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Hydrodynamic Impact-Load Alleviation with a Penetrating Hydro-SkiA penetrating hydro-ski was mounted below a model tested previously in the study reported in NACA Technical Note 4401, and a series of impacts were made in the Langley impact basin to determine load alleviation with this type of hydro-ski. The hydro-ski was designed to penetrate through seaway irregularities with a minimum of drag and with small impact loads. The penetrating hydro-ski was small (beam-loading coefficient of 111) and of a streamline shape with the bottom designed for flush retraction into the main model. A series of impacts at fixed trim angles of 8, 16, and 30 deg were made in smooth water and at a fixed trim angle of 8 deg in rough water. The loads and motions of the model were recorded, and photographic observations of the flow and cavities generated in the water by the penetrating hydro-ski were made. The data are presented and the maximum impact loads and maximum drafts of the model with the penetrating hydro-ski are compared with those of the model obtained without the penetrating hydro-ski. Maximum load reductions of 30 to 70 percent in smooth water and of 50 to 80 percent in rough water are indicated. Cavity and flow generation by the penetrating hydro-ski are discussed, and it is indicated that the penetrating hydro-ski moved smoothly through the water and generated deep cavities which are shown by stereophotographs.
Document ID
19980228305
Acquisition Source
Headquarters
Document Type
Other - NASA Memorandum (MEMO)
Authors
Edge, Philip M., Jr. (NASA Langley Research Center Hampton, VA United States)
Date Acquired
September 6, 2013
Publication Date
February 1, 1959
Subject Category
Fluid Mechanics And Heat Transfer
Report/Patent Number
NASA-MEMO-1-9-59L
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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