Brent,
You misspeak for the group. Those people that have been
operating submersibles for some time and those with submarine experience strive
for KISS (and they keep telling you this) while those just building and/or no
experience love redundancy and extra safety features.
Please review the emails and note that anyone with any
submersible experience has repeatedly told you that dive brakes are a poor
idea. While on the surface they sound like a great idea (go-cart,
bicycle, or car…what about boats?), they don’t work. You are
better to rely on procedure than a mechanical gimmick underwater to avoid a
hazard, especially in your typical PSUB. Speed is hazardous underwater:
1.
Close to the bottom you are going to run into something despite
any mechanical or electronic contraption;
2.
Speed will force you out of your operating envelop in a jammed
planes causality resulting in a violation of your test/crush depth.
It has been demonstrated that dive brakes and braking chutes
have not worked to mitigate these two safety issues. A five-point safety
belt doesn’t do you much good when you are stranded on the bottom, just
makes it more difficult to get the body out.
Speed was designed into Deep Flight for one reason only and
that was to get to a very deep bottom, not for cruising on the bottom. Graham
Hawks recognized that much of the ocean was very deep and most submersibles only
penetrated the top veneer. Alvin took hours to get to an even
moderate depth and Graham wanted to return to the bottom of the Marianas Trench,
over seven miles down. He knew he would need a unique vehicle to get
there fast and Deep Flight is the proof of concept. If you can go
to the bottom of the Trench it is tough to operate outside of your depth
envelop and small propulsion motors were to be used for cruising at a safe
speed on the bottom. Hawks promoted this concept back in the 80s and hasn’t
reached it fully yet.
Jay
Respectfully,
Jay K. Jeffries
Andros Is., Bahamas
Talk sense to a fool and he calls you foolish.
- Euripides (484 BC - 406 BC)
From:
owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Brent
Hartwig
Sent: Thursday, August 28, 2008 6:18 PM
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] Stopping Flaps
Greetings Sean,
Your items one thru four, I find to be very sound. As a general rule,
this group tends to love redundant and extra safety features. So having brakes
of some sort seem very important/useful/desirable. Braking flaps can be used
when on the surface as well. If you have paddled a canoed or kayak much, you
will know that you usually can only go as fast as an average K-boat and if you
turn your paddle flat you stop very quickly. Of course a canoe is lighter so
that just means we need larger flaps, if we want/need to stop that fast.
Having only two seconds to react, as Jon was writing about, many times isn't
enough time to do much of any thing. One reason Alec might not of even seen the
cable, could be he wasn't looking out the forward port at the time. Look
at how little time and stopping distance we have in a car many times over and
over and yet still stop in time. I was thinking about installing a
braking flaps system, that operates much like a cars brakes, with a foot peddle
in the same position as a cars, and hydraulic assist, or perhaps a brake lever
like used on many cars for there emergency brake, could work very quickly as
well. Even if you still hit the boulder, you might of slowed down enough to
make the collision far less of a problem. But that's just me, I like
convoluted mechanical means if I can learn from those prototypes how to make
them really function properly, or abandon them to explore other ideas.
Have you ever driven a go cart, bicycle, or car that didn't have brakes. It's
quite hard unless you stay with in a safe operating envelope, which would be on
pretty flat ground, and at very low speeds. So your safe operating envelope
will change in a sub if it has good braking flaps and you know how to use them.
Of course with a car with no brakes, you usually have some built in collision
protection like bumpers, air bags, and seat belts. But you still don't want to
hit people and there flower gardens. In are case we don't want to hit nasty
rocks, coral reefs, boats, SCUBA divers, etc., etc., etc.....
I plan to have a five point seat belt system installed in my gliding hydrobatic
subs, much like those installed in the Bionic Dolphin and Bioniorca. Perhaps I
need a air bag system as well. It might be a really bad idea for a air bag to
go off in a small sub. My be it would be better to use them on large subs. I
would expect a lot of the injures that have a cured to sailer's on subs that
have hit some thing, were a result of them not being seated with a seat belt
on.
Another possible use for braking flaps is to help you drift with the current,
if it's going the same way you are, to save power.
Your
resident possibility thinker ;)'
Date:
Wed, 27 Aug 2008 17:46:48 -0600
From: cast55@telus.net
To: personal_submersibles@psubs.org
Subject: Re: RE: [PSUBS-MAILIST] Stopping Flaps
Not to make light of the many creative contributions to this discussion, but
I can't help but feel like this is an unnecessary solution to a self-imposed
problem, much like the guy who lined his car windshield with pillows in case he
had a collision from not being able to see correctly due to the gas mask he
wore in case of a leak from the gasoline canister strapped in the passenger
seat which he carried in case he ran out of fuel. Sometimes, the
solution requires taking a step back and eliminating a problem further up the
chain.
In the case of submarine collisions, you have two identifiable primary
risks: 1) entanglement, and 2) damage. In the context of the
anticipated operating conditions, I can't help but wonder if design effort to
reduce entanglement potential by
1) streamlining the hull and superstructure, and minimizing appendages to
prevent entanglement or entrapment
2) accomodating impacts to the hull and superstructure by incorporating such
features as collision bulkheads, space frames and guards where appropriate
3) implementing better systems to warn of impending collision, including
attempts to increase range of visibility, lighting, sonar, etc.
4) defining operating parameters consistent with the vehicle design and
anticipated operating conditions to firstly avoid collisions altogether, and
where a collision may not be avoided, to enable the vehicle to withstand
collision without sustaining critical damage
- are better uses of resources than convoluted mechanical or other means of
reducing vehicle momentum on an impending collision, which may represent increased
risks from other perspectives.
A common error made in "what if" contingency planning is failing to
determine if the "what if" event in question can be avoided
(preventative), thus eliminating the requirement for a contingency plan
(reactive).
Just my $0.02.
-Sean
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