Brent,
You make a valid, reasoned, and well thought out response. I
may have been tired and too crotchety when responding to your post…way to
rough with the bubbling enthusiasm that you constantly display. The point
is that we must all consider when we post what the consequences are potentially
for some newbie that is only a lurker on the list and thoroughly reads the
archives without true understanding. I am adamant on this point as there
is a responsibility to others. I read every post and do not block those
senders that in my opinion are off the wall…once in a while they present
nuggets of wisdom or a link to some information that opens up a new avenue of
thought on how to approach an issue from a different direction (boy do you have
to wade through a lot of BS to get there J). Open discussion is valuable
but it should be prudent and measured.
It is not the job here of members to teach others how to design and
build subs. While some of that does occur, the onus is on the individual
to do some basic research. The prudent person should cross-reference any
serious matter presented here as the credentials of many presenters here is
unknown. While you don’t have to certify your boat to ABS Rules,
the prudent person should read this free resource and use the Rules as guidance
in building their submersible. That person needs to fully understand the
hull strength spreadsheet, where the calculations come from, their limitations,
and that if a particular hull type is not covered then there is a pretty good
reason why an amateur should not attempt to configure their sub with an unusual
hull shape. Every naval architecture text and school tells you that you
need to start a “Weights & Moments” spreadsheet the minute
design is commenced…otherwise you end up with an unstable sub (most think
of only static stability on the surface, surfaced dynamic stability and
underwater stability can make a statically-stable, great looking submersible
into a hell ride). A submersible is an expensive endeavor, if you can’t
afford a few basic reference texts how will you be able to build even a small
simple sub? The money spent on PVHO and Dr. Stachiw’s text
is money well spent that will save money when building your sub and even may
save your life. Dan Lance also suggested as a welding reference Gas
Metal Arc & Flux Core Parameters by Ed Craig.
Joe Perkel has a great approach to submersible design. He
focuses on his conceptual design and repeatedly fends off questions pertaining
detailed design that he can’t immediately answer. Often the answer
presents itself later or is learned as experience is gained through the design
process. Unfortunately quite a few people rush out and buy steel early on
without properly understand ALL of the basics of submersibles. They end
up with a dangerous sub or one that they feel uncomfortable with taking below
20 feet once they learn more. They exerted the same effort and spent the
same dollars that would be needed for a proper K-350. Please remember
while you may be comfortable with a higher than normal level of risk in
operating your submersible, a failure on your part reflects poorly on the PSUB
community and may lead to government intervention. A little guidance that
I have found fruitful in the approach to many things, “Would I feel
comfortable with a loved one using this item or having this person take care of
my loved one?” We all are more willing to risk more with our life
than risk others but we need to consider the consequences. And if you
decide not to heed what is here, “Shear stupidity is self correcting”.
Maybe Dan Lance can repost a previous email that I posted that several members
noted was very valuable in guidance on submersibles and design.
R/Jay
Jay K. Jeffries
Andros Is., Bahamas
A skimmer afloat is but a submarine, so poorly built it will not
plunge…
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Brent
Hartwig
Sent: Wednesday, August 22, 2007 5:11 AM
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] Open Discussion's Allowed in PSUB's Mailing
List
Jay,
I've heard a number of
times in the past how some choose to be blunt with new comers to the group
and/or amateurs in the field of subs. I think one can be straight forward with
important information in a way that doesn't come off as rude or disrespectful to
those that lack or one believes, lacks there expertise and experience in
that area. This group is primarily for, and always has been for learning and
exploring of how to design, build, and safely operator ones own sub through
open discussions and sharing of information and/or hardware with amateurs and
experts alike.
Perhaps there is a need
for a new forum for a select group of individuals that don't wish to deal with
teaching and/or reading what amateurs are talking about, and want only very
serious factually accurate post in there group. To join this group one would
need to have done more then 500 dives in a sub worth more then $100,000, and/or
been in the submarine field professionally for more then ten years, and/or they
have a doctorate in a related field.
I've seen discussions
more or less shut down by a type of intimidation, on subject matter that some
were tired of discussing and/or not interesting in. I think that is wrong for
this group, and that if one doesn't want to read and/or respond to subject
matter(s) they are tired of and/or not interested in, it is very easy to just
delete all messages with said subject matter and/or content. We will hopefully
always get new comers into this group with basic questions and great new
insights to old problems, and they shouldn't be required to read and understand
the whole PSUBS archive before they post a question to the group. I spend a
massive amount of my time researching subs and related data, and I barely have
time to read and try to fully understand the current emails from the list, let
alone read and understand the whole archive. Perhaps I'm slow, and if that's
the case then I'm ok with that. Those are the jeans my parents gave me, and I'm
happy to have what I got.
I once posted a
question about whether or not I needed to anneal acrylic, if I only cut it with
a aqua jet cutter. Since I had reason to believe the aqua jet cutting process
wouldn't put any heat stesses on the acrylic that would need annealing to take
care of. I did a PSUB's archive search before I posted my question. Along with
the speculation that my question wouldn't be answered in a great but slightly
dated $200 book, (I hadn't aquired yet) since I believed aqua jet cutting of
acrylics was basicly a new process, I asked the question. I got the
patt answere of that, all acrylic needs to be annealed after cutting, in such a
way I couldn't tell if they really knew that, with regards to my question, or
if they just didn't want to deal with it. Then they shut the discussion down by
intimidation by being an expert in the group (most don't want to
perturb) and stated that the topic was basicly old and dead.
When I said, " How
about an non educated guess. ; )' " that was tough
and cheek Jay.
In my opinion, I'm
reasonably well educated and practiced in a fair number of areas, and I worked
very hard to get to where I am today. I have so many skill sets and interest
it's hard to keep on track most days. Almost everything is of interest to me.
Many far more negative people then you, have tried to get me to hide in a
corner because I've chose a very different path then them selves. You can see
the result.
I would guess that for
most of us here in this group, this is a passionate hobby of there's. Hobby's
are supposed to be fun and enriching, not negative things that suck the life
out of you.
We have talked
about using the KISS (Keep It Simple Stupid) principle for sub design. I
agreed with you that one should do that if at all possible. How simple is
simple? The fact is that most subs in order to have the capabilities one
wants them to have, can't have all aspects of there design be simple.
Just recently you gave
me a link for a book called Simplicity in Design, as a response to one of my
post. Again I ask, how simple is simple? It's all subjective to ones brain
power and understanding of how things work. What makes art beautiful? It's
mostly all in ones head.
During that same period
in your post in response to mine, you made it sound pretty
clear that I shouldn't post to this group until I read and understood
the ABS manual and reams of other technical manuals, science articles, and
books relating to sub design and operations. If I and or others were required
to do that, then it would likely be years before we could post here.
"Instead
of “guessing” all of the time, please do some real research."
I do massive amounts of
research almost every day before I send most of my longer post to the group.
But at some point with all the massive amounts of data out there on the net,
one just needs to post a question or two to the group and see if anyone
can, or is willing to give some insight, or even give a guess, that can help
discover the answere.
I'm not interested in
perturbing or annoying anyone on this group. I'm here primarily to learn and
share what I've learned.
Since many subs are
military or trade secrets for large organizations, many times we are left
guessing why they designed it a certain way. It's a mystery, and who doesn't
love a good mystery. It's like a puzzle that with enough brains but to task can
figure it out or find someone that can.
I think that if the MIR
subs have one or more very large drop weights, that if dropped could make
vortex shedding a problem that the rear stabilizer would be very helpful in
dealing with.
When I said I don't
know if that is a Kort or Rice nozzle, that was a prompt for someone that does
really know to please speak up and so we could learn more about the sub.
"I
can tell you from an early proposal for building the Mir subs that they are
size constrained for carrying in aircraft holds and the fins on top are
probably a means for shortening the overall length due to deck housing issues
(this is a factor in a number of submersible designs)…but it is pure
speculation on my part."
So why is it you can
speculate and I can't? I had reason to believe I had a couple of possible
good reasons they designed the rear stabilizer the way they did and I was
bouncing them off the group for an open discussion to pool the groups large
knowledge base. I don't know how many times colabortion with others
has produced wonderful things in my life and others. If I had a part of a good
idea, one or more people would come along and fill in the blanks and
make it a whole good idea.
"Neophyte
PSUBers often take as gospel any information that is found here on the PSUB
list and can lead to misconceptions on their part in the future…some of
which may be dangerous if not down right deadly."
I would expect anyone
with the were-with-all to build, and then operate there own sub wouldn't
believe that this "DISCUSSION" groups postings are all, or even
mostly all the gospel truth. Such a person wouldn't likely able to read and
understand enough of what this group is talking about to hardly get started on
there own sub, let allot survive the walk to the garage.
Regards,
From:
bottomgun@mindspring.com
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] MIR aft planes
Date: Tue, 21 Aug 2007 15:59:28 -0400
Brent,
Instead of “guessing” all
of the time, please do some real research. Neophyte PSUBers often take as
gospel any information that is found here on the PSUB list and can lead to
misconceptions on their part in the future…some of which may be dangerous
if not down right deadly. You will note that many of us refrain from
making replies here unless we have some expert knowledge to bring. A
number of us have to waste a good deal of time better spent on other endeavors
dispelling misinformation that is either represented as fact or not clearly
labeled speculation by a non-engineer or scientist.
I did not respond to this particular
request by Joe as I do not know why the Russians have used this configuration
but I can tell you it is not because the water is not disturbed yet and vortex
shedding is not an issue here. Both issues are related to speed here and
speed is not one of Mir’s fine points. You can not tell whether it
is a Kort nozzle, a Rice nozzle, or simply an entanglement guard without
viewing the cross section of the nozzle or someone more closely associated with
the Mir submersibles making a response. Due to the small size of most all
submersibles, there is little reserve buoyancy that can be effectively designed
in…all of them have handling issues on the surface. While a lot can
be learned from images and visiting various submersibles, hard calculations
along with weight and trim spreadsheets are necessary prerequisites for a
successful submersible with a long, safe lifespan. How do you know you
are not looking at a given submersible’s weak point or a poor design?
I can tell you from an early proposal
for building the Mir subs that they are size constrained for carrying in
aircraft holds and the fins on top are probably a means for shortening the
overall length due to deck housing issues (this is a factor in a number of
submersible designs)…but it is pure speculation on my part.
A dunce can appear brilliant if he
holds his tongue.
Jay K. Jeffries
Andros Is., Bahamas
A skimmer afloat is but a submarine, so poorly built it will not
plunge…
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Brent
Hartwig
Sent: Tuesday, August 21, 2007 2:39 PM
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] MIR aft planes
How about a
non educated guess. ; )'
Thanks for the link to
the pic Joe. I would "GUESS" that the aft plane is controlled my
the pilot directly or by hydraulics or the like. The swept-back feature is for
coolness factor Joe. Na for that I would say it helps if you lightly hit some
thing you'll just bounce off and keep going instead of braking the aft plane,
but more importantly I would say its for reducing entanglement issues. That is
why I like to have surfaces on my sub rounded over and swept back to some
degree, with no item protruding forward like the weapons systems on the Star
Wars X-wing fighter.
On another
note since the aft plane is acting like a planes elevator, having the said aft
plane up and out of the way of the swirling water coming off the subs hull,
gives the pilot more control then if its down and directly behind the
sub. This is why allot of ships are now using forward facing props, that
pull instead of push. This is more efficient since the water hasn't be really
disturbed yet and you can get a better directional bit into it.
I would say
that the whole stabilizer assembly also really helps to deal with vortex
shedding. But for that I would use a larger assembly.
I like the
Kort nozzle on the sub, or is that a Rice nozzle? From what I understand
the Rice nozzle is more efficient.
I wish they
would add some soft saddle tanks to the Muir subs, to give them more freeboard
staybility. Allot of people get really sick in them when at the surface.
Watching the Zodiac cowboys try to attach the crane cables to the subs in rough
water is one of the reasons I started designing trimaran subs. I know that
adding tanks to the subs gives them more hydo drag, but that is another one of
these trade-offs we have been talking about.
> From: joeperkel@hotmail.com
> To: personal_submersibles@psubs.org
> Subject: [PSUBS-MAILIST] MIR aft planes
> Date: Tue, 21 Aug 2007 12:15:46 +0000
>
>
> Can someone please explain to me the precise function and mechanics of the
> aft planes / stabilizer on the MIR submersibles?
>
> In this image, you can see it rotated at an exaggerated angle, which makes
> me wonder if this was done mechanically by the pilot from within, or the
> unit is "free pivoting" for some reason which escapes me.
>
> http://www7430.nrlssc.navy.mil/7432/hydrates/images/Muir_1.jpg
>
> Why then I also wonder, the extreme sweep-back of these planes? You see
this
> in aircraft for aerodynamic purposes in the transonic flight envelope
> (airliners) but, why here? This is repeated in both MIR's as well as the
> proposed Alvin replacement.
>
> Any info is most appreciated, even an educated guess.
>
>
> Joe
>
>
>
>
>
> ************************************************************************
> ************************************************************************
> ************************************************************************
> The personal submersibles mailing list complies with the US Federal
> CAN-SPAM Act of 2003. Your email address appears in our database
> because either you, or someone you know, requested you receive messages
> from our organization.
>
> If you want to be removed from this mailing list simply click on the
> link below or send a blank email message to:
> removeme-personal_submersibles@psubs.org
>
> Removal of your email address from this mailing list occurs by an
> automated process and should be complete within five minutes of
> our server receiving your request.
>
> PSUBS.ORG
> PO Box 53
> Weare, NH 03281
> 603-529-1100
> ************************************************************************
> ************************************************************************
> ************************************************************************
>
|