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01-19-13, 08:48 AM | #16 | |
Silent Hunter
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Quote:
//off off-topic |
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01-19-13, 09:52 PM | #17 | |
Cold War Boomer
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while on the bow planes at 400' on a 350' diesel submarine (USS Salmon SS-573)
I will never forget the Officer of the deck and the Chief of the watch yelling blow negative at the same time. We came up very fast for a more qualified study of surfacing a submarine you can go here: http://www.heiszwolf.com/subs/tech/tech01.html Quote:
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01-20-13, 11:36 AM | #18 |
Ocean Warrior
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Correct. As you go shallower the water pressure decreases allowing more of it to be discharged from the ballast tanks by the higher pressure air. As more water is expelled from the tanks the air pressure will drop as it has more room to expand. As far as compensation is concerned, yes they could open the MBT vents to vent some of that air. But the $100K question is WHY would they want to do that? Like I stated before if you merely wanted to change depth you use your planes to proceed to the new depth. You don't blow ballast to go to a shallower depth.
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USS Kentucky SSBN 737 (G) Comms Div 2003-2006 Qualified 19 November 03 Yes I was really on a submarine. |
01-20-13, 12:37 PM | #19 |
Navy Seal
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Actually it's Onkel Neal.
Busted again.
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01-20-13, 02:41 PM | #20 |
Eternal Patrol
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Very true. My German isn't what it once was. In fact my German never was what it once was.
"Your" absolutely right.
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01-21-13, 05:30 PM | #21 |
Commander
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I meant as a way of slowing the ascent or even to prevent it from speeding up as more and more balast is expelled by the expanding air already in the tanks.
Perhaps similar to rising and descending in a gas balloon? On the other hand, would decreasing water density compensate anyway by reducig the boat's bouyancy as she rises?
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01-21-13, 07:36 PM | #22 | |
Ocean Warrior
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A submarine operates on a completely different principle. When it submerges it takes on water in its ballast tanks to maintain a state of neutral buoyancy. Depth changes are accomplished by the use of the control planes. Once submerged the main ballast tanks aren't touched except to surface the boat. There's no need to blow water out or take water on except for when your displacement would change (consuming food stores, firing torpedoes, etc) and there is an auxiliary system for this purpose. As for your second question about water density affecting buoyancy, I'll hold off on answering that for now.
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USS Kentucky SSBN 737 (G) Comms Div 2003-2006 Qualified 19 November 03 Yes I was really on a submarine. |
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01-22-13, 06:36 AM | #23 |
Commander
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I know about hot air balloons, I was making the comparison with gas balloons which are rather different.
Do they close the valves at the bottom of the ballast tanks once blowing has been done and the vessel is on the way to the surface?
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01-22-13, 01:28 PM | #24 | |
Ocean Warrior
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Quote:
Now about your question here, I can only speak to American submarines. The US boats have a vent valve on the top of each ballast tank and flood grates on the bottom. This maintains the water pressure in the ballast tank equal with that of sea pressure on the outside. It is my understanding that Russian boats have valves on the top and bottom of their ballast tanks. They submerge by opening both sets of valves. Once the ballast tanks are full of water both valves are shut. This maintains a constant pressure of the water in the tanks, that which would be nearer to surface water pressure. My conjecture is that you could blow HP air into the tanks and then open the bottom set of valves to force the water out quickly even at great depth. I would imagine that the valves would be closed again once the tanks were blown dry. I either used to have a diagram of this or saw one somewhere but damned if I can find it now.
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USS Kentucky SSBN 737 (G) Comms Div 2003-2006 Qualified 19 November 03 Yes I was really on a submarine. |
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