Applying pressure for clearing land mines

[ferchotous]

Hi, I am a Industrial Design student working on my senior Thesis. Since antipersonal landmine cleareance is a very dangerous process; I am working on a remote controlled vehicle concept that will be able to do a controlled detonation. That way the human won't have to manually disarm the landmine which is the current dangerous and slow process. Basically to detonate a landmine you need no more than 10 pounds of pressure. The only thing I can think of is compressed air, but obviously is a problem to have those compressed air tanks next to a explosion, even if is controlled.
Or maybe I am mistaken?
Any Help would be greatly appreciated

 

[berkeman]

Hi, I am a Industrial Design student working on my senior Thesis. Since antipersonal landmine cleareance is a very dangerous process; I am working on a remote controlled vehicle concept that will be able to do a controlled detonation. That way the human won't have to manually disarm the landmine which is the current dangerous and slow process. Basically to detonate a landmine you need no more than 10 pounds of pressure. The only thing I can think of is compressed air, but obviously is a problem to have those compressed air tanks next to a explosion, even if is controlled.
Or maybe I am mistaken?
Any Help would be greatly appreciated

Welcome to the PF.

What has been used in the past for doing this? How are you going to improve on existing technologies?

http://2.bp.blogspot.com/-poBh5X4vP...k/s1600/USZ+Mine+Sweeper+Tank+(Mine+Wolf).jpg

 

[Baluncore]

As pictured above, the reliable technology was developed 75 years ago. https://en.wikipedia.org/wiki/Mine_flail
On solid ground, the flail will give a very high clearance confidence at a very low cost of consumables.

The relative cost to the enemy of the original mines and the cost of mine clearance to the survivor is not important. The problem should be resolved safely for minimum cost. A pneumatic actuator would be quite expensive if it was destroyed each time a mine was found. If the location of the land mine is known then it can be counter-mined with a small explosive charge. That can be arranged to give the best probability of cutting the trigger mechanism from the mine, possibly without detonating the main charge. An alternative would be to use something like a shotgun to apply the pressure to the mine. A heavy shotgun barrel will survive the detonation of the mine.

In soft ground such as a swamp or rice paddy, the mines may circulate up and down until it may be triggered at the surface years later. Where stray land-mines may have surfaced, a dense herd of goats or sheep are driven through prior to planting. The cost and probability of killing an animal is small, but it can still feed the village. The small area of hoof that does so much damage to the land while grazing increases the ground pressure needed to trigger a mine.

 

[ferchotous]

Thank you guys so much for the info.

I have looked into those big deminer trucks, the problem is the logistics to move them from one country to the other makes them very expensive, the other issue is that you have very uneven terrain with small paths where they don't fit and they will highly damage the ecosystem. They are mainly used to clear a specific path so the military demining, I am focusing on humanitarian demining.

If the location of the land mine is known then it can be counter-mined with a small explosive charge.

Yes, the location will be known, the rc car that I am designing will work cooperatively with a Drone that have a ground penetrating radar to locate the landmines (they use those already in archeology). So basically the drone will scan a suspected area and will pin point the specific spots where landmines are located, and this ground car will detonate them almost like a controlled explosion, Landmines don't have big amounts of explosive, around 1 pound, so that's why I think it can be contained, I am just stuck on how to make them detonate. I am leaning towards a small explosive that is strong enough that will make the landmine detonate.

 

[CWatters]

Perhaps some sort of fuel air explosion could create enough downward pressure or are they immune to pulses of pressure?

 

[jim hardy]

10 pounds of pressure.

Pressure ? Over what area ? Or did you mean force ?

I'd drop a gallon jug of water on it from about three feet. The water will not become a dangerous missile.
Or use water instead of compressed air to deliver the force of your small explosion.

 

[gjonesy]

I'd drop a gallon jug of water on it from about three feet. The water will not become a dangerous missile.
Or use water instead of compressed air to deliver the force of your small explosion.

Unless you know exactly where the mine is located compressed water may only serve to uncover, dig up and or displace a landmine without detonation.

Perhaps a solid metal roller (Like on a steam roller maybe smaller) set on a long "spring arm" a good distance from a blast shield, not sure how well something like that would hold up to an explosion, BUT if it could absorb the blast by bouncing off the ground, you could make it as wide or as slim as you need it as long as you have a power plant capable of pushing the weight and a way to steer the roller around corners.

Just a thought

 

[jim hardy]

Unless you know exactly where the mine is located compressed water may only serve to uncover, dig up and or displace a landmine without detonation.

Yes, the location will be known, the rc car that I am designing will work cooperatively with a Drone that have a ground penetrating radar to locate the landmines (they use those already in archeology). So basically the drone will scan a suspected area and will pin point the specific spots where landmines are located, and this ground car will detonate them almost like a controlled explosion,

I assumed he found the approximate location by drone and zeroed in on it with a magnetometer mounted on his RC vehicle (Sears riding lawnmower ? )
and he knows its location precisely enough he could hit it with a sledgehammer on a long arm if he wanted to
the water jug idea is just to prevent flying sledgehammers .

Might be a bad assumption on my part ...

the question as i understood was 'how to safely apply 10 pounds of force to a landmine trigger without generating dangerous flying pieces of the applicator'
what immediately popped into my alleged mind was:
"Place a plastic milk jug full of water on it and set off a blasting cap* inside the jug" (*Can't buy cherry-bombs anymore)

but dropping the jug from above might work as well

just brainstorming...

 

[gjonesy]

but dropping the jug from above might work as well

use water instead of compressed air

I was commenting to the compressed water idea, i was thinking spraying water like out of a hose... the milk jug idea would work if you could hit it on the trigger mechanism. Spraying water i think it would spread the force out in all directions (as would air) on something buried a couple inches under ground. That is unless you had a precision water cannon or air gun and it would probably have to be right on top of the mine. Perhaps a large caliber firearm, as has been suggested mounted on a bomb disposable robot. There is a round called a ( breaching round) or a (plug round) that if you could get within 2 feet you could shoot the mine...it should have the power to either detonate the mine or render it inoperable. A milk jug full of water would have a "tamping" affect and would be a competing force with the blast going up and the water trying to go out. Could possibly even limit the mines blast radious actually. A milk jug with a blasting cap may have the ablity to render the mine inoperable as well do to the directional tamping force.

 

[gjonesy]

Just to clarify my vision would be a solid steel rolling cylinder on a long spring loaded arm mounted to the front of a small vehicle with a blast sheild to protect the vehicle, heavy enough to detonate the mine, but tough enough not to turn to shrapnel and springy enough to absorb the blast. But then again i was thinking reusablity. Small enough to transport manuverable enough to turn corners and able to go over rough ground.

 

[Baluncore]

There is no need to be sudden when clearing a landmine. For example, you could drill into a plastic mine with a solid “unicorn horn” or “screw extractor” shaped drill, then if the mine had not detonated, pull back to lift it out of the ground. It would not matter where you penetrated the mine, or how the trigger was rigged, it would either detonate or not. Either way you have removed it from the ground.

I suspect that in anyone minefield, the number of models of mine being cleared will be limited. Each type of mine will have some sensitive primary trigger. Once those trigger mechanisms have been identified it will be easier for an autonomous vehicle to reliably trigger or lift that design of mine with minimum resources. You might also expect to find one mine laid on top of another somewhere in the field, or possibly a booby-trap trigger to cripple a mine clearance officer. Your vehicle should be designed to survive that event, or at least provide some evidence as to what was abnormal prior to it's destruction.

When a mine is triggered, the ground provides a reasonably solid backing, so all the energy will be radiated upwards into the air above, which is how it was designed to work. Any confinement above is liable to increase shock-wave pressure and at best, could only reflect half the air-blast into the Earth. For that reason the clearance mechanism needs to be both “sparse” above the landmine, and mine type specific in it's approach.

The idea that mine clearance equipment will need to be moved more than once, is wishful thinking. The equipment should be multiple, cheap and replaceable. It will be abandoned when it's job is done, or when the accumulated injury / damage is beyond repair.
The flail tank is expensive but has a high probability of survival. A goat is cheap but has a zero chance of survival. A mine clearance automaton needs to clear mines somewhere near the minimum cost per mine. Finding that minimum is a design challenge.

 

[Baluncore]

Just to clarify my vision would be a solid steel rolling cylinder on a long spring loaded arm mounted to the front of a small vehicle

What if the mine is located between two rocks? The roller will ride over the rocks and so not trigger the mine.

 

[gjonesy]

What if the mine is located between two rocks? The roller will ride over the rocks and so not trigger the mine.

..

True...there would be drawbacks to anything you would use for this purpose, Damage to a clearing device, places where you couldn't use it, flying goats.
BUT if you could locate mines with such precision you could simply use a sniper rifle and take them out like target practice. And how acurate a picture can you get from GPR...would a 50 year old mine be identifiable? From the air with this technology? There are many approaches...which one is full proof?

 

[gjonesy]

And how acurate a picture can you get from GPR...would a 50 year old mine be identifiable? From the air with this technology? There are many approaches...which one is full proof?

Again to clarify...these are just questions that must be considered. This young man's engineering idea is both noble and very much needed in some parts of the world. And if successful would save lives.

 

[mister mishka]

I've seen dogs and rats being used to sniff out areas where there are land mines, one person collects an air sample from a certain area, and then dogs sniff the samples to see if there are any traces of explosives. I am not sure what exact explosives they are trained to smell though..

Another thing Terahertz Spectroscopy, and some relatively new and quick ways of using this to scan / find "fingerprints" of certain chemicals used in explosives. Here is an article about it:

http://phys.org/news/2016-05-speedy-terahertz-based-explosives.html

I do like the solid steel barrel idea, but yeah what if there are rocks or something else. Maybe it can be a skewed barrel like how a drill bit looks like, that would maybe help with the dispersion of energy after the mine is triggered. To save weight with transport, maybe make it hollow and fill it up with water / sand when in use? Though the shell has to be quite tough to withstand the explosion (though I guess not that tough if they are anti-personell mines). I know depleted uranium is quite tough and resistant to explosions (the US military uses this on their Abrahm tanks, along with explosive reactive armour). There is also something called Composite Metal Foams (CMF) which have quite impressive armour protection, you can read more about it here:

http://phys.org/news/2016-04-metal-foam-obliterates-bullets.html

I'm no expert on this, but I would presume that finding ways to locate many different types of mines, for large diverse areas, in a relativiley easy / cost effecient way is the best bet. Once mines are located, then there are many ways to detonate / get rid of them. Maybe for now smell is the best option, and hopefully later in the future more advance types of spectroscopy.

 

[mister mishka]

Yes, the location will be known, the rc car that I am designing will work cooperatively with a Drone that have a ground penetrating radar to locate the landmines (they use those already in archeology). So basically the drone will scan a suspected area and will pin point the specific spots where landmines are located, and this ground car will detonate them almost like a controlled explosion, Landmines don't have big amounts of explosive, around 1 pound, so that's why I think it can be contained, I am just stuck on how to make them detonate. I am leaning towards a small explosive that is strong enough that will make the landmine detonate.

Yeah I would use small explosives to detonate them, like an upside down claymore or some other simple shaped charge.

 

[Baluncore]

I know depleted uranium is quite tough and resistant to explosions (the US military uses this on their Abrahm tanks, along with explosive reactive armour).

Unfortunately DU is a toxin. https://en.wikipedia.org/wiki/Depleted_uranium#Health_considerations

There is also something called Composite Metal Foams (CMF) which have quite impressive armour protection, …

If the device will be used repeatedly in a minefield it is important that damage is not quickly accumulated. I suspect that metal foams will be expensive and quickly damaged by the products of the mine explosion.

Ideally a mechanical triggering device should be massive and survive the detonation. But that requires an actuating vehicle to be close at the time of the mine explosion.

Yeah I would use small explosives to detonate them, like an upside down claymore or some other simple shaped charge.

It could be something like a thin conical sheet of explosive that does not produce shrapnel. The advantage of a light weight explosive is that it can be detonated remotely, which will reduce damage to the remotely controlled vehicle by the landmine detonation.

 

[JBA]

In the oil industry small (1/2" dia x 3/4" long) cylindrical shaped electrically fired well casing perforating charges (with a conical depression in one end to direct and concentrate the blast force) that do not damage the down hole charge carriers, have been used for many years. They function in the same manner as the shaped charges that are used in the should fired missiles used to penetrate military tank armor.

(Note: For those not familiar with petroleum drilling and production operations, a number of these charges are placed around a cylindrical steel carrier lowered into a drilled well on an electrical cable to the depth of the oil containing formation where they are then fired to create a carrot shaped hole through the steel casing wall, its surrounding cement liner between the casing and surrounding formation and into the oil producing formation. It is these holes that allow the oil/gas in the formation to enter the well bore and be produced from the well.)

In construction site ground detonations reusable blasting mats of woven wire rope are laid over the blasting areas to control surface debris while still allowing venting of the explosive gases through the mat to minimize its damage.

In your system, where the location of the mine is already accurately determined, possibly a combination of these two items combined with a remote controlled wheeled vehicle to place the assembly over the mine would create a cost effective solution. (The charge should be inserted into the lower face of a thick steel plate in the center of the circular mat to effectively direct the blast force downward toward the mine.)

 

[Baluncore]

(The charge should be inserted into the lower face of a thick steel plate in the center of the circular mat to effectively direct the blast force downward toward the mine.)

Such a steel plate will also trap the energy from the detonating mine between the plate and ground. That will result in more side-blast and shrapnel being directed to damage the trigger vehicle.
A heavy steel cover plate can only double the initial trigger blast towards the mine. It would be better to double the small mass of explosive used for the trigger. The mass needed for a cover plate could be better allocated to a woven blast mat that would distribute the energy over time and space rather than concentrate it.

 

[Voracious Reader]

I was thinking of a device that could be suspended a few feet above the ground by an arm, connected to a vehicle. The device forces 11-20 pounds PSI of air pressure downward towards the mine, with the pressure concentrated in about 2-5 sq feet of area. Or more, if one thinks outside the box.

The mine would detonate from the increased air pressure being directed over it.

The vehicle carrying the apparatus would supply the device via the arm with enough compressed air to power it. Perhaps an auxiliary engine mounted to the vehicle's bed. The device and arm would have to be designed to take the brunt of the explosive blast, which for anti-personnel mines is much smaller than anti-tank/anti-vehicle mines. It could swing upward, or retract. Or go in a safe direction via something I haven't even thought of.

 

[Rive]

I was thinking of a device that could be suspended a few feet above the ground by an arm, connected to a vehicle. The device forces 11-20 pounds PSI of air pressure downward towards the mine, with the pressure concentrated in about 2-5 sq feet of area. Or more, if one thinks outside the box.

Overthinking.
Just go with style and make it smash

 

[Baluncore]

@ Voracious Reader. Welcome to PF.

Unfortunately, the trigger pressure is not applied to the surface area of the mine, but to a mine trigger that may only be the size of a pin or a matchstick. For that reason, air-pressure alone will probably not trigger a land mine, the force must be applied directly to the trigger pin.

A trigger that measures 1” long by 0.05” across will only have an area of 0.05 sq”. Using air-pressure to apply a force of 20 pounds would require a wavefront with a step pressure change of about 20 / 0.05 = 400 psi. That would require a shockwave. You might use an LPG fuelled gas gun to generate that wave. It would be easier to hit the mine with a plastic bottle full of water.

Also, some mines are built with two charges, the first to lift the mine out of the ground to a height of a metre or two, before the second charge detonates, spreading shrapnel like a hand grenade. There is no time to retract a fragile trigger device, it will become part of the shrapnel, or be filled with holes.

Imagine there was a field of mines that you had to identify and remove. What could the enemy do to slow you down? How could you counter all those techniques without taking the risk that will kill you? When you have finished the job, you must sign a statement that the area is now safe. How can you ever be sure that you have found all the mines? Will you feel guilty if it later turns out you were wrong and someone loses a leg?

Don't rush to solutions, that will kill you and others.

 

[LURCH]

Seems to me that if you can precisely locate the mines, and you have a drone hovering above them, you don’t need a second vehicle. Just load the drone with a net full of small water balloons, and take a bombing run at the thing! You might even lift several loads, depending on the lifting capacity of your drone, and take out a bunch of mines with a single flight. Just fly high enough to avoid destroying the drone.

 

[LURCH]

Btw; this was an adaptation of a technique that first occurred to me for military applications. Replace the nice cheep drone with a big expensive multi-engine bomber, its bomb bay filled with large-piece gravel, and this could clear a long straight corridor in a big hurry. (Actually, I was thinking of several bombers in tandem, just to be certain. )

But without the need to clear the mines quickly, and with the ability to see where they actually are, a drone with water balloons should be adequate.

 

[LURCH]

Also wanted to add:

Whatever you end up doing (if your idea ever gets put into practice) FILM IT! If you make a show out of the process, you might have a solution that is not only cheap, but may even make money. Clearing mines and clearing a profit. This could fund entire project right through to its conclusion.

You could even include advertisements that show charities for the victims.

 

[NTL2009]

Also wanted to add:

Whatever you end up doing (if your idea ever gets put into practice) FILM IT! If you make a show out of the process, you might have a solution that is not only cheap, but may even make money. Clearing mines and clearing a profit. This could fund entire project right through to its conclusion.

You could even include advertisements that show charities for the victims.

Not to be a wet blanket, but realistically, the OP has a steep hill to climb to achieve anything in this area. It is an area where a lot of resources have been applied for many years. Even if OP has a better idea that has not been considered before, there is a long way to go to bring that to fruition and demine even a single acre of land.

As was mentioned earlier, demining needs to be very, very effective. Otherwise, the land is opened up to humans, and more injuries/deaths occur, due to the false feeling of safety.

http://www.un.org/Depts/mine/Standard/chap_5.htm

CLEARANCE STANDARDS
5.9 An area is cleared when all mines and munitions have been removed and/or destroyed. All debris, from mines and munitions, such as fuzing systems, percussion caps and other items that constitute an explosive hazard, is to be removed.

5.10 The area should be cleared of mines and UXOs to a standard and depth which is agreed to be appropriate to the residual/planned use of the land, and which is achievable in terms of the resources and time available. The contractor must achieve at least 99.6 % of the agreed standard of clearance. The target for all UN sponsored clearance programmes is the removal of all mines and UXO to a depth of 200mm.

Think about that. Out of 250 devices, the process can only miss one of them. That's a high standard, for a good reason.

May I suggest that the OP (and any of us) could make more of a difference by donating money to fund the purchase/maintenance/operation of current demining equipment. Each of us is probably better at earning money than re-inventing this wheel.

 

[hmmm27]

None of the methods in this thread will work, effectively. You got mines ? Complain to the UN. Loudly and oftenly.

 

[Nik_2213]

Wasn't there a 'crazy' pogo-stick bot tried some years ago ? It ran on a small canister of gas, bounced around field. Heavy enough to set off mines, light enough to be thrown clear...

Given its absence from the field, it cannot have been reliable...

Sadly, older mines will have moved around, and newer mines have become extremely difficult to detect...

Worse, IIRC, some modern mines have been designed to 'refuse' simple clearance methods, remain in wait for materiel to arrive...

 

[Baluncore]

This thread was specificaly looking for ways to detonate individually located mines.
It does not need to locate those mines, or sweep entire areas.

Replace the nice cheap drone with a big expensive multi-engine bomber, its bomb bay filled with large-piece gravel, and this could clear a long straight corridor in a big hurry.

The problem with sowing mine fields is mine separation. If the mines are too close, sympathetic detonation will trigger more mines with the shrapnel from the first to be triggered. That could run away to trigger the majority of the field. For that reason a mine field must be sown sparse, and the mines need to be small. Unfortunately, a bomber full of rocks is expensive, that makes it very expensive to guarantee clearance because you need to cover 100% of the ground with falling rock. It could become very expensive in bombers and pilots as about 10 truck loads, or about 100 tonnes of gravel would be needed.

So why quarry all that rock, crush it to gravel and transport it when that is not actually needed? An old technique that has been used to blow pathways through minefields is to drop a line of HE shells or bombs that will penetrate the ground before detonating. Those shells throw local rock in the air, along with a few mines, and so leave a line of craters and blown mines that mark a safe route. The weight of a barrow load of HE is small compared to many truck loads of gravel, and it costs much less to deliver.

“Operations research” was developed during WW2 to increase the effectiveness of available resources. https://en.wikipedia.org/wiki/Operations_research#Second_World_War
The most obvious solution with the biggest bang is rarely an optimum solution. Dropping heavy depth charges on submarines was always spectacular, but throwing out a circle of 24 mortar shells that sank and only detonated on contact was not exciting at all, but it was more than 10 times as effective in destroying submarines. See the statistics at; https://en.wikipedia.org/wiki/Hedgehog_(weapon)

There is no question that if you can accurately locate all the landmines in a field, you can destroy them individually very efficiently. Just what you use to trigger the mines is the subject of this thread. It should be cheap, expendable and frangible, such as a bag of sand or a plastic bottle of water.

 

[Stephen Tashi]

I have looked into those big deminer trucks, the problem is the logistics to move them from one country to the other makes them very expensive,

A random thought: A semi-serious concept for air-mobile armored vehicles is to construct them with big empty bins on their sides that will be filled up with sandbags of local dirt after they arrive at their destination.

That general line of thinking may actually be useful. Is there a design that utilizes local resources? For example, perhaps a vehicle could catapult an expendable bin with a sandbag ahead of the vehicle and pull the bin back toward the vehicle with an expendable rope.

 

[Baluncore]

For example, perhaps a vehicle could catapult an expendable bin with a sandbag ahead of the vehicle and pull the bin back toward the vehicle with an expendable rope.

It might work well in a flat sandy desert, a farm field or on the school football field, but it will not be much use amongst the fenced-off thickets or overgrown forests that naturally develop following a mine sowing operation. Yet it seems so easy to sweep the entire problem away over a few beers, by just getting a bigger truck, or throwing a bigger bomb at it. That way lies madness.

Goat tracks in the mountains are cleared initially by stray goats. Sheep and goats walk a very narrow line, which is why mines are planted to the side of the track where only passing traffic or grazing animals will be the victim. That cuts small vehicle access by effectively narrowing the track.

Mathematically ideal Cartesian solutions are not usually applicable to a real world, as there is an inverse law to mine fields. If an area could be swept easily, the mines will be planted sparsely. If heavy vehicles can access the area there will be a few anti-vehicle mines thrown in where they might pull off the road, and the mines will be planted in the roots of trees. The easy mine fields are swept during hostilities. Any clearance using heavy vehicles will be done within a year of the end of hostilities. The most difficult to sweep areas will be the least grazed and the most overgrown. Five years later you will be dealing with the most difficult overgrown fields, in more remote areas, without heavy vehicle access.

The solution to the problem of clearing the remaining mine fields tends towards the safe detection of each mine, followed by the safe destruction or removal of that mine.

 

[LURCH]

As I understand the OP, detection is already handled; we are only discussing disposal. This of course is utterly dependent on the ability of GPR to locate all of the mines in a specific search area without missing any ( ferchotous, do you have any data on how reliable GPR is at this task?).
Of course, what’s needed is a safe and reliable method of disposal that is as cheap as possible, which brings me back to using the drone to drop a bag of water balloons or dump a bucket of rocks on the mine. The results will be immediately obvious; either the mine will detonate or it won’t. If it doesn’t, the process can be repeated at very little cost and virtually no risk to people or equipment (or goats).
If the more precise method of using a second ROV is preferred, then allowing the vehicle to plant a Dragon is probably the best method. It’s a pyrotechnic torch made by Disarmco. The vehicle could plant it and then move away to a safe distance. Dragon can be ignited remotely.

 

[Rive]

safe destruction or removal of that mine.

I think that one there is an 'and', not 'or'. Even if the detection is false, even if the detonation was not successful, even if it was successful, that thing (the remains of) has to be digged out and collected.
Water balloons and flying drones won't do that.

 

[256bits]

I think that one there is an 'and', not 'or'. Even if the detection is false, even if the detonation was not successful, even if it was successful, that thing (the remains of) it has to be digged out and collected.
Water balloons and flying drones won't do that.

That was going to be my comment.
Object remotely located under the ground may or may not be a mine. If a mine it could be a decoy, a dud, or live.
Adding layers of surface material impedes and makes more unsafe the verification of the object if a detonation does not occur.

 

[Baluncore]

I think that one there is an 'and', not 'or'. Even if the detection is false, even if the detonation was not successful, even if it was successful, that thing (the remains of) has to be digged out and collected.
Water balloons and flying drones won't do that.

According to the aforementioned http://www.un.org/Depts/mine/Standard/chap_5.htm
Minefield Clearance Operations. Sect 5.9 An area is cleared when all mines and munitions have been removed and/or destroyed. All debris, from mines and munitions, such as fuzing systems, percussion caps and other items that constitute an explosive hazard, is to be removed”.

My bold. So fragments may remain if they are not an explosive hazard.
By all means bicker over the punctuation, but realize that detonation in place is sufficient.
Water balloons and flying drones will do that.