Tail separation and density effects on the underwater trajectory of the JDAM

Abstract

The Navy is in need of an organic, inexpensive, swift method to neutralize or sweep waterborne mines. This thesis presents an alternative to current mine countermeasure technologies that fulfills this criteria-the use of the Joint Direct Attack Munition (JDAM) to clear a minefield. It updates the general, physics-based, six degrees of freedom model, STRIKE35, to predict the three-dimensional, free-fall trajectory and orientation of a MK-84 bomb (simulating the JDAM) through a water column. It accurately predicts the final detonation position relative to an underwater mine in the very shallow water environment. Input parameters include accurate water impact speed and surface impact angle of attack. Because the model results compare well with experimental data from the Stand-Off Assault Breaching Weapon Fuze Improvement (SOABWFI) Program, we analyzed the trajectory of the weapon with structural failures. This thesis solves for the impact speed and impact angle of attack limitations to remain within the Technology Transition Agreement, the detonation location for each fuze delay setting (to include its 20% tolerance), and the trajectory changes due to different water densities. This gives strike planners a tactical decision aid to clear the minefield accurately and efficiently with existing aircraft and weapons.