Reusable Launch Vehicle Technology Development and Test Program (1995) / Chapter Skim
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2 PRIMARY VEHICLE STRUCTURE
2 PRIMARY VEHICLE STRUCTURE
Pages 19-27
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From page 19... ...
Final material selection for the X-33 design will be based on systems analyses that incorporate the results of the technology program. The primary issue relevant to the development of a PVS is the lack of data for estimating material properties, life cycle, manufacture, inspectability, and repairability of composite materials potentially applicable to primary structures in launch-vehicle environments.
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From page 20... ...
At least one composite thrust structure test article will be constructed and integrated with the required TPS, health monitoring, and attachment subsystems, and will be under test. Appropriate coupon and other sub scare testing (e.g., pull-test, pane} specimen)
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From page 21... ...
Economically viable gross liftoff weights and technically feasible specific impulse asp) restrict the dry-mass fraction to a narrow range of 10-~l percent, of which the structural mass fraction is about 5 percent, which emphasizes the importance of rigorous weight control of all vehicle components.
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From page 22... ...
The primary function of the thrust structure is to transfer and distribute engine thrust loads through the launch vehicle. The thrust structure is a highly loaded system and must perform in a severe thermal and vibroacoustic environment.
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From page 23... ...
Fundamental tests that yield information critical to joint designs include lap shear tests, bearing, interlaminar tension, and pin or bolt tension tests. The results of these tests, particularly for lap shear, are susceptible to many factors.
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From page 24... ...
For example, for a new fixture under development at NASA Langley, intertank section panels will be subjected simultaneously to multiaxial enplane loading, pressure loads from one side, and a complex thermal environment. In another case, composite tanks will undergo both thermal cycling and extensive, repeated mechanical loading after which they will be tested functionally (e.g.' for hydrogen leaks)
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From page 25... ...
Extensive sub scare tests, moving from coupon size through pane} size to reasonably large test articles, are to be accompanied by continuous validation of the predictive cools. However, ways to validate as-built structural mass fractions and their required growth margin have not been fully determined at this time.
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From page 26... ...
Critical elements include assuring that the conditions under which testing is done Particularly the complex conditions for the component tests) are accurate; in cases of uncertainty, determining worst case scenarios; and designing tests so the information can be used to demonstrate that mass fraction goals have been achieved.
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From page 27... ...
must be defined for each vehicle concept. NOTES I. Aldrich, Arnold D
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