Water Crash Dynamics and Structural Concepts for Naval Helicopters

The objective of this study is to provide state-of-the-art crashworthiness engineering to better protect the occupants of Naval helicopters which crash into the sea. To date, crash dynamic analysis and crash design criteria have been based mainly on rigid ground impacts and are therefore not of real use to the Navy, where nearly 90 percent of crashes occur into water. When a helicopter crashes into water, it usually is very unstable, inverts and rapidly sinks. Some of these accidents are survivable, but little has been done to reduce the injury from impact and increase the occupants chance of survival by introducing crashworthiness principles specifically protect against the special hazards associated with water. The determination of impact pressure and force distribution time histories on typical hull shapes in combination with achieving water impact survivability is therefore of prime interest to helicopter manufacture and operator. In this study wer propose to develop and demonstrate the effectiveness of ALE (arbitrary Lagrange Euler) finite element technology as a tool that can be used to improve helicopter crashworthiness at sea.