[Date Prev][Date Next]
[Chronological]
[Thread]
[Top]
Re: [PSUBS-MAILIST] Pressure hull
Jeff,
Because of the height it can't be to difficult to achief a low center of
gravity. The only problem is that the weight of the hull is relatively high
compared to the displacement . I mean there is not much "room" to ad much
ballast. When the MBT''s are more or less flat on the upper side, they
will have a ballancing effect while on the surface. It maybe also be an idea
to give the thrusters there final position after trials.
Thijs Struijs
----- Original Message -----
From: "Jeff Post" <jeffpost@rawbw.com>
To: <personal_submersibles@psubs.org>
Sent: Wednesday, February 12, 2003 5:48 PM
Subject: Re: [PSUBS-MAILIST] Pressure hull
> I too am intrigued by the idea of using boiler endcaps. Does anyone have
any
> ideas about it's tendency to spin about it's minor axis? In the Cousteau
saucer,
> because it was horizontal in the water, any tendency to roll about it's
center
> would mean the sub spun left or right. However, in the vertical design,
this
> tendency would have you going head over heals.
>
> The Cousteau saucer had jets on it's perimiter, which stabalized it's
tendency
> to roll side to side. Unless you also thrusted from the top and bottom of
the
> vertical saucer, you might tend to roll forwards or backwards at times.
>
> I guess have sufficiently low center of gravity is the key. It still seems
to me
> that you are going to have problems rolling forward and backward,
certainly on
> the surface, and certainly while not under power.
>
> Anyone care to comment?
>
> Jeff
>
>
> Quoting Cliff Redus <dr_redus@devtex.net>:
>
> > Thijs,
> >
> > Even though this hull design is very different from the normal PSUB
> > hull, it does have a number of nice features. It fits well with a
> > streamlined FRP outer shell in that it presents a smaller projected area
> > to flow relative to other hull shapes that will accommodate a seated
> > pilot. For it displacement, it also has good freeboard and might
> > actually make it possible to meet the ABS 2.5 ft (76 cm) minimum
> > freeboard rule for a small boat without destroying the hydrodynamic
> > lines of the boat. The viewport locations are great for forward and
> > downward viewing. Side viewports could be easily added to improve port
> > and starboard visibility Because all viewports are flat, the cost
> > becomes manageable for a PSUB. Orientation of MBTs are going to take
> > some thought in order not to have the CB of the boat to close to the
> > bow. I am not sure I would go with mild steel for hull. You should be
> > able to find off the shelf torispherical endcaps made of a higher yield
> > point steel such as A516, Gr 70 or something equivalent without
> > significantly impacting the hull cost. I agree with Alec that it would
> > be a good idea to run an FE analysis of the hull including viewports to
> > get a better handle on crush depth. I am not sure the ABS equations to
> > calculated hull stress are applicable given such a short cylindrical
> > section.
> >
> > I for one like the hull.
> >
> > Cliff
> > ----- Original Message -----
> > From: Thijs Struijs
> > To: PSUBS
> > Sent: Sunday, February 09, 2003 11:02 AM
> > Subject: [PSUBS-MAILIST] Pressure hull
> >
> >
> > To all,
> >
> > I would like some reactions on a drawing i made a while ago. You can
> > find it at:
> > http://www.prismnet.com/~moki/20030126.073208/doubleXendXcapX.jpg .
> > The idea is to construct a very simple pressure hull out of two
> > torispherical endcaps. The conning "tower" is made out of a standard
> > line pipe with a little overdimensioned wallthickness and the smallest
> > possible diameter. The endcaps are made with a small cilindrical section
> > on it but i am afraid that the tower will intersect with the
> > torispherical part.
> > In order to keep it simple i chose a very common steel for the
> > endcaps. It is P265GH (yield strenght 265 n/mm^2, 38500 psi, tensile
> > strenght 410 n/mm^2, 59500 psi). This is an "off the shelf" material at
> > Afflerbach, the german manufacturer. I think you could call it soft
> > boiler steel.
> > To calculate the strenght of it (apart from the conningtower and
> > viewports) one can use the formulas for a sphere, using the dishing
> > radius of the endcap (in this case 1040 mm). Maybe it is my age, to much
> > alcohol or lack of intelligence but watever method i use (ABS, Lloyd's
> > or an old pressure vessel codebook) i get different outcommings. Can
> > anyone of you say something sensible on this? I am considdering a
> > wallthickness of 12 mm, divingdepth 100 mtr?
> > If it is ever going to be build it will be tested unmanned to a depth
> > 50% more than its safe working depth. Should it collapse i will hold no
> > one responsible for that. So please be free to give your advise.
> >
> >
> > Thank you very much,
> >
> > Thijs Struijs
>
>
>
> Jeff Post
>
> Everything can be inherited except sterility.
>
> ================================================================
> Deze e-mail is door E-mail VirusScanner van Planet Internet gecontroleerd
op virussen.
> Op http://www.planet.nl/evs staat een verwijzing naar de actuele lijst
waar op wordt gecontroleerd.