Tank destroying a building

[Fed]

I was wondering how many 88mm round it would take to take down a 3 story building. Any ideas?

[poesel]

Test it and tell us.

[Sailor Malan2]

Or did you mean in RL? In which case 'how long is a piece of string'. Depends on the building

[agusto]

'how long is a piece of string'.

If you dont mention wich scale you are using for comparision of the strings lenght every number greater than 0 is always a potentially correct answear.

[Seedorf81]

If you dont mention wich scale you are using for comparision of the strings lenght every number greater than 0 is always a potentially correct answear.

Are you really sure???

:eek:

[Erwin]

Only slightly OT but it seems useful info. Toxiczen at BoB did tests on bridge demolition:

"Out of curiosity I ran a test to time bridge destruction.

I used 2 81mm mortars for the first tests.

I used 2 M4A3 shermans with 75mm guns for the second round.

and finally I used some called in battleship fire in a linear pattern for the final test.

I also tried using engineers but when I targeted the bridges they ignored the command...

SO!

I used 7 length 16 bridges in all as follows:

(1) wood foot bridge

(2) steel rail bridge

(3) stone foot bridge

(4) stone bridge

(5) stone rail bridge

(6) stone wide bridge

(7) urban wide bridge

The two mortar teams destroyed the wood foot bridge in a minutes time. They destroyed all the other bridges in 2 minutes time, with the exception of the wide stone bridge which took 3 minutes.

The 2 tanks destroyed the wood bridge instantly. They destroyed all the other bridges in one minutes time.

And finally the spotter called in the strike which lasted a couple minutes after it began, resulting in all but two bridges being obliterated. (they were missed)"

[Seedorf81]

Useful indeed. I would never have guessed that the 81 mortars would destroy any bridge other than the wooden one.

I can't imagine they would destroy a stone bridge in real life and most certainly not in two minutes.

[agusto]

Are you really sure???

:eek:

You should take a look at the mathematics that are behind of what he says. To bad we dont have a smilie that points a gun to its head .

Like that:

http://t00nfish.de/wp-content/uploads/2009/12/awesome-guy-smiley-headshot-z00m.jpg

@Erwin: Those are interesting test results. Thanks for posting.

[dieseltaylor]

I would agree that the mortar effectiveness seems very unlikely against stone bridges. I can see parapet walls being damaged and destroyed but given mortar bombs barely penetrate thin armour and the explosive effect is upwards it does seem wrong.

Perhaps this a hangover from the early days of CMBN before buildings became more robust - can you provide data on when this was done?

Interesting research which for a gamer can be a handy piece of knowledge!

[Erwin]

If you are referring to when Toxiczen did his tests on the bridges, it was this week.

[altipueri]

These modern bridges, just aren't built like the ones in my youth.

[dieseltaylor]

Thanks Erwin.

Yikes! So presumably V2.01. Does not seem believable for mortars and tanks to be doing this in the timescales. Still it does explain why Market Garden was doomed : )

Anyway what can be found on bridge destruction by mortars and tanks.

http://www.slobodanpraljak.com/english/knjiga_most_eng.htm

PS. For the tanks I suppose if they were very close and firing at their highest rate they may be effective against some of the bridges as they can aim at the weakest point in each structure. Knowledge of where the weakest point is would be good knowledge to have. The fact that engineers are sued to lay explosives does however tend to suggest that two tanks or two 75mm + guns are not the best method.

http://www.napoleon-series.org/military/OrdnanceJournal/Issue1/3002_Bridges.pdf

[Doug Williams]

How strong were stone bridges in 1940s Normandy compared to modern rebar reinforced concrete bridges?

[dieseltaylor]

Stronger in what way. A modern bridge may be "stronger" in terms of what it can carry in weight but that is not the same question as how hard is it to destroy.

There is quite a lot on concrete bridges falling down and being demolished. Also on them being built. Concrete bridges tend to be pre-stressed concrete bearers with panels and designed without any excess over-engineering. I suspect that stone bridges are over-engineered and therefore more massive.

[womble]

My gut feeling is that there's something odd going on if 81mm mortars can rubble a stone bridge that fast. They can't rubble the top storey of a modular house that quick (well, mine never seem to be able; lucky if 3 or four rounds actually hit the house...) and those certainly ought to be less resistant to mortars than a bridge...

[John Kettler]

Hats off to Toxiczen for all that work! I find the results, though, bear no resemblance to reality. It takes a lot of munitions to take down any steel bridge, let alone using puny 81mm mortar fire. I say this having looked at the relevant JMEM (Joint Munitions Effectiveness Manual). Here's how tough a steel truss bridge can be, and notice the hits. In one raid on the Thanh Hoa Bridge alone 300 bombs struck the bridge and did very little. It took laser guided bombs to do in this moose.

http://en.wikipedia.org/wiki/Thanh_Hoa_Bridge

Raining random hits on something like this does squat all. The key to killing it lies in hitting the right places. Hard.

Here's what the artillery site World War II Artillery Notes has to say about bridges vs artillery under the category of Targets.

http://www.poeland.com/tanks/artillery/targets.html

(Fair Use)

"Bridges

Heavy bridges are very difficult to knock out. Heavy-caliber HE with concrete-piercing fuze is most effective. It's easier when the bridge axis runs along the line-of-fire, since the dispersion area is much longer along that axis, and a direct hit is required.

Wooden and pontoon bridges can be knocked out by almost any artillery."

(Fair Use)

I'm looking for further data, but it's not easy, a situation worsened by an awful connection.

Regards,

John Kettler

[akd]

My gut feeling is that there's something odd going on if 81mm mortars can rubble a stone bridge that fast. They can't rubble the top storey of a modular house that quick (well, mine never seem to be able; lucky if 3 or four rounds actually hit the house...) and those certainly ought to be less resistant to mortars than a bridge...

81mm mortars should not knock down anything more than a wooden bridge. They will not penetrate at all (quick-fuzed, thin-cased rounds), which means rounds bursting on the surface and blast deflected away from the structure. I think the demolition effect of mortars may be generally exaggerated. I've noticed they often knock walls down even with fairly distant impacts.

[Baneman]

81mm mortars should not knock down anything more than a wooden bridge. They will not penetrate at all (quick-fuzed, thin-cased rounds), which means rounds bursting on the surface and blast deflected away from the structure. I think the demolition effect of mortars may be generally exaggerated. I've noticed they often knock walls down even with fairly distant impacts.

That would seem to imply that a blast effect is modelled, but strangely it doesn't seem to affect infantry - I've landed an 81mm mortar round within 2m of a running man and he was unfazed, so I presumed that only the shrapnel could do any damage and he'd had a "lottery" moment.

I feel some testing coming on...

[womble]

That would seem to imply that a blast effect is modelled, but strangely it doesn't seem to affect infantry - I've landed an 81mm mortar round within 2m of a running man and he was unfazed, so I presumed that only the shrapnel could do any damage and he'd had a "lottery" moment.

I feel some testing coming on...

I don't think the blast effect is unmodelled, judging from a comment I noticed from BFC (Steve, I think) which talked about blast effects. It's just not a dead cert killer. I'm not commenting on how realistic that is, merely that I think it's more subtle than "blast/no blast".

[Doug Williams]

Well, I'm convinced. It does indeed sound like stone bridges are too easily demolished with "small" HE fire.

[John Kettler]

akd,

81s can be fuzed for Delay, but that's to defeat things like exposed log bunkers with sandbag overlays, not thick reinforced concrete or stone. You can see the first in the many times cited War Department training film "Infantry Weapons and Their Effects." There, the sandbagged log bunker 60s do nothing to, the 81s on Delay kill via roof penetration and detonation inside.

Regards,

John Kettler