RE: [PSUBS-MAILIST] OSS (Pressure hull)

[Phil Nuytten <72020.572@compuserve.com>]

Re: Elliptical hull shape:
        Alec - the other elliptical hulled sub you were trying to think of
is probably the 'Markasub' - actually, there have been a handful of hulls
in this form, over the past few decades. It is not a particularly efficient
shape re: weight/depth etc. The ellipse is not too terrible, but the
cylindrical transition is a killer. Ellipses (ellipsii ?) are not designed
to be butt-welded. An ellipse without the cylindrical transition ( the soft
'corner') is a semi-sphere. They become more efficient as they become
deeper (obviously . . . sorry to go kindergarten for those who know this
stuff) in curvature for a given diameter. Full efficiency is reached when
the depth of curvature is half the diameter - a hemisphere - and receedes
again as you pass this number - half an egg. 
        I noted in a previous post that some-one said something to the
effect that the 'end-caps' need to be thicker than the cylinderical hull
between them. If the 'end-caps' are hemis, the exact opposite is true - and
if they are ellipsii ( I kinda like that word!) they are still likely to be
thinner than the tubular hull for a given depth.
        My point?? Hmmmm . . .perhaps I don't have one.
Phil Nuytten