[PSUBS-MAILIST] Hull design

["Wade Carson" <wacarson@interchange.ubc.ca>]

Has anyone ever built or does anyone know anything about a high speed
laminar flow type hull (ie. the center of volume is ~10-20% aft of mid-ship.
The opposite of a tear drop shape).  I am wondering how one might overcome
the dynamic stability problems.  Is there another way aside form enlarging
the control surfaces and there-by probably negating the added efficiency of
the form?  My current sub is more of a conventional tear drop shape and I
have put four static fins in an x-foil configuration about 30% of the way
back from the forward end and four control fins at the aft end in a cross
configuration.  This provides excellent stability but I'm not sure if it
would transfer very well to a different hull shape.  Laminar hulls are very
prone to flow separation when they are turned out of the flow path and tend
to "skid out" (they just keep turning and never come back.  That's not
exactly a technical term, I just made it up because it's pretty descriptive
of what happens).  Some time ago there was discussion on the list about the
advantages of this hull form and I read the paper that was suggested.  I was
disappointed to discover that all of the testing was done by filling the
nose with foam and the tail with lead and testing through a vertical rise,
thus making the form artifically stable. Anyways, I haven't thought of any
clever ideas for fixing the problem yet but if any of you can, I'd love to
hear them.

Wade