Abstract: Multicurved copper films having fine-line elements suitable for radome applications can be improved by cutting the elements with reproducible precision to close tolerance (typically line widths of 3-10.+-.0.25 mil) using an etchant comprising a concentrated saline solution of CuCl.sub.2.

Abstract: An asymmetric coil which has an "A" winding on one pole of the "C" core and a "B" winding of opposite helical twist, on the other pole, we can achieve relatively uniform, intense heating between the poles with relatively insignificant heating outside the poles. Only one core winding is active at one time. This coil allows us to heat uniformly to the ends of the susceptors on the ribs without remelting or overheating the welded area under the abutting spar, as FIG. 6 illustrates. The asymmetry provided by the two windings of opposite helical sense and the core design allows us to travel in either direction by activating the appropriate coil.

Abstract: Apparatus for applying heat to a patch on a composite structure repair site is disclosed. The apparatus includes a sealed bladder containing both a thermally conductive fluid and a heating element in thermal contact with the fluid. The heating element which comprises a flexible sheet having an electrical resistance wire uniformly placed thereon can be immersed in the fluid or otherwise in direct thermal contact therewith. Electrical power is applied to the heating element by conductors passing through the bladder surface. The heating element of disclosed structure can be attached to seal the bladder interior into two reservoirs, to permit fluid flow throughout the bladder or to form at least one outer surface of the bladder. Flexible supports can also be attached from the heating element to an interior bladder surface to maintain spacing between the heating element and the surface.