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At least 487 records · Page 27

The Long Duration Exposure Facility - A shuttle transported low cost technology experiment carrier

The Long Duration Exposure Facility (LDEF) is a passive spacecraft capable of remaining in space for extended periods. Its primary role is to accommodate advanced spacecraft technology experiments. The LDEF is space-shuttle delivered and retrieved. With retrieval, it offers unique opportunities to study, in ground-based laboratories, results from a wide variety of experiments after exposure in space.

Dibattista, J. D.↗

Long Duration Exposure Facility - A multipurpose free-flying experiment carrier

The Long Duration Exposure Facility (LDEF) is being developed by NASA to accommodate, using the Space Shuttle, a class of technology, science and applications experiments which require a free-flying exposure in space, but which do not require a sophisticated or dedicated satellite. The facility is a simple reusable structure about 14 ft in diameter and 30 ft long, which is three-axis gravity-gradient stabilized when free flying in space. Various aspects of the LDEF are examined, including the attitude stabilization system, the experiment trays, the experiment exposure control canister,and the environment monitoring system. LDEF mission plans are considered, as is experiment selection - the space debris damage experiment, the thermal coating experiment, the solar cells and arrays experiment, and the active optical components experiment.

Kinard, W. H.↗

Thermodynamic analysis of alternate energy carriers, hydrogen and chemical heat pipes

Hydrogen and chemical heat pipes were proposed as methods of transporting energy from a primary energy source (nuclear, solar) to the user. In the chemical heat pipe system, primary energy is transformed into the energy of a reversible chemical reaction; the chemical species are then transmitted or stored until the energy is required. Analysis of thermochemical hydrogen schemes and chemical heat pipe systems on a second law efficiency or available work basis show that hydrogen is superior especially if the end use of the chemical heat pipe is electrical power.

Cox, K. E.↗

Long duration exposure facility - A multipurpose free-flying experiment carrier

The Long Duration Exposure Facility (LDEF) is being developed to accommodate, using the Shuttle, a class of technology, science, and applications experiments which do not require a sophisticated or dedicated satellite. The LDEF is a simple reusable structure approximately 4.3 m in diameter and 9 m in length. The basic LDEF consists of a structural framework whose cross section is a 12-sided regular polygon. A facility description is provided, taking into account the structure, aspects of attitude stabilization, the experiment trays, the experiment exposure control canister, the environment monitoring system, and Shuttle bay environment measurements. Missions and questions of experiment selection are discussed, giving attention to orbits, dynamic motions, a space debris damage experiment, thermal coating experiments, the solar cells and arrays experiment, and the active optical components experiment.

Kinard, W. H.↗

The effects of an ion-thruster exhaust plume on S-band carrier transmission

The study reported here was undertaken (1) to develop models of the effects of an ion-thruster exhaust plume on S-band signals, and (2) to measure the effects. The results show that an S-band signal passing through an ion-thruster plume is reduced in amplitude and advanced in phase. The mathematical models gave reasonable estimates of the average signal attenuation and phase shift. Negligible fluctuations in the signal amplitude and phase were measured during steady-state thruster operation. However, large jumps in phase occurred when changes were made in the thruster operating state. This study confirms that the thruster plume can have a significant effect on S-band communication link performance; hence the plume effects must be considered in S-band link calculations when electric thrusters are used for spacecraft propulsion.

Ackerknecht, W. E.↗

Damage-detection system for LNG carriers

System utilizes array of acoustical transducers to detect cracks and leaks in liquefied natural gas (LNG) containers onboard ships. In addition to detecting leaks, device indicates location and leak rate.

Mastandrea, J. R.↗

Carrier-interference ratios for frequency sharing between frequency-modulated amplitude-modulated-vestigial-sideband television systems

For just perceptible interference, an FM television signal interfering with another FM television signal must have an average signal power that is 26 to 37 db less than the wanted signal power. For an AM-VSB television signal interfering with an FM television signal, the AM-VSB television's sync peak average power must be 18 to 31 db below the FM television signal's average power. Also, when an FM television signal interferes with an AM-VSB signal, the average signal power of the FM signal should be 56 to 59 db below the sync peak average power of the AM-VSB television signal. The range of power ratios occur as a result of different TV scenes used in the tests and different FM-signal frequency deviations used. All tests were performed using 525 line, system M, color-television signals.

Barnes, S. P.↗

Load and dynamic assessment of B-52B-008 carrier aircraft for finned configuration 1 space shuttle solid rocket booster decelerator subsystem drop test vehicle. Volume 1: Summary

The B-52B airplane was identified for use in solid rocket booster (RSB) parachute drop flight testing. The purpose of this study was to determine by theoretical analysis methods the compatability and structural capability of B-52B drop test vehicle configuration (with fins) to accomplish the drop test mission. This document consist of four volumes. This volume presents a summary of airplane flutter and load strength evaluation analysis results and a comparative study of the pylon loading resulting from drop test vehicle inertia and aerodynamic considerations.

Quade, D. A.↗

Load and dynamic assessment of B-52B-008 carrier aircraft for finned configuration 1 space shuttle solid rocket booster decelerator subsystem drop test vehicle. Volume 2: Airplane flutter and load analysis results

The airplane flutter and maneuver-gust load analysis results obtained during B-52B drop test vehicle configuration (with fins) evaluation are presented. These data are presented as supplementary data to that given in Volume 1 of this document. A brief mathematical description of airspeed notation and gust load factor criteria are provided as a help to the user. References are defined which provide mathematical description of the airplane flutter and load analysis techniques. Air-speed-load factor diagrams are provided for the airplane weight configurations reanalyzed for finned drop test vehicle configuration.

Quade, D. A.↗

Load and dynamic assessment of B-52B-008 carrier aircraft for finned configuration 1 space shuttle solid rocket booster decelerator subsystem drop test vehicle. Volume 3: Pylon load data method 1

The pylon loading at the drop test vehicle and wing interface attach points is presented. The loads shown are determined using a stiffness method, which assumes the side stiffness of the foreward hook guide to be one-fourth of the fore and aft stiffness of each drag pin. The net effect of this assumption is that the forward hook guide reacts approximately 85% of the drop test vehicle yawing moment. For a comparison of these loads to previous X-15 analysis design loadings, see Volume 1 of this document.

Quade, D. A.↗

Load and dynamic assessment of B-52B-008 carrier aircraft for finned configuration 1 space shuttle solid rocket booster deceleration subsystem drop test vehicle. Volume 4: Pylon load data

The pylon loading at the drop test vehicle and wing interface attack points is presented. The loads shown are determined using a stiffness method, which assumes the side stiffness of the forward hook guide and the fore and aft stiffness of each drag pin to be equal. The net effect of this assumption is that the forward hook guide reacts approximately 96% of the drop test vehicle yawing moment. For a comparison of these loads to previous X-15 analysis design loadings, see Volume 1 of this document.

Quade, D. A.↗

Probabilistic analysis of air carrier accidents

In order to estimate the potential risks due to carbon fibers (CF) released from aircraft accidents, it was necessary to quantify the probability of an accident or incident at a major hub airport. This probability was contingent upon various conditions surrounding the incident including the phase of operation, aircraft type, and the weather conditions. The type of accident predicted was categorized according to its location relative to the runway and the severity of damage sustained. The methodology utilized to estimate the probability of a specific type of accident is outlined and the various models that were developed in the course of this work are described.

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