British bombs in Koblenz.. Oh, my heart!

I'm flying in on a DC10 tonight.

Evacuating a 1.8 kilometer radius area. Or 1.118468146 miles in 'Murican distance.

I can't imagine a blast radius anything like that! They must be trying to be really, really careful. Broken windows, etc.

Wonder if they'll try to sue the UK for cleanup costs...

Not an uncommon occurrence. When I was stationed there, an unexploded 500 pound bomb was unearthed while building the new base bowling alley. Many bricks were shiat. There was also another instance of an old bomb exploding on its own at the far corner of the airfield. Also knew a guy that found an old German hand grenade in the woods while out hiking.

johnson442: Evacuating a 1.8 kilometer radius area. Or 1.118468146 miles in 'Murican distance.

I can't imagine a blast radius anything like that! They must be trying to be really, really careful. Broken windows, etc.

Wonder if they'll try to sue the UK for cleanup costs...

It's a 3600lb bomb... and they're evacuating everything within two kilometers?

Come on, Germany, the blast radius of a MOAB - 16000lb of explosives - is less than 200 meters. And a MOAB hasn't been rotting and waterlogged for 2/3 of a century.

are there any cases of these accidentally going off?

Hey British, bombs in Rhine River won't help win the war!

Virulency: are there any cases of these accidentally going off?

hell yes. used to all the freaking time. still does actually. especially in arid areas like north africa there are people killed yearly still. northern europe would certainly still have its fair share of actives. korean war era stuff still goes off there.
i grew up in the pacific on islands where a lot of fighting happened, and in the jungle stuff rots pretty quick, yet we still had a lot of crap turn up. caves we used to play in as kids got concreted up due to live ordinance stored in them. once, a 500 lb bomb was found by a neighbor girl, another time a grenade turned up in a ladies garden down the street. there was always an eod truck around doing something or other. they kept busy, although in our climate much of the stuff wasn't actively live anymore. in northern europe, a lot of it would be still.

Allen262: Hey British, bombs in Rhine River won't help win the war!

Top hole. Bally Jerry pranged his kite right in the how's your father. Hairy blighter, dicky-birdied, feathered back on his Sammy, took a waspy, flipped over on his Betty Harper's and caught his can in the Bertie.

The blast radius seems to me to have been extended that far due to A) the rocks on the beach of that picture. Who knows how far those could shoot with a bomb like that and B) the 2 smaller bombs nearby which might increase the explosive yield of the total explosion or might just be hurled by the big bombs explosion somewhere else to explode (unlikely)

Virulency: are there any cases of these accidentally going off?

The French have a team of people who's job is to locate and destroy old German ordinance found all over the countryside from both world wars. They estimate the time it will take to completely clear everything at 800 years. They manage to clear about 900 tonnes a year.

Call James May. He defused one using materials purchased at a hardware store.

He's definitely the coolest of the three presenters. BTW, when does the next season of Top Gear start?

Virulency: are there any cases of these accidentally going off?

Oh yes.

I've read that there are parts of northern France that are considered basically uninhabitable due to the amount of unexploded round/shells there from WWI and WWII.

Rent Party: Virulency: are there any cases of these accidentally going off?

The French have a team of people who's job is to locate and destroy old German ordinance found all over the countryside from both world wars. They estimate the time it will take to completely clear everything at 800 years. They manage to clear about 900 tonnes a year.

I'd assume in 800 years there will be a new layer added by then...

Rent Party: Virulency: are there any cases of these accidentally going off?

The French have a team of people who's job is to locate and destroy old German ordinance found all over the countryside from both world wars. They estimate the time it will take to completely clear everything at 800 years. They manage to clear about 900 tonnes a year.

France and Belgium are stil removing tons of unexploded ordnance in The Iron Harvest (new window).
France alone clears 900 tons/year, this is true. But the thing is, most of it is WWI stuff. Including poison gas shells that are still volatile and dangerous after all these years, they're much more likely to still be dangerous than the explosives.

erik-k: johnson442: Evacuating a 1.8 kilometer radius area. Or 1.118468146 miles in 'Murican distance.

I can't imagine a blast radius anything like that! They must be trying to be really, really careful. Broken windows, etc.

Wonder if they'll try to sue the UK for cleanup costs...

It's a 3600lb bomb... and they're evacuating everything within two kilometers?

Come on, Germany, the blast radius of a MOAB - 16000lb of explosives - is less than 200 meters. And a MOAB hasn't been rotting and waterlogged for 2/3 of a century.

1.8 tons... 1.8km... did they actually use a "km/ton" conversion here?

That is not an unreasonable distance for the size.
What most people do not understand is when a device is detonated, a large ring column of compressed air rises up. This ring will expand up and out from the center of the explosion until it reaches a certain height. Then it falls. This can be a Loooooong way from where the explosion took place. When it hits the ground, it can do serious damage or injuries.

mr lawson: That is not an unreasonable distance for the size.
What most people do not understand is when a device is detonated, a large ring column of compressed air rises up. This ring will expand up and out from the center of the explosion until it reaches a certain height. Then it falls. This can be a Loooooong way from where the explosion took place. When it hits the ground, it can do serious damage or injuries.

"ring of compressed air"?

No, in general they follow the inverse square rule- at 2x the distance, you get 1/4 the blast force. At 10x the distance you get 1/100th. That's the dominant mechanism of explosives. And an explosive on the ground has a notably lower effective radius of destruction over an airburst.

Virulency: are there any cases of these accidentally going off?

YES. June 2010, Link (new window):
"Germany is mourning the loss of three bomb disposal experts killed yesterday by a 2,000lb World War II aerial mine.
Three others were seriously injured by the explosion which occurred when a bomb disposal team was cutting through the acid fuse of the bomb buried 24ft down in the university city of Goettingen."

"Work was proceeding with a water cutter to get through the fuse of the bomb when it went off. It was due to be defused at 10.30pm but detonated at 9.45pm."

Is anybody updating the total for people killed in WWII? Still going on, apparently.

Rent Party: Virulency: are there any cases of these accidentally going off?

The French have a team of people who's job is to locate and destroy old German ordinance found all over the countryside from both world wars. They estimate the time it will take to completely clear everything at 800 years. They manage to clear about 900 tonnes a year.

Good lord, the French still haven't done away with local German laws impressed upon them? They're still following curfews and rules against excessive noise and parking rules laid out by the GERMANS??

Just an echo?

"Yoo-hoo!"

/in the valley
//yoo-hoo

Fairly common in Germany, every time new construction happens they survey the area for old ordinance... During 4.5 years living in Hamburg I remember a number of times roads were shut down for old bomb removal.

CaptainBeer:

BTW, when does the next season of Top Gear start?

Christmas.

Oznog: No, in general they follow the inverse square rule- at 2x the distance, you get 1/4 the blast force. At 10x the distance you get 1/100th. That's the dominant mechanism of explosives. And an explosive on the ground has a notably lower effective radius of destruction over an airburst.


I for the life of me forget the name of this effect, but it does happen.
This was the best I could find (new window)
/Combat engineer USMC
//i.e landmine warfare
Basically what happens is the difference in air temp at ground level and the (usually cooler) air temp above the explosion creates the ring that propagates from the explosion.
CSB. We were doing a demo shoot at Quantico and ummmm went a little over the range limit (15lbs vs 40lbs :it was a cratering charge), next thing we knew we had all kinds of brass on our asses about windows being broken 5 miles away...whoops
/csb

erik-k: I've read that there are parts of northern France that are considered basically uninhabitable due to the amount of unexploded round/shells there from WWI and WWII.

I don't think it's quite that bad, most of what's left is a quite few feet underground now. There's definitely places where they're really careful about digging holes.

Time Team did an episode in France where they had to stop digging because they found a pile of bombs.

Hey mister, can we have our bomb back?

mr lawson: Oznog: No, in general they follow the inverse square rule- at 2x the distance, you get 1/4 the blast force. At 10x the distance you get 1/100th. That's the dominant mechanism of explosives. And an explosive on the ground has a notably lower effective radius of destruction over an airburst.


I for the life of me forget the name of this effect, but it does happen.
Basically what happens is the difference in air temp at ground level and the (usually cooler) air temp above the explosion creates the ring that propagates from the explosion.

I doubt temperature has time to have an effect at the speed of sound, ie. the propagation of the shockwave (which is what does the most damage). I would have thought it was more that most of the targets are at ground level and if you explode the bomb at ground level there's more chance of stuff being between bomb and target. Most bombs will penetrate the ground and make this effect much worse.

There's an episode of Mythbusters where they test stuff like tipped over tables to see how well they protect you from shockwaves. The answer was "very well indeed". Ideally you want nothing at all between bomb and target.

nb. I'm not saying there's no temperature effect but I suspect it's completely swamped by the line-of-sight effect.

Oznog:
No, in general they follow the inverse square rule- at 2x the distance, you get 1/4 the blast force. At 10x the distance you get 1/100th.

Nope. It's a sphere so it follows the inverse cube rule.

Brian Ashe, we have a category 1 for you.

Joce678: Oznog:
No, in general they follow the inverse square rule- at 2x the distance, you get 1/4 the blast force. At 10x the distance you get 1/100th.

Nope. It's a sphere so it follows the inverse cube rule.

Well, for radiating effects which don't have substantial attenuation (light, sound, radiation), the effect per sq in is proportional to the spherical surface area. The total energy released at 1 ft is about the same at 100 ft, but at 100 ft the energy is distributed over a sphere with 10,000 more surface area. But an explosion's got some dissipation.

Looking at Wikipedia:

Overpressure calculation (explosive)
Overpressure is determined using "Wiebull's formula":[3]

deltaP=2410*(m/V)^0.72

where:
2410 is a constant based on 1 bar (100 kPa; 15 psi)
m= net explosive mass calculated using all explosive materials and their relative effectiveness
V= volume of given area (primarily used to determine volume within an enclosed space)

Wow, what an annoying format for an equation. Well, if you were at 100 ft vs 1 ft, volume is 100^3 greater, but there's the 0.72 exponent, of 20,893x smaller.
So, the net exponent is 2.16. Close to a square, but not quite.

Professor Emelius Browne thinks the Germans are a bunch of candyasses.



=Smidge=

Joce678: mr lawson: Oznog: No, in general they follow the inverse square rule- at 2x the distance, you get 1/4 the blast force. At 10x the distance you get 1/100th. That's the dominant mechanism of explosives. And an explosive on the ground has a notably lower effective radius of destruction over an airburst.


I for the life of me forget the name of this effect, but it does happen.
Basically what happens is the difference in air temp at ground level and the (usually cooler) air temp above the explosion creates the ring that propagates from the explosion.

I doubt temperature has time to have an effect at the speed of sound, ie. the propagation of the shockwave (which is what does the most damage). I would have thought it was more that most of the targets are at ground level and if you explode the bomb at ground level there's more chance of stuff being between bomb and target. Most bombs will penetrate the ground and make this effect much worse.

There's an episode of Mythbusters where they test stuff like tipped over tables to see how well they protect you from shockwaves. The answer was "very well indeed". Ideally you want nothing at all between bomb and target.

nb. I'm not saying there's no temperature effect but I suspect it's completely swamped by the line-of-sight effect.

I think he's referring to differences in air density like you'd get with a thermal inversion, and can reflect and refract sound like looking at a pole sticking out of the water. But it's only got subtle effects on sound propagation, and I wouldn't expect it to have any notable effect on explosions.

when my father and i toured the western front of ww1 in 1996, there were literally STACKS of these all pyramided up at the entrance to every farm. its absolutely everywhere.

we went from verdun up the loire to the somme, saw where the british army committed suicide along thiepval in july 1916, then up to paesschendaele where the survivors of the somme were all slaughtered the next year during 3rd ypres. saw crecy and agincourt as well, and walked around pointe du hoc and omaha beach in normandy too. i know i know... csb. but it was great, everyone should go at least once.

Oznog

Good lord, the French still haven't done away with local German laws impressed upon them?

Looks like the grammar Nazis are waiting it out in the shelters.

I'm sorry, I got a bit confused because everyone keeps mentioning the war.

Oznog: I think he's referring to differences in air density like you'd get with a thermal inversion, and can reflect and refract sound like looking at a pole sticking out of the water. But it's only got subtle effects on sound propagation, and I wouldn't expect it to have any notable effect on explosions.

Oh thank god. I've been racking my brains and Googling every damn thing I could think of trying to come up with that!
Thermal Farking Inversion.
That what they called it and it does "carry" the sound, but ONLY for certain types of explosives, namely cratering charges (new window), due to its low R.E. factor (new window). (c-4, tnt, Pent. does not produce the effect)
Maybe I can now get some farking sleep!!!!! Thanks! lol

also...If i remember correctly, it is a very low freq sound and that is what cracks the windows. Like a loud car bass system.

Here..... (new window)

fig 44
Bottom pic
/*****warning pdf

Oznog:
So, the net exponent is 2.16. Close to a square, but not quite.

That's inside an enclosed space, not the same thing at all...

Unavailable for comment:



// Fortunately.

They should send a bill to Buckhingham Palace. Attached to a V2.

This isn't all that uncommon.

When new construction takes place in the UK (and I assume France, Germany and other heavily bombed countries) it's pretty standard to do a study to determine if there is a decent chance of finding unexploded bombs. You go through all the ordinance survey maps from just before WW2 then just after then ~10 years after looking for signs of bombing in the area, like a line of empty/rebuilt lots across a series of terraced houses. There are also records of areas known to have been bombed that you would not expect - for example you know if you're building in the London Docklands or Liverpool you know that they had the shiat bombed out of them but there were plenty of cases where bombers dropped their bombs in the wrong place or just dumped them in an emergency so these things are even found in rural areas.

Pic of what an OS map showing bombed housing looks like:



Over the years the OS have been working on maps that save leafing through old maps and you can now get new ones that look like this (red dots are houses/buildings that were bombed):

http://blog.ordnancesurvey.co.uk/wp-content/uploads/2010/11/soton-bli t z-map.jpg

Smidge204: Professor Emelius Browne thinks the Germans are a bunch of candyasses.

[img205.imageshack.us image 420x311]

=Smidge=

Ahh the memories, thank you.