Evaluation of Hydrodynamic Drag Reduction Concepts for High-Speed Amphibious Vehicles

The Marine Corps has a desire for a high-speed amphibious vehicle for ship-to-shore operations. The Expeditionary Fighting Vehicle (EFV) was developed to meet this need but the program was cancelled before fielding due to affordability issues. The EFV was a semiplaning amphibious vehicle with deployable appendages that achieved water speeds in excess of 27 knots in a seaway. A study team was stood up to tackle the affordability issue and identify technologies that could solve this problem. Hydrodynamic drag improvements through the use of longer deployed bows and the use of lifting bodies both fore and aft were identified as concepts that warranted further investigation since they increased the weight the vehicle could plane. This allows heavy and cheaper components to be used in vehicle subsystems and still achieve high water speed which is defined for this study as 22-25 knots. This paper examines the evaluation of these concepts using both Computational Fluid Dynamics and physical unpropelled model basin tests as a precursor to full-scale testing on an EFV for the most promising concepts. The results highlight the ability of scaled physical testing, used in tandem with numerical tools, to aid in the rapid development and analysis of conceptual designs in order to facilitate full-scale evaluation.