Investigating Helicopter Ditching And Flotation Stability Using Cfd: Analysis Of Mass Configurations, Door Openings, And Floater Conditions

Abstract

Ditching is a type of aircraft accident characterized by a planned and controlled emergency landing in water. Since ditching occurs under emergency conditions, it often results in injuries and fatalities. This paper presents a numerical investigation into the ditching and flotation stability of a helicopter following a water landing. The study employs CFD simulations based on the Navier-Stokes equations to model helicopter behavior during ditching on a calm water surface and subsequent flotation stability in irregular sea state 6 wave conditions. Four different mass configurations within the flight envelope were examined. For the ditching analysis, two initial pitch angles were studied as the helicopter made initial contact with the water. Given that all scenarios involve the helicopter touching the water at the same velocity, the ditching simulations reveal that the mass configuration has a minor impact on the maximum pressure peaks, which are characterized by their short duration and increased pitch orientation during impact. In the flotation stability analysis, the study considers the effects of one or two open doors, the presence of water inside the cabin, and the integrity of the flotation devices, represented by reduced flotation capability. Flotation stability simulations indicate that, over time, the helicopter tends to align perpendicular to the incoming waves, with no capsizing observed after 600 seconds in most scenarios. However, for the heaviest mass configuration and a damaged front-right floater, capsizing occurred when one or two doors were open. These findings significantly contribute to the understanding of helicopter ditching dynamics and flotation stability, providing a foundation for future research aimed at enhancing safety in helicopter operations over water.