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Comment by beloch | Hacker News Reader

It would be great to think that littering the countryside with unexploded ordinance was a thing of the past and we no longer do such things, but the conflict in Ukraine is just one example to the contrary.

Has any effort been put into making duds easier to find after the fact? e.g. Has anyone thought of putting something like an upscaled RECCO reflector on bombs? i.e. A passive radar reflector that would allow searchers to just hit a field with radar and get reflections back from unexploded ordinance.

Obviously, this wouldn't work for cruise missiles, etc. that need to have a low radar profile while in flight, but why not for bombs (especially cluster munitions) that are used in much greater numbers?

This is just one idea. I'm sure other methods could be used to make duds easier to find. Is there military value in leaving stealthy duds in your enemy's territory?

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> Is there military value in leaving stealthy duds in your enemy's territory?

In all fairness -- probably, yes. It's the enemy's territory, and now you've made it more deadly, like an accidental minefield.

But I don't think any consideration is given to what happens to duds, what are the civilian consequences or environmental impacts of any part of the weapons lifecycles. It is an industry of death and destruction after all.

It'd likely to be more accurate to say that some are left that simply don't explode yet. A good example would be certain cases of cluster munitions that are designed to hit airfields. A most of the explosives will go off and crater the concrete and asphalt, but others will remain unexploded and sensitive to detonation. As runway repair work cannot commence until those unexploded munitions are cleared, the airfield is out of action longer than it would be otherwise.

I understand in these cases and other ones such as scattering mines that a timer can be set so the mine or munition deactivates after a set time (say, a week) by deactivating the fuse.

Not all are designed in this way of course. And apologies, I'm looking for source links, but I can't find them at the moment. Edit: Here's an example https://en.wikipedia.org/wiki/GATOR_mine_system

Given the sometimes impressive fraction of duds among bombs, I am not sure I trust a mine that supposedly deactivated itself on a timer. It may work 9 times out of ten. But it doesn't really make a big difference if it's the first, second or the tenth mine that gets you and rips off your leg.

They deactivate by discharging their power supply, after which they are lacking the stored electrical energy needed to trigger the electrical detonator.

It's not fool-proof, but a lot better than chemical/mechanical mechanisms that try to go inert.

>But I don't think any consideration is given to what happens to duds

On the contrary. Duds causing UXO is the reason the US and most of NATO chooses not to build cluster munitions anymore, preferring instead pre-formed tungsten balls that are fired like a shotgun when the munition is over it's target.

The dud rate was something like 2%, not that much but enough to make the US decide that leaving tens of thousands of UXOs in formerly enemy territory isn't okay.

Russian cluster munitions being used in Ukraine right now have a much much higher dud rate, and that's before any bad storage or handling.

For similar reasons, many NATO countries have given up types of landmines

Modern US munitions have a mechanism that bricks the warhead after a certain amount of time from being fired (years). That way they retain use on the battlefield as a threat to enemy soldiers even if they don't properly detonate but will not pose a long term risk to civilians.

Maybe something useful happens to disable the fuse? The hundreds of pounds of high explosive are still hundreds of pounds of high explosive, in a rusty container, no?

The really useful explosives don't go off because of rough handling and don't become unstable over time - both very desirable properties to prevent handling accidents. Ideally, the fuse is the only thing capable of setting it off. So hopefully, the explosive will just sit there in it's shell and stay inert. Most WW II duds are dangerous because of their fuses, not the bulk explosives, as I understand it.

While not universal, a lot of modern US munitions use polymer-bonded explosive (PBX) which is much less sensitive to accidental detonation from heat, shock, etc. so it is very unlikely to detonate from anything other than an intentional effort [1, 2]. They also use electro-mechanical fuzing systems, which are good but not great for safety, but are much better than mechanical fuzing [3]. All electric fuzing systems are the safest and are making their way into newer munitions [4].

[1] http://characterisationexplosiveweapons.org/studies/annex-e-... [2] https://en.wikipedia.org/wiki/Polymer-bonded_explosive [3] https://trace.tennessee.edu/cgi/viewcontent.cgi?article=2979... [4] https://sdquebec.ca/en/news/fmu-139-db-replaces-three-legacy...

Modern US policy is a maximum of 30 days. [1]

[1] https://media.defense.gov/2020/Jan/31/2002242359/-1/-1/1/DOD...

I’m not sure there’s much value in blowing up some poor farmer years after the fact, and the impact for either government is pretty much zero.

I think it'd be pretty hard to convince North Korea, Iran, or Russia to alter their munitions.

We can't even convince them not to throw bombs at other countries.

War should be a thing of the past.

We can't even convince our own military.

Maybe the US and its proxies should lead by example before trying to convince anyone else, given they are the ones who dropped far more bombs than all of those combined.

The US also, as well as everyone else starting and participating in wars of aggression

Radar is sometimes used for detecting incoming artillery rounds, so yeah, no need to make it easy for the enemy by filling it with radar reflectors.

I wonder if you could put the radar reflector on the end of the shell or bomb. It would only be visible from behind which is only possible when in ground.

The other way would be have fuse that shows reflector after hitting something but not detonating.

How about 20ft of kevlar string or tape, with a retroreflective tip?

Duct tape an AirTag on'em.

I'm only half joking. "not even Apple knows the location of your AirTag"

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