Mortars Against Hard(er) Targets?

[Major Belles]

On map mortars work great against infantry. Obviously....

Now, how about against bunkers? Does anyone know what size mortar works and what does not? How about against pillboxes (no, right?) How about against scout cars? Half tracks? Light tanks? Heavier tanks? (I'm talking on board mortars, remember - you can take out anything with a 14 inch shell...) Tnx in advance for the responses.

[Akula2]

I don't know much, but it's my experience that any AFV with an open top has a justifiable fear of those high trajectory bomby things.

Sometimes when an enemy AFV (M-10 for example) is being a nuiscience from a hull down position I'll target him with a mortar. Generally, he freaks out and breaks cover, oftentimes driving over the crest into the waiting arms of something more lethal.

I've never made an AFV kill with a mortar, but I bet it's not impossible. I just don't shoot at them frequently enough to have accomplished it.

I've never fired mortars at either bunkers or pillboxes either. It just didnt seem like the right tool for the job considering the combination of high trajectory and firing slits.

In my limited experience, mortars are best used against high value targets in trenches. Trenches can be a real pain. Mortars ease that a little.

They're also quiet useful against anything lurking around in trees of course. Airbursts, ya know.

... but I'm sure your aware of that already.

[YankeeDog]

AFAICT, on-board mortar HE of any size is worthless against log bunkers and concrete pillboxes. Maybe a little bit of a suppressive effect, but that's about it.

From what I've seen in the game, with indirect fire (from on-board mortars or off-board anything), it takes a direct hit of at least 105mm to top penetrate a log bunker, and log bunkers can sometimes (but not always) survive 105mm hits. I've see concrete pillboxes survive direct hits from 500 lb. bombs and 155mm arty, so it takes something larger than this to reliably knock them out even with a direct hit. Any way you look at it, taking out bunkers and pillboxes with indirect fire is a waste; it's techically possible, but it takes a huge number of shells unless you get really lucky.

On-board mortar smoke is, of course, another matter -- it is a very useful tool with trying to maneuver around pillboxes and bunkers.

As far as AFVs, you can definitely KO them with on-board mortars. Open-topped vehicles are obviously vunerable, and especially so if there's trees nearby and you can get an airburst. But even with fully armored AFVs, the top armor is far thinner than front and side armor, and depeding on the exact matchup can sometimes be top-penetrated by mortar bombs.

AFAIK, there are no hard statistics on how much armor various caliber mortars can penetrate in the game, but I've KOed PzIVs with 3" and 81mm mortars, and German Armored cars with American 60mm mortars. I don't have any direct experience with pentrations by 50mm mortars, but I wouldn't be surprised if they could get through the really light armor, like the 8mm plate on light ACs.

The 81mm/3in. on-board mortars can also sometimes kill really light armor with near misses. For example, Allied M3 halftracks can definitely be KOed by near misses of 81mm rounds. 81mm rounds can also rarely cause immobilization or gun damage on heavier AFVs, though in my experience this is a very rare occurrence and generally not worth trying for.

One tip if you're trying to go for a direct hit kill with a mortar on an AFV: Try to get the range as short as possible. Range deviation with on-board mortars decreases as the target gets closer, so at very close ranges (sub-250m), the mortar bombs have a much smaller dispersion and so you're more likely to actually score a top hit.

Of course, you probably want to make sure you've got a good LOS break between your mortar and the AFV (and a spotting HQ in good cover, of course) if you're going to open up at such a close range.

Cheers,

YD

[walpurgis nacht]

Originally posted by YankeeDog:

Any way you look at it, taking out bunkers and pillboxes with indirect fire is a waste;

In BB, that is true. AK is a different story.

Area fire just in front of the pillbox with HE, 75mm-ish in size or bigger, and the splash from the HE will cause a random casualty. Once you have caused 3 casualties, the crew bails. It takes a healthy amount of HE and time to pull it off, but it works very well.

[Redwolf]

In CMBO you could reliably hit vehicles in one turn with a veteran mortar with a 1+ combat HQ or a regular mortar with a 2+ combat HQ.

This has been tuned down in CMBB and CMAK. However, the TacAI will still make the enemy vehicle retreat, and since the paths are often "interesting", it might very well present a flank or otherwise screw up allowing you to take on it by other means.

Airbursts near open-top vehicles should be more reliable, not sure this is actually modeled.

As for penetration, a 3" mortar round gets through any tank roof with a direct hit.

[Major Belles]

Thanks all! That's exactly what I had in mind. I'm just digesting all that info...

BTW, What do "AFAICT" and "AFAIK" mean?

[junk2drive]

as far as i can tell

as far as i know

iirc if i remember correctly

[Akula2]

Originally posted by Walpurgis Nacht:

</font><blockquote>quote:</font><hr />Originally posted by YankeeDog:

Any way you look at it, taking out bunkers and pillboxes with indirect fire is a waste;

In BB, that is true. AK is a different story.

Area fire just in front of the pillbox with HE, 75mm-ish in size or bigger, and the splash from the HE will cause a random casualty. Once you have caused 3 casualties, the crew bails. It takes a healthy amount of HE and time to pull it off, but it works very well. </font>

[SpitfireXI]

As for penetration, a 3" mortar round gets through any tank roof with a direct hit.

Even a Tiger??

[Mr. Tittles]

Depends on fuze setting. 81mm with a delayed fuze setting would KO most log bunkers IRL. Thats what made the US 81mm heavy bomb so useful. It was no better than the light bomb against troops in the open. It was really a thin walled HE package and HE does not cause great casualties as a function of distance. Fragments will. The US heavy 81mm set on delay had enough mass to punch through roofs and reinforced positions and the healthy HE load did the rest.

[Mr. Tittles]

Originally posted by SpitfireXI:

As for penetration, a 3" mortar round gets through any tank roof with a direct hit.

Even a Tiger??

This relys almost entirely on fuze setting. An instantaneous fuze would detonate the HE on the outside of the roof and the blast alone would have to cave in the roof (unlikely for most roofed afvs). On delay, for larger diametr/mass mortar bombs, there might be a chance of velocity making some penetration before the HE detonates. Mortar shells are very thin walled and it would take a rather large mortar bomb with considerable velocity to penetrate most afv roofs.

The panther had a thin roof and perhaps something like a soviet 120mm set on delay could punch a hole before detonating.

[ October 18, 2004, 12:06 PM: Message edited by: Mr. Tittles ]

[SpitfireXI]

So that begs the question, could artillery do the same? I've tried it, but have yet to see it do anything.

[Mr. Tittles]

Mortars drop at extremely steep angles. Artillery does not and strikes top armor (even when thin) at a disadvatagous angle. Artillery does come in at higher velocitys (typically).

Again, fuzes would play in.

[Redwolf]

Originally posted by SpitfireXI:

So that begs the question, could artillery do the same? I've tried it, but have yet to see it do anything.

The precision of the off-map modules, both mortar and guns/howitzers is entirely isuffient to hope for a top hit.

In CMBO onboard mortars could do the trick as I outlined.

[Goetz]

What about using conjoint mortar smoke shells, and using flamethrowers?

[John D Salt]

Originally posted by Mr. Tittles:

Depends on fuze setting. 81mm with a delayed fuze setting would KO most log bunkers IRL. Thats what made the US 81mm heavy bomb so useful. It was no better than the light bomb against troops in the open. It was really a thin walled HE package and HE does not cause great casualties as a function of distance. Fragments will. The US heavy 81mm set on delay had enough mass to punch through roofs and reinforced positions and the healthy HE load did the rest.

It might go through a tiled roof (although Che Guevara in his "Basic tactics" reckons tiles or thatch will pretty well keep out 81mm bombs), but I wouldn't have thought it even slightly likely to get through a bunker roof. Do you have any evidence to back your statement up?

All the best,

John.

[YankeeDog]

Would an 81mm mortar shell really need to go through the armor to cause significant damage on the other side of a deck armor plate?

With just a few exceptions (The Tiger, for example), top armor plates are less than 20mm thick, and some otherwise fairly well armored tanks have significant portions of their top armor below 15mm -- the PzIV's turret top is only 10mm until the very late war versions, for example.

I'm no expert on stuff like this, but I would think that most 81mm bombs contained enough HE to cause significant spalling, and possibly even scab detachment, when exploding in contact with a plate of around 15mm thickness.

I'd be curious if anybody knows more about this. . .

Cheers,

YD

[Mr. Tittles]

Originally posted by John D Salt:

</font><blockquote>quote:</font><hr />Originally posted by Mr. Tittles:

Depends on fuze setting. 81mm with a delayed fuze setting would KO most log bunkers IRL. Thats what made the US 81mm heavy bomb so useful. It was no better than the light bomb against troops in the open. It was really a thin walled HE package and HE does not cause great casualties as a function of distance. Fragments will. The US heavy 81mm set on delay had enough mass to punch through roofs and reinforced positions and the healthy HE load did the rest.

It might go through a tiled roof (although Che Guevara in his "Basic tactics" reckons tiles or thatch will pretty well keep out 81mm bombs), but I wouldn't have thought it even slightly likely to get through a bunker roof. Do you have any evidence to back your statement up?

All the best,

John. </font>

[Mr. Tittles]

Would an 81mm mortar shell really need to go through the armor to cause significant damage on the other side of a deck armor plate?

Awhile back there was an extensive HE effectiveness thread. The main point of HE as a armor defeating mechanism was that it had to be set on delay. That is, it acts as a poorly designed AP round and thats what penetrated armor, not the HE itself.

Mortar rounds are very thin walled themselves. They are like aircraft bombs in that they have high HE content. When a mortar bomb is set on instantaneous fuze and lands on a sheet of armor, the nose usually breaks off in one piece and the blast goes out the sides.

Even if set on delay, the slow velocity and light weight and poor shape do not lend it to piercing armor.

[YankeeDog]

Yes, I read that thread.

And I agree with the general statement that, for HE rounds from guns, the best penetration is usually going to be achieved by a delay fuze setting that allows the shell to basically function as a kinetic AP round.

However, with mortar rounds, which as you note are structurally very poor penetrators and also contain a higher HE content relative to their overall mass, I speculate whether they might not actually do better set on quick fuze and functioning as a poorly designed HESH round, rather than a poorly designed kinetic AP round.

But I don't know the answer. I would be very curious to see actual hard figures on spalling and scab formation caused by various mortar bombs detonating in close proximity to armor plate.

Given the large HE load, I don't think it's a big leap to conjecture that a 120mm mortar shell exploding on contact would easily cause spalling , and possibly even catastrophic failure on a plate of less than 20mm thickness. I would also guess that 81mm mortar rounds would have no trouble spalling or caving in the 6-8mm plates generally found on the top of light armor. What I'd be really curious to see is whether an 81mm round (of any manufacture) has a chance of defeating a plate in the 15mm range by shockwave effect.

The reason I bring this all up is that, even if a mortar round technically could defeat an

AFV's top armor by kinetic penetration, setting the mortar bombs to a delay fuze would cause a dramatic reduction in their effectiveness against softer targets. Mortar bombs on delay fuze would bury themselves in the ground before detonating, so much of the shrapnel and blast energy would be absorbed by dirt.

As such, if Mr. T is correct and mortar bombs generally defeat top armor by using an HE delay setting, I wonder if CM is kind of letting the player have his cake and eat it, too. Usually, when I direct mortar fire at an AFV (either on-board or off-board), I'm doing so with the intention of buttoning the AFV; if I actually manage to score a direct hit, it's a lucky bonus. However, if the mortar bombs actually have to be set on delay to penetrate top armor, then IRL I would have to choose; either HE quick to button up the AFVs, or HE delay in the hopes of getting a lucky top hit.

OTOH, if 81mm bombs set on HE quick will case significant damage of the opposite side of a 15mm plate by spalling, then it's mostly a moot point, since then even HE quick would have a decent chance of KOing most AFVs on a top hit.

Curious to know if the Arty/Armor grogs have more detailed info. . .

Cheers,

YD

[Mr. Tittles]

HESH works by having the explosive in contact with the armor. The shell of the HESH is acting as a damping container.

A mortar shell is a very poor HESH shell in that the HE is separated from the armor by the nose (which acts as a standoff and 'adds' to the armor).

Ive read of quite a few tanks being hit by mortars. Carrius describes two Tigers being damaged by mortar fire (fragments getting into the radiators). This is the more likely effect of mortar fire. Light damage to the fans, radiators, fuel system, vision blocks, exhaust fans (a critical item to remove gases from fighting compartment).

[John D Salt]

Originally posted by Mr. Tittles:

</font><blockquote>quote:</font><hr />Originally posted by me:

Do you have any evidence to back your statement up?

I believe I read it in one of the Lessons Learned pdfs. Also, the US FMs online about building trenches, bunkers mentions minimum thicknesses to be safe from different rounds. </font>

[Mr. Tittles]

d. If the enemy has prepared fighting positions with overhead cover, only impact-fuzed and delay-fuzed rounds will have much effect. Proximity-fuzed rounds can restrict the enemy's ability to move from position to position, but they will cause few, if any, casualties. Impact-fuzed rounds cause some blast and suppressive effect. Delay-fuzed rounds can penetrate and destroy a position but must achieve a direct hit. Only the 120-mm mortar with a delay-fuze setting can damage a Soviet-style strongpoint defense. Heavy bunkers cannot be destroyed by light or medium mortar rounds.

I would assume light bunkers could be destroyed by light or medium rounds.

[Mr. Tittles]

In any case, I find it hard to believe that if a US heavy 81mm landed on a turret roof and went off, it would not have some behind armor effect. Even if not penetration or spalling but some kind of concussive effect. The heavy 81mm HE content was 4 pounds (40%). In the case of most crewmen, their heads would be very close to the roof area. To have 4 pounds of TNT go off against metal must ring your bell if you are on the other side. Just a 10 pound metal weight alone coming down at a few hundred feet per second striking a plate over your head will shake you up. Many tankers did not wear helmets or just padded helmets perhaps. Headphones would give minimal hearing protection.

[Spears]

Dont see why they would use 81mm mortars vs armour. If they used them against armoured attack, i would of thought it was to break up the infantry with them. Normally tanks wont go alone without the infantry, if they want to live. But, but if it did hit top like Tittles says, i wouldnt be suprised if ur ears popped just a little.