Analysis of Aircraft Survivability Against Fragmenting Warhead Threat

The article presents the methodology of the aircraft survivability analysis considering vulnerability of the aircraft against fragmenting warhead threat. The initial step of the survivability analysis against a fragmenting warhead threat is to position the target and the warhead in proper coordinate systems for the calculation of warhead-target engagement. Once the warhead detonates at a miss distance from the target, the motions of the fragments are calculated considering the drag and the gravity forces and the initial velocity of the fragments. For the hit calculations, the shotline method is employed, and hit locations, thickness and material information are obtained. For the shotline analysis, the functions and required libraries of the BRL-CAD software are integrated in the code which is used as the shotline subroutine of the main survivability analysis code developed in Fortran 90. Fragment penetration calculations are performed based on THOR equations, and vulnerability assessment of the aircraft against fragmenting warhead threats is carried out in terms of cumulative probability of kill of the aircraft considering all redundant and nonredundant critical components. Cumulative probability of kill calculations are performed according to the fault tree which is established for the particular aircraft being studied. Kill criteria for fuel tank fuel fire is presented. Survivability analysis of an aircraft against fragmentation warhead threat is performed by means of the developed code.