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Re: [PSUBS-MAILIST] OSS (Pressure hull)
I have seen some tanks made with full hemispherical end caps. I think they
were large propane tanks ( propane tanks, a bad word when associated with
subs). They were as large as railway car tanks. Large 180 degree endcaps
must be commercially available out there some where?
Why is it that elliptical end caps are produced in the ratios they are? Is
there a particular reason that makes this elliptical ratio better? I
believe it's a 3:1 ellipse.
Thanks, Dan H.
----- Original Message -----
From: "Phil Nuytten" <72020.572@compuserve.com>
To: <personal_submersibles@psubs.org>
Sent: Friday, February 14, 2003 11:36 PM
Subject: RE: [PSUBS-MAILIST] OSS (Pressure hull)
> 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
>