Evolution of ordnance subsystems and components in air force strategic missile systems

Ordnance subsystems and components are critical elements in intercontinental ballistic missile systems. Ordnance is required for stage ignition, stage separation, thrust vector control system actuation, fluid isolation valve actuation, battery actuation, thrust termination, and release of reentry vehicles. In addition, an ordnance destruct subsystem is mandatory for. each flight test. The similarity between missile systems enabled the development and evolution of ordnance designs; for example, the isolation valves, linear-shaped charges for destruct subsystems, linear explosives for stage separation rings, and confined detonating cords for explosive train interconnections were used on all five missile systems developed by the U.S. Air Force since the early 1960s. The approach did not prevent the adoption of new technologies to improve performance. High-temperature resistant hexanitrostilbene explosive was adopted and the through-bulkhead initiator-and exploding bridgewire initiator replaced the hot bridgewire-based squibs and detonators. A laser/fiber-optics-based ordnance firing system was developed for a mobile missile system. Hermetic seal technologies were adopted for achieving a longer service life for explosive devices. Better methods were adopted for ordnance testing, for example, the thermal transient pulse test and the builtin reflectometry. These approaches dramatically improved reliability, safety, weight efficiency, service life, and cost effectiveness.