Water Crash Dynamics and Structural Concepts for Naval Helicopters

A Phase I and Phase I option research program is presented which is designed to provide the DOD, DOT, and aircraft manufacturers with a valuable design tool to help improve water impact survivability. It is recognized that impacts into water can be more deleterious to structure and occupants as compared to similar accidents on rigid terrain. The proposed program involves the use of existing codes, analytical models, and accident and test data. Both a hybrid (KRASH) and FEM/CFD (MSC/Dytran or Dyna3D) code will be used. The program proposes to use available Seahawk, Lynx (accident), and Ospry (scale-model test) data in establishing a preferred developmental approach and determining the technical merit and feasibility of such an approach. The acceleration, pressure, and kinematic responses of typical helicopter hull shapes, along with the assessment of a complete crash survivable envelope will be determined and compared to available measured and/or observed data in the Phase I program. The Phase I option provides a comprehensive test plan, taking into consideration the Phase I analysis results and the overall goals to establish validated methodology, applicable water impact design criteria, and Potential structural design concepts to improve occupant survivability. The benefits to the aircraft industry, as well as potential commercial and Government applications, are addressed.