From: Shannon Wiley [shannonwiley@home.com] Sent: Friday, January 05, 2001 8:03 PM To: blue_planet@lists.ient.com Subject: RE: [BLUE PLANET] - Submarine warfare > Unfortunately I'm not sure about WHY they are silent below 5 knots, just > like I'm not sure why nuclear submarines aren't. Anyone have an > explanation > for this? > The basic principal behind it has to do with moving parts. A Nuclear Submarine uses the Nuclear Reaction to boil water and create steam. The seam then operates a turbine, which in turn rotates the submarine's driveshaft. Boiling Water makes noise. Steam under pressure to operate a crankshaft makes noise. The turning Crankshaft makes noise. An electric engine, however removes some sounds from the equation. Electric Current directly turns the crankshaft with no connecting gears or other moving parts. There's still sound, but because it only comes from one source, it becomes harder to detect. As far as the 5 knots thing goes, A good sonar operator can actually hear the sound of the subs screws turning in the water. At under 5 knots, they aren't turning quite fast enough to make a significant sound. > 3) Has the shielding technology advanced far enough that the noise of a > submarine's nuclear plant can be masked? > The Nuclear Plant itself isn't that noisy. In fact, it's very much quieter than a straight I.C. Engine of any sort. The exact Science behind it all are much more complex, but that is the very basic principle behind it all. Shannon *************************************************************************** To unsubscribe from this list send mail to majordomo@lists.ient.com with the line 'unsubscribe blue_planet' as the body of the message. From: ChrisTheS [stormsurge@stormsurge.org] Sent: Friday, January 05, 2001 12:40 AM To: blue_planet@lists.ient.com Subject: [BLUE PLANET] - Submarine warfare I have some questions with regard to the state of submarine stealth technology in BP: 1) Have the choices for power-supply advanced beyond the current two (diesel-electric and nuclear)? Judging from FluMech, I would say probably not, although the diesel would probably have been changed for some other form of fuel. 2) Have there been any advances in sonar monitoring that could diminish the diesel-electric submarine's advantage of near-total silent running at under 5 knots? Unfortunately I'm not sure about WHY they are silent below 5 knots, just like I'm not sure why nuclear submarines aren't. Anyone have an explanation for this? 3) Has the shielding technology advanced far enough that the noise of a submarine's nuclear plant can be masked? For scientific reasons, I'd say quite possibly. Not perfectly masked, but enough so that someone would only detect it if they were looking. For gameplay reasons, I'd say that something else should balance out the d-e and nuclear subs besides cost (but that could easily be handled in adventure by using an old nuclear boat without as good shielding). 4) How does the presence of cetaceans affect stealth boats? On first glance it would appear that the existence of uplifted cetaceans would make stealth submarine warfare obsolete, since the boat's presence would turn up on a normal cetacean sonar sweep. But thinking about that, I think I've found a way that it could work (although my knowledge of the mechanics of sonar is somewhat limited, so I don't know if this is actually plausible.). Until recently the problem with hunting with a stealth submarine is that it was impossible to identify objects using active sonar, since doing so would give the boat's location away; sonar imaging had to be by passive sonar. However, this problem could be overcome by disguising the active sweep as the sound of whalesong, thus preventing the target from being warned by a sonar ping. Now, I'm thinking that a similar concept could be used, not to disguise the sound of the sweep, but to disguise the shape of the boat. If there were extremely accurate sensors placed around the hull of the boat that could detect if the boat were being pinged, either by another boat or by cetacean sonar, then it could transmit carefully modulated sound in response that could mask the reflected sound and make whoever pinged it think it was something other than a stealth submarine. Of course, the instruments on this would have to be extremely precise, or otherwise it wouldn't work, but it seems to me to be plausible (anyone who has a more complete knowledge of sonar than I have, of which I have no doubt there are many, please feel free to correct me so I don't mistakenly use something like this in an adventure). Also, to anyone interested in some submarine-based adventures and needing a good starting point, I suggest Patrick Robinson's books 'Kilo Class' and 'HMS Unseen,' both of which offer some great adventure ideas (particularly the second, which could practically BE an adventure in itself). -- ChrisTheS *************************************************************************** To unsubscribe from this list send mail to majordomo@lists.ient.com with the line 'unsubscribe blue_planet' as the body of the message. From: ChrisTheS [stormsurge@stormsurge.org] Sent: Friday, January 05, 2001 10:24 PM To: blue_planet@lists.ient.com Subject: Re: [BLUE PLANET] - Submarine warfare Ah thanks. Much obliged. ----- Original Message ----- From: "Shannon Wiley" To: Sent: Friday, January 05, 2001 6:02 PM Subject: RE: [BLUE PLANET] - Submarine warfare > > Unfortunately I'm not sure about WHY they are silent below 5 knots, just > > like I'm not sure why nuclear submarines aren't. Anyone have an > > explanation > > for this? > > > > The basic principal behind it has to do with moving parts. > A Nuclear Submarine uses the Nuclear Reaction to boil water and create > steam. The seam then operates a turbine, which in turn rotates the > submarine's driveshaft. > > Boiling Water makes noise. Steam under pressure to operate a crankshaft > makes noise. The turning Crankshaft makes noise. > > An electric engine, however removes some sounds from the equation. Electric > Current directly turns the crankshaft with no connecting gears or other > moving parts. There's still sound, but because it only comes from one > source, it becomes harder to detect. > > As far as the 5 knots thing goes, A good sonar operator can actually hear > the sound of the subs screws turning in the water. At under 5 knots, they > aren't turning quite fast enough to make a significant sound. > > > 3) Has the shielding technology advanced far enough that the noise of a > > submarine's nuclear plant can be masked? > > > The Nuclear Plant itself isn't that noisy. In fact, it's very much quieter > than a straight I.C. Engine of any sort. > > The exact Science behind it all are much more complex, but that is the very > basic principle behind it all. > > Shannon > > *************************************************************************** > To unsubscribe from this list send mail to majordomo@lists.ient.com > with the line 'unsubscribe blue_planet' as the body of the message. *************************************************************************** To unsubscribe from this list send mail to majordomo@lists.ient.com with the line 'unsubscribe blue_planet' as the body of the message.