Balloon Tank Skin Strain Measurements at Liquid-Hydrogen Temperature on Centaur Flight Vehicle
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CENTER
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The Centaur liquid-hydrogen tank at station 402 was instrumented with four strain gage installations on the Atlas-Centaur AC-3 flight vehicle. These gages were subjected to an extremely severe environment both during vehicle assembly at Cape Kennedy and during flight when the temperature at the gage was -423 degrees F. This report covers the installation of the gages, the signal-conditioning equipment and system calibration, and analysis and evaluation of data obtained from the flight. In spite of the severe environment both before and during the flight, useful data were obtained to evaluate structural performance. Incremental loads from launch to booster engine cutoff obtained from the strain gages were compared with the values computed from known mass distribution and gravity environment. Of the values at the four gage locations, two agreed almost exactly with the calculated values. Of the other two, one differed by 12 percent and the other by 15 percent. Although bonded gages have been in use in the laboratory at liquid-hydrogen temperatures, this technique on flight vehicles presented many problems. The results indicate, however, though the bonding process is a painstaking one, such gages can be a valuable tool for evaluating flight structural performance.
- Test Facilities, Equipment and Methods