Military Types - Fuel-Air Bombs and Mountains

[usedtobe]

Hearing of the trouble the Good Guys (tm) are having with the Jihadist in the Afgan/Pakistani mountains and caves therein.
Why not send a formation of heavy bombers to lay down a grid of fuel-air bombs?
My understaing is that they kill (yes, everything, but was is unpleasant, issn't it?) by sucking up all available oxygen, and doing so REAL fast.
Q:
1. Would this work against cave-dwellers (excepting those in heavy-duty pressure vessels with their own air supply)?
2. Aside from ethics of mass killing, is there some reason not to use them. Hey, we ARE the only folks (do date) to use nukes - at least the thermobarics don't leave radiation.
Wiki states that small versions have been used in both Iraq and Afganistan - does a version suitable for carpet-bombing exist?

[Lumpy]

We are trying to fight a war presuming that we must only kill some of the inhabitants of that country, the bad people, while avoiding as far as possible killing any of the good people there whom we are trying to save from the bad people. Which is in fact as stupid as it sounds.

ETA: sorry, have no information on the strategic utility of fuel-air bombs.

[GreasyJack]

I think the issue is more a matter of not knowing which caves to bomb than of not having an effective way to bomb them. And if we just went around bombing caves willy-nilly, what of the hearts and minds of the local speliological society?

[AK84]

The US did use FAE in the Tora Bora Campaign and achieved.................... very little. The terrain is such that airpower becomes far less effective and you have to actually fight on the ground, something the US in 2001 was loath to do and today has troop shortages.

[Tripler]

First, most FAE munitions typically don't fit onto bombers--they fit into cargo aircraft. And you don't want cargo aircraft always doing your tactical strikes.

Fuel-air explosives work great for shaking the bajeezus out of stuff in the immediate area, but don't really transmit a whole lot down into the ground. You'll fry/rattle/f*ck up anything within the kill radius, but a lot of that energy is going into the air as an overpressure wave. The transition from a less dense (air) to a more dense (soil) medium doesn't propagate the overpressure very well.

If you want to dig deep, through the ground, you want a 'Penetrator' bomb like a BLU-109 or a BLU-119 with a time delay fuze. You want that sucker to fall from 30k and travel down into the earth before it goes off and transmits hell, hate, and discontent to the recipient. If you can locate the cave, you can drop one penetrator through the overlaying earth and have it pop into the cave from above. With a properly timed fuze, it'll know when to detonate inside the mountain.

So, why send dozens of costly bombers to drop dozens of FAEs when one small fighter-bomber with a BLU-109 will do the trick?

Tripler
IIRC, penetrators are cheaper in cost, too--plus, a lot less collateral damage.

[ExTank]

Originally Posted by Lumpy

We are trying to fight a war presuming that we must only kill some of the inhabitants of that country, the bad people, while avoiding as far as possible killing any of the good people there whom we are trying to save from the bad people. Which is in fact as stupid as it sounds.

So, we should just kill everyone, and let God sort 'em out? I'm having trouble figuring out why attempts at minimization of collateral damage and civilian casualties is "stupid."

[The Great Sun Jester]

Originally Posted by Tripler

... and transmits hell, hate, and discontent to the recipient.

I just gotta say, Man, I miss military vernacular. So colorful and so accurate!

[glee]

Originally Posted by usedtobe

Hearing of the trouble the Good Guys (tm) are having with the Jihadist in the Afgan/Pakistani mountains and caves therein.
Why not send a formation of heavy bombers to lay down a grid of fuel-air bombs?
My understaing is that they kill (yes, everything, but was is unpleasant, issn't it?) by sucking up all available oxygen, and doing so REAL fast.
Q:
1. Would this work against cave-dwellers (excepting those in heavy-duty pressure vessels with their own air supply)?
2. Aside from ethics of mass killing, is there some reason not to use them. Hey, we ARE the only folks (do date) to use nukes - at least the thermobarics don't leave radiation.
Wiki states that small versions have been used in both Iraq and Afganistan - does a version suitable for carpet-bombing exist?

I'm sorry, but I find this simplistic idea very depressing.
You appear to think that:

- there are a fixed number of 'Jihadist' (presumably you mean the Taliban)
- they all live in mountains + caves
- it's possible to wipe out a terrorist movement by killing everyone

The reality is:

- any 'terrorist' movement is seen by some as 'freedom fighters'. For example the IRA received regular financial support from some US citizens.
The Taliban run Sharia courts and collect taxes. They used to run the country and were undoubtedly supported by the US to fight the Soviet Union when it invaded Afghanistan. They are considered better than violent local Warlords by much of the population.

- if you kill 'terrorists' and civilians alike (especially by bombing large areas), you will act as a recuiting officer for the 'terrorists', since you are seen as the murderous one.
Here's the reaction to a US bombing that killed around 90 civilians.

- there are Taliban in Pakistan too - are you going to bomb them?

[HorseloverFat]

According to this website, the blu-109 can only penetrate 6 inches of concrete. I would think a mountain cave would require something that can do dozens if not hundreds of feet.

Another site claims 15 feet of concrete. Is this weapon even effective against caves or only against bunkers and other artificial structures?

[Paul in Qatar]

The US has bombs capable of detonating deep in the earth. They are the weapon of choice for sealing off tunnels. That is the thing about tunnels, they are easy to close up.

[Sailboat]

Well, the US has been talking about the pros and cons of building a new generation of small tactical nuclear penetrators (the "bunker busters" you may have heard being discussed during the previous administration).

IMHO the purpose of such a bomb is to be used -- unlike strategic weapons which (theoretically) have deterrent effect even when unused, a bunker buster doesn't come up in conversations about "making opponents think twice;" instead, people talk about bunker busters in terms of "if we had one we could get those bastards" and "we'll hit them in their holes," which sounds to me like we'd use them. Again, IMHO, use of nuclear weapons will be bad, in the long run, for our reputation; bad in terms of supplying "moral" justification to all sorts of people who wish to harm us. If the US is seen as eager to nuke goatherders hiding in holes, it seems more like an admission of fear and weakness and an invitation to nuke us back than a show of strength.

Furthermore, if one could identify a cave entrance that contained bad guys (yes, that's a very big if) it seems like a nuke isn't even needed. All we really have to do is seal it up -- I'll call it the Cask of Amontillado tactic.

The engineering problem is simple; the danger would be that people in the cave would be able to attack engineers sealing the cave. Therefore I would use a three-pronged approach:

1. Special Forces guys identify the cave and mark the entrance with a targeting laser invisible to the naked eye
2. Air Force drops a theoretical sticky bomb (some kind of sealant) with a laser guidance package attached, temporarily plugging the hole
3. Engineers land by helicopter and permanently seal the entrance with concrete and rebar before anyone can fight through the sticky bomb to shoot at them
4. Bad guys scream "For the love of God, Motresor!"

If the bad guys come out of the cave before step 2, light them up; if not, proceed.

The weak point in this plan might appear to be the theoretical sticky bomb, but I don't think so. We have all sorts of fantastic weapons already (the FAE in the OP, for example, or the carbon-fiber bomb used in the Balkans to bring down electrical grids) and we routinely airdrop masses of chemicals to smother fires. Lord knows there's a lot of sticky/gummy/adhesive materials in the world. Making a suitable sticky bomb should be a weekend's work for a couple of munitions designers and they'd still have time to barbecue.

No, the weak point is, as always, identifying the Bad Men and determining which cave entrances contain them (possibly several entrances open to the same cave).


.

[Paul in Qatar]

The Minutemen silos had a neat escape system.

The command capsule was mounted on springs in a concrete chamber. There was a certain amount of volume between the capsule and the chamber walls. A plastic tube ran to a meter or so below the surface. The escape tube was filled with sand, preventing it from collapsing in an attack.

So after the Soviet nukes impact, you sit tight and wait until your food runs out. Then open the hatch, drain the sand into the chamber and climb up the tube to face the surviving zombies.

Pretty grims stuff.

[flyboy]

Originally Posted by Lumpy

We are trying to fight a war presuming that we must only kill some of the inhabitants of that country, the bad people, while avoiding as far as possible killing any of the good people there whom we are trying to save from the bad people. Which is in fact as stupid as it sounds.

Actually, we are not trying to fight a "war." This is why your statement is totally wrong. We are conducting counterinsurgency operations, and this type of operation can ONLY be won by getting the people to side with us and resisting the insurgents. This is why you will see more and more of our troops over there walking around without battle armor, out of the up-armored Humvees, etc. Mingling with the people in a less-soldier-like way so that the people begin to trust us. Otherwise, our time and presence there are wasted. You can never win against an insurgency if you can't get the people behind you. And blowing them up indiscriminately is not the way to get them behind you.

As for the OP, as has been mentioned here and there, you can't simply start carpet-bombing with any type of munition. The caves there aren't used closely together enough to warrant that. If you have two caves being used (and of course, you'd have to have near-real-time intel confirming their use) and they're three miles apart, are you going to carpet bomb that entire area? That's a relatively huge area, with expensive ordnance, just to get two caves which 1) may have openings you don't know about and aren't targeting, and 2) may not have very important people in it. If they do have very important people in it, you're going to want to be more precise than carpet-bombing. The only way to accomplish a good hit is to drop a precision munition, probably optically guided since you simply don't have time to get someone up there to mark it. You'd want to take air assets with the desired payload already in the air and make the strike.

And I can't even get into the problems of having an air asset with an optically-guided precision munition trying to find a cave entrance in those mountains. It's one thing for a Predator to have it locked on; it's quite another to take that information and have a pilot or Wizzo get to the same place with his camera.

Bottom line--it's a very difficult problem and process, and carpet-bombing isn't a good solution--it's not time-sensitive, and it's very inaccurate and inefficient.

[MOIDALIZE]

Can someone provide an answer for the OP's first question: could a fuel-air bomb detonated near a cave suck all the oxygen out of the cave and suffocate anyone residing within?

[Squink]

June 1988:

According to several Western journalists, the Soviet forces
in Afghanistan are using during the last days of their
occupation a new type of bomb against their Mujahideen
opponents. This new weapon is said to create a massive blast
that kills troops over a wide area in the open and even causes
casualties inside buildings and underground bunkers.[1]

This new Soviet weapon is dropped from the air and has been
described as a "fuel-air explosive" or FAE. According to the
Stockholm International Peace Research Institute, experiments
with fuel-air explosives were conducted during the Second World
War, but it was not until the 1960s that the technical problems
were sufficiently mastered to allow a workable weapon.[2]

http://www.osaarchivum.org/files/hol...43-4-204.shtml

The bombs don't appear to have won the war for them.

In June 2008, the United Kingdom revealed that its forces had used thermobaric munitions in Afghanistan. The munitions were delivered by the Hellfire AGM-114N from WAH-64 Apache attack helicopters. American forces have also apparently been employing the weapons in Afghanistan from Apaches and from unmanned drones. The UK stated that the weapon will also be configured to be delivered from its own MQ-9 Reaper drones

Thermobaric Weapons

[Oakminster]

Originally Posted by HorseloverFat

According to this website, the blu-109 can only penetrate 6 inches of concrete. I would think a mountain cave would require something that can do dozens if not hundreds of feet.

You misread your own site, which says in pertinent part:

The BLU-109's advanced technology one-piece high-strength forged steel casing is one inch thick and can penetrate up to six feet of reinforced concrete.

And that's only a 2000 pounder. We have bigger and better ones than that.

[HorseloverFat]

In terms of caves, 6 feet is nothing. I think this is why there's so much talk about nuclear weapons. The conventional ones arent going to drill through a mountain.

[Stranger On A Train]

Originally Posted by MOIDALIZE

Can someone provide an answer for the OP's first question: could a fuel-air bomb detonated near a cave suck all the oxygen out of the cave and suffocate anyone residing within?

Not effectively. The problem is that the combustion process can only be sustained in the presence of both combustible fuel and oxidizer (petroleum and atmospheric oxygen) and enough heat to achieve combustion temperature. Once you either starve the reaction of enough oxygen or chill it sufficiently that the temperature can't sustain combustion, the "explosion" is over. In the case of an FAE, the fireball can do horrendous damage over open area because the pressure wave just pushes unburnt combustible out along the shock front AND compresses the atmosphere, making the reaction faster. This can clear whole swaths of land and completely obliterate unreinforced structure. However, in convoluted terrain the blast effects are attenuated as the wave is reflected, and any local constriction may restrict the fireball from drawing in enough oxygen to efficiently combust. Unless you placed an FAE in front of a tunnel, it'll run out of air to draw from before it completely evacuates the tunnel. The mountain tunnels used by Taliban forces in the mountains of Afghanistan are deep and convoluted, and hence well protected against this type of attack. Many of their strongholds are also at high altitudes where FAE bombs are less effective because of the lower oxygen levels.

Originally Posted by HorseloverFat

In terms of caves, 6 feet is nothing. I think this is why there's so much talk about nuclear weapons. The conventional ones arent going to drill through a mountain.

Neither, really, are nuclear weapons. Ground level detonation of nuclear weapons leaves the same shallow crater that conventional explosives do; just broader, slightly deeper, and of course, spewing radioactive dust downwind. Deep penetration weapons are something of a misnomer, as it is very hard to design even a single monolithic penetrator that can survive and penetrate more than a few tens of feet, much less a delicate and dimensionally precise 'physics package'. Of course, if you located a bunker, you could dig or drill down adjacent to it and place one or more nuclear weapons; the shock wave would probably collapse any natural cavity nearby.

The idea that we could go in and just clearcut the mountains of Afghanistan to eliminate the Taliban demonstrates a clear lack of understanding about both the function of bombing and the tactics of war. The o.p. is not alone in this those, as many generals have demonstrated the same degree of appalling ignorance about actual effects and successful tactics of war.

Stranger

[Zany Zeolite Zipper]

Originally Posted by MOIDALIZE

Can someone provide an answer for the OP's first question: could a fuel-air bomb detonated near a cave suck all the oxygen out of the cave and suffocate anyone residing within?

I don't think so. Explosions are reactions that happen so fast that there isn't time for oxygen to diffuse into the reacting area. The fuel is mixed with the air until there is precisely enough oxygen to react with all the fuel, then the bomb is detonated. The only oxygen used up is that within the fuel air mixture. It would take a truly massive bomb to dilute the oxygen any distance away from the bomb. I don't think it is helpful to see the bomb as "sucking" oxygen so much as producing a large cloud of CO2 that could cause a problem in an enclosed area, but in an enclosed area the pressure effects would be more important.

So the question becomes, will the created cloud of CO2 go into the cave?

The explosion is in three parts: creation of CO2, pressure expansion, collapse after the pressure expansion. After the explosion the CO2 should remain in the same area, because it is a fluid, it will not retain its energy like shell fragments which can travel great distances.

The reaction products of the bomb would have to be drawn into the cave, after the explosion, for there to be an effect. Perhaps the bomb could force a large volume of CO2 into a cave, but as the pressure would collapse quickly I don't think there would be a large bulk movement of CO2 down a cave. The pressure wave isn't from the bomb itself, it is transmitted energy, so the traveling pressure will not be oxygen depleted air; think of a cork moving on the waves, it only moves up and down, it does not move in the direction of the wave. However, the wave of energy can turn corners, which allows it to kill people where fragments cannot reach.

If you wanted to "suck" oxygen out of somewhere, it would be better to use napalm because it draws oxygen continuously while it is burning. I would think that a napalm bomb that produces the same CO2 as a FAE bomb would have a greater effect because the napalm can draw O2 from its surroundings, and can be placed closer to the cave. While a FAE needs to be mixed with air completely before it can explode, which prevents it from being dropped right outside the cave, which means most of the O2 turned to CO2 will be far enough away from the cave to be blown, or rise, away.

[Tripler]

Originally Posted by HorseloverFat

Another site claims 15 feet of concrete. Is this weapon even effective against caves or only against bunkers and other artificial structures?

Yes. Yes they are. They have newer ones--I can't recall their designation off the top of my head--that are long, slender, and really drive home. They may be of the "Small Diameter Bomb" class, but they're a good 1,000 lb gravity weapons that are six inches in diameter. A really good lawn dart for drillin' home.

Tripler
I know things, about things.

[Zany Zeolite Zipper]

Originally Posted by Stranger On A Train

In the case of an FAE, the fireball can do horrendous damage over open area because the pressure wave just pushes unburnt combustible out along the shock front AND compresses the atmosphere, making the reaction faster.

Stranger

If there is unburnt fuel I agree with this. However, I thought the point of a fuel air bomb was that you mixed the fuel in the stoichiometric ratio to get a huge explosion. By the time there is a pressure front, there should be no more fuel.

The way I visualize this is first you have fuel distributed in a sphere. The outer portion is too lean to react, the inner too rich, and the middle which reacts instantaneously to create your FAE. I'm having trouble imagining how the outer lean portion, when compressed, will react violently enough to add a significant pressure effect to the bomb. It would probably look cool and yellow though. I think it might slightly oppose the FAE part. Any idea how significant the unburnt fuel element of the bomb is?