Center-of-mass and minimal speed limits of the great hammerhead
Data files
Oct 05, 2020 version files 17.41 MB
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6mmDorsalPlug.STL
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6mmPlug.STL
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9515.cfc
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9516.cfc
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9517.cfc
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9518.cfc
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9523.cfc
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9524.cfc
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9525.cfc
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9526.cfc
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9527.cfc
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9530.cfc
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9531.cfc
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9568.cfc
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9569.cfc
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9574.cfc
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9575.cfc
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9576.cfc
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9577.cfc
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9578.cfc
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9579.cfc
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9580.cfc
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9581.cfc
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9582.cfc
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9583.cfc
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Anal.STL
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BodyOfMk321.STL
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CaudalFinOfMk321.STL
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Collar0deg.STL
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Collar10degDownV2.STL
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Collar10degUpV2.STL
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Collar5degDownV2.STL
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Collar5degUpV2.STL
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Dorsal1Mk321.STL
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Dorsal1Mk321Rectangular.STL
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Dorsal2.STL
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DorsallLeveling.STL
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HammerlessHeadV2.STL
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HeadOfMk321.STL
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ListOfExperiments.pdf
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ListOfParameters.pdf
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LongitudinalBalanceOfTheGreatHammerhead252Drawings.pdf
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PectoraMk321.STL
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PectoraMk321minus10.STL
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PectoraMk321minus5.STL
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PectoraMk321number2.STL
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PectoraMk321plus10.STL
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PectoraMk321plus5.STL
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PectoraMk321Rectangular.STL
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PectoraMk321RectangularNumber2.STL
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PelvicMk321.STL
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PelvicMk321number2.STL
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TailOfMk321noFins.STL
Abstract
The great hammerhead is denser than water, and hence relies on hydrodynamic lift to compensate for its lack of buoyancy, and on hydrodynamic moment to compensate for a possible misalignment between centers of mass and buoyancy. Because hydrodynamic forces scale with the swimming speed squared, whereas buoyancy and gravity are independent of it, there is a critical speed below which the shark cannot generate enough lift to counteract gravity, and there are anterior and posterior center-of-mass limits beyond which the shark cannot generate enough pitching moment to counteract the buoyancy-gravity couple. The speed and center-of-mass limits were found from numerous wind-tunnel experiments on a scaled model of the shark. In particular, it was shown that the margin between the anterior and posterior center-of-mass limits is a few tenths of the product between the length of the shark and the ratio between its weight in and out of water; a diminutive 1% body length. The paper presents the wind tunnel experiments, and discusses the roles that the cephalofoil and the pectoral- and caudal- fins play in longitudinal balance of a shark.
Methods
The model of the great hammerahead was designed using SolidWorks®2014. Each '*stl' file is associated with a single part of the model.
Forces on the model were measured in a 1m by 1m by 3m subsonic wind tunnel at 50 m/s. Each file contains forces amd moments measured on a particular configuration at angles of attack ranging between -15 to +17 degrees.
Usage notes
All data files - these are files that end with '*cfc' - are ASCII.
'List of experiments' associates a data file with the particular configuration.
'List of parameters' explains each column in a data file.
All model files end with '*stl'.
' LongitudinalBalanceOfTheGreatHammerhead252Drawings.pdf' gives an overview of the model