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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 1,243 records · Page 69
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Failure mode and effects analysis (FMEA) for the Space Shuttle solid rocket motor

The recertification of the Space Shuttle Solid Rocket Booster (SRB) and Solid Rocket Motor (SRM) has included an extensive rewriting of the Failure Mode and Effects Analysis (FMEA) and Critical Items List (CIL). The evolution of the groundrules and methodology used in the analysis is discussed and compared to standard FMEA techniques. Especially highlighted are aspects of the FMEA/CIL which are unique to the analysis of an SRM. The criticality category definitions are presented and the rationale for assigning criticality is presented. The various data required by the CIL and contribution of this data to the retention rationale is also presented. As an example, the FMEA and CIL for the SRM nozzle assembly is discussed in detail. This highlights some of the difficulties associated with the analysis of a system with the unique mission requirements of the Space Shuttle.

Russell, D. L.↗
NASA NTRS1988

Evaluation and mitigation of lightning hazards to the space shuttle Solid Rocket Motors (SRM)

The objective was to quantify electric field strengths in the Solid Rocket Motor (SRM) propellant in the event of a worst case lightning strike. Using transfer impedance measurements for selected lightning protection materials and 3D finite difference modeling, a retrofit design approach for the existing dielectric grain cover and railcar covers was evaluated and recommended for SRM segment transport. A safe level of 300 kV/m was determined for the propellant. The study indicated that a significant potential hazard exists for unprotected segments during rail transport. However, modified railcar covers and grain covers are expected to prevent lightning attachment to the SRM and to reduce the levels to several orders of magnitude below 300 kV/m.

Rigden, Gregory J.↗
NASA NTRS1988

Lightweight structural design of a bolted case joint for the space shuttle solid rocket motor

The structural design of a bolted joint with a static face seal which can be used to join Space Shuttle Solid Rocket Motor (SRM) case segments is given. Results from numerous finite element parametric studies indicate that the bolted joint meets the design requirement of preventing joint opening at the O-ring locations during SRM pressurization. A final design recommended for further development has the following parameters: 180 one-in.-diam. studs, stud centerline offset of 0.5 in radially inward from the shell wall center line, flange thickness of 0.75 in, bearing plate thickness of 0.25 in, studs prestressed to 70 percent of ultimate load, and the intermediate alcove. The design has a mass penalty of 1096 lbm, which is 164 lbm greater than the currently proposed capture tang redesign.

Dorsey, John T.↗
NASA NTRS1988

Cyclic loads tests of carbon involute solid rocket motor outer boot ring segments

The cyclic loads tests performed on the 30-in. segments of the DM-9 (Development Motor-9) configuration solid rocket outer boot ring are described. The tests found that the effect of the cyclic loadings on the structural integrity of the outer boot ring was negligible. The results are compared with a hand analysis of the strength of a 30-in. outer boot ring segment. Several phenomena of engineering interest are also described.

Ahmed, Rafiq↗
NASA NTRS1989

Effects on motor unit potentiation and ground reaction force from treadmill exercise

This study was conducted to analyze the characteristics of motor unit potentiation (MUP) and ground reaction force (GRF) in treadmill exercise at the inclines of 0, 5.5 and 11 percent with conjuctive speeds of 7.5, 6, and 5 mph respectively. These speeds and corresponding inclines were set to provide equivalent physiological workloads at 12.5 METS. EMG recordings were taken from the rectus femoris and gastrocnemius of the right leg from 5 subjects. Simultaneous GRF recordings were obtained from a Delmar Avionic treadmill rigged with load cells. Measures for MUP and GRF were taken over a period containing 10 strides at steady pace. It was concluded that the gastrocnemius was more evident in EMG activity in all speed/incline settings over the rectus femoris, and that inclines from 5.5 to 11 percent produced greater GRF's over 0 percent. Recommendations for future studies was made.

Elam, Reid P.↗
NASA NTRS1988

Flight motor set 360L001 (STS-26R), volume 1

The NASA space shuttle flight STS-26R, launched at 11:37.00.009 a.m. EDT on 29 Sep. 1988, used the redesigned solid rocket motors (RSRM) 360LOO1A and 360LOO1B. Evaluation of the ground environment instrumentation (GEI) data recorded prior to flight showed: (1) no launch commit criteria violations, (2) that the field joint heater and aft skirt thermal conditioning systems performed adequately, and (3) that the GEI data showed good agreement with thermal model predictions. Evaluation of the developmental flight instrumentation (DFI) revealed excellent agreement with both the predicted and required ballistic specifications. All parameters were well within the CEI specification requirements including propellant burn rates, specific impulse values, and thrust imbalance. Recorded strain values also indicated satisfactory radial growth and stress levels, as well as verification of adequate safety factors. Postflight inspection of the insulation, seals, case, and nozzles showed overall excellent performance. Some thermal DFI protective cork was missing, and inoperative field joint vent valves on the thermal protection cork allowed water entry into the field joints upon splashdown. Evaluation of these anomalies, as well as complete evaluation of all RSRM components, is presented.

Ricks, Glen A.↗
NASA NTRS1988

Power conditioning for large dc motors for space flight applications

The design and performance of a prototype power-conditioning system for use with large brushless dc motors on NASA space missions are discussed in detail and illustrated with extensive diagrams, drawings, and graphs. The 5-kW 8-phase parallel module evaluated here would be suitable for use in the Space Shuttle Orbiter cargo bay. A current-balancing magnetic assembly with low distributed inductance permits high-speed current switching from a low-voltage bus as well as current balancing between parallel MOSFETs.

Veatch, Martin S.↗
NASA NTRS1988

ac bidirectional motor controller

Test data are presented and the design of a high-efficiency motor/generator controller at NASA-Lewis for use with the Space Station power system testbed is described. The bidirectional motor driver is a 20 kHz to variable frequency three-phase ac converter that operates from the high-frequency ac bus being designed for the Space Station. A zero-voltage-switching pulse-density-modulation technique is used in the converter to shape the low-frequency output waveform.

Schreiner, K.↗
NASA NTRS1988

Space Shuttle solid rocket motor testing for return to flight - Transient Pressure Test Article test program

The Transient Pressure Test Article (TPTA) test program, which is being conducted at a new facility at NASA-Marshall, is described. The facility is designed to test and verify the sealing capability of the redesigned solid rocket motor's (RSRM) field, igniter, and nozzle joints. The test article consists of full-scale RSRM hardware loaded with inert propellant and assembled in a short stack configuration. The test facility is described as well as test implementation, test effectiveness, and test results.

Vibbart, Charles M.↗
NASA NTRS1989

Strength of a thick graphite/epoxy rocket motor case after impact by a blunt object

The National Aeronautics and Space Administration is developing graphite/epoxy filament-wound cases (FWC) for the solid rocket motors of the Space Shuttle. The membrane region is about 36 mm thick. A study was made to determine the reduction in strength of the FWC due to accidental damage caused by low-velocity impacts. Two 76.2 cm diameter by 30.5 cm long cylinders were impacted every 5 cm of circumference with 1.27 cm radius impacters of various mass. The impacters represented tools and equipment dropped from various heights. One cylinder was empty and the other was filled with inert propellant. Five cm wide test specimens were cut from the cylinder. Each was centered on an impact site. The specimens were X-rayed and loaded to failure in uniaxial tension. The strengths and depths of impact damage were analyzed in terms of maximum impact force. Rigid body mechanics and the Hertz law were used to derive an equation for impact force in terms of kinetic energy and the masses of the impacter and target. The depth of damage was predicted in terms of impact force using Love's solution of pressure applied on part of the boundary of a semi-infinite body.

Poe, Clarence C., Jr.↗
NASA NTRS1988

Plasma motor generator tether system for orbit reboost

This paper describes a comprehensive study of an electrodynamic tether used as a Plasma Motor Generator (PMG). The paper summarizes the work performed in the study and includes: (1) a detailed design of a 2 kW PMG tether system to be used for orbit reboost, (2) the selection of the Orbiting Maneuvering Vehicle (OMV) and the European Retrievable Carrier (EURECA) as the primary candidate spacecraft to host the experimental system, (3) analysis of the integration of the PMG tether system with these two spacecraft, (4) the simulation of the deployment of the tether, and (5) an engineering design and development plan leading to a flight demonstration of this PMG tether.

Hulkower, Neal D.↗
NASA NTRS1989

Erosive burning threshold conditions in solid rocket motors

Erosive burning has been predicted to be enhanced by factors that increase the level of turbulence close to the propellant surface, such a high cross flow velocity, low surface blowing rate, propellant surface roughness, and adverse pressure gradient. A study is reported which was carried out with the objective of measuring the effects of these parameters on the scaling to larger rocket motor sizes of the transition to, or threshold conditions for, erosive burning rate augmentation. The results are used to develop a scaling criterion for the threshold conditions for erosive burning.

Strand, L. D.↗
NASA NTRS1989

Plasma torch testing for thermostructural evaluation of rocket motor nozzle materials

This paper presents data from the thermostructural testing of tape-wrapped carbon phenolic. This work has been performed with the use of a plasma torch and loading device in an effort to study the anomalous erosion characteristicfs of that seen in the Space Shuttle Solid Rocket Motor Nozzle STS-8A. Testing is conducted in an effort to determine conditions or parameters involved in this mode of failure.

Prince, Andrew S.↗
NASA NTRS1989

Decentralized control of the COFS-I Mast using linear dc motors

Consideration is given to a decentralized control design for vibration suppression in the COFS-I Mast using linear dc motors for actuators. The decentralized control design is based results from power systems using root locus techniques that are not well known. The approach is effective because the loop gain is low due to low actuator authority. The frequency-dependent nonlinearities of the actuator are taken into account. Because of the tendency of the transients to saturate the the stroke length of the actuator, its effectiveness is limited.

Lindner, Douglas K.↗
NASA NTRS1988

Space Shuttle solid rocket motor testing for return to flight

Significant design changes made to major components of the NASA Space Shuttle SRM are summarized. The extent of changes made in the nozzle-to-case joint to better protect the joint O-ring seals is indicated schematically as are changes made to the motor nozzle. It is noted that the use of subscale, full scale/short duration burn hardware tests to provide data for structural and thermal analytical models was necessary.

Coates, Keith D.↗
NASA NTRS1990

Balanced-Bridge Feedback Control Of Motor

Sensitivity to variations in electrical and mechanical characteristics reduced. Proposed control system for motor-driven rotary actuator includes three nested feedback loops which, when properly designed, decoupled from each other. Intended to increase accuracy of control by mitigating such degrading effects as vibrations and variations in electrical and mechanical characteristics of structure rotated. Lends itself to optimization of performance via independent optimization of each of three loops. Includes outer, actuator, and driver feedback loops, configured so that actuator is subsystem, and driver is subsystem of actuator.

Lurie, Boris J.↗
NASA NTRS1989

Age-related changes in human posture control: Motor coordination tests

Postural responses to support surface displacements were measured in 214 normal human subjects ranging in age from 7 to 81 years. Motor tests measured leg muscle Electromyography (EMG) latencies, body sway, and the amplitude and timing of changes in center of pressure displacements in response to sudden forward and backward horizontal translations of the support surface upon which the subjects stood. There were small increases in both EMG latencies and the time to reach the peak amplitude of center of pressure responses with increasing age. The amplitude of center of pressure responses showed little change with age if the amplitude measures were normalized by a factor related to subject height. In general, postural responses to sudden translations showed minimal changes with age, and all age related trends which were identified were small relative to the variability within the population.

Peterka, R. J.↗
NASA NTRS1989

Flight motor set 360L001 (STS-26R). Volume 5: Nozzle component

A review of the performance and post-flight condition of the STS-26 Redesigned Solid Rocket Motor (RSRM) nozzles is presented. The nozzle assemblies, flown on the Space Shuttle Discovery on 29 September 1988, were tested to demonstrate flex bearing system reusability. The evaluation indicated no condition that would adversely affect the reusability of the flex bearing system. Inspection showed that the flex bearings did not leak, were not damaged by water impact, had the expected erosion profiles, and that the remaining ablative liner thicknesses met the performance margin of safety. Applicable Discrepancy Reports and Process Departures, the Nozzle Component Program Team performance evaluation, and the Redesign Program Review Board assessment are included.

George, Russell J.↗