AFRL Develops Brassboard GI Published Dec. 11, 2006 By Plans and Programs Directorate AFRL/XP WRIGHT-PATTERSON AIR FORCE BASE, Ohio -- Presently, all Air Force glide bombs incorporate fuzes that contain an embedded safety and arming (S&A) device. The S&A mechanism is responsible for maintaining the fuze in a safe state until a prescribed set of postlaunch arming conditions is satisfied. Because of the potentially catastrophic consequences associated with fuze safety failures, all S&A devices must conform to the stringent design criteria set forth in MIL-STD-1316E, the military standard for fuze safety. Under a Small Business Innovation Research contract, AFRL and System Dynamics International, Inc. (SDI), are developing and testing an innovative glide bomb fuze that eliminates the air turbine initiator and derives arming power from the bomb's thermal battery. One advantage of this configuration is that the fuze's source of arming power is no longer inhibited by low air densities at high altitudes or by inlets occluded by mounting hardware or weapon attitudes. Another advantage of the new fuze is its elimination of the (somewhat unreliable) lanyard for exposing the air turbine to the airstream after launch.AFRL and SDI identified acceptable arming environments and an S&A algorithm for three glide bomb systems. The algorithm, known as the Guidance-Integrated Safety and Arming (GISA) algorithm, processes data from microelectromechanical systems inertial sensors embedded both in the fuze and in the glide bomb's autopilot system to detect the sequence of postlaunch events that satisfy the second arming environment. Embedded within a microcontroller built into the fuze, the GISA algorithm will begin executing upon the weapon's release. To facilitate the GISA algorithm's development and test its performance within a brassboard guidance-integrated (GI) fuze, the AFRL/SDI team developed the Guidance-Integrated Fuze Test Software application. In addition, Kaman Dayron, Inc., and L-3 Communications KDI Precision Products, Inc., each began development of a brassboard GI fuze that incorporates the GISA algorithm. Both manufacturers designed their respective brassboard GI fuzes to detect the launch event following a prescribed sequence of subevents. Both GI fuzes maintain a direct connection to the bomb's thermal battery for their arming power.After detecting the launch event, both fuzes execute the GISA algorithm to search for the prescribed second (i.e., postlaunch) arming environment conditions. Upon detecting these conditions, both GI fuzes activate their respective arm delay timers (ADT) to satisfy the safe separation requirement. After their ADTs expire, both fuzes arm by closing switches that allow battery power to flow to the firing circuitry.