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This Defense Intelligence Reference Document, DIA-08-0912-008, is dated 12 January 2010. It was prepared by the Defense Warning Office's Acquisition Support Division at the Defense Intelligence Agency as one of a series of FY 2009 technology reports under the Advanced Aerospace Weapon System Applications program. It reviews materials for launch vehicles, space vehicles and reusable rocket engines, including aluminum alloys, polymer and metal matrix composites, titanium and nickel alloys, and titanium aluminides. It concludes that newer materials and integrated design could improve on the space shuttle.
From the source: Release of 2026-09-18 Incident: 1/12/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys the structural materials needed for advanced aerospace platforms and argues that material choice cannot be separated from overall vehicle design, because launch vehicles, space vehicles, reusable systems, and propulsion hardware each face different temperature, durability, weight, and manufacturing constraints. The report reviews a range of candidate material classes, including advanced aluminum alloys; polymer-, aluminum-, and titanium-matrix composites; titanium alloys; nickel-base alloys; refractory metals; ceramic-matrix composites; carbon-carbon composites; and titanium aluminides. It emphasizes that balancing performance against practical limits such as fabrication methods, cost, inspection, contamination control, and service environment remains a major challenge. Its overall conclusion is that many promising materials exist, but their usefulness depends on application-specific tradeoffs and on closer integration of material selection with design and manufacturing, with some systems judged to be more valuable targets for development than others.
UNCLASSIFIED/ JFOR OFFICIAL USE 014[ I 13-Ti alloys would be an attractive option for a launch vehicle with a very heavy payload. These alloys can be processed and heat-treated to ultimate tensile strengths greater than 1,300 mega-Pascals (MPa), making them very efficient structural alloys. However, at these strength levels, the fracture toughness is decreased to about 40 MPa-m 0 •5 , making damage tolerance marginal. For example, using a design stress that is two thirds that of ultimate tensile strength, the critical crack size for an alloy with these properties is about 4 millimeters. Such a small critical crack size poses a challenge to any required field inspections associated with reusability requ irements. p-Ti alloys' stiffness also is as much as 10 percent lower than that of a+ J3 alloys. Ten percent lower stiffness generally is not an issue in a tension-loaded structure, but it can be an issue for a compression-loaded structure because of the potential for buckling. Designs with a higher section modulus can eliminate this concern, but the additional shape complexity will almost certainly add cost. In extreme circumstances, Ti alloys can be reinforced with ceramic fibers (typically silicon carbide) to increase their intrinsic stiffness, as will be discussed later. Ti alloys are reactive when exposed to air at temperatures of 550 °Celsius or above. Consequently, any manufacturing operations that exceed this temperature limit must be performed in a protective atmosphere of argon (Ar) or helium (He) gas. An exception occurs during forging if enough excess material is left on the raw forging to conta in the oxygen -contaminated layer so it can be machined away during the final machining of the finished component. How to deal with this reactivity issue is well understood, and it poses no concern other than the additional costs associated with the excess material and additional machining. In other operations, such as welding, use of specially designed fixtures incorporating inert shielding gas also effectively eliminates concerns about oxygen contamination. In hot-forming applications, the as-formed part is typically chemically milled to remove the oxygen-rich surface layer because this layer typically has lower ductility and can cause fatigue cracking in service. The practice of eliminating all oxygen-contaminated material has served the aerospace industry well over the years but is quite conservative and restrictive. This matter is discussed in greater detail in the Reusable Reentry Vehicle section of th is document. In summary, although the choices of materials for launch vehicles are in principle numerous, in practice these choices are reduced by a variety of application-specific considerations that include manufacturing capab ility for large components and manufacturing cost. The foregoing discussion has attempted to examine the prospects for advanced Al alloys, PMCs, and Ti alloys in light of these perceived practical constraints. On a case-by-case basis, a variety of requirements are imposed by design constraints, which some materials meet more readily than others. In all cases, discussion of available material options was constrained by the assumption that the maximum service temperatures would be relatively low. Consequently, the material classes discussed here are all intended for relatively low-temperature use. The separate case of a reusable single-stage-to-orbit veh icle, where operating temperature requirements are considerably higher, is discussed in a later section of this document. Ultimately, materials are selected to optimize structural performance, and a coordinated approach of materials selection and geometric design is essential to this. Going forward, a design using a synthesis process that treats form, fit, function, and materials capability as equal constraints is needed to achieve true optimum structural efficiency. 8 UNCLASSIFIED/ /570A OFFl&IAk W&E 8HL\«
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 27 pages are in the text index: search them above, or from the library's search.