experience of flight control system electronics currently in use on passenger carrying jet aircraft. Two airlines B-747 airplane fleets were analyzed to assess the component reliability, system functional reliability, and achieved availability of the CAT II configuration flight control system. Also assessed were the costs generated by this system in the categories of spare equipment, schedule irregularity, and line and shop maintenance. The results indicate that although there is a marked difference in the geographic location and route pattern between the airlines studied, there is a close similarity in the reliability and the maintenance costs associated with the flight control electronics.

Dade, W. W.↗

NASA NTRS1978

Summary of static load test of the Mod-0 blade

A static load test was performed on the spare Mod-0 wind turbine blade to define load transfer at the root end of the blade, and to validate stress analysis of this particular type of blade construction (frame and stringer). Analysis of the load transfer from the airfoil skin to the shank tube predicted a step change in spanwise stress in the airfoil skin at station 81.5 inches (STA 81.5). For flatwise bending a 40% reduction in spanwise stress was predicted, and for edgewise bending a 6% reduction. Experimental results verified the 40% reduction for flatwise bending, but indicated about a 30% reduction for edgewise bending.

Miller, D. R.↗

NASA NTRS1978

A maintenance model for k-out-of-n subsystems aboard a fleet of advanced commercial aircraft

Proposed highly reliable fault-tolerant reconfigurable digital control systems for a future generation of commercial aircraft consist of several k-out-of-n subsystems. Each of these flight-critical subsystems will consist of n identical components, k of which must be functioning properly in order for the aircraft to be dispatched. Failed components are recoverable; they are repaired in a shop. Spares are inventoried at a main base where they may be substituted for failed components on planes during layovers. Penalties are assessed when failure of a k-out-of-n subsystem causes a dispatch cancellation or delay. A maintenance model for a fleet of aircraft with such control systems is presented. The goals are to demonstrate economic feasibility and to optimize.

Miller, D. R.↗