shuttle_guy - What alloy of aluminum - or just plain free aluminum with a coating of aluminum oxide (Alumina)?<br /><br />Concerning glass types - a few notes I have already gleaned from Britannica:<br /><br />Near perfect glass fibers (flaws greatly weaken glass) can support loads of up to 500 tons per square inch and have a tensile strength 5 times that of available steel and double that of the theoretical limit for steel - <br />"The New Encyclopedia Britannica," 1989 print edition, volume 21, p. 234.<br /><br />"Borosilicate glass (pyrex type) is far more resistant to tensile strength; while both the so-called Vycor glass, containing 96% silica, and pure silica glass are virtually immune to thermal shock." - Ibid., p. 235<br /><br />Borosilicate glass is 60-80% silica (SiO2). 10-15% boric oxide (B2O3), 1-4% alumina (Al2O3). <br /><br />Antiradiation glass is 20% silica; 80% lead oxide (PbO)<br /><br />High silica (Shrunken glass) is 96% silica; 3-4 % boric oxide.<br /><br />Thinner glass is more resistant to thermal shock because glass insulates and therefore the interior of thick glass is hotter on rapid cooling and therefore more expanded that the surface and therefore causes great tensile stress.<br /><br />However, Borosilicate glass, pyrex, expands more slowly. Low expansion glass is therefore used in telescopes (like on Mt. Palomar).<br /><br />Shrunken glass is lower expansion than Pyrex and also has a very high melting point - so it is used for applications involving extreme thermal shock.<br /><br />This type of glass is formed from borosilicate glass larger than the final size, non-silicate materials are leached out, the glass is then heated to remove the resulting pores.<br /><br />Shrunken glass is virtually immune to thermal shock and can be used in working applications well over 1,000 C (1800 F). - Ibic., p. 241<br /><br />The same variability in properties exists with the various aluminum alloys which is why I am interested in what type of aluminum is used on the shutt