The suitcase nuke question.

Cecil's Columns/Staff Reports
21

Basically, yeah.
Rockets carry their propellant with them, and guns leave the propellant with the launcher.

Recoilless launchers may be rifled or smooth-bore, but whichever they are, the propellant stays with the launcher while the munition leaves the launcher, and all associated mass, behind.

OTOH, when a rocket’s propellant is exhausted, it must carry the remaining mass of it’s propulsion system (rocket case) with it, or have some means of jettisoning the waste mass. With single-stage rockets, there’s no real point to dumping the motor case, as it’s already up-to-speed, and you’re not going to get much benefit from a lighter rocket after the motor has burned out. Multi-stage rockets, of course, always want to dump as much weight as possible before lighting the next stage.

Guns give much higher innitial velocity, at the cost of down-range performance. Rockets tend to have lower initial velocity, but accelerate, or at least maintain their velocity, all the way to the limits of the range. An obvious exception to this are RPGs, Bazookas, and the like. In those cases, the rocket burns its entire fuel grain very rapidly, almost explosively. By the time the projectile has left the launcher, it’s a ballistic projectile, having already burned out. This gives no-recoil launch, and saves the operator from getting a rocket-exhaust facial, but comes at a serious range penalty. Some anti-tank launchers in the past have used longer-burning motors, and had shields attached to protect the operator’s face and head. For example, the WWII German Raketenpanzerbüchse 54, seen here, has an obvious faceshield. The operators were also given special protective clothing.

As for the advantages of one over the other?
Recoilless guns generally fire heavier shells, while rockets use much lighter, more simple, launchers. For the most part, the recoilless rifle has been reduced by advancing rocket & missile technology to a specialty item, though some examples, like the old reliable Carl Gustav launcher, reamain viable weapons systems.

22

Oh, and regarding the new nuke shells - They might be RAP (Rocket Assisted Projectiles - A hybrid of gun and rocket), but more likely they’ll be Base-Bleed shells. A base-bleed shell uses a slow-burning fuel grain at the bas of the shell, which burns off just fast enough to fill the low-pressure area formed directly behind the shell in its flight, thus radially reducing drag.

23

Huh? Is there a comma missing after “technology”?

24

Awkward phrasing - Sorry about that. What I was trying to say is that the recoilless rifle doesn’t see much use anymore, outside of a few old standbys like the Carl Gustav. You can sometimes find surplus RRs used by ski resorts to help control their snow avalanch problems.

25

Excellent reply, but just to add to the confusion: Some anti-armour rounds for the Carl Gustav are actually rocket-assisted(!) - a sustainer engine kicks in to accelerate the warhead and increase range. The downside to that is the need for a mathematician to calculate windage: The projectile coasts for some distance (veering downwind), then the sustainer kicks in. As the fins on the projectile has a “weatherwane” effect, the projectile will actually veer upwind until the sustainer burns out and the warhead coasts the rest of the way. Try keeping that straight while correcting for distance and leading the target. The running joke was that once the gunner had finished calculating windage, the target would be at point-blank anyway, so why bother.

(Disclaimer: I was never truly qualified as a recoilless gunner - not beefy enough - but I did get the basic “How to pick up and discharge in the general direction of the enemy” lesson for all our squad weapons.)

26

Ah! You’re referring to the FFV651 munition, I think. Sounds a proper muddle for some poor crunchy to have to figure… A bureaucrat’s response to a extending the useful life of a fading weapon. Mind you, as a bunker-buster, it’s still a fine weapon, and it’s still damned dangerous to tanks. The Carl G has had a far longer life than many weapons systems.

The confusing issue of weapons types blending into each other is an old story. For instance, do the Shillelagh missiles fired from the M-551 Sheridan light tank make their launcher a gun or a missile launcher? It seems that even the Army is confused, sensibly (if confusingly) calling it a gun-launcher. Is a RAP projectile a rocket, or an artillery shell? The M-47 Dragon AT rocket has some similarities with a recoilless launcher, using a breech gas generator to kick the missile on its way.

When talking ordnance, there is almost always an overlap between related or competing systems.

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Isn’t the bigger issue here a suitcase with a conventional explosive device surrounded by radioactive material?

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“Bigger?” Dunno. A “dirty bomb” of that sort could certainly be nasty, but obviously wouldn’t cause the sort of devastation a nuke would. But if you mean it’s a more realistic threat, you’re probably correct.

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[INDENT]
Take a coffee can and fill it up with some radioactive sand or powdered plutonium and poke a couple of holes in the bottom. Then attach it to a cab that drives around a major city. :frowning: [/INDENT]

best regards,

buck

30

Perhaps this buggers the question, but to echo Enrico Fermi’s famous “Where are they?”…

Why haven’t they? Are there no fanatical Muslim grad students? I think Dr. Khan’s recently reported nuclear Amway sale puts paid to that. So then, if its all so simple, why has it not been done?