Attacking hardened and deeply buried target is one of the Air Forces biggest challenges. They are meeting this challenge with a devastating new approach: a focused underground shockwave that amounts to an artificial earthquake.
At present the kinetic approach a.k.a. brute force is favored; the most powerful weapon in the inventory is the BLU-113, a 4,600 lb weapon with a thick steel casing capable of piercing 22 feet of concrete — or 100 feet of dirt — before exploding. There are plans to go even bigger, with a monster 30,000 lb Massive Ordnance Penetrator which would take the maximum depth to 60 feet. Thats about as big as you can carry on a plane.
Ive described Deep Digger here previously. Unlike earlier weapons this is an active penetrator, a bomb that actually burrows into the ground by drilling a shaft with volleys from seven cannon. In a demonstration last year a Deep Digger prototype penetrated more than 30 feet of limestone. The makers were tight-lipped about how much further it could go.
This presentation from David Burns of the Medium Caliber Weapons Systems Branch of ARDEC reveals much more about the weapon than previously released. In particular, it is described as being able to dig down to 150 feet. Thats impressive on its own, but the Concept Of Operations in Slide 4 is staggering: an array of 20 Deep Diggers would be detonated together to produce a shockwave which will collapse all underground structures to a depth of 300 feet over a 200-yard square area.
Compare this to this description of the B61-11, the only bunker-busting nuclear bomb in the arsenal:
For a penetration depth of three meters and a yield of 0.3 kilotons, the B61-11 could destroy a target buried under roughly 15 meters [= 50 feet] of hard rock or concrete. For the same penetration depth and the maximum yield of 340 kilotons, the destruction depth would be roughly 70 meters [ =210 feet ] for a hardened target.
In other words, the Deep Digger array is more effective than a 340-kiloton nuclear weapon optimised to attack underground targets.
The secret is in effectively combining 20 separate explosions into a coherent pulse. This area has been researched for many years, in particular in the 90s under the name of ACE, for Array of Conventional Explosives. It takes a phenomenal amount of computing power to calculate the non-linear effects of multiple explosions combining in a three-dimensional volume (which may not be homogenous), and new software tools were developed for the job. In addition, real-world testing is needed to validate these models hence exercises like the notorious Divine Strake which involves a underground explosion of 700 tons of explosives.
The last I heard the Array Of Conventional Explosives had been axed, in favor of simpler and more straightforward approaches, but Deep Digger has some key advantages over earlier weapons that make it more suitable:
– Deep penetration means that all of the blast goes into creating an underground shockwave, not just digging a crater. For blasting rock, its basic that the charge need to be drilled to a depth to be effective.
– Deep Digger parachutes down to a soft landing before digging in. Other bunker busters hit the ground very hard and experience a deceleration tens of thousands of g’s. This affects their reliability, and the loss of a few warheads may make the whole array ineffective.
– Deep Digger may be able to maneuver underground, correcting the configuration of the array after it is in place.
And Deep Digger is only a first-generation active penetrator. Devices like General Dynamics Worm which Noah described last week may burrow much more effectively.
Or course, bunkers can always be dug deeper. One British Cold War plan involved relocating government centres to coal mines 5,000 feet underground. However, given that the Deep Digger array can collapse the entrance tunnels to a depth of 300 feet, any such deep bunker may become a tomb from which the occupants will never escape.
More importantly, such an array would make the vast majority of existing bunkers obsolete, or at any rate insecure. This would include nuclear facilities such as missile siloes.
((Of course the idea is not new. In WWII Barnes-Wallis used the shockwaves from Grand Slam bombs to bring down German railway viaducts when standard bombs proved ineffective. A Deep Digger array might also be used to cause the simultaneous collapse of blocks of skyscrapers, or dams or other large structures.))
Ive been advised that the Deep Digger program is undergoing a security review. If past experience is anything to go by, this means you wont be hearing any more news updates on the program.
Meanwhile, DARPA have started their Strategically Hardened Facility Defeat (SHFD) program which :
…seeks to leverage recent advances in non-nuclear earth-penetrating technologies for the defeat of strategically hardened targets. System and technology areas to be developed in this program include: new penetration technologies, robust self-contained aerial deployment options, sensing and navigation subsystems
This sounds like someone is going to start throwing a heap of money at something very much like Deep Digger. In the near future, digging yourself into a hole is not going to offer any protection — and that could change a lot of things.
– David Hambling
How is our remote parachute guidence ?
Good. There are a number of GPS-based parachute systems that will deliver a payload to within a few metres of the aim point.
The parachute delivery concept is not new — other weapons like MOP and CLAWS also use it.
I don’t see how this can possibly work.
Back of the envelope estimate:
Minimum energy required to fracture rock is ( yield strength ) x ( volume of rock).
Volume of rock is 200 yds x 200 yds x 100 yds = 3 x 10^6 m^3.
Typical yield strength is 100–200 MPa (see plot on page 6)
Thus, minimum energy required is 100 MPa x 3 x 10^^6 m^3 = 3 x 10^14 Joules = 75 kilotons of high explosive equivalent.
Largest conventional warhead in US arsenal (MOAB) is about 20 tons of high explosive equivalent.
If each of 20 deep diggers had 20 tons of high explosive, that would be equivalent to 400 tons = 0.4 kilotons.
Thus, an array of 20 deep diggers has at most an explosive yield of 0.4/75= 0.005 (0.5%) of the explosive yield required to fracture that much rock.
==> It won’t work.
Rob,
I agree the effects seem massive considering the relatively modest amount of explosive. But these people are not idiots, and they have carried out a great deal of work on computer simulations and modelling. And they are not proposing to crumple all the rock, just collapse structures inside it…my suspicion is that there may be some major non-linear effects being called into play here.
The trick is that you are not fracturing all of that rock. You are using the rock to carry the shockwave from your explosion.
In solid rock, no fracturing occurs because each volume of rock has surrounding rock to pass the shockwave off to.
When the shockwave reaches a void (the bunker), the sides of the bunker fail, because they don’t have more rock to pass the shockwave on to. Because the rock is unsupported on one side, the shockwave causes the rock to bend enough that it fails.
I like how .3 kilotons becomes 340 kilotons.
Brilliant.
If they can tailor the energy wave to target the resonance of the material used to build or reinforce the underground tunnels or main bunker, in theory the energy should pass through the surrounding material and wreak havoc on the target materials.
Another thought would be a concentrated sonic weapon along the same principle.
Locating the vent and other access points via advanced infrared and thermal imaging and closing those up would be the other approach versus any brute force method. Working on a locally placed sensor technology or satellite monitoring in this regards I would think would be fruitful. Scan a region known for activity, look for pattern changes, and the ingress and egress points should reveal themselves..then pay them a visit.
HowlerMonkey — Yes, the B61-11 does have variable yield, and the .3 and 340 kt are the upper and lower limits — see -
http://www.brook.edu/FP/PROJECTS/NUCWCOST/lasg.htm
Greg — “Locating the vent and other access points via advanced infrared and thermal imaging and closing those up would be the other approach versus any brute force method. “
– and there are also AFRL plans along these lines, ‘Watch This Space,’
Don’t forget that a nuke, even placed on the earth’s surface, produces a FIREBALL that “eats it way into the earth” as well as producing a primary and many secondary reflected waves in a “fracture zone” eminating outward from the FIREBALL. Ground-coupling can occur @ minimal penetration depths and using several Nuclear Earth Penetrating Warheads using the same general theory as the EARTHQUAKE ARRAY would be much more effective in meeting the desired “Target Destruction Requirements” placed upon Targeting & Weaponeering Officers by Senior Leaders.
We should press-on full-speed with both Enhanced Conventional and Nuclear Earth Penetrator Weapons so we have a full spectrum to use vice restricting ourelves as we always do.
I wondered if vents could be located by co2 detection,then send a surprise down the vents;tried to get the message and several others to DARPA when DOD asked for public ideas at the beginning of the war,but the website would only accept bids from manufacturers;after all what does a surgeon know?
I wonder if the makers of the Deep Digger also make back scratchers…?
Truly impressive.
Still no cure for cancer.
http://www.google.com
http://www.yahoo.com
http://www.msn.com
Other app:
Test CA for Early Quake warning??
Create Quake types??
For Western US, Japan alone.
Great Peace Dividend project.
CA State Quake Testing Facility.
Thanks DOD.
Due the emergence of RF, on the network lone me around a lot of like minded allies, let me alone lonely, witness the heart began to beat the temperature up gradually. It is precisely because of the existence of these friends I love more RF. So I would like spend RF money in the game.
I would establish a strongest gang! I decide to buy hero coins on line.
Requiem is Cyclone Studios’ second game, after Uprising, and is a dark peek into a far-flung world where the war between righteous and misguided angels has spilled onto the doorstep of cheap Requiem Lant humanity.
Maybe this was the 2moons
But look the cabal money and the equipment, I had a little tear away, by my effort, in the game I already had a tall level, if now I give up the game, then I will lose the all things.
Maybe this was the 2moons
At that time I do not know how to play this game, nothing to know, all things I will asked her, at the beginning we were very happy, we together to play and together to buy dofus gold but a long time after, she was not happy again
But when I play it again, my mother told me that: if you play it again your effort will be waste, I think my mother words was right, I can not give up my effort so I leave the EVE but I think it was temporary. I gave up the friends