Using German 75mm infantry guns in indirect fire mode

[c2yeung]

I always use infantry guns as direct fire weapons. When used in on-map indirect fire mission, the shells for their flat trajectory hit obstacles, be it a tree, a building or higher ground, in front of the guns. The guns do not operate like howitzers. Questions: Did anyone use them successfully as on-map indirect artillery? If they are not meant to be used as indirect artillery, they should not be made available on the artillery menu. Correct?

[altipueri]

I think CM maps are mostly too small for indirect fire other than mortars. Even then some one has to have LOS don't they? You cannot blast bit of a map unless someone (with fire authority and contact or whatever) can see the target.

[YankeeDog]

It's possible to use them for indirect fire, but it requires the right placement on a fairly large map.

I suspect it's something that might become more useful as we move to the East Front game, and see larger maps with more open terrain.

[MikeyD]

I just gave them a try in the game. The LeIG18 infantry gun seems 'ideal' for CM indirect fire use. The round is so slow and the arc is so high that the rounds easily clears intervening terrain. The closest allied equivalent is 75mm pack howitzer which fired a much bigger charge so doesn't get such a high arc in flight. Another good indirect fire weapon is sIG33 150mm which also has a tall slow arc to the big round. I recall there's a scenario that starts out with the AI on-map 150mm guns indirect-firing on distant Normandy beaches. No, you can't do extreme angle firing.

[John Kettler]

YankeeDog,

We've been down this road before. I believe it was ArgusEye who ran the numbers and concluded the Rmin for the leIG 18 was of the order of 600 meters, with the siG 33 in the 700 meter range. Yes, that's well within Direct Fire range, but I'm talking Charge 0 and 73 degrees elevation for Indirect Fire. Therefore, there's no fundamental physical reason both weapons couldn't be used for Indirect Fire on even a Small map. But physical real world capability isn't necessarily the same as representation in the game. There may be coding limitations to address, but I've previously presented a case in which a siG 33 battery first used Indirect fire on a fog shrouded ravine from which a great deal of Russian vocal noise was being heard. An effective shoot (lots of screams) was conducted, but it wasn't enough to stop a regimental strength infantry attack which eventually forced the sIG 33 battery to switch from Indirect Fire to Direct Fire to beat back the Russian assault.That whole engagement, were the Rmins I listed permissible, could easily be depicted on a multitude of maps.

Regards,

John Kettler

[akd]

The core limitation is that there are no variable charges in game.

[YankeeDog]

The core limitation is that there are no variable charges in game.

That's not entirely true. If you watch on-map mortar trajectories, they clearly model variable charges -- short range trajectories are much slower and lower than long range trajectories.

I have no idea whether it's even technically feasible for the variable charge coding used for mortars to be applied to infantry guns & light howitzers, tho.

[c2yeung]

From all your replies, it is good to know that the infantry guns can be used in indirect fire mode with of course with a forward observer with LOS provided the guns are placed correctly, I guess that means open terrain with preferably no obstacles in their immediate front so as to allow the shells to travel in a arc. When using them in direct fire mode, I found I have lost the guns' advantage of long range engagement. In indirect fire mode, I can place the guns way behind the front line without exposure to enemy fire other than counter battery.

[akd]

That's not entirely true. If you watch on-map mortar trajectories, they clearly model variable charges -- short range trajectories are much slower and lower than long range trajectories.

I have no idea whether it's even technically feasible for the variable charge coding used for mortars to be applied to infantry guns & light howitzers, tho.

Sorry, I meant specifically for IGs/howitzers, which have to be capable of low-trajectory direct fire, which is not an issue with mortars. Mortars use the same trajectories whether firing direct or indirect.

[Quintus Sertorius]

I love watching those slow 7.5cm IG rounds float through the air. They seem to take forever to reach their target.

FWIW, I've successfully used the 7.5cm IG for indirect fire on a couple of occasions.

[YankeeDog]

Sorry, I meant specifically for IGs/howitzers, which have to be capable of low-trajectory direct fire, which is not an issue with mortars. Mortars use the same trajectories whether firing direct or indirect.

Ah. So the problem is not variable charges as such, it's creating code which would allow the gun to "know" when to use high-angle fire, and when to use low-angle fire. Makes sense.

[Erwin]

If the gun can't see the target, how can you use the gun to target the desired unit/object? I thought all CM on-map guns could only fire direct. (I have only seen indirect fire work by accident in CM, when the shell missed the target and kept going.)

[HistoryLover]

C2yeung,

the problem is, that the gun does not recognize that it's firing into an obstacle. Using on field guns in indirect fire role works very well, but you must make sure to give their trajectory a buffer to the highest obstacle. Do not aim at the nearest possible action spot but imagine the target area must be a few meters further away - and also place the gun in setup accordingly.

As a general rule: the further they are placed away from obstacles in their planned firing direction, the bigger their potential target area becomes.

It would help players to understand these issues better, if the game would draw an approximated trajectory when the player is aiming.

[Michael Emrys]

If the gun can't see the target, how can you use the gun to target the desired unit/object?

The same way I use onboard mortars now, I guess. Have someone with a radio close to the gun and use a spotter who also has a radio. Haven't tried this yet, but I can't think of a reason why it can't work.

Michael

[Lt Belenko]

The same way I use onboard mortars now, I guess. Have someone with a radio close to the gun and use a spotter who also has a radio. Haven't tried this yet, but I can't think of a reason why it can't work.

Michael

I just tested it and it works. Indirect Fire is permitted for german infantry guns and pack75s. I had always thought mortars were the only on-board units that could use IF.

I made a long 1400m board and placed a line of level 4 houses near one end. I positioned 4 pack75 at varying distances behind the houses and a FO on level 3 of a house looking down range. Depending on the distance behind the house the min range that IF could be used varied.

6 square behind houses - min range greater than 1320m* (could not use IF)

10 square behind houses - min range greater than 1350m* (could not use IF)

13 square behind houses - min range 1000m

17 square behind houses - min range 750m

*NOTE: These range limits are just the map I made. Extending the map could get different results. And I'm too lazy to retest.

[MikeyD]

In CMFI the 45mm Breda AT gun is also permitted to do indirect fire but the trajectory's so freakin' flat that there's not much you can do with it. I did manage to indirect fire over some low stone walls that were blocking LOS halfway across a map once. But Italian lack of radios makes that a difficult trick too. I think it was only v2.12 (perhaps v2.11) that Charles finally gave up on on-map 88 flak having indirect fire capability.

[Erwin]

That is amazing news. From the very start I had always thought that onmap guns (as opposed to mortars) could not indirect fire. Stunned this was never discussed b4.

Presumably however, the same is not true for HE AFV's since an HQ or FO can't communicate with em(?)

[Saferight]

The german recoiless rifles have the same ability as well. Ive used them to good effect before.

[YankeeDog]

That is amazing news. From the very start I had always thought that onmap guns (as opposed to mortars) could not indirect fire. Stunned this was never discussed b4.

Presumably however, the same is not true for HE AFV's since an HQ or FO can't communicate with em(?)

It's actually been discussed quite a bit. Guess you were out sick those days.

It's certainly *would* be possible for certain types of AFVs to set up for indirect fire within the context of a CM scenario, especially in longer scenarios on larger maps. But there would need to be new features added to the code so this functionality couldn't be gamily abused.

I would assume primary reason it's not allowed for AFVs is that a vehicle would have to register its own location before engaging in direct fire; it definitely would not be realistic to have SP guns just flying around the battlefield, engaging in indirect fire without significant setup delay. Modern AFVs built for indirect fire can do this, but not their WWII ancestors.

Many WWII SPA vehicles also had restrictions on the elevations and/or bearings upon which they could execute direct fire without aids like earthen ramps to create additional elevation.

With infantry guns and howitzers, putting up the aiming stakes etc. indirect fire registration can probably be assumed to be a part of the gun setup time.

[Lt Belenko]

It's actually been discussed quite a bit. Guess you were out sick those days.

It's certainly *would* be possible for certain types of AFVs to set up for indirect fire within the context of a CM scenario, especially in longer scenarios on larger maps. But there would need to be new features added to the code so this functionality couldn't be gamily abused.

I would assume primary reason it's not allowed for AFVs is that a vehicle would have to register its own location before engaging in direct fire; it definitely would not be realistic to have SP guns just flying around the battlefield, engaging in indirect fire without significant setup delay. Modern AFVs built for indirect fire can do this, but not their WWII ancestors.

Many WWII SPA vehicles also had restrictions on the elevations and/or bearings upon which they could execute direct fire without aids like earthen ramps to create additional elevation.

With infantry guns and howitzers, putting up the aiming stakes etc. indirect fire registration can probably be assumed to be a part of the gun setup time.

I have moved mortars and then used them for indirect with no delay for alignment to a stake or KRP.

[YankeeDog]

I have moved mortars and then used them for indirect with no delay for alignment to a stake or KRP.

It's probably not completely realistic that mortars are allowed to execute called fire missions without a delay of at least a couple of minutes to establish a registered position when they move.

With this said, light and medium mortars fire over much shorter ranges than most other indirect assets and it usually takes much less time to register a mortar for indirect fire than it does a gun or SPA, especially if the move from the prior position is fairly short.

Further, CM doesn't let you do things like send the mortar section NCOs to move ahead of the mortar crew(s) to scout the new location and start establishing coordinates. Mortars also often pre-mapped and prepared alternate firing positions, something CM doesn't explicitly model.

Of course, many of these tactics are also applicable to guns and SPA, but with heavier stuff they generally take much more preparation since the guns/vehicles are heavier, generally require more time to set up for firing, and also have to register more precisely due to longer typical engagement ranges.

So overall, it doesn't bother that light and medium mortars can shift position and be available for indirect fire calls quickly, but on-map guns take much longer to do this and SPA can't currently do indirect at all.

I *would* like to see indirect fire from SPA added to the game at some point, and also better modeling of indirect fire from on-map guns. This becomes more important as the maximum map sizes increase. But I don't see this as a particularly high priority.

[Michael Emrys]

With this said, light and medium mortars fire over much shorter ranges than most other indirect assets and it usually takes much less time to register a mortar for indirect fire than it does a gun or SPA, especially if the move from the prior position is fairly short.

Indeed. My impression is that, especially with company assets, the mortar crew already have a pretty good idea of where they are at, where the calling officer is, and where he wants the rounds to land. So by guess and by gosh they can figure out the range and bearing pretty quickly, add some yardage for windage and danger close and drop a spotting round in. Then from that, the FO can talk them onto the target. (I believe it was also standard practice for troops within one or two hundred meters of the enemy position to take cover when a round was on the way, if they hadn't already. )

Michael

[Erwin]

Re indirect fire when using a FO or HQ... With a heavy weapon platoon one generally has a platoon HQ (usually 4th Platoon) and maybe a section HQ.

I am never sure whether the 4th Platoon HQ is the one that needs to go and be the spotter while his section HQ stays behind to communicate with the mortar(s) or gun(s). Or is it the section HQ that goes and spots while the platoon HQ stays with the mortars/guns?

Or do both heavy weapons HQ's need to stay with the mortars/guns while another HQ or FO does the spotting? Which is most efficient/appropriate?