Abstract: A method of making an monolithic metallic sandwich structure includes selecting at least two chemically clean metal core sheets having superplastic characteristics and placing them face-to-face. The core sheets are welded together into a core pack along intersecting lines that will form junction lines of webs defining cells between the core sheets when the core pack is expanded superplastically. Gaps are left adjacent to the intersections of the weld lines to produce openings through which gas can pass to pressurize each cell. The position of the gaps adjacent the weld line intersections minimizes strain on the marginal regions around the openings as the core pack is inflated, to reduce the tendency of the sheets to tear or rupture around the openings. A gas pressure line fitting is inserted between one edge and the core pack is welded around its periphery with the gas fitting protruding from the edge for connection to a gas source that will purge and pressurize the core pack with gas.

Abstract: Improvements in oxygen generators and inert gas generators in aircraft. Separate gas generators are inefficient and thus present the problems of excess weight and heavy space and bleed air requirements. This invention provides an integrated system of generating oxygen and inert gas to pre-enrich the supply gas and increase overall efficiency. Bleed air is supplied to a first module (14) that separates it into a nitrogen enriched product gas and an oxygen enriched waste gas. The waste gas is fed into a second module (26) which separates it into an oxygen enriched product gas and a second waste gas. The modules (14, 26) may be reversed, with bleed air being fed into the oxygen generator and waste gas being fed into the inert gas generator. The system may include three modules (34, 42, 56). The waste gas from first module (34) is fed into second module (56), and the waste gas from second module (56) and the product gas from first module (34) are fed into third module (42).