Sub physics - experts needed

[TopTorp '92]

When that thread (Dr. Sid) goes tactical let me know as I'd like to provide input.

By far this has been among the most interesting threads I have read in a long time. Only Bubblehead Nuke can provide the level of detail I see here.

However I must make a tactical insertion here because there is after all a tactical problem associated with all the engineering discussion. Earlier BH Nuke claimed that “[w]hen submerged there is NO AIR in the MBT's. You open the MBT vents and close them when you are fully submerged and the tanks are full of water.”

In fact we did cycle MBT vents once submerged to 150’. The idea was to remove trapped air as BH Nuke correctly identifies. Unfortunately there is still some air remaining in the tanks and the effects of this trapped air may not be detected on sonar until the ship makes a depth excursion or turns with enough roll to make the air bubbles shift causing the noise-tactical problem. Not only would we need to cycle vent valves once submerged but also we would need to complete an excursion combined with an additional vent cycle to provide an added measure of certainty in the removal of trapped air in the ballast tanks.

Finally this adjustment requires a tactical trade-off in that any self-induced noise may be detectible on another sonar platform. That’s why we always cycled vents once submerged to 150’ but had to live with the possibility that yet more air bubbles may appear after returning to shallow depth (150’ or above) after a period of operations at deeper depth.

TopTorp

[Dr.Sid]

Interesting ! I read microbubbles can live quite long and quite deep with rough sea or in the ship wakes. Can that be trouble ? Like microbubbles getting into the tanks (through lower openings) from outside ?

[TopTorp '92]

Originally Posted by Dr.Sid

Interesting ! I read microbubbles can live quite long and quite deep with rough sea or in the ship wakes. Can that be trouble ? Like microbubbles getting into the tanks (through lower openings) from outside ?

Your biggest concerns are the bubbles in the ballast tanks after the ship submerges. I don’t know anything about micro bubbles in the wake (cavitation maybe?) or seeping in from the outside (seems a bit farfetched to me.) But the idea was that even if we cycled vents at 150’ there was always an additional concern that some air may return upon returning to shallow depth after operating deep for a period of time. Basically those microbubbles trapped in the ballast tanks are a non-issue until they become bigger bubbles as the ship changes depth from deep to shallow; don’t forget that water pressure at deeper depths keeps the bubbles small while the change in water pressure causes the bubbles to expand, making noise, on the way up.

[Dr.Sid]

Ok .. understood.

[Bubblehead Nuke]

Hey there Top Torp, Long time no see.

As you have probably been reading, I have been trying to give some insights without breaking the rules.

[Dr.Sid]

I wonder .. how exactly are those 'rules' defined ? You are told what you can tell and what not ? Generally NDAs are more like 'you wont tell anything'.

[TopTorp '92]

Originally Posted by Bubblehead Nuke

Hey there Top Torp, Long time no see.

As you have probably been reading, I have been trying to give some insights without breaking the rules.

I tend to keep it simple . . .stupid (KISS.)

Keep up the good work. Maybe the sim guys will strike a better trade-off between a game that sells and a sim that educates.

I monitor the threads and add perspective when I think it appropriate. Unfortunately modelling tactical considerations is much more difficult than modelling engineering factors. However, I must add that Bill comes up with some really good scenarios. Very good.

To be honest I have trouble organizing knowledge that was/is unclassified separate from the other knowledge (the Top Secret stuff) that could potentially endanger lives or worse become self-incriminating.

You know I think I read somewhere that either DW or Sub Command has been used to train Naval Academy students as some kind of introduction to submarine operations and general warfare. If any of you guys can confirm, I'd like to know.

Top Torp