alex1
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Post by alex1 on Sept 30, 2014 18:44:30 GMT -6
Just speaking aloud….
Me and my buddy always consider that the Rate of Fire for Surface to Air Missiles is a little bit low, and we always wonder why is it, if there is a formula to get that number or is just a limitation to do the game realistic or whatever.
Just some examples:
Bunker Hill. SM2MR missile..AN 32.. it can guide 32 missiles at targets detected 75nm away
OH Perry. SM1MR missile..AN 3..only 3 missiles against targets detected 25 nm.
Type 42 Sea Dart.. AN 3.5.
Them subtract columns shifts from table 9.1.8b because of target speed and target transverse rate and the final AN (Attack Number) will be quite low.
Something similar happens with Shipwreck rules, and there is some discussion about it at yahoo groups.
Probably we are used to the higher Harpoon rates of fire, either paper, computer, and even harpoon captain edition, (Can Mr Bond be wrong with his model? Only the US NAVY knows), even computer games like Command Modern naval operations and Jane’s Fleet command gives a high Rate of Fire to SAMs.
In Harpoon paper rules, the first scenario, Target Practice, gives a good value of how many targets can engage each class, for OH Perry it goes from 6 up to 21 sea skimmer targets in three salvoes)
A few days ago, playing Command PC, a Kongo class fired 36 SM2 against 16 SS-N-22 sunburn salvo fired from two Chinese ships, (high speed and Sea skimmers) and survived.
In Modern naval conflicts it will be something like this:
Kongo Class DDG (Aegis+ 3 Directors). Attack Number for SM2 will be 32. (AN 32)
Max Radar line of sight from a Medium size warship to a sea skimmer missiles is 1 25nm hex.
From table 9.3.1.2 Target transverse rate, max range of 3 hexes from SM2 versus 1 Hex transverse within Weapon Range gives 5 additional column shifts to the right on Table 9.1.8 Part B
From Table 9.1.3.1 Missile speed Modifier.. For SS-N-22 Sunburn speed 22 correspond 5 additional column shifts to the right on Table 9.1.8 Part B. (Sovremeny data card list it as 4, probably a typo)
In Table 9.1.8 Part B there is no line for AN of 32, so you have to do 30 +2. Ten columns shifts means that Attack Number of 30 is reduced to 6, and Attack number of two is reduced to 0, so per rules aegis ships can only fire 6 SM2MR against supersonic, sea skimmer SSM,
From here I get, among others, two big conclusions: Either Aegis is a full or……. ....
I will do some maths with rates of fire and number of directors/channels, as well as speed from both missiles, but can you give your insight?
Thank You
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Post by williammiller on Sept 30, 2014 22:08:27 GMT -6
Alex,
I am not at home right now so I am answering part of this from memory, so keep that in mind please:
IIRC a single mid-80s Bunker Hill CG SM-2 system should have a 9 net AN against an incoming SS-N-22 salvo (I will have to double-check when I get home in a couple of days). When I first started to work on MNC I created a rather complex program that calculates the Attack Number (AN) value for each weapon system based on a number of factors (and assumed standards) that had to be determined and entered for each weapon system...it was simply too complex to easily calculate manually. [Please note that I cannot release the program as it is proprietary to NWS] Of course the typical USN carrier battle-group of the period would have 2 or 3 Aegis ships, likely 1-2 DD, an FFG, plus of course the weapon systems on the CVN itself; its total defensive capability would be much greater than that of a single Aegis ship.
Different games/simulations will look at things differently and come up with different values, I think that is a given. I frankly took a conservative approach with MNC, based on a number of reasons, one rather important reason being that history has shown that systems in combat almost never equal the results either calculated on paper or from peacetime tests.
I will note that the Aegis system, while it certainly had limitations, was very likely the best such system available for naval area air-defense purposes in the 1980s. It is also important to note that Aegis (and the missiles themselves) have been continually improved since the early versions (which should tell us that perhaps there was room for such improvement?) The USN has also added entirely new capabilities with the CEC (Cooperative Engagement Capability) and ESSM missile systems (along with other changes) on the modern Aegis ships, which are rather strong indicators to me that the Navy wanted (or needed) to improve certain aspects of the system.
As an example of the above changes, I calculated the SAM AN value for an Arleigh Burke Block II DDG a couple of years ago...in a typical formation with the current CEC implementation, each Burke would have an base AN value 40-50% higher than a 1980s Bunker Hill, and far more importantly would have a much, *much* higher net AN value against supersonic SS threats such as the SS-N-22 due to the effects of CEC and other improvements to the systems [this would of course require new rules in MNC to handle CEC and other technology changes of course].
Thanks!
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alex1
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Post by alex1 on Oct 1, 2014 18:00:23 GMT -6
I see your point, thank you. “I frankly took a conservative approach with MNC, based on a number of reasons, one rather important reason being that history has shown that systems in combat almost never equal the results either calculated on paper or from peacetime tests. “
I thought you would talk about warm up time of a system, as my brother usually do to explain low rates of fire in games, jane’s described that SA-N-7 system needs 16 to 19 second to fire the first missile if the system is alerted, about 3 min from cold start. OK. Another quick math: A typical SSM speed is about Mach 0.85 (Harpoon), Typical SAM speed is Mach 2.5 (SA-N-7, Sea Dart, Sea wolf, SM1MR) or about three times faster. First, We can say that any SAM system can fire three times, (at mach 0.85 you need a X time to travel a distance, mach 2.5 missiles can travel the same distance for three times during the same amount of time) . Limitations to this rate of fire will be number of directors/channels, ROF of the launcher and how long is the process of switching targets once one is destroyed/dropped. Second, generally AAW ships carry two or more directors with 1 channel each director, and later, more than one channel per director. So it isn´t simplistic to say that OH Perry with two director (STIR and MK92) can guide, been conservative, at least 4 SM1MR (two salvoes x Two directors) (a subsonic Mach 0.85 needs 2 minutes and a half to travel 25 nm, rate of fire of MK13 launcher is about 10 seconds per missile, and SM1MR needs aprox 1 minute to travel 25 nm). Looks like 6 SM1MR is the correct number, the first salvo will travel about 66% of 25 nm, and each subsequent salvo, as the SSM is closer, will travel less distance. IN modern naval conflicts the Attack Number for OH Pery is 3. Type 42 class with Sea Dart. It has two launches and two Radar 909 director (1 channel each director), same as above, been conservative 4 Sea dart can be launched but maths shows that at least 6 can be launched an guided easily, and still the operator will have some seconds to relax . In modern naval conflicts the AN is 3.5. Sovremeny Class, Two launchers and 3 Front dome to each side with at least 2 channels per director. Mach 0.85 you need 1min 55 sec to travel 18nm. SA-N-7 can travel 18nm in 39 sec.. Rate of fire is 2 missiles per 10 seconds, been conservative at least 12 missiles, two salvoes of 6 SA-N-7 guided at same time (3 directors to one side x 2 channels each director). In Modern Naval Conflict the AN is 6. Just my two cents. I’m sorry if this makes some inconveniences.
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alex1
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Post by alex1 on Oct 1, 2014 18:00:47 GMT -6
duplicated
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Post by williammiller on Oct 1, 2014 21:01:39 GMT -6
Hello Alex,
There are a number of potential factors which I am not sure you have considered; (1) for non-automatic missile systems the human reaction-decision-time-cycle can be significant (and which, while it can overlap with the re-target time of the machinery/software involved, can exceed that particular factor even in some of these older systems), (2) the time required to classify incoming missile threats and 'unlocking the system' to be free to engage (this could be in additional to any system warm-up time in certain cases), (3) even some "automatic engagement" systems during the 1980s time frame (and certainly many non-automatic systems) have demonstrated issues with 'faults', 'hard resets', and other engineering issues which can increase their overall response and re-target loop times on the average (or even cause them to fail and not engage at all), (4) if a SAM system is subject to jamming not only will the accuracy be degraded but the effective ROF will be reduced due to decreased information and target awareness levels; these are some of the 'other' factors that can reduce the effective ROF of such systems (and yes the warm-up time of certain systems can be an additional factor).
My calculation program determines the 'on paper' AN values and then adjusts that 'perfect conditions' value based on the above and a number of other factors (including certain known issues with particular systems)...all of that is rolled into the calculations to get a 'statistical' net AN value that accounts for such issues. I would submit that, for a manual war-game, this aggregation of a typical/expected level of such issues into the Attack Number is a reasonable method to address it without making the game far more complex with many more calculations required during game play.
Of course the great thing about a manual war-game is that, as players, we can adjust the values to what we think they should be...I have done this myself with a number of games, so I certainly would not be offended if others did so with my own work :-)
Thanks!
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Post by nukesnipe on Oct 8, 2014 15:55:59 GMT -6
A side note to William's discussion that probably is not factored into his calculations is missile fire doctrine. I don't know Alex's background, so I will apologize in advance if I step on professional toes. An FFG-7 class ship had 40 slots in her magazine. One was always left empty to allow for missile swaps; one always had a "blue bird" maintenance missile; and, four were generally reserved for Harpoons. That left 34 slots for SM-1s. SM-1s are semi-active homers, which means a channel had to be dedicated to a target for the entire engagment. As stated in the previous posts, the FFG-7s effectively had two directors. SM-1 missile fire doctrine at the time was "shoot-shoot-look-shoot". That translates to shoot two missiles and evaluate the kill (shoot-shoot-look). If you missed after the first two missiles, you would then shift to "shoot-look" to conserve your missile inventory (the third "shoot"). The two-missile salvo gave the SM-1 a probability of kill (pK) of somewhere around 80% (best guess, of course). A word of caution: you do not want to be the FFG-7 trying to shoot down an AS-4. When you finally get to the point where you can actually shoot at it, you'll lose it on radar. And, CIWS at the time would not have seen the missile once it entered its final dive. All the more reason to shoot the archer and not the arrows. SM-2, for a variety of reasons, had a "shoot-look-shoot" missile doctrine. I can't speak for foreign navies, but I suspect most of your non-Aegis platforms had a doctrine similar to SM-1 for similar reasons. Shooting at crossing targets severely restricts the range of an SM-1 as the nature of a semi-active homer places it in a tail chase nearly every time. So, while the missile might have a range of 25nm, against a crossing target you would be hard pressed to get half of that. Again, I suspect that would be true of foreign navies as well. As for the Aegis platforms, especially the vertical launch platforms, a lot of their magazine space was taken up with Tomahawks. With the high rate of fire of the VLS they could eat through their inventory very quickly. Also, the early Aegis system had a hard time against sea skimmers and targets in dusty environments. The original flight profile of the SM-2 traded chemical energy for potential energy by sending the SMs to a stupid high altitude; consequently, to counter a sea skimmer, they had to fly to stupid high altitude, then come back down and try to find the target in the back scatter from the ocean. As for dust, the system was so sensitive it would frequently alarm on atmospheric dust eddies. Not sure if this was helpful, but hopefully it was interesting.
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Post by williammiller on Oct 8, 2014 23:08:24 GMT -6
Scott,
Actually fire doctrine rules are included in MNC:
"9.3.1.4 Doctrinal Naval SAM Engagement Rule (Optional) ------------------------------------------------------- Each Navy has developed engagement sequences for its SAM systems that reflect certain system limitations and/or tactics. This generally has to do with firing a certain number of SAMs at a target, then waiting to determine the results of that fire before firing again; this is called the “Shoot-Look-Shoot” engagement doctrine in the USN, for example..."
So yes, that aspect is covered in MNC :-)
Issues you mention about the early Aegis system were factored into the formulas to calculate base and effective AN (Attack Number) values for early-era Aegis ships.
Thanks!
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Post by nukesnipe on Oct 9, 2014 10:54:36 GMT -6
Scott, Actually fire doctrine rules are included in MNC: "9.3.1.4 Doctrinal Naval SAM Engagement Rule (Optional) ------------------------------------------------------- Each Navy has developed engagement sequences for its SAM systems that reflect certain system limitations and/or tactics. This generally has to do with firing a certain number of SAMs at a target, then waiting to determine the results of that fire before firing again; this is called the “Shoot-Look-Shoot” engagement doctrine in the USN, for example..." So yes, that aspect is covered in MNC :-) Issues you mention about the early Aegis system were factored into the formulas to calculate base and effective AN (Attack Number) values for early-era Aegis ships. Thanks! William, MNC's been on my to-buy list for quite a while - I'm actually quite embarrassed that I haven't pulled the trigger on its purchase. The problem is that everytime I get ready to buy it someone puts 15mm miniatures on sale. Now that I've caught up on my miniatures purchases, this one has moved to the top of the list! Of course, if my wife ever opens up my game cabinet in the garage and sees all the miniatures I've been accumulating I'll probably not live to play MNC....
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alex1
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Post by alex1 on Oct 14, 2014 16:08:37 GMT -6
Final decisions
There are four range bands:
T0-T3 range x1 salvo ........................................less than two minutes of travel at 0.85 mach T4 to T 6 range x2 salvo.....................................more than two minutes of travel at 0.85 mach 1 long range msl x2 salvo....................................about 2min 30sec of travel at 0.85 mach 2 or more long range msl x3 salvo
Modifiers to multiplier: If the system is autonomous add +1 salvo. If the system uses I/M/TSARH and range is more than T2 add 1 salvo. IF SAM speed is +3.5 mach add +1 salvo
What is a salvo?..it is the maximum number of missiles a ship can guide at once depending on the number of directors (not weapons mounts). A ship with 1 director usually can guide only one msl., so count the number of directors and that is the number of missiles per salvo (in other words the number of missiles that can be guided at the same time).. For exceptions to this rule, there are directors that can guide more than one missile per director at the same time such as SA-N6 or SA-N-9, or Missiles with I/M/TSARH…google search, harpoon annexes or jane's books are good places to search is a director has more than one channel to guide SAMs.
So Bunker Hill in MNC has an Attack Number of 32.
With this rules the new AN is: 60
Each director can control 4 targets at same time (harpoon 4 rules). Only 3 director can bear to a single axis so the salvo is 12,the max number of missiles that can be guided at once. SM2ER can fire to long range>2 so x3, +1 for autonomous and +1 for I/M/TSARH, for a final x5…and a AN of 60 For kirov SA-N-6 each director has 4 channels at different targets, and there are two directors, so a salvo is 8, as it is long range (2x25nm hexes) multiply by 3, and +1 because missile is about Mach 4 for a total salvo modifier 4. The new AN is 32 msls.
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alex1
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Post by alex1 on Nov 12, 2014 18:28:19 GMT -6
I've done some more numbers, and I must admit my fault, in general AN in the ships forms are correct, again, I opted for a simplified model without taking into account launcher reload time. The premisses that I take care of are: The number of channels per directors Speed of targets and SAM. Reaction time since targets enters SAM envelope to first launch. For 20nm and up, delay is 30 sec to first launch, for 15nm and less delay is 15 sec (it is expected than sensors will detect the attackers before they enter the SAM envelope, allowing more reaction time). The reload time of the launcher is not that important, the builders of the system adapt their products, they won't do a high reload rate launcher and a single channel diretor, or al multiple channels dircector with a launcher that can fire once every minute and a half, that's no brain, and a waste of resources and money, so it's assumed that the numbers of launchers, rates of fire and directors are in concordance (except twin launchers in USS ticonderoga? ) The result is the following table: T0 to T2...........x1 salvo T3 to T6...........x2 salvo 1 Hex(25nm)......x2 salvo 2 Hex (50nm).....x3 salvo Modifiers If system is autonomous:....................... +1 salvo If system uses I/M/TSARH:..................... +1 salvo If sam speed is more than 2200 kts and range 1 Hex (25nm) or more...........+1salvo-----------------------speed is good but the operator still needs time to determine if target was hit, and selects another target. System IOC year 2000 or newer.............. and range 1 Hex (25nm) or more*...........+1salvo-----------------------the operator need less time to swicht targets. *If SAM system IOC is post year 2000 do not add +1 salvo modifier for speed more than 2200 kts., (you can't sum them together.) By comparing this with the AN number of ships forms I determine that I was wrong, they are quite similar, and as I said, this is a simplistic procedure, so if the designer have a complex formulae, I believe that their AN factors are quite correct. Thank you for your patience and devoted time, somehow I still think that AN for Aegis and Kiro's SA-N-6 are too low, but I reduce this feeling to only two systems, wich is great. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- . . ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- P.D. if the queue for new products is in standby, is there any possibility to release Arleigh Burke ship form?
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Post by williammiller on Nov 12, 2014 22:57:50 GMT -6
Alex,
Interesting setup for a quick method to calculate AN numbers for SAM systems.
Let me look over my Burke data and see if I can put together a form for that class this weekend. However, it is important to bear in mind that there are a number of rules that would need to be written/implemented to accurately model the *full* capabilities of such current combat systems, such as the USN Cooperative Engagement Capability (CEC), along with other very new and important ancillary systems. If I ever get an ultra-modern expansion out those rules would be included in that volume, of course :-)
Thanks!
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alex1
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Post by alex1 on Nov 21, 2014 17:46:21 GMT -6
Let me look over my Burke data and see if I can put together a form for that class this weekend. I hope that you find time this weekend, regards
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Post by williammiller on Nov 22, 2014 15:04:29 GMT -6
Let me look over my Burke data and see if I can put together a form for that class this weekend. I hope that you find time this weekend, regards Alex,
I had worked up a Arleigh Burke Flight I sheet but forgot to post it! Here it is. Thanks!
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alex1
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Post by alex1 on Nov 23, 2014 7:41:58 GMT -6
thank you
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