2
$\begingroup$

So, in my story the United States Army created a large amount of new weaponry and armor to protect its troops while they marched into the resource rich countries of South America. They invented powered armor, warrior robots, and energy powered weapons. The most devastating weapon of theirs was the DC defender 16 portable nuclear warhead launcher. It gives a load of 100 tons and is supposed to be lightweight enough for an average soldier to carry. How could you make a weapon to do these tasks?

$\endgroup$
7

5 Answers 5

4
$\begingroup$

It looks pretty difficult. According to a chart I found, lightest nuclear bombs the US has built weighed about 20 Kg and had a yield of around 0.1 Kt -- ten thousand times smaller than what you want. The lightest 1 Mt bomb built seems to be in the neighborhood of 200 Kg -- so just the bomb itself is not man portable, never mind the launcher.

It's hard to imagine a launcher which weighs markedly less than what it launches. Again, not man portable!

I'd also note that it's considered good practice to lob hand grenades far enough that the lobber is not injured. Likewise nukes. So for a 1 Mt bomb, you need to lob it 5-10 miles, at least.

I don't think that there is a possible man-portable, real-world, 1 Mt bomb and launcher. (At least as long as you're only talking one or two men.)

$\endgroup$
5
  • 2
    $\begingroup$ It's also much easier to equip your front-line troops (Forward Artillery Observer) with radios to communicate with launchers in the rear. Also, the only practical use of tactical nukes would be to stop an advance by opposing forces, as you really don't want your forces advancing across areas that you've nuked. I'll not even go into the idea of handing out small nukes to average troops :-) $\endgroup$
    – jamesqf
    May 23, 2018 at 5:49
  • 1
    $\begingroup$ "Don't worry. They're very well trained and won't misuse them." $\endgroup$
    – Mark Olson
    May 23, 2018 at 11:20
  • 1
    $\begingroup$ @MarkOlson You may want to make a note that this answer predates the OP's edit revising down the nominal yield, otherwise it doesn't make that much sense. $\endgroup$
    – Ash
    May 23, 2018 at 12:47
  • $\begingroup$ @Ash: Heh -- yes, the question seems to have morphed in important ways since I answered it! $\endgroup$
    – Mark Olson
    May 23, 2018 at 12:59
  • $\begingroup$ 0.1 Kt -- ten thousand times smaller than what you want The OP asked for a 100 ton nuke, not a 100 Kt nuke. This is actually the exact size the OP asked for. $\endgroup$
    – Nosajimiki
    Apr 11 at 13:40
8
$\begingroup$

Several problems exist with this idea (and the one real life example perfectly demonstrates it)

In the 1950's, as part of the "New Look" reorganization of the US Army, small nuclear weapons were devised to provide tactical nuclear firepower at very low levels to make up for the lack of numbers between deployed US forces in Europe (and presumably anywhere they would be deployed) and Soviet forces. In addition to nuclear artillery (see the "Atomic Annie" nuclear howitzer), the Army devised the M28/M29 Davy Crockett Nuclear Weapon System.

enter image description here

M-65 nuclear artillery piece. While self propelled, not very portable

enter image description here

Setting up the Davy Crockett for firing

If the rather complicated firing sequence wasn't enough to dissuade people from using it, the fact that the small projector barely put the firing crew out of the blast radius of the weapon probably inspired some second thoughts about actually using the thing....

The power of atomic weapons actually makes them largely unsuitable for tactical missions on the ground. The launching crew will pretty much be in harms way, the nuclear devastation and radioactive fallout will make crossing the ground difficult post blast and there are generally few high value targets that even require nuclear ordinance on the front line (ships are almost by definition high value targets, so using small nuclear warheads on torpedoes makes much more sense). Attacking targets with sledgehammers really doesn't work well except for a very limited number of targets.

For the sorts of targets which actually do justify nuclear servicing, sending a long range strike via aircraft or missiles works far better, and the deeper in the rear the target is in relation to your forces, the better for your troops.

$\endgroup$
4
  • 1
    $\begingroup$ The implementation of power armor in the setting makes a Davy Crockett style weapon a little more feasible, so as long as the armor can protect against the radiation and initial shock/heat. $\endgroup$
    – hehe3301
    May 23, 2018 at 12:32
  • $\begingroup$ That is still a big trade off (extra protection vs nuclear effects) against carrying more conventional weapons and supplies, especially since the nuclear weapons have very few suitable targets. Everyone is still saddled with the protective equipment, and the logistical effects of that also need to be considered. $\endgroup$
    – Thucydides
    May 23, 2018 at 12:40
  • $\begingroup$ I guess it depends on the proliferation of power armor, if all your front line troops have the safety gear built in (I'm thinking like T series from fallout) having one per 100 troops as a first strike or entrenchment clearing device is not unreasonable. Especially if you don't care if the area is livable afterwards. $\endgroup$
    – hehe3301
    May 23, 2018 at 13:05
  • $\begingroup$ From all things Fallout brought us, I had no idea that the frigging mini-nuke was not only possible, it already existed for quite a long time. The game version now looks like a wimp. $\endgroup$
    – Mermaker
    Apr 11 at 13:10
1
$\begingroup$

Let your Warrior Robots carry it, instead of the human soldiers. As a bonus, they can also deliver on foot and detonate the device - eliminating the need for a separate delivery system.

Since your robots' weight capacity and cleverness is whatever you decide, you can pack whatever warhead size you need without worrying about human stamina, danger-close friendlies, and misdelivered ordnance...except to further your plot, of course.

$\endgroup$
2
  • $\begingroup$ But there are times when EMP devices are used against the army, so the humans also need to be able to use it $\endgroup$
    – DT Cooper
    May 23, 2018 at 1:26
  • $\begingroup$ Nobody expects, for example, artillery to be human-portable if their carrying platform becomes disabled. You can harden your Warrior Robots to be EMP-resistant. Or send a second wave of robots to recover the device from disabled robots and continue mission. Or suppress the enemy use of EMP weapons using your own other weapon systems. $\endgroup$
    – user535733
    May 23, 2018 at 12:07
1
$\begingroup$

http://blog.nuclearsecrecy.com/2013/12/23/kilotons-per-kilogram/

Look at the chart showing what we've built. The only warhead that matches your edited requirement is about 100 kilograms. That's not something a soldier carries around.

Note that the absolute minimum is 11 pounds of U-235 plus the weight of the detonator and such a weapon will be unreliable. By the time you add a rocket to deliver it you're beyond what a solider can carry into battle.

The closest anyone has come to what you're after are nuclear demolition charges meant for special forces use--and they're carried as two pieces and the delivery system is by hand--infiltrate and place the bomb on what you want to destroy. The nature of nuclear physics makes it unlikely there will be any substantial improvement in such weapons.

$\endgroup$
-1
$\begingroup$

Critical Mass Makes This Improbable

There is no known nuclear fuel that has long enough of a half life to pack into a weapon system that can also go critical with less than about 10kg of mass. Without enough mass concentrated in one spot, nuclear fuels just fizzle out. This means that 16 portable nuclear warheads will require a bare minimum of 160kg of nuclear fuel. Adding rockets and detonators to give you something like a W54 will increase this to somewhere in the 370kg range for your ammo alone... not to mention that each shell is about the size of a 5 gallon barrel. Even with robotic strength augmentation, there is no way for a person sized combatant to carry that many shells.

So, this weapon system will need a bit of hand-waving to be viable

Let's pretend for a second that your setting has a heavy element isotope that is both stable to decay and has a much lower critical mass than U-235. You could then make a reasonable assertion that smaller nukes are possible in your setting thanks to this made up, but scientifically plausible fuel source.

A 0.1Kt nuke takes about 10kg of nuclear fuel, but not because the energy density of fissile fuels is 1kg:0.01Kt. Nukes that are too close to thier critical mass have a harder time detonating all of thier fuel; so, mini nukes like W54s actually only explode at about 10% efficiency. If your micro-nuke isotope had a critical mass well under 1kg, then you could get a much higher efficiency out of a much smaller warhead. Higher efficiency like this also means the weapon will produce far less radioactive fallout. The biggest contamination from mini-nukes is the unspent fuel. So while this will not be a radiation free weapon, it will have a lot less fallout than any other nuke designed to date.

So, if we pretend your isotope has a similar energy density to U-235, but way lower critical mass, then you could reduce your rocket's total mass down to about 2-5kg which is about the size and weight of a RPG-7 Rocket. While 16 40mm RPGs is a lot of weight for one soldier to carry, with power armor and a very large backpack, it becomes doable.

Minor Frame Challenge: Why 16 rounds of ammo?

Personally carried weapon systems like this have a very limited range, and this weapon can lay waste to just about everything in that range using just 1 rocket; so, there is no good reason to deploy that many short ranged nukes into one place. Don't exactly have to worry about missing. Instead, it would be much better to deploy separate troops with 1-2 rockets each several km apart along your front line. This will give you a lot better coverage. Also, the fewer nukes you need to carry, the more you can invest in the rocket's range. A single nuke with a range of 20-40km is way more helpful (and less hazardous to your own troops) than a lot of nukes with a range of 5-10km.

$\endgroup$
3
  • 1
    $\begingroup$ Having a lot of nukes on a single load also create the issue that, if your enemy puts their hands on one of your systems, now they have 16 warheads and you have 16 very big problems. $\endgroup$
    – Mermaker
    Apr 11 at 15:05
  • $\begingroup$ While the lack of capitalisation makes it unclear, the "16" appears to be part of the fictitious designator for the launcher, not the number of rounds that it carries. $\endgroup$ Apr 11 at 17:43
  • $\begingroup$ @KerrAvon2055 Even so, that does nor mean you should use a parallel launcher design. Pretty much all modern multi-shot infantry RPGs use a single launch tube that fires in sequence feed by a chain or clip because parallel tubes are too cumbersome to carry and waste a lot of added weight and materials. $\endgroup$
    – Nosajimiki
    Apr 11 at 19:03

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .