Nuclear Explosions

[kerbiloid]

1 hour ago, Nothalogh said:

You know what we really need, an above ground test filmed with modern camera technology

Against Enceladus. To dig a well and look inside.

[magnemoe]

3 hours ago, Nothalogh said:

Correct, but we're also talking about a vehicle built like an aircraft carrier, instead of like a soda can

Still it would be like the magazine of an warship going off.
It would destroy the ship. 
an larger orion would use larger charges so you would keep this result. 

On the other hand its very hard to set off nuclear weapons by accident, even easier in orion charges as you might add fuse as part of moving the charge to launch tube. 
 

[p1t1o]

11 hours ago, sevenperforce said:

Eh, the optimal effective range of a shaped-charge megaton nuclear directed energy weapon (i.e., nuclear lance of fiery destruction) is "only" 2000 km.

 

10 hours ago, sevenperforce said:

And, if you're exoatmospheric...

...a one-megaton nuclear lance will blow a hole 70 meters deep and 200 meters wide...

...through solid aluminum...

...at 10,000 km.

 

This apparently HAS been tested, although the results are a little different to a searing fiery death-beam. There isn't too much to go on, unsurprisingly, but it seems a test, codenamed "Chamita" was carried out in support of a "Project Prometheus" and was investigating using a orion-pulse-unit-style setup to project a "beam" of solid shrapnel at velocities in the 100km/s area in a cone 0.001radians wide.

Whether this can really be extrapolated to megaton versions vaporising kilotons of metal at extreme ranges, is probably guesswork though. But what appears to have been empirically verified is still quite eye-opening.

 

 

This document (http://extremal-mechanics.org/wp-content/uploads/2012/11/Fenstermacher.pdf) makes reference to a "The one known NKEW test (having yield under 20 kilotons) occurred on 17 August 1985 and was named "Chamita."

This document (http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/31/060/31060372.pdf) lists "chamita" as a 20kt test burst in a shaft, listed as "weapons development"

This document (https://books.google.de/books?id=_fwwAQAAMAAJ&pg=RA1-PA160&lpg=RA1-PA160&dq=chamita+nuclear+test&source=bl&ots=QZjzw2SUar&sig=pnm2pKX56sTnRvgzue4INC3-VWU&hl=en&sa=X&ved=0ahUKEwippM6Go_vSAhVBKyYKHYunBjgQ6AEIMDAE#v=onepage&q=chamita nuclear test&f=false) states in a reference:

"[Ref#]68.  Christopher E Paine, unclassified presentation at the Washington Test Ban Workshop, 20 March 1990. It has been reported that the 17 August 1985 “Chamita” test, in support of a nuclear-powered kinetic energy weapon, accelerated a 1-kilogram tungsten-molybdenum plate to 70 kilometres per second and that five known x-ray laser tests occurred between 14 November 1980 and 28 December 1985, all but the first of which having yields in the range 20-150 kilotons."

"Up to 5 percent of the energy of a small nuclear device reportedly can be converted into kinetic energy of a plate, presumably by employing some combination of explosive wave-shaping and "gun-barrel" design, and produce velocities of 100 kilometers per second and beam angles of 10^-3 radians: (The Chamita test of 17 August 1985, reportedly accelerated a I-kilogram
tungsten/molybdenum plate to 70 kilometers per second. t) If one chooses to power 10 beams by a single explosion, engaging targets at a range of 2,000 kilometers with a kill energy of 40 kilojoules per pellet (one pellet per square meter), then such a device would require an 8-kiloton explosive and could tolerate random accelerations in the target, such as a maneuvering RV or satellite, of up to 0.5 g (5 m/s2).*

* SPARTA Workshop, 1986. This scaling presumably holds up to about 50 kilotons but, due to blackbody x-ray emission, decreases to about 1 percent for larger yields"

 

 

Note that 5% figure - not the 60-80% figure that is often reported alongside Project Orion materials. 

Also note that this is a "beam" of solid particles, not a beam of x-rays.

Also note the predicted degredation with larger yields.

 

Further:

"There is also a fundamental problem with both the Casaba and Prometheus concepts that becomes relevant at higher yields. Despite the alleged success in directing 5 percent of the energy of a small nuclear explosion into flying debris, a good portion of the remaining energy inevitably becomes blackbody radiation, which would quickly overtake the pellets. Even at 1 kiloton with optimistic assumptions, this poses the risk that most of the particles will be vaporized or even ionized, rendering them ineffective: The NKEW concept is thus one that may require subkiloton explosives to be feasible. If its feasibility also depends on employing shaped thermonuclear explosives to help direct the pellets or dust more efficiently, then the concept is further burdened by the difficulty of designing thermonuclear
devices with yields less than 1 kiloton. Whatever the case may be, it is clear that demonstrating a rush of hypervelocity pellets from a nuclear blast, while perhaps impressive, in no way guarantees that a useful weapon will ever be derived from this concept." [emphasis mine]

 

 

 

[sevenperforce]

Pah, that's clearly just an engineering problem.

[DerekL1963]

On 3/28/2017 at 3:48 PM, Nothalogh said:

Correct, but we're also talking about a vehicle built like an aircraft carrier, instead of like a soda can

At the scale of the energies involved the difference between a soda can and a couple of feet of solid steel is essentially irrelevant.

This is what was left after a magazine explosion inside a battlecruiser in WWI...

[Nothalogh]

37 minutes ago, DerekL1963 said:

At the scale of the energies involved the difference between a soda can and a couple of feet of solid steel is essentially irrelevant.

This is what was left after a magazine explosion inside a battlecruiser in WWI...

Yes, and good engineering can help negate those kind of catastrophic structural failures.

Modern ships store explosives and such in ways that when it explodes it may blast a massive hole in the hull but it won't break the ship in half

[kerbiloid]

While the puny trusses right near the explosion center look enough well.

Spoiler

 

[Nothalogh]

12 minutes ago, kerbiloid said:

While the puny trusses right near the explosion center look enough well.

  Hide contents

 

Fun fact, the inspiration for Orion came from the fact that the tower wasn't actually vaporized, rather it was pulverized by the pressure wave and the fragments were found scattered over the nearby area

[Nibb31]

1 hour ago, Nothalogh said:

Fun fact, the inspiration for Orion came from the fact that the tower wasn't actually vaporized, rather it was pulverized by the pressure wave and the fragments were found scattered over the nearby area

No it didn't. It originated from the urban legend about sending a manhole cover into space:

http://io9.gizmodo.com/no-a-nuclear-explosion-did-not-launch-a-manhole-cover-1715340946

 

7 hours ago, Nothalogh said:

Yes, and good engineering can help negate those kind of catastrophic structural failures.

Modern ships store explosives and such in ways that when it explodes it may blast a massive hole in the hull but it won't break the ship in half

No degree of good engineering would allow a modern ship to survive a nuclear warhead going off inside the hull.

[p1t1o]

1 hour ago, Nothalogh said:

Fun fact, the inspiration for Orion came from the fact that the tower wasn't actually vaporized, rather it was pulverized by the pressure wave and the fragments were found scattered over the nearby area

 

20 minutes ago, Nibb31 said:

No it didn't. It originated from the urban legend about sending a manhole cover into space:

http://io9.gizmodo.com/no-a-nuclear-explosion-did-not-launch-a-manhole-cover-1715340946

 

From the wiki:

"The idea of rocket propulsion by combustion of explosive substance was first proposed by Russian explosives expert Nikolai Kibalchich in 1881, and in 1891 similar ideas were developed independently by German engineer Hermann Ganswindt. General proposals of nuclear propulsion were first made by Stanislaw Ulam in 1946, and preliminary calculations were made by F. Reines and Ulam in a Los Alamos memorandum dated 1947.^[1] The actual project, initiated in 1958, was led by Ted Taylor at General Atomics and physicist Freeman Dyson, who at Taylor's request took a year away from the Institute for Advanced Study in Princeton to work on the project."

 

Ref:

http://www.webcitation.org/5uzTHJfF7

 

Edited March 30, 2017 by p1t1o

[kerbiloid]

1 hour ago, Nibb31 said:

3 hours ago, Nothalogh said:

Fun fact, the inspiration for Orion came from the fact that the tower wasn't actually vaporized, rather it was pulverized by the pressure wave and the fragments were found scattered over the nearby area

No it didn't. It originated from the urban legend about sending a manhole cover into space:

http://io9.gizmodo.com/no-a-nuclear-explosion-did-not-launch-a-manhole-cover-1715340946

Orion's biographist clearly tells that the inspiration source was Jules Verne, with his cannon from "From The Earth To The Moon", and idea appeared after the first nuclear tests.

P.S.
Unlikely Ulam and Dyson were familiar with the book of Kibalchich.

Edited March 30, 2017 by kerbiloid

[DerekL1963]

16 hours ago, Nothalogh said:

Yes, and good engineering can help negate those kind of catastrophic structural failures.

Modern ships store explosives and such in ways that when it explodes it may blast a massive hole in the hull but it won't break the ship in half

Um, no.  No amount of engineering is going to be able to 'negate' the equivalent of anything from couple hundred tons to a kiloton equivalent of TNT going off inside the hull and breaking it in twain.  Speaking from experience, the US Navy's safety manuals for heavy ordinance pretty much all have the same summary for accidents which lead to mass detonation...  "In the event of this accident occurring, loss of the vessel is considered probable or certain.  This accident is to be avoided at all costs".  (Emphasis mine.)

[Shpaget]

Of course. This is what happens:

 

 

[sevenperforce]

Munitions are, you know...

...weapons.

Blowing up armored targets is their specialty.

[Nothalogh]

17 hours ago, Nibb31 said:

No it didn't. It originated from the urban legend about sending a manhole cover into space:

So the engineers and scientists that BBC interviewed for their documentary were wrong?

And the Pascal-B test occurred 1957, after the origins of the Orion project

https://en.wikipedia.org/wiki/Operation_Plumbbob#Propulsion_of_steel_plate_cap