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Geronimo
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st cloud USA
Jan 1970
time: 05:37
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quote:
Originally posted by Dr Strangelove
Steel armor doesn't stop radiation as well as lead shielding, plus a nuke is going to be detonated in the air, so the radiation will strike the ship from an angle not protected by armor anyway. |
true but even the thickness of a couple of decks would probably block most of that. Lethal radiation from nuclear explosions isn't as penetrating as people seem to think and it's not an instantaneous killer either. People have had exposures greater than would be received at the deck of a ship in the H-bomb tests and taken hours to feel really sick. The fire fighters at chernobyl got zapped really hard and didn't become incapacitated for hours (though they all died). They didn't have any shielding and they had a much longer exposure than a nuclear blast would give.
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Geronimo
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st cloud USA
Jan 1970
time: 05:37
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quote:
Originally posted by shawnmmcc
Also, there is a problem with cascade radiation in the armor. Steel is LOUSY radiation shielding, as instead of simply absorbing the radiation, the iron nuclei release there own lethal radiation under the right circumstance. The estimation is that the crew would die several days after an airburst. At that time they were not talking about super-heated air, I suspect that the armor belt would stop enough direct radiation to prevent that. It will definitely protect against the initial blast damage. You coujld survive to operate the ship for a couple of days before dying.
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Partly for the reason you describe Iron is inferior to most other common materials as a shielding material but not to an extant that prevents it from being an effective shielding material regardless of possible secondary emission.
Note from the table on this page that 1.3 inches of iron actually provides as much protection as 4.7 inches of concrete against gamma radiation which tends to be the most dangerous and penetrating radiation component of a nuclear blast.
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Geronimo
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st cloud USA
Jan 1970
time: 05:37
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quote:
Originally posted by PLATO
So from that table we are to assume that iron is 1/2 as effective as lead in stopping gamma rays? |
Actually pound per pound iron is superior to lead. Lead has an MW of 207 while iron is 58. So 120g of iron can provide as much protection as 207g of lead at the price of that reduced mass of iron occupying about 2x the volume that the heavier mass of lead would need to.
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Sikander
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Boulder, Colorado, United Snakes of America
Jan 2000
time: 22:37
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quote:
Originally posted by Mordoch
I already covered how its going to hit the deck armor, so its going to at a minimum go through the initial 1.5 inch steel plate on the battleship's initial deck level, there is a noticable space between this layer of armor and the main one. At the time this was originally, this was a sensisble move because it could sucessfully detonate gravity bombs before they could reach the main level of armor, avoiding their sucessful penetration. However, against modern anti-ship missiles the scheme is flawed because it means the missile will explode inside the initial layer of armor, trapping most of its fuel in the relatively confined space. Since neither shells nor bombs had very volitile jet fuel inside. As shown in the case of the Stark, the fuel fire started by the missile would reach about 1500 degrees in one minute.
http://www.dcfp.navy.mil/mc/museum/STARK/Stark3.htm
This fire can eventually go further up in temperature to 2200 degrees, which is hot enough to melt steel. This means the fire can potentially melt all the deck armor in the area above it, and even melt the main armor belt and splinter belt armor. Any equipment or electronics in the area could also end up destroyed by the heat, including any connecting wires going through the ship. In other words an anti-ship missile can definately do a substancial amount of damage.
Its also worth noting that the deck armor can only take a 1600 pound armor piercing round in its "immune zone" portion of the deck, there is a substancial portion of the deck where it lacks such capability. |
The excocet doesn't dive down to penetrate deck armor (or at least that wasn't how it was designed in the 1980s). The reason it pops up is to acquire its target before it makes its final run, not to dive downward through deck armor. While it's been skimming the sea it has been cruising toward a destination. It can't / doesn't actually see its target and if everything is going as planned its target can't see it. Not announcing its presence helps it approach stealthily and significantly reduces the size and weight of the missle. One it reaches a predetermined point close to the target the missle swoops into the air in order to give it the ability to look around with its own active terminal guidance system. Hopefully it will see a ship. If it does it calculates the geometric center of that ship and busts ass trying to drive itself into that geometric center before it is detected or destroyed. Note that this method results in hits to the sides of the ship, and not the decks.
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shawnmmcc
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One other item, reference the fuel issue on missiles. One of the reasons the Exocet was so devastating in the Falklands was that the Frigate it hit had an Alloy hull, not steel. Steel when subjected to those temperatures melts, warps, and looses it's structural strength. Many of the modern Super-alloys BURN. Once you start that kind of fire, it will burn in water, Nitrogen, in almost anything. That is why, even in the case of a diving penetrating strike between the splinter deck (stops shrapnel) and the armor deck on the Iowa, all you end up doing is some damage in areas that were designed to take that damage anyway. As Sikander shows, that's not even what happens. However, this shows why it is not some crisis that would endanger the ship. In fact a mine would do more damage, slowing the ship down slightly and possibly causing the loss of some fuel oil (carried in those outer compartments because you would rather lose that then crewmen).
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15-08-2005 00:56
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