Articles: "Nuclear Warfare 101".

[Fingolfin_Noldor]

That said, there have to be limits; they can't classify the laws of ballistics.

Ballistics at that speed becomes rather nonlinear, and also, it is now possible to make minute corrections to the direction.

[Stuart]

I'm quite sure that the figures for the maximum ground spread (I don't know the official term) for MIRV warheads of any operational missile is highly classified.

The official term is "footprint".

We know that while they must surely have independent engines to spread them out and direct them to their targets,

Actually, they don't. The bus maneuvers, points them in the right direction and off they go. The individual RVs have no propulsion systems or guidance equipment (they look a little bit like ice cream cones with a long pointed end and a rounded end.) That's one reason why release heights tend to be low; the innaccuracy of the system mounts up dramatically with distance. If one operated the bus during boost phase, the RVs could land pretty much anywhere.

So even within those constraints, they have to fly on more or less parallel trajectories- maybe a few dozen miles of separation in a few hundred, and that's being (I feel) optimistic.

Have a look at the picture I posted and you can see the divergence quite clearly (there's a distance divergence as well, the RVs are not landing in a straight line. Some are quite close, others are out on the horizon. Look at the shadowing from clouds to give a clue as to which is which.)

[Stuart]

Ballistics at that speed becomes rather nonlinear, and also, it is now possible to make minute corrections to the direction.

Not really. Some warheads (called MARVS) can make changes on their final descent but that's correcting the aim rather than engaging a different target. MARVs are very rare, except under very specific conditions, they just aren't worth the effort.

[Simon_Jester]

We know that while they must surely have independent engines to spread them out and direct them to their targets,

Actually, they don't.

Yes. After reading your first response post (the one before the one I'm now quoting), I realized that I had screwed up; more below.

If I can bother you further say that there is a crisis over Taiwan and China feels that US strike is inevitable and decides to launch its long range missiles at US west coast. Say that US intercepts a good number of missiles but Los Angeles goes up in flames (or whatever Chinese would target). Could you elaborate more specifically what US response would look like? Would they obliterate all powerplants, major factories, ports etc. in China? How would US execute the strike: with B-2 bombers or B-52s or Tridents or Minutemans or all of the above?

Until very recently, the answer was "all of the above until the rubble bounced." Now, with the jackass we've got in the White House, I honestly don't know. Nor does anybody else and that's very, very dangerous. It might tempt somebody to make a guess.

The fundamental problem being a lack of specific and clear nuclear policy of the form "if you do this we will do that?" The fundamental problem being the discontinuation of capabilities? Both? Both plus other things I didn't think of?

EDIT: By the way roughly how far apart can the targets be for warheads launched from the same missile to be able to hit them? For example I don't think warheads launched from the same missiles can hit both Shanghai and Beijing. Or am I wrong?

Warheads from an MRV or MIRV bus fall inside a footprint that's determined by a lot of factors. MRV busses traditionally had a maximum footprint that was about 10 - 15 miles across so the most extensive case was an equilateral triangle with the initiation points at the apexs and the sides 10 - 15 miles long. MRVs were aimed at individual targets. With MIRVs, the footprint is larger but how much larger is something that is kept very quiet.

Re-examining my previous remarks, I see that I made a really serious mistake. I confusing MIRVs with MARVs and assuming that you got a MIRV system by sticking maneuvering thrusters on individual MRV warheads, rather than steering the bus itself. My previous comments apply only to MRVs.

However, I still doubt that the maneuvering thrusters of a MIRV bus can provide enough lateral delta-v to put a warhead on Beijing and then retarget to put a second warhead on Shanghai, when launched from somewhere in North America. Not unless the warhead release phase is very early in the missile's flight path, and the bus's maneuvering thrusters are considerably more powerful than I'd think practical.

Which would, as you say, lead to major accuracy problems.

This is actually an MIRV coming in. Trace the lines back and you'll see how low the release point really is.
[gigantic image]
(sorry the picture is a bit big but I thought you'd prefer the sight in all its glory rather than dumbed down.)

Well, it won't fit on my screen, so I can't see it in all its glory whether I want to or not...

[Stuart]

The fundamental problem being a lack of specific and clear nuclear policy of the form "if you do this we will do that?" The fundamental problem being the discontinuation of capabilities? Both? Both plus other things I didn't think of?

The first. Doubt and uncertainty is a very bad thing where nuclear weapons are concerned. Policy must be absolutely clear and transparent. Until the jackass got to work it was. "Toss a nuke at us and we reduce your country to a parking lot and then send in the Marines to paint the white lines". Now, its 80 pages - I kid you not - of legalese. And the Jackass actually believes that is a good thing.

However, I still doubt that the maneuvering thrusters of a MIRV bus can provide enough lateral delta-v to put a warhead on Beijing and then retarget to put a second warhead on Shanghai, when launched from somewhere in North America. Not unless the warhead release phase is very early in the missile's flight path, and the bus's maneuvering thrusters are considerably more powerful than I'd think practical.

It's safe to say they don't.

Well, it won't fit on my screen, so I can't see it in all its glory whether I want to or not...

Download it and use it as a wallpaper. A lot of us do. It cheers us up on a depressing Monday morning.

[Pelranius]

Stuart: How desirable would practicing brinksmanship be if one possessed a clear superiority in nuclear weapons (if you can call having a few thousand warheads capable of reaching China as opposed to China's hundreds or so at best capable of reaching America)? I take it that it still really wouldn't be a good idea to fudge the rules?

[MKSheppard]

With MIRVs, the footprint is larger but how much larger is something that is kept very quiet.

MY FUHRER, I CAN SHROOM!

The “footprint” of a MIRVed missile depends on the number of re-entry vehicles carried by the warhead bus.

Poseidon's [no mark given] capabilities broke down as follows, according to From Polaris to Trident: The Development of US Fleet Ballistic Missile Technology by Graham Spinardi:

14 RVs (Max) 1,800 nm downrange, 50 nm crossrange
10 RVs - 2,500 nm downrange, 150 nm crossrange
6 RVs - 3,000 nm downrange, 300 nm crossrange

Translated graphically onto a map, Poseidon's performance is shown below, using a launch point 430 nautical miles east of Delaware:



Of course; this is a very *rough* diagram, useful only for generalized planning purposes. The PBCS on every MIRVed ICBM/SLBM has a limited amount of delta vee -- and it gets used up by manouvers to launch the MIRVs. So if you waste all your delta vee to dump three MIRVs onto the D.C. area on a six warhead Poiseidon, it's very likely you will not have enough delta vee to successfully attack San Francisco with your last two warheads, and will have to settle for a target in the heartland.

FYI: Land based ICBMs have higher PBCS delta vees; due to them using liquid fuelled hypergolic PBCS systems. SLBMs (at least US ones) have much lower PBCS delta vees, due to them using solid rocket motors as "gas generators" to provide thrust -- this is due to the US Navy's INSISTENCE that there will be no god-darn hypergolic rocket fuel on it's submarines.

[MKSheppard]

Darn edit timer.

It is said that the "footprint" of Trident II D-5 is three times smaller than that of LGM-118 PEACEKEEPER due to the use of solid fuel for PBCS control.

Here's an illustration of what I was talking about about energy management for PBCS:

[MKSheppard]

Now, here is a assembly line photograph of the PBCS for Peacekeeper.


Here is a simplified diagram of the PBCS on Peacekeeper:


Another Simplified Diagram of how it's laid out:


Now, we can figure out that the RED tank is the helium pressurization tank; and the YELLOW ones are for fuel and oxidizer.

We know that the RS-34 combined axial thrust/roll control engine which consists of a single 2,600 lbf vectored axial thrust engine, and eight 70 lbf roll control engines runs off those two tanks.

We know that the ISP of Dinitrogen Tetroxide and Monomethyl Hydrazine is about 300-308 seconds; and we can look up the average density of those two fuels; and then scale the fuel tank diameters off the known diameter of Peacekeeper (2.3 meters)....do some mathy, and them come up with a very accurate guess as to the delta vee of the Peacekeeper PBCS, and then divide it by three, to get the Trident II D-5 PBCS delta vee....

but I'm a bit busy for now (going to US National Archives today)...so...

[Simon_Jester]

Shep, are you trying to give Stuart a heart attack?

Stuart: How desirable would practicing brinksmanship be if one possessed a clear superiority in nuclear weapons (if you can call having a few thousand warheads capable of reaching China as opposed to China's hundreds or so at best capable of reaching America)? I take it that it still really wouldn't be a good idea to fudge the rules?

A few hundred nuclear weapons is still a few hundred nuclear strikes waiting to happen. No country on Earth can soak up a few hundred nuclear strikes without being, for all practical purposes, destroyed. There may be people alive, there may even be a surviving government that can more or less keep them under control, but as far as international affairs go, they've already lost the war even if their opponent lost it harder.

So... I'm betting that Stuart will say "brinksmanship in this situation would be completely idiotic" or something to that effect.

The only case I can imagine where brinksmanship is even vaguely sane is where you know, with absolute confidence, that you have enough air defense/ABM/whatever to kill any and all nuclear attacks launched at you several times over before they hit the ground.

[Stuart]

If I can carp slightly on this, the series of ellipses shown are not the footprints of a single MIRV. What they are is the area that can potentially be covered by a missile fired from the position in question. In fact, the actual footprints would be smaller ellipses contained within the larger ellipse (rather like a train of balloons). Using the six RV example, one could put six in California or six in Texas but not one in California and five in Texas.

The energy management thing is very real (and one I wish hadn't been mentioned ) and a major impact on strike planning. One of the reasons why very large numbers of RVs per bus went out of fashion is the difficulty in having enough energy to target all of the beasts.

At short ranges it takes a lot of energy to target each RV. At very long ranges likewise. There is a maximum distance limit between RVs and that's a lot less than is shown here.

[Simon_Jester]

The energy management thing is very real (and one I wish hadn't been mentioned ) and a major impact on strike planning. One of the reasons why very large numbers of RVs per bus went out of fashion is the difficulty in having enough energy to target all of the beasts.

At short ranges it takes a lot of energy to target each RV. At very long ranges likewise. There is a maximum distance limit between RVs and that's a lot less than is shown here.

See what you've done, Shep? You made a professional apocalypse planner cry. You ought to be ashamed of yourself.

Though I suppose I should take partial responsibility, since I brought up the energy management issue myself, but only in vague terms.

[montypython]

The energy management thing is very real (and one I wish hadn't been mentioned ) and a major impact on strike planning. One of the reasons why very large numbers of RVs per bus went out of fashion is the difficulty in having enough energy to target all of the beasts.

At short ranges it takes a lot of energy to target each RV. At very long ranges likewise. There is a maximum distance limit between RVs and that's a lot less than is shown here.

See what you've done, Shep? You made a professional apocalypse planner cry. You ought to be ashamed of yourself.

Though I suppose I should take partial responsibility, since I brought up the energy management issue myself, but only in vague terms.

I had heard back in the 90's about how having large numbers of MIRVs on individual missiles were best for striking disparate targets located in a relatively closely-spaced geographical area in order to make maximal effective use of a missile's energy reserves, just didn't connect the dots at the time though.

[Exonerate]

The energy management thing is very real (and one I wish hadn't been mentioned ) and a major impact on strike planning. One of the reasons why very large numbers of RVs per bus went out of fashion is the difficulty in having enough energy to target all of the beasts.

But why is this an issue at all? Given how many potential targets there must be, surely you could stick a large number of RVs into one missile and assign that missile a smaller area and target something farther away with another missile? If you had less missiles than regions this could be a problem, but given how many missiles the US has, it seems unlikely.

[Simon_Jester]

Think this way.

Suppose you put four warheads on each missile. Then you only have to find four targets within the zone each missile can hit to use all the missiles to their full potential. If you put six warheads on each missile, you have to find six targets. If there are only four or five targets in the zone, you wind up wasting warheads on targets that aren't very valuable, which increases the total number of missiles and warheads you need to do the strike.

Or what if you've got an isolated target, far from all others? Hitting it requires a full MIRV missile, but there's only one or two points you need to target.

The bigger the number of warheads per missile, the more of your target zones get hit with wasteful overkill. The overkill factor gets worse when you realize that each missile (and, for that matter, each warhead) as some chance of simply failing outright. For targets that absolutely must be destroyed, you really need to launch multiple missiles... each of which winds up falling prey to the overkill problem. And for isolated targets, using many-warhead MIRV missiles means launching sixteen or more warheads at a target that only takes one hit to destroy. Not good.

[SVPD]

Think this way.

Suppose you put four warheads on each missile. Then you only have to find four targets within the zone each missile can hit to use all the missiles to their full potential. If you put six warheads on each missile, you have to find six targets. If there are only four or five targets in the zone, you wind up wasting warheads on targets that aren't very valuable, which increases the total number of missiles and warheads you need to do the strike.

Or what if you've got an isolated target, far from all others? Hitting it requires a full MIRV missile, but there's only one or two points you need to target.

The bigger the number of warheads per missile, the more of your target zones get hit with wasteful overkill. The overkill factor gets worse when you realize that each missile (and, for that matter, each warhead) as some chance of simply failing outright. For targets that absolutely must be destroyed, you really need to launch multiple missiles... each of which winds up falling prey to the overkill problem. And for isolated targets, using many-warhead MIRV missiles means launching sixteen or more warheads at a target that only takes one hit to destroy. Not good.

That's mitigated, however, by the fact that you probably want to target anything worth hitting with at least 2 warheads in case one is a dud or misses. Also, you don't have to put the same number of warheads on each missile; if you have one target by itself, you can attack it with just 2 warheads, but make them bigger warheads, especially if it's a very hardened target.

Or you could attack that target with a bomber instead. If the bomber has cruise missiles, you might not even need to go far out of your way to attack it.

[Simon_Jester]

As I see it, bombers avoid the problem, especially with cruise missiles. It's when your main deterrent revolves around MIRV missiles (which for the modern US it mostly does, and always will for first strikes because it takes bombers so damn long to get there) that there's an issue. You can put a dozen warheads on a bomber and have the bomber hit a dozen targets, especially with ALCMs. You can't put a dozen warheads on a MIRV bus and have the bus hit a dozen high value targets, not consistently, because there may not be enough targets in the MIRV footprint. So it's still a problem, I'd say.

[Beowulf]

The energy management thing is very real (and one I wish hadn't been mentioned ) and a major impact on strike planning. One of the reasons why very large numbers of RVs per bus went out of fashion is the difficulty in having enough energy to target all of the beasts.

At short ranges it takes a lot of energy to target each RV. At very long ranges likewise. There is a maximum distance limit between RVs and that's a lot less than is shown here.

Well, there's a missing bit required to accurately determine the dV budget of missile. You need the bus mass and warhead mass (and this probably gets a bit more complicated due to the fact that your available dV is going to depend on how many warheads are left on the bus. If you drop the five on DC first, then you'll have more dV available to drop the sixth on Wright-Pat, versus releasing the one that goes to Wright-Pat first, and dropping the remaining five on DC.

[MKSheppard]

Well, there's a missing bit required to accurately determine the dV budget of missile. You need the bus mass and warhead mass

LGM-118 Bus weighs 3,000 pounds. No idea if that's the bus alone, or the bus weight with all the warheads on.

LGM-30G Minuteman III is a bit easier to find information on. It's 2,400 lbs with 3 x Mk 12 RVs, and 2,535 lbs with 3 x Mk 12A RVs.

Course; keep in mind that ICBMs are constantly changing as preventive maintenance goes on -- the PBCS of the first LGM-30G in 1970 is going to be a lot different than the current PBCS of the currently inservice LGM-30Gs, due to the fact that we've incrementally upgraded it since then -- e.g. we have to replace x component every y hours of alert duty to maintain the desired reliability rates; and the manfuacturer for x component went out of business, and we only have z parts left, so we are designing a newer, lighter bus computer system.

[K. A. Pital]

Targeting an industrialized nation like the US of A or, alternatively, European nations with lots of R-36M missiles with 10 high-power RVs each is quite fine. There's a lot of industrial targets wherever you'd want to toss them.

On the other hand, the Trident has 14 RVs. I'm not sure the US is not keen on "just toss many RVs on their industrial centers" approach. And those are ~50% of the US' strategic delivery arsenal, IIRC.

I'm not sure there were attempts to stuff 20 or more RVs on a missile here in Russia (I'll need to read up on that). However, 6-10 RVs is quite fine for a missile.

[MKSheppard]

Targeting an industrialized nation like the US of A or, alternatively, European nations

You know comrade stas, I really would like to see a lot of Soviet-era targeting documents declassified and translated.

Targeting the USA presents a interesting set of challenges, particularly from the 1960s onwards and it would be interesting to see how much of their thinking paralleled ours; due to the dispersion of the US mirroring that of the USSR -- e.g. both countries can afford to lose major cities -- it would hurt losing them, yes -- but it wouldn't be as crippling as in Europe or in other countries, where a large amount of socio/politico/economic power is concentrated in a few key cities.

[Sea Skimmer]

If you had a big enough missile, like the proposed N-1 and Saturn V based ICBMs, you could have as many warheads as you want since you'd have the weight budget to include multiple warhead buses. I suspect this would have worked with the buses released in a pattern not unlike a higher version of simple multiple warhead release. Then MIRV release performs as usual. This could work fairly well for targeting large systems of targets with somewhat uniform target dispersal, mainly ICBM silo farms. Of course such huge missiles have other glaring drawbacks like being too large for a silo with more then minimal hardening.

[Uraniun235]

You'll need a highly developed metals industry since these machines require various specialty alloys, a highly developed precision machine tools industry to machine those alloys to the required tolerances, AI vision systems, precision optics, and a whole bunch of other stuff. There's exactly 3 countries right now with the domestic tech base to build these machines, Japan, Germany, and the US. That's it. South Korea depends on Japan & Germany for the glass & optics.

Without those machines, modern electronics and production lines do not exist. Your computer, cell phone, TV, iPod, radio, Xbox, once it's dead it's gone and never getting replaced. Everything else in your home that's made in a modern factory is now several times more expensive.

Was there ever any study done on the feasibility of stockpiling the information, plans, and some key materials necessary for a ground-up rebuild of advanced technology industries? It seems like it would be a massive advantage in a post-war world to be able to open up the vault, work through the checklists, and immediately begin building or rebuilding the necessary infrastructure to produce relatively modern technology.

Of course, any such plan would also likely depend on implementing a command economy for some time, but in the immediate post-war scenario I would imagine it'd be martial law all over anyway.



Along those lines, if getting hit in a nuclear war pretty much puts you out of action anyway, and if the first nation to really successfully rebuild has a decisive technological advantage, wouldn't it then become imperative to really wipe out as much of the enemy population as possible? Seems like you can't rebuild shit if your country doesn't even have enough people left to remain a cohesive nation.

[aerius]

Was there ever any study done on the feasibility of stockpiling the information, plans, and some key materials necessary for a ground-up rebuild of advanced technology industries? It seems like it would be a massive advantage in a post-war world to be able to open up the vault, work through the checklists, and immediately begin building or rebuilding the necessary infrastructure to produce relatively modern technology.

I don't know. It would probably help a bit but then you'd run into problem #2, the people. There's a bunch of highly specialized jobs which few people can do, and worse yet some of them are industry trade secrets so we may not even know how important those people are until they're dead and we're trying & failing to train their replacements.

To use an example, my parents have a family friend in Europe who eventually became upper management in an aerospace contractor. One of the things they do is make precision ball bearings for airplanes and for certain types of those bearings there were only 2 people in the entire company with the skills to make them. Those 2 people had to make a whole bunch of extra bearings before they could go on summer vacation each year or else a large part of the European airline industry would grind to a halt.

There's stuff like that in a lot of industries, not quite that bad in most cases but bad enough that losing those people would set us back years, or worse depending on how many are lost.

[Simon_Jester]

Well, that's what you'd have to look into. "How much of these people's knowledge can we write down, at least to the level where some poor fool assigned the task of duplicating what a prewar Expert Ball Bearing Maker does will be able to do it given the same tools after several years of trial and error?" You can't make such high order technical specialists expendable, but it isn't in anyone's interests* for them to be irreplaceable. As de Gaulle put it, the graveyards are full of indispensable men, and that holds even in peacetime.

I can't see how it makes sense to just shrug and say "never mind, it's impossible, we're fucked." Though the scale of making every specialist quasi-replaceable (given a certain amount of time for trial, error, and experiment to relearn how people did things) may be too big, at which point you do have to give up, or devote only limited resources to the problem.

*I mean it. That's not in the interests of the company, the economy, the nation, and arguably not of the specialists themselves.