VictorInThePacific -> RE: hunter-killer sub tactics (12/6/2008 2:12:41 AM)
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I am going to have another crack at this topic. The feedback I have received so far is either “it won’t work against a human” or “it won’t work in real life”. I will restate the case, including more details, and attempting to refute the counterarguments I have seen so far. First let me define air superiority. If one side can safely operate slow, unarmed aircraft in a region, and the other side cannot, the first side has air superiority. This is a relative concept, and it will depend on just what is available to contest the airspace. In general, NATO will have air superiority anywhere over the Atlantic or in the GIUK area, except possibly within a few hundred miles of a Soviet airbase. The Atlantic is a given, because Soviet aircraft will simply never be there. The airspace within several hundred miles of a US CVBG will always be controlled by NATO. Otherwise, the CVBG will shortly cease to exist. The airspace within 50 nm of a Kirov or Slava will generally be controlled by the Soviets, unless there is a Tomcat nearby, in which case that region is not safe for either side. Second, I think that we will agree that the most effective way to KILL an enemy sub is with an aircraft. On the one hand, the sub can never shoot back. On the other hand, the aircraft will always be able to rapidly approach the sub, almost always be able to rapidly locate the sub exactly, and generally be able to drop large amounts of nasty ordnance on the sub from point-blank range. Finally, if one aircraft is insufficient, you can generally replace that aircraft with another one, and another one, and so forth. But I think that it is incorrect to claim that an aircraft is the most effective way of HUNTING a sub, that is, generating an initial contact. The most effective ASW aircraft, the Orion, carries a MAD and about 100 sonobuoys, and cruises at about 400 kn. If the Orion flies in a straight line for an hour, its MAD will sweep out an area 2 nm x 400 nm = 800 sq miles. It may be only half that, and there is a depth restriction, and it only works on steel subs. Unfortunately this long, narrow strip is not that useful. The MAD is a nice bonus, but it doesn’t work that well for the purpose of clearing an area of subs. The sonobuoys cover, I believe, 2 x 7 nm = 14 sq miles. (Or is it 1 x 5 nm ?) Placed in a dense pattern, 1400 sq miles can be covered. Unfortunately, the Orion then has to return to base for resupply. And by the way, although the pilot could probably do it in real life, you’re really not going to be able to get the Orion to search any appreciable area in the game under manual control. Now consider what a ship- or sub-mounted sonar can do. A good passive sonar has a range of about 25 nm, which gives a baseline of 50 nm. As the unit advances, say at a speed of 15 kn, it sweeps out an area of 750 nm. But as opposed to the aircraft, it can continue to sweep out this area hour after hour without resupply. And the area swept has a useful shape. The disadvantage is that the passive sonar detection probability is sufficiently low that you cannot guarantee that the area is actually clear of enemy subs. A good active sonar has a range of about 15 nm, which gives a baseline of 30 nm. As the unit advances, again at a speed of 15 kn, it sweeps out an area of 450 nm. It can continue to sweep out this area hour after hour without resupply, and the area swept has a useful shape. The active sonar detection probability is on the order of 50% per 30 s round. At 4 min per nm, each nm will be searched 8 times, so the probability of failing all the searches in that mile is only .25%. I think it’s fair to say that that region has been swept. It has been pointed out that if your sonar range is only 15 nm, and you are travelling towards a stationary, silent enemy sub, you will first detect it when launches the weapon that will kill you, and I that we can agree that that isn’t acceptable. But what about the convergence zones? My understanding is that active sonar works out there. Now we’re talking a 35 nm range for any decent sonar, 65 nm for a good one, and 100 nm for the best ones. Furthermore, if your ship or sub is travelling towards a stationary, silent enemy sub, it will see you regardless of whether your sonar is on or off. If your sonar is off, it is almost certain that you will first detect the enemy sub when it launches the weapon that will kill you. If your sonar is on, you have a good chance of detecting the sub before it kills you. In fact, this is the main argument for running with your sonar on! There is also the circumstance that the computer tends to shoot at the first opportunity. So in game terms, if you can defeat what the enemy is going to throw at you, you will want to make as much noise as possible, although this needs to be considered a flaw in the program. No real opponent is going to waste ordnance firing at the first possible opportunity. It has been pointed out that if your sonar is on, then many more enemy units will see you than if it is off. This gives them a better chance to coordinate attacks on your hunting unit. What can they throw at a ship? Lots of stuff: long range bombers, long-range missiles, and so forth. Ships are pretty vulnerable to all this stuff, although they do have defenses. What can they throw at a sub? Almost nothing. Bear in mind that you are assumed to have air superiority. If the enemy has air superiority, HE will be doing the sub hunting, not you. To be specific, there are only 2 possible threats to your hunting sub. First, the sub-launched ASW torpedo. But all these torpedoes have very short lethal ranges, and your active sonar will detect the enemy sub in good time. So there is only one threat that your sub actually needs to be concerned about, and that is the sub-launched stand-off missile/torp. Most Soviet subs carry this weapon, and a few US boats, but that’s all! Next I am going to show how the sub-launched stand-off missile/torp can be defeated, at which point your sub-hunting sub becomes invulnerable. The missile phase of the weapon appears to have no guidance. If the weapon is launched at maximum range (50 nm), traveling at 660 kn, and your sub flees at 30 kn when the missile is detected, your sub will have moved about 2 nm by the time the missile arrives where the sub used to be. Then the torp chases your sub at 38 kn. It needs 15 min to close the 2 nm gap at a speed difference of 8 kn. But this weapon (I am referring to the Soviet version) appears to have only 10 min (or less) of endurance, so your sub never gets caught. Each knot of speed above 30 that your sub can manage will have a dramatic effect on this calculation. However, this argument does not make your sub invulnerable; it merely demonstrates why you should never launch this weapon at maximum range. If we assume, as is reasonable, that the weapon will not be launched until your sub is within its lethal range, then you need to provide some additional air support in the way of a good fighter for the sub, and probably more than one fighter, and certainly you have to ensure a continuous resupply of fighters. How about a Tomcat at 80 miles? Phoenix missiles are free, right? Then it’s good-bye, sub-launched stand-off missile/torp, and then it’s good-bye, enemy sub. It has been pointed out that coordinating a hunter-killer group including a sub is not possible because a submerged sub cannot communicate with the outside world. But this is a doctrine, not a physical restriction. As early as WW II, subs were in communication with other subs, airplanes, ships, and shore stations. For example, Admiral Galatin discusses this in his book “Take Her Deep”. (He does point out that one of the reasons the German wolfpacks were ultimately unsuccessful was that their communications were monitored by the Allies, once the Allies had that technology.) The main reason why subs don’t communicate is that they don’t want to reveal their presence. Since I am advocating that the sub turn its sonar on, it may as well be in direct communication with its air support. And, oh heck, travel on the surface with active radar as well! What are we afraid of? We have air superiority. What depth the sub is at and what sensors it is using have no bearing on how vulnerable our sub is to the only weapon that can actually hurt us: the sub-launched stand-off missile/torp. To summarize, I claim that the optimum hunter/killer group for clearing a region of enemy subs is 1) Any fast sub with a good sonar. Its sonar will be ON. It may want to travel on the surface with radar active as well. The task of the sub is to either detect a stationary, silent enemy sub with the active sonar, or to provoke the enemy sub into taking some action that will reveal itself. Moving or noisy enemy subs will be revealed in any case. 2) A unit with a good SS radar whose primary task is to detect sub-launched stand-off missile/torps in the missile phase. 3) A good fighter to shoot down above missiles. 4) An ASW aircraft to exactly locate and then kill the enemy subs. Several of these requirements might be handled by one unit. For example, the F/A-18 (probably configured for the long-range air-air mission) covers 2 and 3. If nukes are in use, none of the above can be considered valid. It has been pointed out that anyone can sit here and propose theoretical tactics, and the only meaningful test is to try them out against a human opponent. I agree. However, I do not have the technology to do this at this time. Perhaps someone else will be willing to give it a try.
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