largest nuclear weapons, and other related questions.

I’ve a few questions about nuclear weapons perhaps a few in the know might answer.

  1. What is the largest nuclear weapon currently “used”. Who owns it?

  2. What would an incoming ICBM look/sound like? Would it be fairly quiet as it burned most it’s fuel on the trip over or would the rockets still be burning as it explodes? If one was looking at the sky, would they notice an ICBM as something different from a plane?

  3. I know there was a great thread about the difference between the “A-bomb” and the “h-bomb” but I can’t find it. Are most the of current nukes used A or H? Which is more effective/nasty?

Recent thread: Whats the advantage of an H-bomb over an A-bomb

  1. A ballistic missile (as in, inter-continental ballistic missile or ICBM) is unpowered for most if its flight. It’s rocket powered only at the start. The actual warhead is fairly small, so you probably wouldn’t see it. It would also be travelling faster than sound, so you wouldn’t hear it, either.

A brief internet search came up with the B83 warhead as used by the US, which is 100 times Hiroshima (which I think was about 15-20 kiloton yield).

As to what they look like, a lot of ICBM carry MIRV’s (or at leats they did in the magazine I read about 20 years back).
MIRV - Multiple Independant Re-entry Vehicle - whereby a single ICBM splits into several warheads, perhaps as many as 6 or so, which then fly on to different targets.

  1. My WAG: During the right conditions (Say, at night.) an incoming ICBM warhead might look like a shooting star. Most nuclear weapons would be detonated a few hundred feet above ground, btw. Though a “bunker buster” nuke would be designed to penetrate underground, but I don’t think any of those are fitted to any ICBMs or SLBMs.

  2. A link to a site describing difference between an atomic bomb and hydrogen bombs. Just keep in mind that all fusion bombs (“H” bombs) have to be triggered by a fission bomb (“A” bombs) to create the neccesary heat and pressure for fusion to occur-at our level of technology, at least.

I believe that the largest nuclear weapon ever deployed had a yield of about 20 megatons. As a practical matter, there’s little point in building a larger warhead because around this yield you get “atmospheric blowout” – the little mushroom clouds sticking out of the earth’s atmosphere in Farside cartoons. If you built a 40 MT weapon, most of the additional blast energy would vent out into space.

In 1961, the Soviets exploded an H-bomb with an estimated yield of 50-60 megatons of TNT, or roughly 3,000 times the raw power of the Hiroshima bomb. Kruschev made noises about that time to the effect that they were developing a 100 MT bomb, but we’re talking about a guy who once took off his shoe and banged it on the podium at the UN to make a point. Current stockpiles consist mainly of much smaller warheads, mostly 1 MT or less, the theory being that you can have a lot more fun with ten little ones than you can with one big one.

An incoming ICBM is something you’ll probably never see or hear. As the name “ballistic” implies, these missiles are unpowered for most of their flight, so there’d be no engine noise. Even if there was, the missile would be traveling at high Mach numbers and would get to you long before the sound did. During WWII, Londoners hated and feared the V-2 for that very reason – you couldn’t hear it coming, and it moved so fast that seeing it wasn’t much help.

With the fissionable materials available, there is a fairly fixed upper limit to the potential yield of fission weapons (“A-bombs”), for practical mechanical reasons. However, the sources I’ve seen generally agree that fusion weapons (“H-bombs”) are unlimited in that respect. Most “H-bombs” are actually combinations of fission and fusion devices, using a fission bomb to generate the heat necessary to set off a fusion reaction, which then sets off a second fission reaction. Triple whammy, so to speak.

The one the Soviets tested had a theoretical yield of 100MT, but they tested it at 50-something-MT.

I had understood that it was just the opposite: That the Germans deliberately attached whistles to the missiles, so that the Londoners could hear it coming. It’s not like that would give a person enough time to get away, but it would cause a lot of panic, even among the people not actually hit by it.

What’s the point of attaching a whistle to something supersonic? The rocket arrives before the whistle sound.

Perhaps the whistles were attached to the sub-sonic V1?

The pulse jet engine one the V1 was incredibly loud all by itself. They were called “Buzz Bombs”.

“on the V1”

Oh that’s right, I remember now. People only had to worry when the buzz stopped.

The point about the people hearing the V1, was that they could take cover when they heard the engine cut out as it ran out of fuel and dived towards the ground.

To stop this happening, the Germans used a timing propellor on the front which (when enough revolutions had turned) tripped the rear elevator on the bomb to make it fall before the engine cut out, thus eliminating the advanced warning.

The warheads are generally unpowered, but you can attach scramjet engines to them to make them really move.

A friend of mine who was a child in Croydon during both the Battle of Britain and the Blitz said that the “doodlebugs,” the local term of the V-1s, were incredibly loud and sounded something like a motorcycle due to their pulse jets.

I don’t know if the missile tests from Vandenberg to Kwajalein are specially designed to leave contrails, or if the RVs do it of their own accord (I suspect the latter). Nevertheless, it’s pretty difficult to mistake these photos for anything but incoming ballistic missile warheads.

You would never hear or probably even see an ICBM warhead coming at you. An ICBM is powered by its rocket motor into space at which time the engines shut off. After that it just coasts the rest of the way. In fact, the rocket engine gets left in space. Most ICBMs are fitted with MIRV (Multiple Independantly targeted Re-entry Vehicles). Essenetially the nose of the rocket falls away revealing several MIRVs inside. These warheads are only a few feet tall, cone shaped and maybe a foot or two wide at the base (widest part). In short they are pretty small. It is this that gets ejected from the missile towards its target. The whole flight of a MIRV is unpowered…kind of like throwing a rock at a target. The MIRV, IIRC, travels around 15,000 MPH which is MUCH faster than the speed of sound. In other words…you’d never hear it before it went off. At 15,000 MPH and given its small size I doubt you’d see it although it is likely glowing from re-entry so perhaps you would see a streak as if it were a meteor (shooting star).

This is partly the reason a missile defense system is so difficult. I have heard it likened to trying to hit a bullet with a bullet (assuming you are using a physical intercept and not a laser or something). Your anti-missile missile is streaking at the target at several thousand MPH and the incoming warhead ismoving at 15,000 MPH giving closure speeds of nearly 20,000 MPH. Add that the target is not very big and you can see why this is exceedingly difficult to do. That’s why, ideally, you stop the ICBM during its boost phase. MUCH bigger target, moving much more slowly with a nice big rocket plume to lock onto. Unfortunately you generally need to be in the immediate vicinity when the launch occurs to have a prayer of getting it at that point. Your next step is satellites than can attack the missile in its coast phase before it deploys the MIRVs. It is now moving very fast but you have no atmosphere to bother you and a big target. Last ditch defense is during re-entry which, as mentioned, is very difficult to achieve.

Some images of incoming re-entry vehicles,minuteman and peacekeeper, (time exposure) at: and