Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!uxc!iuvax!rutgers!att!cbnews!military@att.att.com From: military@att.att.com (Bill Thacker) Newsgroups: sci.military Subject: Re: Ship armor Message-ID: <5929@cbnews.ATT.COM> Date: 26 Apr 89 04:09:43 GMT Sender: military@cbnews.ATT.COM Lines: 112 Approved: military@att.att.com From: military@att.att.com (Bill Thacker) Tim McDaniel writes: >- Missiles seem to be today's general weapon-of-choice, unlike the >shells, torpedos, and mines of previous years. However, conventional >missiles tend to have low explosive yields, so less armor should be >necessary. I've heard that "six hits from any of today's missiles in >the same place still won't pierce battleship armor". This is unlikely >(armor isn't uniformly protective) but indicative. I don't doubt this statement at all; if one explosion won't cave in the armor, it's unlikely that a dozen will. Of course, as Henry Spencer pointed out, the Iowas aren't armored everywhere; the bows and stern, for example, are unarmored, and could be demolished by missiles; meaning that the junior officers cabins will be gone. Even with fully-flooded bow and stern, though, the ship should still be able to float, and probably even fight and maneuver. Essentially, you can't sink them without penetrating the armor belt (which runs from #1 turret to #3 (stern) turret) or torpedoing them. >- Armor is "expensive" in weight, leading to a deeper draft, thus less >fuel efficiency and less maximum speed (any other costs?). This is essentially it. In WWII and before, the "big three" items in warship design were armor, propulsion, and armament; a gain in one could only be achieved to the detriment of the others, unless you could increase displacement (which was limited by docking considerations and, at the time, the Panama Canal). Of course, you also need space (therefore, weight) for fuel, provisions, ammo, crew, electronics, etc, etc. >- Armor gives at least some protection against missiles, torpedos, >shells, bombs, *and* mines. Active protection can be used: making Armor doesn't add much to torpedo or mine defense. Basically, it takes a *lot* of armor to resist an underwater explosion; more than can be economically carried over such a large area. Typically, the approach is to instead provide several torpedo bulkheads, with void space between, to absorb and abate the blast of the explosion; the innermost bulkhead is typically lightly armored to resist steel splinters, thereby maintaining watertight integrity. Similarly, double- or triple-bottoms are used to resist mines. (The Italians employed the complicated Pugliese system, which is another story altogether). Details of Iowa's underwater protection are very vague, but it seems likely that four torpedo bulkheads were provided, the outer two filled with fuel oil or water. A triple bottom was also fitted. This system was used on the South Dakotas which immediately proceded them, and planned for the Montanas to follow. >How much speed would be lost in armoring a cruiser, then? (Recall >that the maximum speed of USS Iowa is a respectable 33 knots.) In a >real-war mix of operations, how important is that extra speed? How >important is the capability to absorb more punishment? I don't know what speed modern cruisers can make, but in WWII, virtually every nation had a 32-33 knot heavy cruiser, with good armor; some made as high as 35 knots. I'm guessing an important tradeoff is magazine space; I'd guess that missiles require more magazine space than powder and shells; this extra space would have to be armored, increasing weight and thus draught, thereby requiring more power to maintain the speed, meaning more volume, thus more armor, ... Still, I wonder how much armor would be necessary to defeat the current and projected antiship missiles... >Some World War II German tank commanders said that they would have >preferred lighter, faster tanks, mobility being more important (was >this in Liddell-Hart?) How well does this generalize to ships? In >the relatively static venues of the Falklands and the Persian Gulf, >armor would seem more important. Lord Fisher was a big proponent of speed-vs-armor in WWI Britain. He felt that speed could replace armor, to an extent; a faster ship was harder to hit. He fathered the concept of the battlecruiser, lightly armored but carrying battleship guns, faster than battleships (and as fast as cruisers). They could outrun anything they couldn't fight, and outfight anything they couldn't outrun. Germany, too, adopted battlecruisers; but they chose to use a lighter armament to allow higher speed, keeping armor protection high. In the battle of Jutland (WWI's decisive naval battle), 3 British battlecruiser (Invincible, Indefatigable, and Queen Mary) received hits from their German counterparts (Lutzow, Derfflinger, Von der Tann, and Seydlitz) and blew up with massive loss of life. The German ships fared better; Seydlitz, for example, took some 21 heavy shell hits and torpedoes, suffered two turrets burned out, shipped 5300 tons of water, and still returned home under her own power, to be repaired and returned to service. Derfflinger took slightly more moderate damage, while Lutzow had to be scuttled while returning home, having taken the same number of hits. Events clearly indicated that speed did not make up for protection. I can't help but think that this lesson is still quite appropriate in the modern battlefield where missiles can be fired from over the horizon and accurately seek out even an evasive target; and one such hit can disable the target (at least, render it ineffective for combat). - - - - - - - - - - - - - - - - - - - - - - - Bill Thacker moderator, sci.military military@att.att.com (614) 860-5294 "War is a matter of vital importance to the State; the province of life or death; the road to survival or ruin. It is mandatory that it be thoroughly studied." - Sun Tzu