The hydrodynamic ram phenomenon generally referred to as HRAM, constitutes an important threat to modern aircraft, especially lightweight aircraft such as UAV that cannot be armoured due to the weight penalty. The aim of the present feasibility study is to determine whether an ALE solver using bi-material fluid permits a qualitative simulation of all the phases of the HRAM event, in particular the oscillations (growth and collapse) of the cavity created during the impact of a non-trivial geometry high speed projectile on a water filled tank. The present study examines the closure of the wake cavity, its shape and the deceleration of the projectile.