Re: Nuclear Weapons Material
In message <paBMkOwscIgG070yn@io.org> Mark Terka writes:
Not to mention the fact that without tritium, the "trigger" for nuclear weapons (and extremely expensive and rare at $ 100m a gram) all you have is a radioactive paperweight.
To the best of my knowledge, tritium is not used in nuclear weapons (meaning A-bombs), only in thermonuclear weapons (H-bombs). One of my teachers was involved in the Manhattan project; he never mentioned any need for tritium. -- Jim Dixon
At the risk of pushing this even further from cryptography, I should say that tritium is used in the "boosting" of *fission* weapons. A mixture of tritium and deuterium is injected into the exploding fission core to increase the "alpha" (neutron multiplication "gain") of the system. The D-T thermonuclear reactions themselves contribute relatively little energy, but the increase in fission efficiency can be dramatic. Thermonuclear boosting was the second major improvement made to US fission weapons after WWII. The first was the "levitated pit", a gap between the conventional explosive/tamper assembly and the fissile pit to allow the former to gain significant momentum before slamming into the latter. Both techniques result in considerably more efficient use of fissile material, but are not absolutely necessary to make a usable weapon (as shown at Hiroshima and Nagasaki). I believe the simple uranium gun used at Hiroshima only fissioned a few percent of its U-235. Fat Man did better, but not that much. Phil
At the risk of pushing this even further from cryptography, I should say that tritium is used in the "boosting" of *fission* weapons. A mixture of tritium and deuterium is injected into the exploding fission core to increase the "alpha" (neutron multiplication "gain") of the system. The D-T thermonuclear reactions themselves contribute relatively little energy, but the increase in fission efficiency can be dramatic.
Been reading our Tom Clancey, have we? <grin> -- Ed Carp, N7EKG Ed.Carp@linux.org, ecarp@netcom.com Finger ecarp@netcom.com for PGP 2.5 public key an88744@anon.penet.fi If you want magic, let go of your armor. Magic is so much stronger than steel! -- Richard Bach, "The Bridge Across Forever"
Been reading our Tom Clancey, have we? <grin>
No, actually I have yet to read my first Clancey novel, though I did see Hunt for Red October. My information comes from "US Nuclear Weapons" by Chuck Hansen, Orion Books, 1988. ISBN 0-517-56740-7. I wouldn't be surprised if Clancey used the same source -- Hansen is the guy who wrote the open letter that sabotaged the government's case in US vs. Progressive back in 1979. Now can we return to cryptography? How about a discussion of fast modular exponentiation algorithms, something we (or at least I) can put to more immediate and constructive use than nuclear bomb designs? Phil
Phil Karn says:
Now can we return to cryptography? How about a discussion of fast modular exponentiation algorithms, something we (or at least I) can put to more immediate and constructive use than nuclear bomb designs?
Indeed. I've been wondering recently, by the way, about what advantages doing some of this stuff on DSPs might have. DSPs are not magical chips, but they are optimized for a few tasks, including, typically, fast integer multiplies. IDEA and modular exponentiation both require lots of fast integer multiplies. Would it make sense to use DSPs as co-processors to things like Pentiums to speed up these processes? Phil? You are the resident expert on DSPs, I believe... Perry
I'm not really an expert on DSPs, but it does seem like they should be good for modular exponentiation given the number of multiplies required. But I don't think I'm the first to point that out. I think I already said that it looks like fast multiply performance is going to be crucial for secure communications. Modular exponentiation for public key algorithms, modulo-65537 multiplies in IDEA, and the many DSP multiplies in CELP speech coding, just to name three. I recently heard of a FED-STD-1016 CELP implementation that runs in better than real time on the PowerPC. It runs in much worse than real time on just about everything else. The PowerPC's multiply performance is clearly the reason. Phil
Phil Karn <karn@qualcomm.com> writes:
Now can we return to cryptography? How about a discussion of fast modular exponentiation algorithms, something we (or at least I) can put to more immediate and constructive use than nuclear bomb designs?
In the Crypto 93 proceedings, there is an article by Bosselaers, Govaerts, and Vandewalle comparing the speed of three algorithms for modular reduction which is the main time-consuming step in modular exponentiation. They compared the classical algorithm from Knuth, a modification to it by Barrett which speeds up the estimate of the first digit of the quotient, and Montgomery multiplication (which is inherently modular). Montgomery was the fastest for taking 1024 bit numbers modulo 512 bit numbers, but not by a lot. For exponentiation, though, where the reduction happens a lot, Montgomery was fastest for all but the very smallest exponents. 512 bit exponents took about 2.93 seconds for the classical algorithm, 2.85 seconds for the Barrett improvement, and 2.55 seconds for Montgomery. The crossover point (below which Barrett is best) is exponents of about 32 bits. So, Montgomery multiplication was best, but the percentage improvement is not that large. Sometimes, as I mentioned yesterday, you can restrict the size of the exponents without losing security (as in DSS), but it depends on the algorithm. Hal
An interesting discussion. Thanks. How about a basic tutorial on these various modexp algorithms, with particular attention to how many of each arithmetic operation (add/subtract/multiply/divide) are needed as a function of the modexp input parameter sizes? I don't really understand all the details yet, especially how they relate to which algorithm is best for a given machine. I.e., if I come up with a list of clock counts for each basic arithmetic instruction, how can I tell which algorithm is probably best for my machine? Phil
An interesting discussion. Thanks.
How about a basic tutorial on these various modexp algorithms, with particular attention to how many of each arithmetic operation
I want to tie this in to that other hot Cypherpunks topic: Pretty Good Nukes. Even though the topic is nearly depleted, and the sabots have jammed the list machine pretty thoroughly, how much faster would a fast modular exponentiation go if the inner loops were encased in a layer of deleted unobtainium? --Klaus! von Future Prime
On Tue, 23 Aug 1994 khijol!erc@apple.com wrote:
At the risk of pushing this even further from cryptography, I should say that tritium is used in the "boosting" of *fission* weapons. A mixture of tritium and deuterium is injected into the exploding fission core to increase the "alpha" (neutron multiplication "gain") of the system. The D-T thermonuclear reactions themselves contribute relatively little energy, but the increase in fission efficiency can be dramatic.
Been reading our Tom Clancey, have we? <grin>
I would recommend 'The Secret that Exploded' by Howard Morland Describes H-Bombs in a language that we can all understand. Brian ---------------------------------------------------------------------------- Linux - the choice of a GNU generation | finger blane@free.org "A little rebellion now and then is a good | for PGP key thing" - Thomas Jefferson | ----------------------------------------------------------------------------
In message <paBMkOwscIgG070yn@io.org> Mark Terka writes:
Not to mention the fact that without tritium, the "trigger" for nuclear weapons (and extremely expensive and rare at $ 100m a gram) all you have is a radioactive paperweight.
To the best of my knowledge, tritium is not used in nuclear weapons (meaning A-bombs), only in thermonuclear weapons (H-bombs). One of my teachers was involved in the Manhattan project; he never mentioned any need for tritium. -- Jim Dixon
I agree. Fission bombs I thought just needed shaped metal with a conventional charge to force compression and make it go critical. Fusion bombs I thought used tritium as fuel and needed a Plutonium trigger or something. They are supposedly set off with some kind of inner mirrored ball with high powered lasers. Fission then fusion I believe. sdw -- Stephen D. Williams Local Internet Gateway Co.; SDW Systems 513 496-5223APager LIG dev./sales Internet: sdw@lig.net OO R&D Source Dist. By Horse: 2464 Rosina Dr., Miamisburg, OH 45342-6430 Comm. Consulting ICBM: 39 34N 85 15W I love it when a plan comes together Newbie Notice: (Surfer's know the score...) I speak for LIGCo., CCI, myself, and no one else, regardless of where it is convenient to post from or thru.
Stephen D. Williams says:
Fusion bombs I thought used tritium as fuel and needed a Plutonium trigger or something.
Sort of.
They are supposedly set off with some kind of inner mirrored ball with high powered lasers.
No. A reality check would tell you that H bombs preceeded the development of the laser by many years. H Bombs use a fission reaction to compress and heat the hydrogen or other fuel until it begins to undergo fusion. Perry
Fusion bombs I thought used tritium as fuel and needed a Plutonium trigger or something. They are supposedly set off with some kind of inner mirrored ball with high powered lasers. Fission then fusion I believe.
The plutonium trigger is set off using conventional explosives to implode a hollow sphere of the material. While this technique is superficially similar to the gun-type triggering used by U-235 fuelled bombs, the geometry prevents the Pu-239 from fissioning prematurely. The tritium is used as a neutron source - it releases neutrons when sufficiently motivated to do so. -- * * Mikolaj J. Habryn dichro@tartarus.uwa.edu.au * "I'm just another sniper on the information super-highway." PGP Public key available by finger * #include <standard-disclaimer.h>
Mikolaj Habryn says:
Fusion bombs I thought used tritium as fuel and needed a Plutonium trigger or something. They are supposedly set off with some kind of inner mirrored ball with high powered lasers. Fission then fusion I believe.
The plutonium trigger is set off using conventional explosives to implode a hollow sphere of the material. While this technique is superficially similar to the gun-type triggering used by U-235 fuelled bombs, the geometry prevents the Pu-239 from fissioning prematurely. The tritium is used as a neutron source - it releases neutrons when sufficiently motivated to do so.
In a fusion, or H Bomb, the tritium (which is just hydrogen with an extra two neutrons) is that which produces the boom -- the main fuel, as it were. Its a "neutron source" only in the weakest possible sense -- the same way dynamite might be considered to need nitroglycerine as a "neutron source". (I'm not sure that people outside of the bomb building industry really know *for sure* what the geometries used in the atomic weapon that sets off the fusion reaction.) Perry
In a fusion, or H Bomb, the tritium (which is just hydrogen with an extra two neutrons) is that which produces the boom -- the main fuel, as it were. Its a "neutron source" only in the weakest possible sense -- the same way dynamite might be considered to need nitroglycerine as a "neutron source". (I'm not sure that people outside of the bomb building industry really know *for sure* what the geometries used in the atomic weapon that sets off the fusion reaction.)
I don't understand your point. The earliest devices used a pie shape with a wedge cut out. The actual geometry is rather unimportant to getting a fission reaction - but it *is* important if you want to maximize your yield. -- Ed Carp, N7EKG Ed.Carp@linux.org, ecarp@netcom.com Finger ecarp@netcom.com for PGP 2.5 public key an88744@anon.penet.fi If you want magic, let go of your armor. Magic is so much stronger than steel! -- Richard Bach, "The Bridge Across Forever"
Ed Carp [Sysadmin] says:
In a fusion, or H Bomb, the tritium (which is just hydrogen with an extra two neutrons) is that which produces the boom -- the main fuel, as it were. Its a "neutron source" only in the weakest possible sense -- the same way dynamite might be considered to need nitroglycerine as a "neutron source". (I'm not sure that people outside of the bomb building industry really know *for sure* what the geometries used in the atomic weapon that sets off the fusion reaction.)
I don't understand your point. The earliest devices used a pie shape with a wedge cut out. The actual geometry is rather unimportant to getting a fission reaction - but it *is* important if you want to maximize your yield.
We aren't discussing fission bombs. Please reread. .pm
We aren't discussing fission bombs. Please reread.
Sigh. At the risk of furthering a way-off-topic discussion, I should elaborate on what I said earlier. My understanding is that the tritium produced for nuclear weapons is used only to "boost" the *fission* reactions in the "primary" that is in turn used to trigger the main fusion reaction in the "secondary". Although the main fusion reaction in a thermonuclear device *is* between tritium and deuterium, the much larger quantities of tritium needed for this stage are produced during the actual detonation by neutron irradiation of lithium-6. That's why lithium-6 deuteride is used as the fusion fuel. Once again, these materials are distinct from the small amounts of gaseous tritium and deuterium used in the fission boosting stage. To summarize the steps (page 22, "US Nuclear Weapons" by Hansen): 1. High explosives detonate and compress the fission fuel in the primary. 2. At the right moment, neutrons are injected from an external generator to start the chain reaction. 3. Small amounts of gaseous tritium and deuterium are injected into the exploding fission core to boost the fission reaction, resulting in much more rapid and complete fission. 4. X-rays from the exploding primary, traveling at the speed of light, are focused onto a physically separated "secondary", the fusion fuel assembly, rapidly compressing and heating it by radiation pressure. Physical separation is essential to give the secondary time to react before the exploding primary physically blows it apart. *This* is the "breakthrough" that Ulam came up with that made the H-bomb practical; before then, Teller had wanted to simply pile deuterium closely around an A-bomb, which clearly wouldn't work. 5. At the center of the rapidly imploding *secondary* is a "sparkplug" of fissionable material. Neutrons from the primary cause this material to fission, producing even more neutrons that breed large amounts of tritium from the lithium-6 in the fusion fuel. 6. The newly produced tritium fuses with the deuterium in the main fusion reaction. 7. Fast neutrons from the fusion reaction may then fission a jacket of U-238 (yes, U-238) surrounding the secondary, producing an even greater yield using material that would otherwise be useless. 8. Additional fusion stages may then react (if present). As you can see, the fission and fusion reactions in a modern thermonuclear weapon are very closely interwined. Just to bring this back somewhat to cryptography, an interesting topic for speculation is the operation of the "permissive action links" (PALs) that control these weapons. The complexity of the procedure suggests that the precise timing of many events is crucial if a high-yield nuclear explosion is to result. This is particularly true for the timing of the many HE detonators, the neutron generator and the fusion boost injector. Perhaps these parameters are stored in encrypted form in the weapon and can be decrypted for use only with the proper externally-provided key? Considering that a brute force key search would consume one weapon per trial key, perhaps this technique isn't too bad against dictionary attacks? :-) Phil
the atomic weapon that sets off the fusion reaction.)
I don't understand your point. The earliest devices used a pie shape with a wedge cut out. The actual geometry is rather unimportant to getting a fission reaction - but it *is* important if you want to maximize your yield. --
Wrong. If you are using a uranium fuelled bomb, then you are right. As long as you thump together two barely sub-critical masses, it will go boom. However, if you try this with plutonium, it will fizzle. In the time that it takes for a standard gun type triggering mechanism to operate, the plutonium will become critical, and then release most of it's energy harmlessly, instead of going super-critical. This is the reason for using fast-triggering bomb geometries. -- * * Mikolaj J. Habryn dichro@tartarus.uwa.edu.au * "I'm just another sniper on the information super-highway." PGP Public key available by finger * #include <standard-disclaimer.h>
the atomic weapon that sets off the fusion reaction.)
I don't understand your point. The earliest devices used a pie shape with a wedge cut out. The actual geometry is rather unimportant to getting a fission reaction - but it *is* important if you want to maximize your yield. --
Wrong. If you are using a uranium fuelled bomb, then you are right. As long as you thump together two barely sub-critical masses, it will go boom. However, if you try this with plutonium, it will fizzle. In the time that it takes for a standard gun type triggering mechanism to operate, the plutonium will become critical, and then release most of it's energy harmlessly, instead of going super-critical. This is the reason for using fast-triggering bomb geometries.
Wrong. If you will notice, I said "the earliest devices". They didn't use plutonium for nuclear devices until much later. -- Ed Carp, N7EKG Ed.Carp@linux.org, ecarp@netcom.com Finger ecarp@netcom.com for PGP 2.5 public key an88744@anon.penet.fi If you want magic, let go of your armor. Magic is so much stronger than steel! -- Richard Bach, "The Bridge Across Forever"
I don't understand your point. The earliest devices used a pie shape with a wedge cut out. The actual geometry is rather unimportant to getting a fission reaction - but it *is* important if you want to maximize your yield. --
Wrong. If you will notice, I said "the earliest devices". They didn't use plutonium for nuclear devices until much later.
That may be what you had in mind - what you wrote was that geometry is irrelevant in fusion reactions, which is incorrect. -- * * Mikolaj J. Habryn dichro@tartarus.uwa.edu.au * "I'm just another sniper on the information super-highway." PGP Public key available by finger * #include <standard-disclaimer.h>
Wrong. If you will notice, I said "the earliest devices". They didn't use plutonium for nuclear devices until much later.
Much as I hate continuing to inject facts into an off-topic discussion... I wouldn't call it "much later". The first bomb *design* was the uranium gun-type bomb. They thought that they could use the same design with Pu239, but discovered when their first significant samples of Pu showed up that it just wouldn't work. The first bomb ever *detonated* (at Alamogordo, NM, on 16 July 1945) was an implosion bomb using plutonium. You see, the implosion design was sufficiently hairy that they needed to test it before using it for real. The "Los Alamos Primer" I cited yesterday contains a photo captioned: "Sgt. Herbert Lehr delivering plutonium core of first test bomb in its shock mounted case to the assembly room at McDonald Ranch, on the Trinity test site in the desert northwest of Alamogordo, NM, July 12 1945." (The "shock mounted case" in question is a rectangular box, roughly 6"x6"x8") - Bill
Wrong. If you will notice, I said "the earliest devices". They didn't use plutonium for nuclear devices until much later.
Actually, to pick a nit, the first a-bomb exploded (Alamogordo) was a plutonium device. The U235 design was dropped on Hiroshima untested. Paul
Actually, to pick a nit, the first a-bomb exploded (Alamogordo) was a plutonium device. The U235 design was dropped on Hiroshima untested.
The media was making a big deal last night about the seizure of twenty pounds of U-238. This, of course, is the non-radioactive isotope of uranium in which trade is relatively unrestricted. It does make excellent shell casings and has a few other mundane industrial uses. I wonder why the issue of bomb parts is now being given such a huge push in the press? -- Mike Duvos $ PGP 2.6 Public Key available $ mpd@netcom.com $ via Finger. $
Mike Duvos says:
The media was making a big deal last night about the seizure of twenty pounds of U-238. This, of course, is the non-radioactive isotope of uranium in which trade is relatively unrestricted.
Its plenty radioactive. It just isn't fissionable. Not all isotopes are fissionable.
It does make excellent shell casings
Actually, depleted uranium tends to be used in place of lead in rounds used for things like Phalanx (sp?) anti-missile gattling guns. Its also used in some sorts of armor. I don't think anyone in their right mind would make a shell CASING from it.
I wonder why the issue of bomb parts is now being given such a huge push in the press?
Because its a real issue. Lots of nuclear material is floating around, and some of it is going to end up in the hands of terrorists at some point. However, as I said in the second message in this thread, this will not be a reasonable excuse to stop strong cryptography, as anyone with the resouces to build a bomb can also buy or build a good cryptosystem. Perry
Perry E. Metzger <perry@imsi.com> writes:]
The media was making a big deal last night about the seizure of twenty pounds of U-238. This, of course, is the non-radioactive isotope of uranium in which trade is relatively unrestricted.
Its plenty radioactive. It just isn't fissionable. Not all isotopes are fissionable.
Uranium is not particularly radioactive, being a long lived alpha emitter. This is true of plutonium and some other fissionable materials as well. I can handle clad uranium or plutonium reactor or bomb components in complete safety with no protective clothing needed. The only hazard is from ingestion of the material, or from accumulation of decay products such as radon in a badly ventilated area. Workers in nuclear fuel fabrication facilities have been known to use small disks of plutonium sintered into a ceramic base as poker chips. Although U-238 can decay both by spontaneous fission and alpha emission, its astronomically long half-life of many billions of years results in a very low level of radioactivity for both these modes of decay. For all practical purposes, we may consider it a stable isotope.
It does make excellent shell casings
Actually, depleted uranium tends to be used in place of lead in rounds used for things like Phalanx (sp?) anti-missile gattling guns. Its also used in some sorts of armor. I don't think anyone in their right mind would make a shell CASING from it.
Uranium is used in munitions because of its mass, which allows it to go through less massive materials like steel or concrete like a hot knife through butter. It is used both for bullets and shell casings. Especially anti-tank rounds and shells designed to penetrate hardened military facilities. The idea is that the uranium penetrates the armor and the charge then explodes once the round is inside. -- Mike Duvos $ PGP 2.6 Public Key available $ mpd@netcom.com $ via Finger. $
Uranium is used in munitions because of its mass, which allows it to go through less massive materials like steel or concrete like a hot knife through butter. It is used both for bullets and shell casings. Especially anti-tank rounds and shells designed to penetrate hardened military facilities. The idea is that the uranium penetrates the armor and the charge then explodes once the round is inside.
I would like to request some reference on the use of Uranium in the casing of a shell or round. The casing gets thrown out on the ground (by both aircraft and tanks) when the round goes off. There is no reason to use anything other than brass or steel for this. As to the use in a round, the idea is like a sabot. When the ke of the shell is conserved on impact the more massive core goes right on into the target. I can find no reference any U-core round being HE or otherwise carrying a charge. In all cases that I am aware of and can find reference to it is simply a KE attack on the target where the by products of the impact bounce around inside the target grinding up whatever is in there. Take care.
[ Still waiting to be slapped down by someone who's pissed off about this crypto-free thread, or else for the NSA to have the FBI arrest all us mad bombers :-) ] Mike Duvos writes:
The idea is that the uranium penetrates the armor and the charge then explodes once the round is inside.
I don't know much about modern munitions, but I do know that armor piercing rounds may have no charge in them at all. Generally, when a round pierces one side of a vehicle, it loses enough energy and is suitably deformed to prevent exit from the opposite wall. It does, however, bounce around quite a bit, which can be plenty of fun in a tank loaded with equipment, munitions, and soldiers. It was discovered in the second world war that (with then-current metallurgical techniques) introduction of a high-explosive charge into the armor piercing round tended to reduce its effectiveness by weakening the structure. | GOOD TIME FOR MOVIE - GOING ||| Mike McNally <m5@tivoli.com> | | TAKE TWA TO CAIRO. ||| Tivoli Systems, Austin, TX: | | (actual fortune cookie) ||| "Like A Little Bit of Semi-Heaven" |
Mike McNally says:
Mike Duvos writes:
The idea is that the uranium penetrates the armor and the charge then explodes once the round is inside.
I don't know much about modern munitions, but I do know that armor piercing rounds may have no charge in them at all.
The Illustrated Encyclopedia of Ammunition, a book that I actually possess, makes this claim. According to it, there are two basic kinds of armor piercing rounds -- one that involves having a potent thin metal projectile usually made of a material like tungsten, that penetrates the armor, and one involving having a shaped charge that squirts a jet of hot metal through the armor. No one seems to have attempted to get explosives through the armor in many many decades. None of the forms of modern shells described in this book involve the use of depleted uranium in shell casings. Perry
None of the forms of modern shells described in this book involve the use of depleted uranium in shell casings.
Perry
The ammo used by the A-10 chain gun uses a depleted uranium core that is designed to defeat Chobam and other types of reactive armor. It is also used in F-14, F-15, F-16, and F-18's that are tasked with ground attack missions where active armor tanks are expected to be encountered. The ammo was specificaly developed for use in the late 70's for use against Soviet T-72's in a Fulda Gap scenario. I know of no ammo that uses anything other than brass or steel (in the case of mini-guns and other motor driven guns) for the case. The reason that the Uranium is used is because of its high density.
Jim choate says:
None of the forms of modern shells described in this book involve the use of depleted uranium in shell casings.
The ammo used by the A-10 chain gun uses a depleted uranium core that is designed to defeat Chobam and other types of reactive armor.
Thats a core, not a casing. Plenty of things use such cores -- phalanx guns, for instance.
I know of no ammo that uses anything other than brass or steel (in the case of mini-guns and other motor driven guns) for the case. The reason that the Uranium is used is because of its high density.
Excactly. Perry
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The ammo used by the A-10 chain gun uses a depleted uranium core that is designed to defeat Chobam and other types of reactive armor. It is also used in F-14, F-15, F-16, and F-18's that are tasked with ground attack missions where active armor tanks are expected to be encountered. The ammo was specificaly developed for use in the late 70's for use against Soviet T-72's in a Fulda Gap scenario.
1. The DU tank & 25mm ammo used by the US military is sabot ammo, meaning that the "bullet" is of significantly smaller diameter than the shell itself; an adaptor, or sabot (from the French for "shoe"), mates the projectile & the shell and falls off after the projectile leaves its barrel. 2. Chobham, not Chobam. Chobham armor refers to a specific type of layered armor, the precise composition and fabrication of which is classified. It's named for the British works which first built it. Reactive armor, such as is presently used by the Israelis and some xUSSR units, is different; it consists of many small charges which explode outward when hit by an incoming round. 2. Of the aircraft listed above, none can carry the 30mm round used by the A-10. There is a 25mm round for the Bradley AFV chain gun; presumably it can also be fired from the Apache. I don't know of a 20mm DU round. (Of course, there's also a 120mm APDS round for the M-1 tank.)
I know of no ammo that uses anything other than brass or steel (in the case of mini-guns and other motor driven guns) for the case. The reason that the Uranium is used is because of its high density.
3. It is interesting to note that US Army tanks are now being equipped with depleted uranium _armor_ precisely because its density makes a great backstop. DU armor can pretty much shrug off most medium AT weapons; it is quite heavy, but that's not a problem for vehicles which already weigh as much as tanks. - -Paul - -- Paul Robichaux, KD4JZG | Demand that your elected reps support the perobich@ingr.com | Constitution, the whole Constitution, and Not speaking for Intergraph. | nothing but the Constitution. -----BEGIN PGP SIGNATURE----- Version: 2.6 iQCVAgUBLlzjH6fb4pLe9tolAQF7SAP/VaCO6Ul6euSOjyT9ZPB/7n/5cVocKK1w 3l49Kva//Jqt3hHG+jGmouKSHmh3BZ3wpyZCX3SCVq8OEIgkK1/oQOTTnYct0Qfa gvmj47IIouwW3hKMlgomFb+qpZToXl3CHpxub/aWC8Zjntgi0C25FPBiHJn0ZNIu zKXSqLtaC2s= =5NX/ -----END PGP SIGNATURE-----
2. Chobham, not Chobam. Chobham armor refers to a specific type of layered armor, the precise composition and fabrication of which is classified. It's named for the British works which first built it. Reactive armor, such as is presently used by the Israelis and some xUSSR units, is different; it consists of many small charges which explode outward when hit by an incoming round.
If your spelling is correct then several of my books have mis-spellings. As to Chob(h)am bing classified, this was true till the late 80's. It is a ceramic based layered with cintered metallics that dissipate the KE of the incoming round. The Russians also developed this method for the T-72's at about the same time. It was discovered that the 'applique' armor on the T-72 was really this type of armor that could be bolted on. The reason that I lump the two together is that they both require a dual warhead to defeat.
2. Of the aircraft listed above, none can carry the 30mm round used by the A-10. There is a 25mm round for the Bradley AFV chain gun; presumably it can also be fired from the Apache. I don't know of a 20mm DU round. (Of course, there's also a 120mm APDS round for the M-1 tank.)
I have seen the exact same chain-gun mounted on F-16's and A-10's here at Bergstron AFB in Austin at at least two different air shows. I am going on this alone. I do not know if this was ever an active use of the gun.
I know of no ammo that uses anything other than brass or steel (in the case of mini-guns and other motor driven guns) for the case. The reason that the Uranium is used is because of its high density.
3. It is interesting to note that US Army tanks are now being equipped with depleted uranium _armor_ precisely because its density makes a great backstop. DU armor can pretty much shrug off most medium AT weapons; it is quite heavy, but that's not a problem for vehicles which already weigh as much as tanks.
Could you provide references for this application? I did technical support for Desert Storm and know of no use of such depleted armor in that campaign. Has Chrysler started putting applique style blocks on the M1 Abhrams? Take care.
I have seen the exact same chain-gun mounted on F-16's and A-10's here at Bergstron AFB in Austin at at least two different air shows. I am going on this alone. I do not know if this was ever an active use of the gun.
Are we thinking of the same A-10? Tank-killer? The one that houses a multi-barrel gun the size of a small car, and fires shells which could pass for milk bottles in a dark room? I've seen an F-16, and i don't think it could carry the chain gun off an A-10 - or have i missed the point somewhere? -- * * Mikolaj J. Habryn dichro@tartarus.uwa.edu.au * "I'm just another sniper on the information super-highway." PGP Public key available by finger * #include <standard-disclaimer.h>
Mike McNally says:
Mike Duvos writes:
The idea is that the uranium penetrates the armor and the charge then explodes once the round is inside.
I don't know much about modern munitions, but I do know that armor piercing rounds may have no charge in them at all.
The Illustrated Encyclopedia of Ammunition, a book that I actually possess, makes this claim. According to it, there are two basic kinds of armor piercing rounds -- one that involves having a potent thin metal projectile usually made of a material like tungsten, that penetrates the armor, and one involving having a shaped charge that squirts a jet of hot metal through the armor. No one seems to have attempted to get explosives through the armor in many many decades.
None of the forms of modern shells described in this book involve the use of depleted uranium in shell casings.
out of curiousity, what does it say under 'sabot'? josh
Mike Duvos writes:
The idea is that the uranium penetrates the armor and the charge then explodes once the round is inside.
I don't know much about modern munitions, but I do know that armor piercing rounds may have no charge in them at all.
None of the forms of modern shells described in this book involve the use of depleted uranium in shell casings.
The U after is goes through the armor is pyrophoric, and there is quite a fireball as a result - lots of hot burning particles flying around. quite spectacular from the downstream side (I've seen it - the back side of a target plate) L
I don't know much about modern munitions, but I do know that armor piercing rounds may have no charge in them at all. Generally, when a round pierces one side of a vehicle, it loses enough energy and is suitably deformed to prevent exit from the opposite wall. It does, however, bounce around quite a bit, which can be plenty of fun in a tank loaded with equipment, munitions, and soldiers.
I was under the impression that the most common techniquoe for creating armour-piercing munitions was to use shaped-charges. While depleted uranium has it's uses (being, as someone said, rather dense), mass alone will not get through everything. A shaped charge will get through more things more violently :) -- * * Mikolaj J. Habryn dichro@tartarus.uwa.edu.au * "I'm just another sniper on the information super-highway." PGP Public key available by finger * #include <standard-disclaimer.h>
On Wed, 24 Aug 1994, Perry E. Metzger wrote:
In a fusion, or H Bomb, the tritium (which is just hydrogen with an extra two neutrons) is that which produces the boom -- the main fuel, as it were. Its a "neutron source" only in the weakest possible sense -- the same way dynamite might be considered to need nitroglycerine as a "neutron source". (I'm not sure that people outside of the bomb building industry really know *for sure* what the geometries used in the atomic weapon that sets off the fusion reaction.)
Perry
Since the bomb thread won't die a seemly death I thought I'd throw in my .00000002 megabucks. Modern H bombs are actually fission-fusion-fission devices. The traditional U-235 (or Pu-239) atomic bomb sets off a fusion reaction burning the tritium, producing alot of fast neutrons that in turn sets off another fission explosion in the otherwise non-fissile U-238 that is wrapped around the outside of the bomb. More bang for the buck, and it gives you something to do with all that U-238 you got while purifying the U-235. C. J. Leonard ( / "DNA is groovy" \ / - Watson & Crick <cjl@welchlink.welch.jhu.edu> / \ <-- major groove ( \ Finger for public key \ ) Strong-arm for secret key / <-- minor groove Thumb-screws for pass-phrase / )
In a fusion, or H Bomb, the tritium (which is just hydrogen with an extra two neutrons) is that which produces the boom -- the main fuel, as it were. Its a "neutron source" only in the weakest possible sense -- the same way dynamite might be considered to need nitroglycerine as a "neutron source". (I'm not sure that people outside of the bomb building industry really know *for sure* what the geometries used in the atomic weapon that sets off the fusion reaction.)
This also depends on the type of bomb. In a two-stage fusion bomb, you are quite correct - the tritium-deuterium/tritium fusion reaction gives the boom. However, in a three-stage bomb, there is an additional fission reaction, this due to the fact that the neutrons produced by the fusion reaction have the precise energy required to fission U-238. Since U-238 is vastly easier to obtain than enriched U-235, there is no great problem with sticking in half a tonne of it. Around that you can add cobalt jackets, etc, for more interesting effects. -- * * Mikolaj J. Habryn dichro@tartarus.uwa.edu.au * "I'm just another sniper on the information super-highway." PGP Public key available by finger * #include <standard-disclaimer.h>
participants (19)
-
Bill Sommerfeld -
Brian Lane -
cjl -
Hal -
jdd＠aiki.demon.co.uk -
Jim choate -
joshua geller -
khijol!erc＠apple.com -
Lawrence Weinman -
m5＠vail.tivoli.com -
Mikolaj Habryn -
mpd＠netcom.com -
paul＠poboy.b17c.ingr.com -
Perry E. Metzger -
Phil Karn -
Phil Karn -
pstemari＠bismark.cbis.com -
sdw＠lig.net -
tcmay＠netcom.com