Challenges facing developers of systems for water impact scoring of advanced weapons

Testing of advanced "smart" weapons being developed by the Army, Navy, and Air Force are presenting an interesting challenge to test designers. Many of these weapons have ranges in excess of the maximum range of existing test ranges. Several examples exist of gun fired weapons currently under development for the Army and Navy with maximum ranges greater than 75 miles. Additionally, unlike existing artillery and naval guns, these weapons include on board guidance packages. These must be evaluated as a part of their testing. This represents a significant departure from traditional gun fired weapons which contain no guidance in the weapon itself. The accuracy of a traditional weapon is determined entirely by the accuracy with which the gun is aimed and the inherent variables in the fall of shot. Additionally these new weapons will be significantly more costly than traditional gun fired weapons. The Air Force is also developing many extended range weapons that exceed the range of existing test ranges. The above factors have led to the need to test these weapons to full range and provide for a "soft impact" such that the test article can be recovered for post-test analysis. NUWC Division, Newport has recognized this need. NUWC has performed preliminary investigations into the feasibility of testing these weapons by firing them into relatively shallow water. Advanced signal processing and localization algorithms could determine the point of impact. These algorithms must detect and process the acoustic signature generated by the impact. These studies have demonstrated that the intact recovery by divers of gun fired weapons from water depths less than 100 feet is feasible. Over the last 25 years NUWC has demonstrated the feasibility of accurately determining the point of impact acoustically for a wide variety of weapons including both missiles and guns. All of these previous projects however have focussed on impacts occurring in deep water. Typical water depths have been in excess of 1000 feet. A preliminary test conducted several years ago off of Wallops Island Maryland in shallow water demonstrated that the deep water algorithms previously developed are not directly applicable to impact scoring in shallow water. As a result of these tests NUWC has initiated the Soft Impact Location Capability (SILC) project to develop suitable algorithms for acoustically scoring impacts in shallow water. This paper presents an overview of past impact scoring efforts and discusses the objectives, plans, and status of the SILC project. Concepts for applying this technology to future T&E and Training requirements are also discussed.