Aerospace vehicles

MetaUic Materials and Elements for Aerospace Vehicle Stmetures," Military Handbook 5-F, Dept, of Defense, Washington, D.C., 1991. 

Other Matrix Materials. Advanced materials, eg, stmctural components, in aerospace vehicles also employ ceramics and metals as composite matrices (see Composite materials, ceramic-matrix Metal-matrix composites). 

Composites fabricated with fixed catalyst VGCF can be designed with fibers oriented in preferred directions to produce desired combinations of thermal conductivity and coefficient of thermal expansion. While such composites are not likely to be cost-competitive with metals in the near future, the ability to design for thermal conductivity in preferred directions, combined with lower density and lower coefficient of thermal expansion, could warrant the use of such VGCF composites in less price sensitive applications, such as electronics for aerospace vehicles. 

The aerospace field is a broad one and has a complex history. A comprehensive review of structural adhesive applications on currently flying aerospace vehicles alone could fill its own book. Hence this chapter will concentrate on the aerospace commercial transport industry and its use of adhesives in structural applications, both metallic and composite. Both primary structure, that is structure which carries primary flight loads and failure of which could result in loss of vehicle, and secondary structure will be considered. Structural adhesives use and practice in the military aircraft and launch vehicle/spacecraft fields as well as non-structural adhesives used on commercial aircraft will be touched on briefly as well. 

Specifically, within the aerospace industry, for aircraft, the airframe manufacture itself is one of the major cost drivers, using the factors already addressed. Let s look at the character of how we would build an aerospace vehicle. There is typically a lot of manpower dependence. The industry itself is cyclic because the demands ebb and flow. There is typically little automation simply because of relatively low production rates, and there are very few customers. But, despite all those characteristics, there is typically also a large capacity that is founded on many highly skilled personnel, and the orientation is much more high tech than that of most other industries. Without product excellence as a driving factor, the whole industry would be an unworkable mess. 

The purpose of this subsection is to familiarize the reader with some of the basic characteristics and problems of composite laminate joints. The specific design of a joint is much too complex for an introductory textbook such as this. The published state-of-the-art of laminate joint design is summarized in the Structural Design Guide for Advanced Composite Applications [7-5] and Military Handbook 17A, Plastics for Aerospace Vehicles, Part 1, Reinforced Plastics [7-6]. Further developments can be found in the technical literature and revisions of the two preceding references. 

Plastics for Aerospace Vehicles, Part 1, Reinforced Plastics, Military Handbook MILHDBK-17A, January 1971. 

Progress in aeronautics and astronautics within the past decades has been remarkable because people have learned to master the difficult feat of hypervelocity flight. A variety of manned and unmanned aircraft have been developed for faster transportation from one point on earth to another. Similarly, aerospace vehicles have been constructed for further exploration of the vast depths of space and the neighboring planets in the solar system. 

Secondary structure A structure that is not critical to the survival of the primary structure. Examples are in aircraft and aerospace vehicles that are not critical to safety of operations such as the interior decorative paneling. See Primary structure. 

Plastics for Aerospace Vehicles, MIL-HDBK-17A 17B, US Supt. of Documents, GPO, 1981. 

The space shuttle and other aerospace vehicles use carbon-carbon extensively in nose cap, leading edges, structural panels, and other components. 

These properties make AT-resins especially attractive for advanced aircraft and aerospace vehicles where material weight is a critical factor and high temperatures as well as humidity are likely to be encountered. 

In military aerospace vehicles, the service conditions are most severe for paints. One way to increase protecion of aluminum in acidic marine environments is to enhance the corrosion inhibiting ability of the inorganic coating. This paper describes the results of such an effort. A new coating which not only inhibits the attacic of chloride ions but also that of the acidic environments such cis SO2 has been developed. 

J. Bedel, Considerations on rocket propulsion for an aerospace vehicle, Paper presented at Eurospace Conf, Brussels, Jan 23-24, 1964 (NASA N 65-24027) 11) G. Hennings G. Morrell, Preliminary investigation of a chemical starting technique for acid-gasoline rocket propellant system, Res Memo E52K21, Natl Advisory Committee for Aeronautics, Wash, DC (Jan 1953) 12) B. Lewis, USP 3177652 (1965)... 

Because of their different structures, polymers may be used for a wide variety of applications, ranging from enhanced oil recovery to components for aerospace vehicles. Fortunately, one can predict the properties of polymers, to some extent, from a knowledge of their structure. 

Fig. 4. Four aluminum sections of this type make up fuel tank for aerospace vehicle. Each section is produced from computer-machined plate and weighs 4750 pounds (2155 kg). (Reynolds Metals Company)...

Cast PTFE films can be laminated with different substrates, most frequently with PTFE-coated glass and aramid fabrics. They also can be metallized, in particular with aluminum for use in electronics. Other applications include as release films for the manufacture of composite materials for aerospace vehicles, in electronics and electrical industries, as selective membranes, and in the chemical industry. 

Polyimides have also been the subject of many review compilations of papers and continue to be the focus of many conferences around the world [28-33]. Having various chemical forms, including isoimides, polyimides have found use in a vast array of applications that in some cases, due to their superior physical characteristics have displaced epoxies, for example, as matrix polymers in aerospace vehicles. 

Daniels—Terrestrial Environment (Climatic) Criteria Guidelines for Use in Aerospace Vehicle Development, 1973 Revision. NASA TMS-64757, NASA/MSFC. 

Military Standardization Handbook 17, Polymer Matrix Composites Guidelines, MIL-HDBK17B, Vol. 1, 1988 Plastics for Aerospace Vehicles, Part I. Reinforced Plastics, MIL HDBK17A, 1971, US Department of Defense, Washington, DC. 

Table 1 lists a variety of environments that can be considered extreme and are the subject of chemical studies. It is difficult to develop general quantitative criteria as to what constitutes an extreme environment. Such categorizations must be viewed from the perspective of the type of system under consideration. For a liquid lubricant in an engine, a temperature of 620 K, above its decomposition temperature, is an extreme environment. For metals exposed to high temperatures, such as titanium and nickel superalloys in aerospace vehicles, temperatures of 1100 and 1400 K, respectively, test their operational limits. In these two cases, thermal degradation of the... 

Use High-temperature coatings, laminates and composites for aerospace vehicles, ablative materials, oil sealants and retainers, adhesives, semiconductors, valve seats, bearings, insulation for cables, printed circuits, magnetic tapes (high- and low-tem-perature-resistant), flame-resistant fibers, binders in abrasive wheels. 

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