Abstract: A rocket engine (10) generates a flow of hot propulsion fluid through a nozzle (14N). Hybrid exhaust gas generators (36,38) have their exhausts (44,54) through the side of the nozzle. Each gas generator includes a fuel grain (46,56) and a source of oxidizer (16,40,50). The fuel grain is kept hot by either or both (a) direct radiation or conduction from the hot propulsion fluid, or (b) by a trickle of oxidizer. When the thrust vector is to be modified, the appropriate one of the hybrid gas generators receives a flow of oxidizer, and the resulting exhaust gas is injected through the side of the nozzle.

Abstract: A joint between materials having disparate coefficients of thermal expansion (CTE) is compensated by a collar which extends a dimension of that one of the different materials which has the lesser CTE. A set of different collars provides compensation for sheets of material of different thicknesses when used with fasteners of a given material. The joint is assembled by selecting the sheets of various thicknesses to be juxtaposed, applying the fastener with a compensation collar corresponding to each one of the different sheets, and tightening the joint.

Abstract: A seam (16) between juxtaposed workpieces (14) is welded or heat-treated by friction-stir using a pin tool (12) driven by an apparatus (18) which controllably positions the pin tool (12) in the vertical direction (8). The workpiece (14) is supported by an anvil (22). The joint is heated by rotation of the pin tool (12) inserted into the joint from the obverse side. In order to provide a good weld through the thickness of the workpiece, a sensor (34, 310) senses electrical characteristics near the heated or welded region, and generates a control signal which tends to control the position of the pin tool near the reverse side of the weld. The sensor is located adjacent the weld (16s) on the obverse side, and is preferably protected by mounting in a depression (22c) in the anvil (22). In one embodiment, the sensor (34) senses magnetic characteristics near the weld. In another embodiment, the sensor (310) senses conduction, conductivity, or eddy currents in the vicinity of the weld.

Abstract: A garment or apparatus worn by emergency workers includes an electrically operated source of multiple, mutually diverging laser light beams. The light beams may be modulated to identify the worker and his status. The worker's location in an emergency environment is readily established as the locus of the diverging beams. A smoke-filled environment makes the laser beams more visible to rescuers.

Abstract: A back-to-back locator instrument includes a first portion with an array of two or more magnetic sensors, and an indicator arrangement. A second portion of the instrument includes an array of correspondingly located magnets. Each of the first and second portions includes a marking arrangement, which either allows marking of the underlying surface, or viewing of a mark on the surface for properly locating the instrument portion thereon. When the two portions are congruent or registered, the indicator arrangement gives a maximum indication of corresponding locations. In a particular use, corresponding locations on the inside and outside of a tank are identified. The indicator arrangement may include a separate indicator for each magnetic sensor. A flux concentrator may be associated with each magnetic sensor.

Abstract: Planishing or stress relief in a welded joint (34) is accomplished with a hammer (12) and a backing bar (26). The hammer is applied on a first side (1) to a first surface (31) of the structure (30). To indicate the proper position of the backing bar, a first magnet (20; 320) is associated with the hammer, and a magnetic sensor arrangement (24; 224; 300) is located on the other side (2) of the structure. In one embodiment, the sensor arrangement is a second magnet (24) which is held in place by the magnetic field (40) of the first magnet. In a second embodiment, the sensor includes a line array (262) of individual sensors, each associated with an indicator of a line array (264) of indicators. In a third embodiment, the sensor includes a line array (300) of two magnetic sensors, which are coupled to a differential indicator (324).

Abstract: A vacuum pump of the steam-ejector type uses steam generated by the combustion of hydrogen and oxygen. The mass of ejected steam is increased, and the temperature of the ejected steam is reduced, by injection of water into the combustion product. Propellant densification is accomplished by using such a vacuum pump to reduce the vapor pressure of a cryogenic liquid, thereby reducing its temperature. The cryogenic liquid may be the propellant, or it may be a coolant medium thermally coupled to the propellant.

Abstract: A portable illuminator for use in an atmosphere of fog, haze or particulate matter includes a laser for generating a light beam, and a light-beam scanner for scanning the laser beam over a line or area to be illuminated. The scanning may be accomplished by mechanically moving the mirror or the laser, or a moving lens may be used. In another embodiment, a microelectronic scanning reflector is used.

Abstract: Aluminum-lithium alloy sheets which are welded together are examined to identify regions requiring repair. A grid is applied to the sheet about the region requiring repair, and the region to be repaired is ground out and rewelded. Residual stresses are relieved by planishing yes to cause localized plastic deformation in the repaired region. The grid is used as a guide to restoring the original dimensions of the sheet in a manner which tends to reduce in-plane shrinkage. The reduced in-plane shrinkage in turn tends to reduce undesired tensile residual stresses. The planishing also tends to work-harden the weld filler.

Abstract: Stir friction welding is accomplished by applying force to plunge a nonconsumable, rotating welding post into the region to be welded. The rotation creates friction which at least partially melts the material to be welded, as the welding post penetrates. The force is continued, causing the post to continue to penetrate. A set of rollers associated with the welding head eventually reaches the surface of the workpiece when the welding post reaches the proper depth, and prevents further penetration of the welding post. In one embodiment of the invention, the rollers have crowned surfaces, and the force is applied by a hydraulic cylinder.