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kbluck
23 Apr 03, 16:41
I recently did a test of mortars. I used the Death Valley Defense since it provides mortar units and a bunch of convenient dismounts to fire them at right at the beginning of the scenario.

The mortars started the scenario in a position area formation. As soon as possible after the clock started (0:05) I paused and assigned 10 WR fire missions to the platoon, HE converged with 5 volleys each, thus exhausing the ammo supply of 50 rounds.

Fire missions assigned: 0:05
First shot: 3:31
50th shot: 40:15

Now, accounting for the 15 second shot time adds up to 750 seconds or 12:30. So, computing and traversing took a total of 27:45. Divided among ten missions, that's about 2:46 compute and traverse per mission. That jives with the typical 2:40 I was observing in between last shot of one mission and first shot of the next. The extra 5 sec on the average value is from that additional 45 seconds or so required for the first shot. I've noticed all artillery seems to have an certain extra "spinup" time for the first shot from a new position area.

At any rate, this seems to be at odds with the values in the vehicle specs of 60 sec compute, 40 sec traverse. The 15sec shot time seems accurate, though.

On another note, after expending all 50 rounds on 10 dismount targets, I had not a single kill to show for it. I observed four brief suppressions and some displacements, but that's about it. I'm not sure what "accuracy 70%" transates into in terms of CEP, but I did notice the shots wandering from nominal target about 50m or so.

So, I was wondering: are mortars really that ineffective? Have the armies of the world been wasting their money and manpower fielding them? Was I just unlucky? :( Hmm...

Thanks,

--- Kevin

Pat Proctor
23 Apr 03, 23:24
At any rate, this seems to be at odds with the values in the vehicle specs of 60 sec compute, 40 sec traverse. The 15sec shot time seems accurate, though.

You also have a time of flight between the time you plan the mission and the time the first round impacts. This varries based on the weapon type and range. Mortars are high angle weapons (as opposed to artillery, which can fire low angle <below 45 degrees> or high angle <above 45 degrees>). High angle fires take longer to go up and down.

Could this have accounted for the missing time?

120 mm mortars are less accurate than 155mm howitzers because:


the round is lighter and more affected by exterior effects such as weather and wind.
the round fires high angle, so is outside the tube longer before impacting (again, meaning more effects from weather)
the muzzle velocity of the weapon is lower, again meaning exterior effects have a greater impact on the round.


The 70% is a in relation to 155mm.

Other causes of your lack of effects are the number of rounds you are placing on the target. If you look at the database for the 120mm HE round, you will see that it is 50% of a 155mm round (these are SAWE II MILES <the NTC simulation of weapon effects> numbers, not ours). The number is based on the ammount of explosive, velocity of impact, and other impirical data.

Also according to the weapon database, there is a 17% chance that a 155mm HE round within the burst radius of an enemy fire team will cause a kill. For 120mm, it is half this, or 8.5%.

Next, you only have two mortars firing. They fire faster, so you will probably get 4 rounds out before the OPFOR moves out of the blast radius, but the average artillery mission is at least a battery mission, 6 rounds.

Finally, the burst radius of a 120mm HE is 20m, while the burst radius of a 155mm is 50m.

So we have 70% the accuracy, 50% the lethality, 66% of the rounds fired by artillery, and 40% of the burst radius. That means that your mortars are 9.24% as effective as a single artillery battery firing a 1 volley mission.

To answer your question, yes, mortars are kind of ineffective. Mortars are fair suppression weapons and they are hell on large infantry formations caught in the open. But, to destroy targets, artillery is the indirect fire killer on the battlefield.

kbluck
24 Apr 03, 03:22
You also have a time of flight between the time you plan the mission and the time the first round impacts...Could this have accounted for the missing time?

No, I was marking the clock at the exact moment of firing. I really wasn't paying attention to the splash times. The 2:40ish figure was time between last round fired of one mission and first round fired of the next mission. That's about 45 seconds longer than I would have expected reading the vehicle specs, not to mention the additional 50 seconds required for the very first shot.

I'm curious --- is there any reason these times aren't overlapped? What is the FDC doing while guns are traversing and missions are being fired? Does it actually take a 155mm gun an extra 45 sec to shift to a new target in addition to the load time? Can't they be computing, traversing, and loading all at once? Or are you abstracting something else, like commo time and other miscellaneous inefficiencies?




So we have 70% the accuracy, 50% the lethality, 66% of the rounds fired by artillery, and 40% of the burst radius. That means that your mortars are 9.24% as effective as a single artillery battery firing a 1 volley mission.

Let me ask you this: using your MILES standards, has anybody ever been "killed" at NTC using mortar fire? How many purple hearts have been awarded to victims of mortar fire? Now, the game. Have *you* ever succeeded in killing a fire team with mortars in your game? Has anybody reading this? Do these results seem consistent?

OK, I understand that mortars would be considerably less effective than 155mm. But, a volley of HE falling on a dismount is pretty effective. Just as a snap calculation, I'd say six 17% chances of a kill adds up pretty close to 70%. So, 10% of that effectiveness is still quite significant. You'd expect an even chance of getting a kill at least every dozen missions or so.

Not in my experience. I just now ran repeated save game trials of mortar impacts, probably about 50 repetitions (I lost count.) Add that to the numerous missions I've played, and I'd say I've put more than 100 mortar fire missions on target. So far, I've got *0* kills to show for it. The only noticeable effects are target units displacing and the occasional brief suppression, lasting a few seconds, not even long enough to get a unit out of defilade.

I still find it hard to believe that mortars are *that* ineffective. Hitting a T-80 with ICM is also about 10% as effective as hitting infantry with HE according to vehicle specs, yet I've killed plenty of tanks with artillery. The utter futility of mortar fire in the game just doesn't seem right to me. Either I'm phenomenally unlucky, I'm doing something wrong, or the modeling for mortars isn't quite right.

--- Kevin

Pat Proctor
24 Apr 03, 04:07
I would, point out that you have two mortars, rather than the MTOE 4 that an armored task force normally has. That would double your chances of a kill.

You might also check the targeting of your rounds. The burst radius of a 120mm is 20m, which is only 1 pixel at 1:50,000. It is entirely possible that some of those 100 missions are just plain missing. You might try zooming way in (like 1:12,500) when you target your mortars.

I am open to the possibility that something is wrong with the model. I will run a few tests tomorrow. I do hope it is not a bug:mad:

kbluck
24 Apr 03, 12:39
You might also check the targeting of your rounds. The burst radius of a 120mm is 20m, which is only 1 pixel at 1:50,000. It is entirely possible that some of those 100 missions are just plain missing. You might try zooming way in (like 1:12,500) when you target your mortars.

My first thought about all this was that I wasn't targeting right. I routinely zoom in as far as possible when planning any fire mission for any battery, and I place the crosshairs dead center of the NATO icon. BTW, I've noticed that you have to position the mouse a little south of where you actually want the crosshairs to go. It would be very helpful to have a ghost crosshar repace the mouse cursor during fire planning mode, both to see where you're aiming before clicking and to remind you that you're in that mode. I still forget to turn it off occasionally, click on something else to select it and have to cancel the resulting bogus fire mission.

Am I correct that fire missions get 8-digit grids, and so have a max precision of 10m no matter how carefully you manipulate the mouse? Just curious; I know that artillery won't be much more precise than that anyway. It might be nice to include that grid in the "info" dialog for unit properties, both friendly and enemy.

I can actually see that mortar fire routinely misses altogether, in the sense of deviation from the planned target. That certainly doesn't help, but at least I can understand what is happening there.

Thanks,

--- Kevin

Pat Proctor
24 Apr 03, 18:52
I can actually see that mortar fire routinely misses altogether, in the sense of deviation from the planned target. That certainly doesn't help, but at least I can understand what is happening there.

The combination of less accurate and smaller burst radius conspires to make this common. That's why you really need at least four tubes to be effective.

kbluck
28 Apr 03, 20:46
Another issue I recently noticed. Mortars seem to have problems with "Immediate" fire missions. When I assign one, I notice they get "stuck", never processing the mission. As soon as you cancel the immediate mission, they go back to working the WR missions normally.

--- Kevin

Pat Proctor
28 Apr 03, 22:18
It may be another bug with mortars that we have ID'd and are fixing in 1.02. First, the mortar min range is set at 2000m instead of 200m and, second, if you fire at 2000m or less, instead of denying the mission, the mission "hangs" preventing any other missions from firing.

But we will check it out, just in case you have found a different bug.

kbluck
29 Apr 03, 02:43
FYI, the range on the immediate mission was about 5000m.

I thought 2000m seemed excessive for a minimum range, but didn't really think about it.