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The nuclear anti-ship missile

C

Carlobrand

SOC-14 1K
Marquis
Per MT and High Guard, a nuclear missile delivers 25,000 "megawatts" times their factor to a black globe. The single TL7 missile is factor 1; the TL13 missile is factor 2. Assuming at least half the blast radiates to space, and assuming that's a megawatt-second, that's 50,000 megajoules - at 4.184×109 joules to the TNT "ton" of blast, only about a 12 ton blast, 0.012 Kt, for the TL 7. One could argue for the blast occurring farther out, more of it going to space, but that only goes so far - and it seems like a waste of a good superweapon.

More likely it's about the size and power of a Davy Crockett, a Korean War era nuclear artillery warhead with a 10 or 20 ton yield, about the smallest fission warhead that could be built with plutonium. Davy Crockett was a 10.75" diameter spherical implosion device with a nose cone containing a contact fuse and a tail section containing a "Safe-Arm" and electronics module with a time fuse. Overall it was 10.75 inches in diameter and about 15.7 inches long, and it weighed 23 kg, which makes it a good candidate for the model for the standard nuke missile warhead.

Incidentally, 50,000 megajoules - at 340 kJ/mol heat of vaporization and 55.845 grams to the mol for iron, that's sufficient energy to vaporize about 8200 kg of iron - a bit over a cubic meter. If we make the (admittedly rather big) assumption that bonded superdense takes about 9 times as much energy to vaporize (using the - again rather big - assumption that soft steel is similar to iron in vaporization point and that bonded superdense is 1/9 the mass for the same strength), that's about 900 kg of bonded superdense. Bonded superdense runs 15 tons to the cubic meter, about 0.06 cubic meters or 60 liters: a crater about 30 cm in radius. Almost 3 times that radius would be liquified, but I'm not up to figuring a mixed blast vaporizing some and liquifying some.

Suffice to say it is quite enough to leave a good-size hole in the hull of the typical armor-40 ship and to send the flash-boiled 900-ish kg 60-ish liter bit of armor blasting into the ship's interior to fry the compartment on the other side and do the damage that shows up in the damage table. It'd take something well north of an armor factor of 62 to keep it from penetrating the hull.
 
The Mk 54 could produce up to 1 kT yield, so I'd suspect that the 10 T versions are simply de-optimized with smaller compression charges to produce a weapon safe for those using it. I don't know why you'd use a Traveller analog with anything less than 1 kT yield in ship to ship fighting.

The same basic warhead was used for the AIM-4 and AIM-26 Falcon air-to-air nuke with 250 T yield. It weighed 200 lb with a range of 6 miles. The indirect successor in development was the AIM-54 which was never produced with a nuke option.

The AIM-54 is 1000 lb, going Mach 5 with a range of 100 mi. The 135 lb conventional warhead is possibly big enough to have a nuke version. I would think a space combat missile, for engaging an enemy tens of Mm away could be no smaller.

The biggest problem with nukes in space is there is no atmosphere to mediate the power directly to the target. No concussion blast, no firestorm. Just a smallish concussion based on the mass of the vaporized missile and direct gamma and neutron radiation.

If you try for a contact or near contact detonation you spend more time in the target's defense sphere, and may be fully thwarted. Stand-off attack is less likely to do damage as stand-off distance grows. You need the biggest warhead you can squish into the missile.
 
Relevant chart from NASA showing the differences Straybow alludes to. The rads have quite a bit of range.

https://history.nasa.gov/conghand/nuclear.htm

However, the boys at Atomic Rockets show some stats on an apparently serious space nuclear weapon design called Casaba Howitzer.

Think shaped charge, only instead of a plasma jet its' particles accelerated from material next to the warhead in line with the target at detonation.

Has ranges I would not have expected. The light warhead is a threat at 1000km. For more heavily armored HG targets, closer detonation would probably work.

http://www.projectrho.com/public_html/rocket/spacegunconvent.php
 
Straybow said:
The Mk 54 could produce up to 1 kT yield, so I'd suspect that the 10 T versions are simply de-optimized with smaller compression charges to produce a weapon safe for those using it. I don't know why you'd use a Traveller analog with anything less than 1 kT yield in ship to ship fighting.

The same basic warhead was used for the AIM-4 and AIM-26 Falcon air-to-air nuke with 250 T yield. It weighed 200 lb with a range of 6 miles. The indirect successor in development was the AIM-54 which was never produced with a nuke option.

The AIM-54 is 1000 lb, going Mach 5 with a range of 100 mi. The 135 lb conventional warhead is possibly big enough to have a nuke version. I would think a space combat missile, for engaging an enemy tens of Mm away could be no smaller.

The biggest problem with nukes in space is there is no atmosphere to mediate the power directly to the target. No concussion blast, no firestorm. Just a smallish concussion based on the mass of the vaporized missile and direct gamma and neutron radiation.

If you try for a contact or near contact detonation you spend more time in the target's defense sphere, and may be fully thwarted. Stand-off attack is less likely to do damage as stand-off distance grows. You need the biggest warhead you can squish into the missile.
Click to expand...

I don't know why either, but that's what the energy output says it is.

The Mk.54 as designed for the Davy Crockett was basically just a nuclear "pit", the smallest possible nuke. They didn't designed it that way because they couldn't get more power into the shell. They designed it that way because they needed something low yield that could be fired without putting the gunner or his unit in harm's way. Some U-238 as a shell around the pit would punch up the power without much added weight, or a bit of deuterium-tritium mix in a fusion bomb design could have been made but - with a range of 1 1/4 to 2 1/2 miles, and with the thing not especially accurate in the first place - either alternative would result in something with a yield high enough to cause problems for their own troops when it was used against an enemy formation.

I guess I could make rationalizations to defend the game's decision regarding the weapon's performance. Maybe missile yield is low to keep it from killing its neighbors when it goes off. The game doesn't have a multiple-hit effect from large batteries (maybe it should), but it does grant increased criticals to large batteries hitting small targets, which tends to imply more than one missile is getting through. A higher-yield missile might throw out enough of a gamma pulse to affect other inbounds of the same battery.

(I'm guessing the "dial-a-yield" design of the W54, in its "suitcase bomb" configuration, could feed varying amounts of a deuterium-tritium mix into the warhead, making it a small fusion bomb.)

Still, given the tendency of up-armored TL15 ships to shrug off nuclear attack and the exceedingly low likelihood of an attack getting through in the first place, I'm all for any argument for an IMTU alternative to power up the missile warhead, even if it means yielding the extra criticals (which only occur against ships of under 900 dT anyway). Only problem is the game doesn't really give more penetration with more power: particle beams penetrate the same whether it's the "A" spinal or the "T", though the "T" delivers twice the energy (again, based on its effect on a black globe - and again, maybe it should). Only reason I can see to keep the yield low is to hold the cost down, since a fleet can go through a ferocious lot of these things in a battle.

(That being said, I think the price of these missiles is way too high. Simple logic says they wouldn't be used unless they were cost-effective. They're not. But, that's an issue for another time.)

I do not see anything in the rules that gives the nuke an advantage to hit or penetrate, as would be the case if it were conducting a stand-off attack to minimize exposure to defenses. The nuke and HE missiles have the same odds to hit and penetrate (excluding the damper), ergo they're encountering identical defensive measures. Certainly the HE missiles don't have the option of conducting a stand-off attack.

I'd think about an ATU stand-off mode, but in vacuum a nuke blast drops power pretty quickly with range, and space-born missile impact speeds are likely to be pretty high given that they're crossing space and hitting 6G targets in a reasonable game time. That being said, I don't think standing off is going to buy them any advantage.

I've been playing with the idea of a number of ATU ideas, including varying the damage roll modifier for higher-power spinals, multiple hits for battery weapons, the use of missiles in an anti-missile role, the use of higher-yield nukes to kill in-bound missiles, missiles with nuclear-pulse laser warheads, and others.
 
Hence why TNE went for nuclear bomb-pumped lasers as the missile warhead a la SDI (and T:2300). For me a lot of the missile stuff in CT requires suspension of disbelief I just can't stomach.
 
jec10 said:
Hence why TNE went for nuclear bomb-pumped lasers as the missile warhead a la SDI (and T:2300). For me a lot of the missile stuff in CT requires suspension of disbelief I just can't stomach.
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I did some work in some CT threads that show from a damage perspective, kinetic impact is horrific and cheap.

Three most difficult parts are the small missile/long range-burn bit, ROF to once every 1000 seconds, and the itty-bitty electronics seeker/detonators vs. a full computer/EW/crew suite.
 
kilemall said:
I did some work in some CT threads that show from a damage perspective, kinetic impact is horrific and cheap.

Three most difficult parts are the small missile/long range-burn bit, ROF to once every 1000 seconds, and the itty-bitty electronics seeker/detonators vs. a full computer/EW/crew suite.
Click to expand...

Well, if we're going to complain, the fact that you can even miss a target glowing brightly in infrared against the backdrop of space, with a laser or any other C-or-near-C weapon, pretty much kills it. However, correcting that would require a fundamental rethink of space combat. Even putting aside the target-standing-out-like-a-sore-thumb issue, they needed ships with good speeds and good weapon ranges - and turns that take long enough for you to get somewhere - or they would have had an unwieldy map with a huge planet at one end and ships basically being slaughtered before they could ever get close to it. That would kinda put a kink in your space smuggler trope, not to mention making piracy a potentially very lethal affair. Not a fun place to role-play in.

Bottom line is the game was written to be fun and to pay homage to some of the more common Sci Fi tropes, not to be good science. Much of the space tech is dictated by game needs, not science. It's basically phaser-and-lightsaber technology: it exists because the story needs it to exist. We can use science to embellish it and in places to smoothe some of the rougher edges, but beyond that we're going to have to accept that a lot of this is Buck Rogers stuff: we do it to thrill the audience, not to teach.

My only real beefs with it are those points where the game logic creates a problem for the role-play logic. Whatever's driving those missiles, for example, is some pretty potent stuff. I can think of a number of useful applications for such technology in the game world. I wouldn't mind hand-waving the missiles if I could apply some of that phlebotinum in other places.
 
The following information comes from Chuck Mansen's book, U.S. Nuclear Weapons, probably the authoritative book on the subject up to the late 1980s.

The Davy Crockett warhead was based on a modified M54 Atomic Demolition Munition, and appears to have selected yields ranging from 20 Tons equivalent of TNT to 250 Tons equivalent. The projectile was 11 inches in diameter, 30 inches long, and weighed 76 pounds, the warhead being somewhere between 50 and 55 pounds of this weight.

The M54 ADM is heavier and can give a selected yield from 10 Tons TNT equivalent to 1 kiloton yield. The warhead weight is 59 pounds and total weight of the munition is about 150 pounds. To the best of my knowledge, some of these are still in service. During the 1980s, there was unclassified discussion in the Army Corps of Engineer journals for surface detonation of the weapons against spearheads of attacking Warsaw Pact forces in Germany.

The eight-inch nuclear round fielded in 1957 weighed 243 pounds and had a selectable yield of either 5 or 10 kilotons, depending on the sub-critical mass loadings. It did use plutonium as the fissile material. Later versions of the round have the option of being converted to use as a "neutron weapon" by insertion of a Tritium capsule.

One kiloton of TNT yield requires the fission of approximately 2 ounces of fissionable material, and is equal to 4.18 X 10 to the twelfth power Joules, or 1.16 Million Kilowatts Hours. In the atmosphere, near the surface, approximately one-half of the energy is expended as blast effects. That changes as the altitude of the explosion rises. For a thorough discussion of the effects of a nuclear explosion, I would highly recommend checking out the following website, http://www.abomb1.org/nukeffct/index.html.

I would also highly recommend reading The Effects of Nuclear Weapons, 1977 edition, published by the U.S. Dept. of Defense. Chuck Hansen's book is also quite worthwhile reading, but does not go into anywhere near the detail on weapons effects and testing that the Dept. of Defense book does. Note, some of the photographs of Hiroshima can be a bit disturbing.

It should be noted that the North Korean nuclear tests have all been in the vicinity of 5 kilotons.
 
Hmmm. Your source has much better information than I had access to. Thank you, this is another post that I'll save for future reference. I hadn't realized they had a pit that could yield 5 tons explosive force. I'm given to understand the lower yields actually require more plutonium: two ounces seems to be the lower limit, so they instead have to engineer it to be less efficient rather than using less mass - something to do with shape and the specific explosives used. That is a level of physics that's a few meters above my head.

Now, see, that little baby would have been perfect for the Striker setting. Just enough power to put paid to a far future tank without killing the infantry who happened to be in the vicinity - well, provided they're in combat armor.

I'm drawing on articles by a guy named Carey Sublette. Not a professional in the field, just a feller with a decent grasp of science and a passionate interest in the subject. Would you be willing to look through some of what he's written and see how it stands up against the authoritative sources?

http://nuclearweaponarchive.org/Nwfaq/Nfaq4.html

Add: "The eight-inch nuclear round fielded in 1957 weighed 243 pounds and had a selectable yield of either 5 or 10 kilotons, depending on the sub-critical mass loadings."

Was this intended to read "tons" instead of kilotons?
 
Carlobrand said:
Hmmm. Your source has much better information than I had access to. Thank you, this is another post that I'll save for future reference. I hadn't realized they had a pit that could yield 5 tons explosive force. I'm given to understand the lower yields actually require more plutonium: two ounces seems to be the lower limit, so they instead have to engineer it to be less efficient rather than using less mass - something to do with shape and the specific explosives used. That is a level of physics that's a few meters above my head.

Now, see, that little baby would have been perfect for the Striker setting. Just enough power to put paid to a far future tank without killing the infantry who happened to be in the vicinity - well, provided they're in combat armor.

I'm drawing on articles by a guy named Carey Sublette. Not a professional in the field, just a feller with a decent grasp of science and a passionate interest in the subject. Would you be willing to look through some of what he's written and see how it stands up against the authoritative sources?

http://nuclearweaponarchive.org/Nwfaq/Nfaq4.html
Click to expand...

I would rather not. Please see signature. In this area, I am very careful to cite my sources.

Carlobrand said:
Add: "The eight-inch nuclear round fielded in 1957 weighed 243 pounds and had a selectable yield of either 5 or 10 kilotons, depending on the sub-critical mass loadings."

Was this intended to read "tons" instead of kilotons?
Click to expand...

Kilotons is correct. The Army wanted something a bit easier to use than the 280mm Atomic Cannon, with its 700 pound projectile and 15 kiloton yield, using a gun-type U-235 assembly. Note, the 280mm projectile was live-tested in 1953, and the 700 pounds includes the weight of the carrier shell, which would likely be about 350 pounds.

Also, the 1977 Edition of The Effects of Nuclear Weapons can be downloaded from the following website. The chapters are broken up into two sections, the first being more of a laymen's description, with the second part much heavier on the math and technical aspects. Even the first half does require a fairly good level of technological knowledge. The circular slide rule that the edition had was very useful for a quick and dirty check of effects. I have a couple of hard copies.

https://archive.org/details/effectsofnuclear1977unit
 
Is good. Thank you for the link, I downloaded the book and am giving it a read. Well, at 672 pages, I'm giving it a start. My limited technical knowledge might bring me to a stop halfway through, but I'm up for a challenge.
 
I see anti-ship nukes as most likely to be either nuclear-pumped lasers or nuclear shaped charges. These are mainly ways to get round the fact that in space there's no medium to transmit a shock wave from the blast into the target. In fact I imagine most conventional anti-ship missiles will use some form of shaped charge or self-forging munition given that even basic hulls are described as being fairly robustly armoured. Some such warheads also obviate the need to a contact hit.

I'm not sure how much research has been done into nuclear lasers or nuke shaped charges, but the theory seems sound. There have certainly been real-world proposals, but I first came across the idea for nuke shaped charges in Fred Saberhagen's Berserker novels.

https://www.quora.com/Is-it-possibl...ver-a-target-to-destroy-a-deep-bunker-complex

Simon Hibbs
 
simonh said:
I see anti-ship nukes as most likely to be either nuclear-pumped lasers or nuclear shaped charges. These are mainly ways to get round the fact that in space there's no medium to transmit a shock wave from the blast into the target. In fact I imagine most conventional anti-ship missiles will use some form of shaped charge or self-forging munition given that even basic hulls are described as being fairly robustly armoured. Some such warheads also obviate the need to a contact hit.

I'm not sure how much research has been done into nuclear lasers or nuke shaped charges, but the theory seems sound. There have certainly been real-world proposals, but I first came across the idea for nuke shaped charges in Fred Saberhagen's Berserker novels.

https://www.quora.com/Is-it-possibl...ver-a-target-to-destroy-a-deep-bunker-complex

Simon Hibbs
Click to expand...

You cannot make a nuclear shaped charge. If you want to destroy a deep bunker complex, you have two options. The first is a large enough device, so that when surface or shallow underground burst, the shock waves will destroy the bunker. The other is a deep penetrating bomb with a high yield, on the order of a megaton or greater, to accomplish the same thing. The ideal for the first option is that the crater depth and diameter will include the bunker.
 
timerover51 said:
You cannot make a nuclear shaped charge.
Click to expand...

The Army did tests - yes, one can. It's still devastating to the area around, but self-forges a metal-plasma lance directionally...

See also the Orion Nuclear Propulsion project (1950's & '60's), where they designed a plate to capture the moment from an exploding warhead... which is a tamped charge. It also used a tungsten plasma mass in the warhead as a focused force device...
 
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