Abstract

This paper describes the use of several computational techniques for assessing the impact of superstructure modifications on ship/helicopter operations. The methods presented rely on the use of unsteady computational fluid dynamics (CFD) to provide high fidelity ship airwake datasets for flight simulation. Several geometric modifications have been made to the vertical hangar edge of the revised simple frigate shape (SFS2), which are assessed in terms of their impact on the airwake turbulence. The CFD results indicate that, compared to the un-modified SFS2, some modifications reduce airwake turbulence while others lead to an increase. Airwake data resulting from the CFD computations have been used as look-up tables in a flight simulation environment, allowing the impact of the modifications to be tested using both offline and piloted simulation. The offline method uses a fixed helicopter model to map airwake severity around the flight deck in terms of RMS loading and is shown to detect significant differences between the airwakes tested. Finally, a series of piloted deck landings and hover tasks have been performed, with pilot workload ratings and control activity analyzed. It is shown that while improvements in airwake characteristics lead to a reduction in control activity, this is not necessarily reflected in lower workload ratings. However, the correlation between modifications which worsen the flow and increased workload ratings is much clearer. Copyright © 2009 by the American Helicopter Society International, Inc. All rights reserved.