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Re: [PSUBS-MAILIST] OSS (Pressure hull)
Dan 180°encaps also everywere available - but much more expensive
than the standard one.
Mostly for the reason that the standard one are more useful for storage
tanks (tank length to volume ratio is better)- so they are ordered
in large quantities.
The elliptical one here are available in at least three different
geometries.
regards Carsten
Dan H. schrieb:
>
> 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
> >