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"Your resident naysayer, Jay" I found Ray's breakdown of communication fascinating and very informative. To my mind, in my nearly three years of membership, I've never found Jay's posts to be anything but well founded and quite clear to the point. Joe
From: bottomgun@mindspring.com 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)
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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
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