A few questions regarding submarines

[EFileTahi-A]

I'm coding a futuristic turn based submarine war game and I need to understand some basic features of nowadays subware.

Please note that some questions might look (or are indeed) dumb, give me a discount will ya? ;)

1 - How fast can a nowadays military sub ascend and descend?

2 - Maximum depth of military subs / maximum depth ever recorded (Cientific piloted subs included).

3 - I understand that electrolysis and special equipment is required to produce air. But what if this life support system fails. Do they imediately need to surface or they also store air in pressurized tanks?

4 - Does depth influences in any way the speed of torpedos or their ability to work? (at very deep depths)

5 - Does depth influences in any way the sonar's efficiency?

6 - Is there any restriction or different behaviour on submarines when in extreme deep depths, i.e. do subs operate the same way dispiting the depth they are?


Thank you for any possible info.

[AntEater]

I'll answer some I know

2. Since Trieste was in US navy service, you can say the maximum depth of a military sub is 10,500 meters.
The woods hole submersibles (Alvin etc) can go around 6000 meters or so.
However, maximum realistic depth for a combat submarine was the russian Komsomolets with around 1500 meters.
Normally today's SSNs operate above 300 meters.

3. In larger submarines, the air supply in the sub itself can sustain the crew for a day or so. Depends on the size of the submarine and the number of men inside.
Oxygen bottles were normally carried in WW2, not sure about today.

4. Since torpedoes do not have any air compartments, depth should not affect them at all. Maybe their components could be damaged by the pressurisation process, but as soon as they are in the ambient pressure, they should work normally.

5. Around 1000 meters (can be lower or higher), there is the deep sound channel, where sounds travel the slowest. In this area, sound travels the widest, sometimes around the globe.
Below that, sonar conditions are similar to the surface.
However, changing temperature in the water can distort sound conditions at any depth (geothermal vents, for example)

6. Below certain depth, submarines are noisier, because of the pressure on the hull.
Also, in a hypothetical deep diving scenario, submarines would avoid fast depth changes because the pressure change could cause damage, or at least noise.

[Takeda Shingen]

Submarines frequently use chlorate candles to generate oxygen as a failsafe. In fact the candles are believed to have caused the explosion on HMS Tireless in 2007. However, in dire emergency, yes, they will ventilate. They also need to do so to run the emergency diesels, which is something they do regularly to ensure their smooth operation in a real emergency.

To add to AntEater and sonar, modern SSNs will frequenly slow to allow the towed array to decend into the deep channel, which allows, through convergence, one to detect sources much farther than could normally be heard. There are some legitimate ex-sonar men on this forum who could tell you a lot more.

In regards to depth, deep submarines are generally quieter than shallow ones. The primary reason for this is the water pressure, which allows for higher speeds without the risk of cavitation. Modern hulls are streamlined and strong enough to be relatively quiet under stress.

[EFileTahi-A]

Thank you for your replies!

With such info I've already constructed some aspects of the sub's attributes that were missing.



Now, I have an attribute which is called "Ballast Tanks", this attribute is intend to control how fast or slow a sub can ascend descend while submerged. It also controls the amount of floods the vessel can sustain, i.e. the more points invested in this attribute the more / bigger ballast tanks the sub will have, thus, making it easier to control its buoyancy.

Does this makes sense? I mean, is the attribute's correctly described?

[SteamWake]

Thank you for your replies!

With such info I've already constructed some aspects of the sub's attributes that were missing.



Now, I have an attribute which is called "Ballast Tanks", this attribute is intend to control how fast or slow a sub can ascend descend while submerged. It also controls the amount of floods the vessel can sustain, i.e. the more points invested in this attribute the more / bigger ballast tanks the sub will have, thus, making it easier to control its buoyancy.

Does this makes sense? I mean, is the attribute's correctly described?

While the ballast tanks are used to control bouyancy they are only part of the equation. Speed, dive plane size and angle, ships mass, even the waters temprature and salinity are all factors.

[EFileTahi-A]

Indeed SteamWake, but this attribute's efficiency is described as is, without having in count other factors, like the engines, mass etc...

Could you describe me the percentage of what each factor weights in a percentual scale for ascending descending?

Like, Ballast Tanks influences the bouyancy by 30%, speed 40% etc...


Thanks alot for the reply. :)

[SteamWake]

Indeed SteamWake, but this attribute's efficiency is described as is, without having in count other factors, like the engines, mass etc...

Could you describe me the percentage of what each factor weights in a percentual scale for ascending descending?

Like, Ballast Tanks influences the bouyancy by 30%, speed 40% etc...


Thanks alot for the reply. :)

Well it would depend on which boat. Im no expert so I'll defer to those that are.

Might want to take a look into the 'Janes' books http://www.janes.com/

[Frame57]

You acheive neutral bouyancy by using the trim tanks. Once that is acheived you use speed and planes to change depth. MBT's are used primarily when surfacing and submerging.

[lesrae]

Regarding point 6, I seem to remember being told that boats will keep their speed up when operating close to their maximum diving depth, as even blowing all MBTs may not be enough to get them to surface in the event of a propulsion failure, or reactor scram, at that depth.

Keeping their speed up should allow them to plane up to a shallower depth with residual speed and propulsion power, up to a depth where the MBTs become effective again.

In a similar way, speed when shallow is kept down, to prevent accidental broaching, cavitation and to minimise any surface wake or disturbance.

[EFileTahi-A]

Interesting!

Now, regarding point 1, any clues? Also, it is faster / easier to ascend or descend?


Thank you all for your replies. :)

[Frame57]

I would have to cite Janes verbage in order to not compromise classified info. There are many factors to this question. At test depth with a flank bell, with full rise on the fairwater water planes and the stern holding about a 40 degree up angle. We ascend the surface in quick order. The depth gage is literaly a blur, so you are dealing with seconds and not minutes. Providing the COW hit the emergency blow valves.

[SteamWake]

All I can say is it must be one hellua ride inside. I dont know how everone doesent loose their footing and get tossed about like peas in a can.

All ahead flank !

http://www.youtube.com/watch?v=782rixz4a1Y

Heres one without 'evidently' forward momentum.

http://www.youtube.com/watch?v=tGKzxZ31QcM

[EFileTahi-A]

Hmmm very interesting!

If the ballast tanks cease to work (Like loosing pressure to empty the tanks), how will the crew / sub handle such situation?

Furthermore, verify if the following is correct:

"If some of the submarine's compartments get flooded with water (for any cause, attack or accident) the ballast tanks would then need to be proportionally emptyed to counter the aditional weight of the water in order to maintain bouyancy."

[SteamWake]

"If some of the submarine's compartments get flooded with water (for any cause, attack or accident) the ballast tanks would then need to be proportionally emptyed to [HOPEFULLY] counter the aditional weight of the water in order to maintain bouyancy."

Edited for you. The tanks are designed for a boat under 'normal' operating circumstances. Get too much dead weight in the boat and the ONLY way you could get to surface is by propulsion.

The usuall procedure would be to try to get the dead weight water out of the boat using pumps.

[Frame57]

All I can say is it must be one hellua ride inside. I dont know how everone doesent loose their footing and get tossed about like peas in a can.

All ahead flank !

http://www.youtube.com/watch?v=782rixz4a1Y

Heres one without 'evidently' forward momentum.

http://www.youtube.com/watch?v=tGKzxZ31QcMThe cooks in particular hated this because it is impossible to prepare chow when doing these evolutions. High speed maneuver's are called "angles and dangles".

[Frame57]

When flooding occurs all SOP's require you to go shallow (if you can). This helps minimize flooding by reducing water pressure. Submarines have three ways to get water expelled from the Main Ballast tank system. The trim and drain systems only use pumps. But the trim system itself, not the MBT system is what allows to acheive neutral bouyancy the degree that you can maintain depth without any speed at all. In damage control, a last resort to control flooding is allow high pressure air into the flooded compartment. Most submarine designs have several watertight doors to accomplish this.

[SandyCaesar]

Regarding point #4, most torpedoes do have a maximum operating depth. For instance, the US Mk48 ADCAP has an officially rated depth of 800ft (~260m), but most people estimate its capability at ~800m. Although they are capable of going quite deep, there is a depth at which water pressure will render them inoperable. I remember reading about WWII torpedoes, when they had exhausted their fuel, sinking until water pressure crushed their impact fuses, which blew up the warhead.

[EFileTahi-A]

Many to thanks to all of you for your awesome replies!

So, how would a submarine benifect by having large ballast tanks?
What could change the ascending / descending speed without propulsion at all?

[D'biter]

Regarding point 6, I seem to remember being told that boats will keep their speed up when operating close to their maximum diving depth, as even blowing all MBTs may not be enough to get them to surface in the event of a propulsion failure, or reactor scram, at that depth.

Keeping their speed up should allow them to plane up to a shallower depth with residual speed and propulsion power, up to a depth where the MBTs become effective again.

True, but they'll also try not to go too fast, as a jam dive at test depth at 35 knots is going to send the boat through crush depth in an instant

[Aramike]

Regarding point #4, most torpedoes do have a maximum operating depth. For instance, the US Mk48 ADCAP has an officially rated depth of 800ft (~260m), but most people estimate its capability at ~800m. Although they are capable of going quite deep, there is a depth at which water pressure will render them inoperable. I remember reading about WWII torpedoes, when they had exhausted their fuel, sinking until water pressure crushed their impact fuses, which blew up the warhead.To add, there is a penalty in high-pressure air used to force the torpedo out of the tube at greater depths. Ideally you wouldn't want to shoot from much deeper than about 300', although that's debatable.

[Frame57]

Many to thanks to all of you for your awesome replies!

So, how would a submarine benifect by having large ballast tanks?
What could change the ascending / descending speed without propulsion at all?Not sure I understand the question entirely. Submarines are designed to be positively bouyant when the MBT's are empty of water. When the MBT valves are opened water fills the tanks and you submerge. A very simple process that is independant of speed. The trim system on subs is more like a fine tuning to maintain neutral bouyancy, which is the ideal state for a submarine to be in. The amount of water brought in to the boat is the sole factor of what affects bouyancy. The size of the ballast tanks have to be designed on the size/weight of the sub being built. Everything has to be proportional.

[Neptunus Rex]

Submarines once,
Submarines twice.....

(Come on, finish it!):up:

[EFileTahi-A]

Many to thanks to all of you for your awesome replies!

So, how would a submarine benifect by having large ballast tanks?
What could change the ascending / descending speed without propulsion at all?Not sure I understand the question entirely. Submarines are designed to be positively bouyant when the MBT's are empty of water. When the MBT valves are opened water fills the tanks and you submerge. A very simple process that is independant of speed. The trim system on subs is more like a fine tuning to maintain neutral bouyancy, which is the ideal state for a submarine to be in. The amount of water brought in to the boat is the sole factor of what affects bouyancy. The size of the ballast tanks have to be designed on the size/weight of the sub being built. Everything has to be proportional.

Well, since in my game the player has to build the submarine by increasing / decreasing to several aspects of the sub's chassis, I need to understand what attribute(s) should I create to increase the subs ascending / descending speed.

Since MTBs are filled with water or air to ascend or descend, will not the maximum quantity of water / air MBT they can hold change the speed of the refered ascending / descending operations?