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While
Andy’s idea appears feasible on the surface, there are some practical
issues to consider: 1.
Air
does not have a lot of mass so its reactive force would be small in comparison
to the 2+ tons of a typical PSUB; 2.
As
demonstrated on Myth Busters, dumping a lot of air into the water in the
direction of your downward trajectory will actually cause you to have a loss of
buoyancy and thus accelerate your descent; 3.
Dumping
that much air (it is going to take a LOT!) at one time will probably freeze up
the valve you are using (unless it is the VERY expensive Marrotta valves used
for big sub’s ballast tank blow systems). Under
most conditions found in typical PSUB operating areas, trying to propel your PSUB
at high speeds can be likened to driving in a heavy rain. You can drive
fast, out driving your visibility window, and risk colliding with a car or
something else before you slow down to avoid the collision. Or you can
slow down and drive within your visibility window and be able to easily avoid
obstacles. Your PSUB weighs several tons and you do not have breaks like
a car, trying to stop a PSUB’s inertia is like trying to break your car
with your foot out the door on the road. SONAR will help see things ahead
but your reaction speed and the maneuverability of your PSUB (stopping or
turning that inertia) will not help you. An issue here is a thermocline
can cause the SONAR beam to bend around an obstacle and you may not see it
until too late. Any high speed vehicle in the water stays up off the bottom
to avoid obstacles and this defeats what the PSUB is trying to do, find things
on the bottom. You need to slow down if you are going to be near the
bottom. It
took years for many of the things learned in the Technical Diving to permeate
out through the old, hard core deep wreck diving community in the NE United
States. One of those things was “Deep air kills!” Well,
thought should be given to “PSUB speed kills!” Other
knowledgeable people have tried to impart this fact to the list. Dean has
put a lot of effort into his PSUB to conquer this very trying environment found
in the Great Lakes and should be applauded for his efforts but care should be
taken in how PSUB speed is promoted. There
are others that seem to periodically bring the same topics up just to stir the
pot. A healthy discussion of these subjects is good but the concepts
should be couched with notes of caution, not as realities and proven
technologies. In fact, usually when there is a citation that appears that
the subject is safe or feasible, further investigation leads to hoary facts. Your
resident naysayer, Jay Respectfully, Jay
K. Jeffries Andros
Is., Bahamas Talk
sense to a fool and he calls you foolish.
- Euripides (484 BC - 406 BC) -----Original Message----- The following should be filed under "insane"
and not attempted without A LOT of testing etc, but for the sake of discussion, A primary benefit of the small sub is enhanced dynamics
and low inertia, which makes systems which are not viable on a large sub
possibly interesting. Think deep flight vs an SSN.... If truly for "extreme and eminent" collision,
it seems that it may be possible to add a few extra external scuba tanks and
some regulators and a control manifold inside the hull.
These extra bottles could normally be held in reserve for backup buoyancy or as
a redundant ballast blow system. Or in an emergency move a valve on the
manifold and blow A LOT of air forward of the sub. An air jet break. It has the added benefit
that if you design it wrong you may instead get aft firing torpedoes :) -a ************************************************************************ |