Along side analysis of Type 23 ship motion as a function of mechanical and dynamic limits of an EH101-like helicopter using the Landing Period Designator helicopter recovery device

The Landing Period Designator (LPD) helicopter recovery aid relates real-time ship motion to safe recovery times on-board a ship. The purpose of the Defence Research Agency test of the LPD is to demonstrate improvement in the landing windows of an EH101-type helicopter on-board a Type 23 frigate. A brief synopsis is presented which summarizes the methodology of the LPD empirical formulation, termed energy index, calculation and theory featuring weighted motion sensitive parameters. The weighted value is measured against a scale indicating ‘deck availability’. In the DRA project, the LPD is used to identify landing windows from recorded Type 23 ship motion data. Landing windows are analyzed through Sea State 7. In no instant did the time delay window (rise-time) measure less than 4-5 seconds, even in sea state 7. Most importantly, the energy index peak always maintained a 5 second time separation from the first aircraft sensitive ship motion peak. A discussion of the rise-time phenomena is presented in some detail. The issue relating practical landing window improvement is addressed using the DRA Advanced Flight Simulator. Simulator test plans form the final subject of this article.