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<div class="moz-cite-prefix">Joe - a couple of things:<br>
<br>
1) Free-flooding compartments still contribute to the vessel's
overall inertia and consequential power requirement. Whether you
are moving usable internal space, or an oddly shaped slug of
seawater, the effective density of the volume is the same when
submerged. The only difference would be the crane weight out of
the water when the free-flooding spaces have drained. Thus, it
behooves the designer to maximize the useful internal volume of
the pressure boundary, or to minimize the total displacement
volume of the vessel for a given pressure boundary volume. In
other words, you want to eliminate free-flooding volume where you
can, and looking at your design, I see the opportunity to add
conical sections to each end of the cylinder, and then use smaller
hemispherical heads at the end of each cone (thus creating a high
volume pressure boundary with more usable internal space), or
alternatively, shortening the length of the superstructure /
fairing assembly to minimize the overall displacement and
unnecessary free-flooding volume. The latter solution would, of
course, minimize the total displacement and dead weight of the
completed vessel.<br>
<br>
2) Dive tank # 1 and #2 : I presume that these are your main
ballast tanks for dive vs. surface operation? I would give a
little more thought to stability here. It seems more advantageous
to have your ballast tank volumes above the vessel CG wherever
possible. In the surfaced condition, the hull form works the same
way as a boat hull in providing increased righting moment with
angle of roll (provided the hull isn't cylindrical). Completely
submerged, you have only the difference between your center of
buoyancy and center of mass to offer righting moment. The
transition between surfaced condition (MBTs blown) and submerged
condition (MBTs full) can be dangerous as your metacentric height
can be eliminated before the CB/CG righting moment is established
on submersion. Ideally, your CB would be above your CG regardless
of operating condition, in which case your vessel is always
stable, and the hull form buoyancy only acts to stiffen the vessel
in the surfaced condition.<br>
<br>
Sean<br>
<br>
<br>
On 2014-05-04 13:07, Joe Perkel via Personal_Submersibles wrote:<br>
</div>
<blockquote
cite="mid:1399230436.63372.YahooMailNeo@web141501.mail.bf1.yahoo.com"
type="cite">
<div style="color:#000; background-color:#fff;
font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial,
Lucida Grande, sans-serif;font-size:14pt">
<div><span>I've incorporated some of the suggestions in the
attached drawing. Still, I've got a lot to think about here
but I am also excited about the possibilities and the
potential outcome. This image should give some idea of
what's on my mind. </span><span>What you see is the water
ballast arrangement on the original Seehund, and how my
proposed pressure boundary fits into this scaled down
version. The following is a list of concerns and or design
considerations.</span></div>
<div style="color: rgb(0, 0, 0); font-family: HelveticaNeue,
Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;
font-size: 18.66px; font-style: normal; background-color:
transparent;"><span><br>
</span></div>
<div style="color: rgb(0, 0, 0); font-family: HelveticaNeue,
Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;
font-size: 18.66px; font-style: normal; background-color:
transparent;"><span>1) Clearly, I have no need to compensate
for the loss of torpedoes</span></div>
<div style="color: rgb(0, 0, 0); font-family: HelveticaNeue,
Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;
font-size: 18.66px; font-style: normal; background-color:
transparent;"><span><br>
</span></div>
<div style="color: rgb(0, 0, 0); font-family: HelveticaNeue,
Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;
font-size: 18.66px; font-style: normal; background-color:
transparent;"><span>2) New pressure boundary provides for
massive MBT volumes (<em>Low pressure compressor to blow
down volumes</em>)</span></div>
<div style="color: rgb(0, 0, 0); font-family: HelveticaNeue,
Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;
font-size: 18.66px; font-style: normal; background-color:
transparent;"><span><br>
</span></div>
<div style="color: rgb(0, 0, 0); font-family: HelveticaNeue,
Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;
font-size: 18.66px; font-style: normal; background-color:
transparent;"><span>3) Torpedo battery pods may need to
incorporate some free flooding spaces to reduce weight, or
perhaps <font style="background-color: rgb(255, 255, 255);"
color="#cd232c">reduce battery capacity</font> to a single
pod in lieu of the former forward water ballast tank, then
completely free flood both torpedoes completely??. (<em>Boat
will incorporate a gen-set</em>)</span></div>
<div style="color: rgb(0, 0, 0); font-family: HelveticaNeue,
Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;
font-size: 18.66px; font-style: normal; background-color:
transparent;"><span><br>
</span></div>
<div style="color: rgb(0, 0, 0); font-family: HelveticaNeue,
Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;
font-size: 18.66px; font-style: normal; background-color:
transparent;"><span>4) Questionable reliability of external
motor pod assembly.</span></div>
<div style="color: rgb(0, 0, 0); font-family: HelveticaNeue,
Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;
font-size: 18.66px; font-style: normal; background-color:
transparent;"><span><br>
</span></div>
<div style="color: rgb(0, 0, 0); font-family: HelveticaNeue,
Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;
font-size: 18.66px; font-style: normal; background-color:
transparent;"><span>5) Stability considerations</span></div>
<div style="color: rgb(0, 0, 0); font-family: HelveticaNeue,
Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;
font-size: 18.66px; font-style: normal; background-color:
transparent;"><span><br>
</span></div>
<div style="color: rgb(0, 0, 0); font-family: HelveticaNeue,
Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;
font-size: 18.66px; font-style: normal; background-color:
transparent;"><span>Thanks for the input gents, It really
helps me to take a step back on occasion!</span></div>
<div style="color: rgb(0, 0, 0); font-family: HelveticaNeue,
Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;
font-size: 18.66px; font-style: normal; background-color:
transparent;"><span><br>
</span></div>
<div style="color: rgb(0, 0, 0); font-family: HelveticaNeue,
Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;
font-size: 18.66px; font-style: normal; background-color:
transparent;"><span>Joe</span></div>
<br>
</div>
</blockquote>
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