First i want to thank Tony for new Model and Dale for explanation about Gunnery in H4 and for providing his Gun Spredsheet. He says it is under development/beta. But i think atm it fits for the purpose.

 

 

The Gunnery in H4 is based on 1 Minute bursts. So all values are based on this.

 

I´ll take the 127mm MK30 as my example. And the russian 100MM BU-34.

 

 

Bu-34 has a Range of 8.8 nm,a near ph of 35 and far of 18

MK30 has a Range of 8,3nm, a near ph of 25 and a far ph of 13

 

Acording to navweaps.com the ROF is

 

BU-34 = 12 with 26 Ready Rounds on the Mount and 850 rounds on a Riga Class FFL for 3 Mounts (772 in the magazine)

MK-30 = 15 with XX (needs to be evaluated/no source atm) Ready Rounds on the Mount and xxx Rounds on a Fletcher Class DD with 4 Mounts

 

Old HCE DB /HCDB Values:

 

Mount: Bu-34, ROF 1, Rounds 120 Tubes 1 Targets 1

Weapon 100mm Burst Range 9.5 Near PH 65, Far 33, DP 24

 

Mount: MK-30, ROF 1, Rounds 120

Weapon: 127mm/38 Shell Range 8.3 Near PH 25, Far 13, DP 6

 

 

Actual Values as used in the DB for Guntest2

 

Mount: BU-34, ROF 12, Rounds 26 1 Tube 1 Target

Weapon: 100mm/56 Shell Range 9.5 Near 10, far 5 DP reduced to 3 from 24

Ship Magazin 722 Rounds (spreaded into 255 portions)

 

 

Mount: MK-30, ROF 15,Rounds 120 (needs to be changed) 1 Tube 1 Target.

Weapon: 127mm/38 Shell Range 8.3 near PH 6, far PH 3

 

[2007-11-29 21:46:35] <Rene> can we go trough the sheet?

[2007-11-29 21:46:36] <VCDH> remember it's for H3

[2007-11-29 21:46:39] <Rene> yes

[2007-11-29 21:46:40] <VCDH> sure

[2007-11-29 21:46:41] <VCDH> take ur time

[2007-11-29 21:46:51] <Rene> http://www.navweaps.com/Weapons/WNUS_3-62_mk75.htm

[2007-11-29 21:46:59] <Rene> 76mm oto melara

[2007-11-29 21:47:09] <Rene> 80-85 rounds/minute

[2007-11-29 21:47:14] <Rene> take 80?

[2007-11-29 21:47:25] <VCDH> depends...up to 120 in some models

[2007-11-29 21:47:45] <Rene> yes for the sr/super rapido

[2007-11-29 21:47:55] <Rene> but not for the normal /mk 85

[2007-11-29 21:48:03] <Rene> mk75

[2007-11-29 21:56:12] <VCDH> Mk75 can do 120 according to the guide

[2007-11-29 21:57:15] <Rene> ok

[2007-11-29 21:57:17] <Rene> sure?

[2007-11-29 21:57:23] <Rene> h4 guide?

[2007-11-29 21:57:30] <VCDH> Guide to World Naval Weapons Systems

[2007-11-29 21:57:32] <Rene> or indepentant source?

[2007-11-29 21:57:36] <Rene> ok

[2007-11-29 21:57:40] <Rene> Near Far

[2007-11-29 21:57:40] <Rene> Estimated H3 Pro Surface PK 0,016 0,008 per second

[2007-11-29 21:57:40] <Rene> Estimated H3 Pro Air PK 0,133 0,083 per second

[2007-11-29 21:57:41] <VCDH> actually it says the gun made 139 rounds per minute on testing

[2007-11-29 21:58:00] <Rene> those values are the SR values...

[2007-11-29 21:58:24] <Rene> only 2 % hit?

[2007-11-29 21:58:37] <Rene> or am I wrong?

[2007-11-29 21:58:38] <VCDH> it's based on a cumlative average

[2007-11-29 21:58:53] <Rene> what do you enter in the db?

[2007-11-29 22:00:45] <VCDH> stand by

[2007-11-29 22:01:06] <VCDH> ok u see the 2 tables on the right?

[2007-11-29 22:01:20] <VCDH> take the 'Variable PK' table

[2007-11-29 22:01:40] <VCDH> change the PK values until the 'Difference' row reaches 0 for all 4 colums

[2007-11-29 22:01:51] <Rene> yup

[2007-11-29 22:01:54] <VCDH> but u have to change the average to take into accoun the number of shots

[2007-11-29 22:05:04] <Rene> so 10% for the db instead of 65 from the rules?

[2007-11-29 22:05:31] <VCDH> yeah because the gun shoots every second

[2007-11-29 22:05:42] <Rene> ok

 

 

 

Sumary:

 

Whant needs to be done in the dbs?

 

1. increase the ROF to real world values (if ROFreal > 255 = n Shells per burst to get ROFgame <255)

2. fit the Rounds per Mount to real world values (if Roundsreal > 255 = n Shells per "Round" to get Roundsgame <255)

3. weight n Shells from 1. and 2. to get a reasonable result

4. decrease ph values

5. check DP Values

6. add Magazine Entrys to match/get close to real loads.

Harpoon_3_Gun_Model_v0.1.xls

From Dale Hillier (aka VCDH) at AGSI:

 

Hi Guys,

 

First things first, I’m claiming intellectual property rights on this spreadsheet. Please ask me for permission modify it and credit me when you do. We’ve had problems in the past with people stealing other guy’s work and I’m not going to take a chance on having it happen to me. There’s only one person that we have to worry about but, like most things, it only take one to ruin it for the rest of us.

 

Finally, this is the very first version of the sheet. There is a lot of work left to do and there’s probably some errors that I have to fix to get these values right. It’s meant mainly as a demonstration device and was build for ANW. So keep that in mind.

 

The spreadsheet that I ginned up here was the result of some modeling issues we’ve been having in H3ANW about guns. I’m not as knowledgeable about HCE as I am about ANW so please bear with me while I describe how the gun model in ANW works.

 

In ANW the gun model uses a mount to fire, and a magazine to feed from. Both use weapon records, which tie into the actual weapon that the gun is. In ANW, the ROF of both the mount and the magazine can be controlled so we can model both gun rate of fire and mount reload (once the on mount ready ammunition has been expended).

 

The ROF settings in ANW are set to integers only so we can’t model a ROF of greater than 1 round per second. This means that for the guns with a higher rate of fire than 60 RPM we need to change the concept of the weapon from a single ‘round’ to a burst. For the weapon this is only a change in name. For example:

 

127mm/54 Mk45 AAW Round

or

40mm/70 Bofors Fast Forty Twin AAW Burst

 

Now here is where it starts to get complicated. Like HCE, ANW uses ATA values to determine PH values against a target. These values are derived from the Master annex that I have been provided to me by the powers that be….but….the values generated in the Masters are based on the 30 second engagement turn that is used by the paper rules. When you are working with an ROF of one second, this means an increase in PH of about 30 times the normal ATA. For a gun like the 76mm Super Rapido with an ATA of 2.5/0 (with 0 being the base PH of 30%), then you get a gun that is disproportionate in effectiveness.

 

This was borne out in a scenario I did back in October when I recreated the Battle of Latikia (1973 Yom Kippur War). I positioned several Styx SSM batteries on the coast of Syria as an added variable to the Israeli missile boats. There were 6 boats for a total of 8 76mm Compact mounts (ATA of 1/-0.5). Twice did the Syrian coastal batteries get to launch on the Israeli patrol boats and the 76mm guns knocked out most of the incoming missiles. In fact of the 12 missiles fired, 9 were shot down by guns, 2 missed, and 1 hit a missile boat destroying it. Now the Israelis were lucky in that they got early warning so it’s hard to say what would have happened if there was no prior warning, especially since it was at night

 

The results were a little unrealistic to say the least, so I emailed Larry Bond and asked him what he thought of the results. He wasn’t very enthuastic to say the least and advised me to lower the values to something that I was more comfortable with. So being the crazy harpoon guy that I am I went about it in a mathematical way.

 

The first thing I had to do was develop a set of variables to model the gun engagement. In modern naval warfare, guns are mainly AAW weapons and in the age of greater stand off weapons, this means missile defense. So I decided that the model would be using missiles as targets.

 

Next I had to determine just what kind of missile to use. This is really dependant on the time the gun was developed so in the case of a 76mm Compact, the main missile it would have defended against was the Styx missile. That gives me some rough performance data to use. For other guns I would use the Exocet and Harpoon missiles but not the high flying missiles like the SS-N-12 because the gun probably wouldn’t be very effective against such a missile.

 

The third set of variables was gun performance. Now actual gun performance is classified and I wasn’t interested in calling up OTO-Melara because they’d call CSIS and the last thing I need is the Mounties checking out my garbage, finances, and being the subject of yet another background check (which is a bigger pain in the ass than you might think it is), so I used public sources.

 

It turns out that gun manufactures determine PK from the number of engagements and that each engagement is composed of a set number of rounds fired. However it takes time for the ships combat system to detect a target, hand off that target to the gun director and for the gun director to train out the gun and start blasting. So I gave each one of those values a time of 1 second (the lowest possible in ANW). We can assume that, in a for-real engagement vs. a missile, the gun system (gun, director, and combat system) will be aware of the threat axis and will have the gun loaded and trained out. We can also assume that once the engagement starts, the gun will be firing constantly against a missile until the target is destroyed or over (or in) the ship.

 

Now I had to figure out the rate of fire of the gun and the number of round it takes to constitute an engagement. A good example here is the Bofors 57mm SAK Mk2 gun that is used on Canadian Halifax class frigates. The gun has 120 rounds on mount and Bofors claims that is sufficient for 15 to 20 engagements. This equates to a 6 to 8 round burst or about 2 seconds of firing time.

 

Finally we had to determine the number of shots that the gun would get based on its response time vs. the speed of the missile. In ANW, all gun rounds travel at a flat rate of 1000m/s so I could also model flight time to impact. Then there is the determination of the director whether or not the target is destroyed. This is a ‘shoot-look-shoot’ process that I set at one second.

 

The spreadsheet I developed takes these variables into account and calculates the total amount of time it takes for the gun to complete what I call the ‘engagement cycle’. Typically this is usually between 4 to 7 seconds. Once you take the range of the gun (3.5nm for the SAK Mk2) and the speed of the Styx (305m/s) into account then you the number of engagements, or shots, that the gun has against a missile. In this case:

 

Gun Range in Meters / Speed of Missile = Seconds from Rmax to impact

Seconds to Impact / Gun Engagement Cycle Time = Number of Shots.

 

The last part of this process is the modifier for the Masters ATA. I couldn’t just divide by 30 because that would not take into account the cumulative PH over time. So I generated a table to develop the cumulative average for the whole 30 seconds that take up the engagement turn in the paper rules. But since you get a specific number of shots then I had to modify the ATA to take into account the fact that the ATA is now spread over the total number of shots. I averaged out the values based on that shot number.

 

The problem is that I haven’t found a way to automate the changing average. So you have to manually change the average value in the tables. Hopefully I’ll be able to get some time on that before Christmas.

 

Either way you get a much lower value for ATA than what you get in the Masters. Usually around –2.7 or around 3% for PH. What this means is that, for the slower missiles like Styx you should be able to get one out an attack by less than 6 missiles. Against the big supersonic missiles you can forget it, as you won’t have time due to their high speed.

 

I’m not 100% certain about the model yet. I strongly suspect I’m going to make some changes to it to give more emphasis on ROF than actual PH values. But one thing at a time.

 

Once again, I’d like to point out that this was developed for ANW so you’ll have to take into account some of the differences between ANW and HCE.

 

Finally, I’ll add again that I’m claiming intellectual property rights on this spreadsheet. Please ask me for permission (and I’ll give it, but you have to ask) to modify it and credit me when you do. I’ll be happy to answer any questions you might have.

 

Later

D

--

Dale Hillier

Merchant Mariner

AGSI RD&T