Engineering Papers⌕ Search

Engineering topics

Schafer, C. F.

Publications and source records attributed to Schafer, C. F..

12 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Paving a Highway to Space

This paper presents the Paving a Highway to Space at the 49th JANNAF (Joint Army-Navy-NASA-Air force) Propulsion Meeting. The topics include: 1) Earth-To-Orbit; 2) Orbit and Beyond; 3) Duct Propulsion; 4) Electric Propulsion; 5) Beamed Energy Propulsion; 6) Externally-Effected Force; 7) Nuclear Propulsion; 8) The Road to Higher Power Densities and Performance; 9) Propulsion Technology Map; 10) Launch Applications; 11) Space Applications; and 12) Advanced High-Energy Concepts. This paper is presented in viewgraph form.

Schafer, C. F.↗
NASA NTRS1989

Numerical simulation of forced convection in a two fluid layered system in a floating zone configuration

Forced convection due to rotational effects has been numerically studied in a stable two-fluid layered system in which the lighter fluid occupies the upper portion of the computational and physical domain. Results are presented for three different fluid height combinations for conditions prevailing in a microgravity environment. It is found that the heavier fluid tends to dominate the flow field, and that equal corotation and counterrotation cases produce nearly identical behavior in the flow and thermal fields.

Ramachandran, N.↗
NASA NTRS1983

Flow in a torsionally oscillating filled cylinder

The flow of a liquid in a completely filled cylinder undergoing torsional oscillations about its longitudinal symmetry axis was studied analytically and experimentally. The objective of the studies was to determine the efficacy of the torsional oscillations in mixing the confined liquid. Flow was found to be confined primarily to toroidal cells at the ends of the cylinder. Cell thickness was about equal to the cylinder radius. The use of baffles at the end walls was shown to enhance the mixing process.

Schafer, C. F.↗
NASA NTRS1983

Mechanics of liquid helium in a partially filled rotating dewar in low gravity with application to Gravity Probe-B

The Gravity Probe-B spacecraft is composed largely of a liquid helium dewar containing an experiment package. It is shown that an unsymmetric liquid helium distribution in the dewar can cause unacceptably high forces, gravitational and gravity gradient forces, at the experiment location. It is further shown that for the planned spacecraft configuration and operational parameters, it is very likely that the liquid helium distribution in the dewar will be unsymmetric. The required symmetry can be attained by using higher operational spacecraft rotation rates.

Schafer, C. F.↗
NASA NTRS1982

Liquid helium management for Gravity Probe-B

The Gravity Probe-B (GP-B) experiment will be degraded if accelerations at a proof mass become larger than one ten billionth g. This makes necessary the management of the configuration and dynamical behavior of the large amount of liquid helium present in the GP-B spacecraft dewar. Three approaches to the solution of this problem are discussed. It is concluded that the most promising technique involves the use of baffles into which the liquid helium can be forced during a relatively high spacecraft rotation period, and in which the liquid helium will be held by capillary forces during the operational period when the rotation rate is much lower. Some likely baffle configurations are suggested.

Schafer, C. F.↗
NASA NTRS1981

Analysis of SPAR 8 single-axis levitation experiment

The melting and resolidification of SPAR 8 payload melting and resolidification of a glass specimen from the in a containerless condition and the retrieval and examination of the specimen from the. The absence of container contact was assured by use of a single-axis acoustic levitation system. However, the sample contacted a wire cage after being held without container contact by the acoustic field for only approximately 87 seconds. At this time, the sample was still molten and, therefore, flowed aroung the wire and continued to adhere to it. An analysis of why the sample did not remain levitated free of container contact is presented. The experiment is described, and experimental observations are discussed and analyzed.

Rush, J. E.↗
NASA NTRS1977

Mixing of two liquid metals on spar payload due to spin-up and spin-down

Unexpected results from SPAR experiments, directed at obtaining fine dispersions of metal systems that in a 1-g environment tend to segregate very rapidly, were considered. The physical processes occurring in fluid samples, such as the SPAR samples before solidification, were shown to be insufficient to produce a well mixed liquid by the time solidification was initiated. This would result in solidified samples with the type of segregation noted in the SPAR samples. Experimental evidence and analytical arguments are presented.

Schafer, C. F.↗
NASA NTRS1977

A technique to correct for sample thickness variations for use with IDAPS X-ray radiograph analysis

The Image Data Processing System (IDAPS) at the Marshall Space Flight Center is used to analyze radiographs of metal samples to qualitatively and quantitatively map compositional variations across the samples. When the X-ray radiographs are of samples having thickness variations, corrections must be made to accomplish compositional analysis. A correction technique is described for cylindrical samples and is applied to radiographs of SPAR Experiment 74-18. Uncorrected and corrected images are shown.

Schafer, C. F.↗
NASA NTRS1977

Spar I liquid mixing experiment

The Liquid Mixing Experiment had as its objective the observation of effects of residual acceleration on a confined fluid system. The fluid system was chosen to be similar geometrically and in fluid properties to a range of materials science experiments. Samples were constructed as cylinders 2.2 cm long by 0.6 cm diameter. Half of each cylinder was composed of pure indium, and the other half of each was an alloy of 80 wt% indium and 25 wt% lead. The samples were enclosed in aluminum cartridges and placed in heaters mounted in three mutually perpendicular directions. The experimental procedure consisted of melting the samples when the low-g phase of the payload trajectory was attained, holding the samples in a molten state for approximately 200 seconds, and then quenching to resolidification before leaving low-g. Two of the samples exhibited very little fluid motion. The third sample, which was oriented nearly parallel to a payload radius, showed a great deal of flow.

Schafer, C. F.↗