NASA Scientific and Technical Aerospace Reports

gravitational perturbation are simulated, showing that the orbits are not significantly affected. This feature implies that no
station-keeping is required. Optimal direct transfer trajectories from Low Earth orbit are briefly examined, showing that
insertion into the characterized orbits may be performed using modest energetic requirements.
Author
Spacecraft Orbits; Orbit Determination; Orbit Calculation
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GROUND SUPPORT SYSTEMS AND FACILITIES (SPACE)
Includes launch complexes, research and production facilities; ground support equipment, e.g., mobile transporters; and test chambers
and simulators. Also includes extraterrestrial bases and supporting equipment. For related information see also 09 Research and
Support Facilities (Air).
20040073441 NASA Glenn Research Center, Cleveland, OH, USA
Infrared Heater Used in Qualification Testing of International Space Station Radiators
Ziemke, Robert A.; May 2004; 24 pp.; In English
Contract(s)/Grant(s): WBS-229799-30-01
Report No.(s): NASA/TM-2004-212332; E-13928; No Copyright; Avail: CASI; A03, Hardcopy
Two heat rejection radiator systems for the International Space Station (ISS) have undergone thermal vacuum
qualification testing at the NASA Glenn Research Center (GRC), Plum Brook Station, Sandusky, Ohio. The testing was
performed in the Space Power Facility (SPF), the largest thermal vacuum chamber in the world. The heat rejection system
radiator was tested first; it removes heat from the ISS crew living quarters. The second system tested was the photovoltaic
radiator (PVR), which rejects heat from the ISS photovoltaic arrays and the electrical power-conditioning equipment. The
testing included thermal cycling, hot- and cold-soaked deployments, thermal gradient deployments, verification of the onboard
heater controls, and for the PVR, thermal performance tests with ammonia flow. Both radiator systems are orbital replacement
units for ease of replacement on the ISS. One key to the success of these tests was the performance of the infrared heater
system. It was used in conjunction with a gaseous-nitrogen-cooled cryoshroud in the SPF vacuum chamber to achieve the
required thermal vacuum conditions for the qualification tests. The heater, which was designed specifically for these tests, was
highly successful and easily met the test requirements. This report discusses the heating requirements, the heater design
features, the design approach, and the mathematical basis of the design.
Author
Infrared Radiation; Heat Radiators; Thermal Cycling Tests; Photovoltaic Cells; Temperature Effects; Infrared Instruments
20040073460 NASA Langley Research Center, Hampton, VA, USA
Linear and Nonlinear Analyses of a Wind-Tunnel Balance
Karkehabadi, R.; Rhew, R. D.; [2004]; 19 pp.; In English; 4th International Symposium on Strain Gauge Balances, 10-13 May
2004, San Diego, CA, USA
Contract(s)/Grant(s): 23-090-80-40; No Copyright; Avail: CASI; A03, Hardcopy
The NASA Langley Research Center (LaRC) has been designing strain-gauge balances for utilization in wind tunnels
since its inception. The utilization of balances span a wide variety of aerodynamic tests. A force balance is an inherently
critically stressed component due to the requirements of measurement sensitivity. Force balance stress analysis and acceptance
criteria are under review due to LaRC wind tunnel operational safety requirements. This paper presents some of the analyses
done at NASA LaRC. Research and analyses were performed in order to investigate the structural integrity of the balances
and better understand their performance. The analyses presented in this paper are helpful in understanding the overall behavior
of an existing balance and can also be used in design of new balances to enhance their performance. As a first step, maximum
load combination is used for linear structural analysis. When nonlinear effects are encountered, the analysis is extended to
include the nonlinearities. Balance 1621 is typical for LaRC designed balances and was chosen for this study due to its
traditional high load capacity, Figure 1. Maximum loading occurs when all 6 components are applied simultaneously with their
maximum value allowed (limit load). This circumstance normally will not occur in the wind tunnel. However, if it occurs, is
the balance capable of handling the loads with an acceptable factor of safety? Preliminary analysis using Pro/Mechanica
indicated that this balance might experience nonlinearity. It was decided to analyze this balance by using NASTRAN so that
a nonlinear analysis could be conducted. Balance 1621 was modeled and meshed in PATRAN for analysis in NASTRAN. The
model from PATRAN/NASTRAN is compared to the one from Pro/Mechanica. For a complete analysis, it is necessary to
consider all the load cases as well as use a dense mesh near all the edges. Because of computer limitations, it is not feasible
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