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Nuclear propelled KE bomb

Thunderwell meets Rods from the Gods
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I've seen ideas for nuclear-propelled spacecraft and for KE projectiles but not nuclear-propelled KE projectiles. We know why KE bombs are nice- significant damage without fallout. Why a nuke tube? Nuclear propulsion gives us a high speed launch without tons of fuel or specialized launch vehicles. Firing from a tube significantly reduces fallout. There's also the possibility of reusing old warheads (as opposed to dismantlement) which would reduce costs.

Launch effectiveness? Ehh, not so sure. Check the link for a bunch of specs on Operation Plumbob. Operation Plumbbob's Pascal-B test had a blast yield 300 Tons (of TNT). The device was at the bottom of a 500ft length, 4ft diameter shaft with a concrete plug directly above the device and a ~900 kg steel cap (approx 2000lb) welded to the top of the shaft. The blast launched the cap at about 66 km/s, so the cap had an energy of about 59400000 J (59.4 MJ) or 0.01419 TNT Tons. A 300 Ton blast yield to get a 0.01 Ton launch energy. That is some crappy efficiency. For reference, the Little Boy had 16 kT yield.

It could be much better though. In the link it describes the effects of the nuclear blast and how it propels objects. There was also the unimplemented Project Thunderwell. "The idea was that a deep shaft would be dug in the earth and filled with water. A spacecraft would be placed atop this shaft, and a nuclear explosive would be detonated at the bottom."

There's also Project Orion which was a nuclear-propelled spacecraft. It was carefully calculated for efficient launch. My brain is taking a fart right now and I can't find anything to calculate launch efficiency.

Placing a guidance system on the projectile is possible. Building a circuit capable of surviving the massive acceleration wouldn't be too difficult. Launch could be dampened to reduce the impulse too. Making guidance fins that actually affect a multi-ton bomb might be another story. Perhaps thrust vectoring with a flat/oval aerodynamic shape would be more effective at turning.

The projectile would need to be aerodynamically designed. It may be useful to have a crumpling/expanding nose for a faster dump of energy on impact.

Cost? You'd need a nuclear warhead. A typical nuke cost $1M USD in the '80s. It's possible that warheads could be reused. Dig a big hole. I dunno. A gigantic aerodynamic rod of dense material. Tungsten would be excellent but stupidly expensive. Repurpose a seamless pipe manufacturing plant perhaps? You could make huge steel pipes and fill them with a cheap dense material (lead comes to mind) and use a heat-resistant nosecone and outer plating. So probably a few million to research, a few million per launch.

some final questions an ideas -What size projectile can one feasibly launch? -What kind of launch angle / trajectory are we looking at? -Can we put the projectiles into low-orbit and drop them on the other side of the earth? -Is it even guidable? -Do we need to worry about terminal velocity? The projectile doesn't have to rely on gravitationally energy when you can turn the projectile and use the horizontal momentum. -While the projectile is an unstoppable slug of metal, how vulnerable is the guidance system? -Where do we launch them from? Land? Sea? Air? -How about a two-stage launch. A light launch puts the projectile and an entire launch tube into the air. Then the airborne launch tube provides the majority of the energy while the device is in a low-fallout area

links below

Maave, Dec 07 2012

Operation Plumbbob wiki page https://en.wikipedi.../Operation_Plumbbob
[Maave, Dec 07 2012]

Learning to Contain Underground Nuclear Explosions http://nuclearweapo...Tests/Brownlee.html
Info about Pascal-B [Maave, Dec 07 2012]

Operation Plumbbob tecnical info http://nuclearweapo...lumbob.html#PascalB
More detailed information about Pascal-B (and all tests) [Maave, Dec 07 2012]

Project Orion wiki page https://en.wikipedi...nuclear_propulsion)
[Maave, Dec 07 2012]

Project Pluto http://en.wikipedia.../wiki/Project_Pluto
Nuclear propelled bomb [spidermother, Dec 08 2012]

Nuclear Thermal Rocket http://en.wikipedia...lear_thermal_rocket
Why nuke your own territory when you can deliver it unto thine enemies? [BunsenHoneydew, Dec 30 2012]

[link]






       There are much more efficient ways to launch a projectile in terms of cost, complexity, safety, and every other metric except "unnecessary use of nuclear warheads". [-]
Voice, Dec 07 2012
  

       unnecessary use of nuclear warheads [++]
Voice, Dec 07 2012
  

       //A typical nuke cost $1M USD in the '80s.//   

       I doubt that very much.   

       Anyhow, the premise here is all wrong. You want to have a huge explosion, gamma/neutron pulse, plus fallout, at your location, in order to transport a small fraction of that energy over to your enemy's location. This is backwards.   

       Honestly, if you're happy to use nuclear weapons, ie that threshold is reached, then there's not much out there that can compete conceptually with a ICBM with MIRV capability. I'd certainly not trade off a smoking hole several miles wide in my backyard, for a dent in someone else's bunker.
Custardguts, Dec 07 2012
  

       Nukes (in atmosphere) are good at high energy (thus high mass), relatively low speed propulsion. Supersonic, yes, but only just. A current tank gun gets a KE penetrator up above mach 5 with much less energy.   

       Since an ideal KE weapon is relatively small, but moving extremely fast, a nuke is going to wast a lot of energy with relatively little result.
MechE, Dec 07 2012
  

       I think this would work, but not well enough, and too expensively, with too much local damage with each "gun" destroyed in 1 use. It would not be aimable.   

       That being said, this would not necessarily do as much damage locally as some of the other annotator have implied. Most underground tests did no above ground damage at all, and I bet this could be engineered (with some degradation of ability) to keep the radioactivity below ground.
Kansan101, Dec 07 2012
  

       The idea of the water-filled tunnel gives the device to launch at much higher speed. The explosion vaporizes the water and the expansion of this heated gas to propels the projectile. I don't think the KE penetrator example is a good comparison. The penetrator is significantly smaller and is used for a different purpose. It's designed with a low diameter to allow it to pierce armor. The penetrators are designed to have as high of a mass as possible without increasing the diameter.
Maave, Dec 07 2012
  

       Maybe a bunch of these could be kept orbiting the sun, moving fast, then steered in to ram into stuff / crash into earth.
bungston, Dec 08 2012
  
      
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