Indirect fire with on-map guns

[Xavierisback]

Thank you BFC for these great piece of software

Just a little question but it's may be a subject you know.

I made some quick test with the german ig18 infantry gun. It seems to me this gun is a howitzer but it seems it always act like a gun. I mean the shell don't have a bell curve trajectory. With this minor restriction the gun is quite less effective no?

[panzermartin]

The 75mm is almost useless in indirect role. It keeps hitting trees or hills with its low flying shell trajectory. I have a significant better (not ideal) epxperience with the 150mm siG.

[YankeeDog]

Yeah; I wondered about this... I haven't played much with indirect-capable on-map guns yet.

I can see how it might be tricky to program this right, as howitzers like the sig18 can choose to use either low-trajectory or high-trajectory fire at many ranges. Ideally, which one it chooses should depend on terrain, weather, and target type.

But if anything, when firing indirect, the game should probably default to choosing the higher trajectory option at most ranges, to avoid the aforementioned problem of hitting intervening terrain.

[StellarRat]

I could be wrong about this, but it seems to me the maps are too small to employ anything other than mortars in indirect fire. I doubt if the other arty can elevate high enough to drop the shell on the map even with a weak charge.

[YankeeDog]

I could be wrong about this, but it seems to me the maps are too small to employ anything other than mortars in indirect fire. I doubt if the other arty can elevate high enough to drop the shell on the map even with a weak charge.

Yep; you are wrong. (No hard feelings, I hope )

It is true with *most* guns would have difficulty firing indirect on a cm-sized map.

But the german leIG and sIG guns (75mm & 150mm, respectively), and to a lesser extent the American 75mm pack howitzer and M2 105mm howitzer (latter two not depicted on-map in CMBN, AFAICT), have the combination of very low velocity and the ability to elevate the barrel well above 45 degrees, the combination of which enables them to execute quite short distance high arc shooting.

The leIG 18 for example, has a muzzle velocity of only 210 m/s, and a maximum elevation of 73 degrees. *Maximum* range for the gun is about 3.5km. I'm to lazy to do the exact calculations, but with the barrel elevated all the way to 73 degrees, the shot would obviously be falling much shorter than this.

Edit: did a very rough calculation.. w/out air resistance taken into account, a projectile shot at 210 m/s at an angle of 73 degrees would fly for about 39 seconds, and hit the ground about 2.3 kilometers from the gun. Air resistance would shave a fair bit off of this, but I can't calculate that exactly without knowing the specific aerodynamics of the projectile, and in any event that's a much more complicated equation. I passed AP physics class 20 years ago, thank you very much.

[StellarRat]

2.3 kilometers! Are there any maps that size in CMBN?

[YankeeDog]

As I noted, actual minimum (high-trajectory) range would be somewhat less than 2.3 km, due to air resistance. Maybe somebody with more artillery knowledge could give us a rough estimate on that...

But the game can do up to 4km x 4km, actually. Not sure my 3.5 year-old rig could handle a map this big, but for the kids with the newer machines...

In any event, I prefer smaller battles, so it's not a big deal to me. At least, that's what I'm telling myself until I can afford a fancy new machine that can handle those 4km x 4km maps. But my point is that you can definitely have situations in CMBN where high-angle on-map fire is possible from the German infantry guns.

I suspect we'll see more larger maps when the Brit module comes out. 16 sq. km of fighting in tight terrain like bocage would be unmanageable, IMHO. But in the generally more open terrain the area of Normandy where the British did their fighting, longer range fights would be more playable, methinks. still don't know if I'd want to play something 4kmx4km, but I'd definitely go over 2km for a long-range tank vs. 88mm fight.

[StellarRat]

I always play QB on medium size maps hence my lack of belief. :-)

[hm_stanley]

Thanks for reminding me about quadratic equations. All they had to do in math class was tell me "this formula will help you solve artillery shell trajectories".. and I would have been all ears...

[gunnergoz]

Many of these infantry guns, AFAIK, fired fixed rounds and did not have the flexibility of varying propellant charges like the regular artillery - or mortars, for that matter. This, along with their comparatively short barrels, limited their firing ballistics. They were something of a holdover from old times and eventually were replaced by inventions like recoiless rifles and later, AT missiles.

The Americans during WW2 eventually ended up pooling most infantry regimental cannon companies in the division into an ad hoc battery and putting it under the direction of the divisional artillery fire control center as a bonus 105mm battalion. That was a better use of these resources.

[Tarquelne]

The Americans during WW2 eventually ended up pooling most infantry regimental cannon companies in the division into an ad hoc battery and putting it under the direction of the divisional artillery fire control center as a bonus 105mm battalion.

What are the figures like for # artillery guns per front line soldier in the various WWII armies?

(Recommend a link?) I suspect it's far lower than I see in QBs.

[TrailApe]

more open terrain the area of Normandy where the British did their fighting, longer range fights would be more playable

I was under the impression that both Armies broke out of the Bocage around about the same time, the Brits/Poles/Canadians hacking around Caen until around the big tank clashes at Op Goodwood only predate Cobra by about 5 days.

Or does the next module push out the end date to the right a bit?

[YankeeDog]

I was under the impression that both Armies broke out of the Bocage around about the same time, the Brits/Poles/Canadians hacking around Caen until around the big tank clashes at Op Goodwood only predate Cobra by about 5 days.

Or does the next module push out the end date to the right a bit?

I was thinking of Goodwood, which I'm sure will be the subject of many a scenario in the Brit module. But it's certainly true that the Brits and Canadian did their fair share Of slogging around the bocage as well.

[Magpie_Oz]

Edit: did a very rough calculation.. w/out air resistance taken into account, a projectile shot at 210 m/s at an angle of 73 degrees would fly for about 39 seconds, and hit the ground about 2.3 kilometers from the gun. Air resistance would shave a fair bit off of this, but I can't calculate that exactly without knowing the specific aerodynamics of the projectile, and in any event that's a much more complicated equation. I passed AP physics class 20 years ago, thank you very much.

Did a calc using air resistance and the range drops to about 1600m (spherical projectile used)

[Redwolf]

Many of these infantry guns, AFAIK, fired fixed rounds and did not have the flexibility of varying propellant charges like the regular artillery - or mortars, for that matter. This, along with their comparatively short barrels, limited their firing ballistics. They were something of a holdover from old times and eventually were replaced by inventions like recoiless rifles and later, AT missiles.

I don't think that is a limitation here. The infantry guns have so slow muzzle projectile speed and high enough maximum elevation that you can do indirect fire over much of the second half of their range while still passing over regular obstacles like tress and buildings.

[Magpie_Oz]

This link : http://www.lonesentry.com/manuals/german-infantry-weapons/75-mm-light-infantry-howitzer.html

Gives the low down on the 7.5cm IG.

From reading it it indicates that the gun fire separate loading cartridges (semi-fixed) and looking at the sight it is graduated to 5 different charges.

[YankeeDog]

What are the figures like for # artillery guns per front line soldier in the various WWII armies?

(Recommend a link?) I suspect it's far lower than I see in QBs.

Well, you can see the assets up to battalion in the CM TOEs (60mm & 81mm mortars). So to give you a rough idea of what's available above that level, the U.S. 1944 Infantry division TOE had a total of 54 105mm howitzers (6 in each of the 3 Regimental Cannon Companies, the rest in the divisional artillery battalions), and 12 155mm howitzers.

So, for each line rifle company of the division (total of 27), there were roughly 2 105mm tubes, plus about 1 155mm tube per 2 rifle companies.

Then you have higher-level assets from Army and Corps, which might be supporting the division's actions, or even temporarily attached to the division command, at various times and places. Generally speaking though, the closer in support missions would be more likely to be fired by the division's organic assets, while the higher-level stuff like the 155mm "Long Toms" in the field artillery battalions and up would more likely be busy with longer-ranged interdiction, counterbattery, and harassing fire. So looking at the guns available up to division is a good way of getting an idea of what's mostly likely to be available at the CM scale.

One significant exception to the above for the US Army is the 4.2" mortars, which were technically organized as independent battalions, each with 48 tubes, organized into 4 companies of 12 tubes each. Practically speaking, though, the individual companies of 4.2" mortar battalions were often farmed out and attached to lower level commands for extended periods of time. From what I've heard, one or two 4.2" mortar companies per division was pretty typical. So you can add approx one 4.2" mortar tube per rifle company to the total if you like. 4.2" mortars are a short-range support asset (~4km max. range) so they don't really make sense as something that would be commanded on a day-to-day basis at the Army or Corps level.

Of course, artillery planners don't really think of artillery this way, allotting tubes out evenly, assigning one or two tubes to support each company - especially longer-ranged stuff is positioned so it can support multiple companies, as needed. And generally speaking, not every company in a division would be engaged, or even on the line, at once.

But if you want an idea of the raw numbers, there you go.

Edit to add: Of course, this is just for U.S. infantry divisions, which were artillery-rich, relatively peaking. Other division types usually have less tubes (though mechanized and armored divisions often have the advantage of having more mobile, self-propelled arty, and tank and TD guns were also sometimes used indirect). Airborne divisions have far less artillery -- only light & medium mortars and pack howitzers organic. However, in situations where the airborne divisions were on the ground and in the line for extended periods of time (which would be any time after about June 10 in Normandy), independent artillery formations we often attached to the airborne units to give them more indirect support.

[Magpie_Oz]

I seem to remember the 4.2"'s being in independent "Chemical Battalions" ? because they were meant to mainly provide smoke screens?

[YankeeDog]

I seem to remember the 4.2"'s being in independent "Chemical Battalions" ? because they were meant to mainly provide smoke screens?

IIRC, the "Chemical Mortar Battalion" name originally came about because they were developed as an asset that could be used to deliver chemical weapons, specifically mustard gas. But that never came to fruition.

Most of the time, they seemed to have been used as you would expect for a heavy mortar asset -- firing HE and WP in support of battalion and company level actions. However, I have read of cases where they were used to fire large smoke screens for extended periods of time in support of operational level stuff. IIRC, in Italy one 4.2" mortar unit fired a ridiculous number of smoke shells maintaining a large smoke screen for three days straight in order to screen engineers building a bridge over the Arno River.

[Tarquelne]

But if you want an idea of the raw numbers, there you go.

Thanks. It sounds like lot more support was possible than I thought.

I won't feel so guilty about slathering on the artillery in QBs.

[YankeeDog]

Another little thing to keep in mind: In most cases, the limit on available artillery support isn't tubes, it's available shells. Even in the case of the usually very well-supplied Americans, and accounting for necessary downtime to move the arty pieces, cleaning & maintenance, etc., the arty tubes available are generally capable of firing shells far faster than they can be supplied. This is especially true at the lower end -- the battalion 81mm and company 60mm mortars. These assets can fire very quickly, and can easily deplete the locally available stocks of ammo. And getting all that ammo out to the units at the "sharp end of the stick" can be logistically challenging.

So higher level commanders have to consider carefully when and how they will use the artillery shells available to them.