Nuclear weapons

Professur said:
Not true. Hardened Tungsten, with an ablative heat shield and an aerodynamic profile. You'll lose less that 20%. Don't forget, most orbitals are designed to shed speed and create lots of friction on the way down. This wouldn't be.
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I got that, that's why you burn off so much more mass. The aerodynamic profile doesn't do much at that speed, the shockwave is the problem, not the aerodynamics. Also, at the temps being generated in a full speed entry tungsten really isn't any better than ice. The reason a comet doesn't burn up in the atmosphere has a lot less to do with mass or what it's made of than with speed. It's a little counter-intuitive, but at a much higher (i.e. cometary) speed, even though there's more energy, it just isn't in the atmosphere long enough to ablate significantly. Dropping 200 pound weights from orbit you lose too much energy and mass in the atmosphere. It's just in the atmosphere for too long. It would make a pretty good hole, but I'll bet it would lose more than 70% of it's energy. Now, shoot them from the moon with, say triple orbital speed to start...

Sorry, I'm kind of a space nerd.
 
Okay, so I'm really just a total fucking nerd (and evidently bored):

Orbital velocity (at LEO, the highest orbital speed) = 8 km/sec
200lbs = 90kg (closer to 91 but I'm lazy)

Kinetic Energy (in joules) = 1/2(mass)V E+2
Energy (in joules) = (tons of TNT)4.184 E+9
Energy released by Hiroshima bomb = 12.5 kilotons

200lbs at impact assuming no friction or ablation = 2,880,000 joules (give or take)
Hiroshima bomb = 523,000,000,000 joules (again, give or take)

Yeah, I did the math.
 
Christ, guys... howzabout just dropping a five ton slug of tungsten thats been coated with space shuttle heat shielding? That way you can have mass and velocity without burnup.
 
unclehobart said:
Christ, guys... howzabout just dropping a five ton slug of tungsten thats been coated with space shuttle heat shielding? That way you can have mass and velocity without burnup.
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Umm... the space shuttle slows down significantly pretty quickly. Otherwise it would burn up. :shrug:

Besides, didn't I show that it wouldn't approach anything like nuclear yield? :nerd: :nerd: :nerd:
 
Yes.. but my intent is to have a baby nuke piggybacked on the damn thing anyway.

Skunkops, baby!

*bam* a meaty middle finger from the military industrial complex.
 
Chic... rerun the math until you get a Hiroshima yield with a just-over-the-edge of friction for reentry speed and tell us how heavy the darn thing has to be. My 5 ton slug with your math was running about 30%, no? A lousy 200 pound slug is barely 4 weight plates at the gym. Thats pathetic... unless you rain down 50 of the damn things all over the target zone. I'm talking about a goldurn Toyota sized mass.
 
chcr said:
I got that, that's why you burn off so much more mass. The aerodynamic profile doesn't do much at that speed, the shockwave is the problem, not the aerodynamics. Also, at the temps being generated in a full speed entry tungsten really isn't any better than ice. The reason a comet doesn't burn up in the atmosphere has a lot less to do with mass or what it's made of than with speed. It's a little counter-intuitive, but at a much higher (i.e. cometary) speed, even though there's more energy, it just isn't in the atmosphere long enough to ablate significantly. Dropping 200 pound weights from orbit you lose too much energy and mass in the atmosphere. It's just in the atmosphere for too long. It would make a pretty good hole, but I'll bet it would lose more than 70% of it's energy. Now, shoot them from the moon with, say triple orbital speed to start...

Sorry, I'm kind of a space nerd.
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Um.... You do know that the heat isnt' produced from surface friction, but from compressing the air in front of the projectile. Aerodynamics are gonna make a helluva lot of difference. And Tungsten is more than up to the challenge. If you were to install a pin-shaped ablative probe similar to that used for supersonic aircraft, it would begin the compression wave well ahead of the "crowbar". Also you're not accounting the pressure wave in front of the 'crowbar' into your math. The Tunguska strike never even made it to ground, but the pressure wave flattened trees for a radius of 30Km and burned them out to 60km.
 
Professur said:
Um.... You do know that the heat isnt' produced from surface friction, but from compressing the air in front of the projectile.
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In other words, the shockwave. At the speeds we're discussing the shape isn't as significant as it could be. It makes a difference, I'm sure, jsut not as much as you'd probably think. I don't have the formulas or the variables to figure out how much it would ablate. I'm simply voicing an opinion.

Hey Unc, what Toyota weighs five tons? Oh, and 200 lbs. is plenty if it's going fast enough. It's the total kinetic energy of the package that's important. I always found the whole idea a bit unfeasible because it costs so much to put enough mass up there to make a difference from that close. Much more economical to put large yield nuclear warheads on ICBMs and airburst them at 25,000 feet. Again, if we had a moonbase...
 
You have to figure that the cost of processing uranium, the security, the precautions, the upkeep.. its maddeningly expensive. Conventional payloads dropped from orbit... or delivered in atmosphere via missiles have to be a helluva lot cheaper by comparison.

If we were already considering a nuclear, mankind violating icky-poo round, we might as well have just delivered a nasty-ass mondo chemical round aka Saddam de fame.
 
unclehobart said:
You have to figure that the cost of processing uranium, the security, the precautions, the upkeep.. its maddeningly expensive. Conventional payloads dropped from orbit... or delivered in atmosphere via missiles have to be a helluva lot cheaper by comparison.

If we were already considering a nuclear, mankind violating icky-poo round, we might as well have just delivered a nasty-ass mondo chemical round aka Saddam de fame.
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Oh sure. I've always considered that to be one of the reasons we haven't used nukes again. There are others, but the cost is certainly significant. I still think it would be more prohibitive (given the infrastructure and limited payload) to put stuff in orbit.
 
What would be better as an 'in atmosphere' approach?

a. A heavy metal missile with pure propellant behind it to get it going at mach 20 when it hits causing a nasty concussion wave... or

b. a normal missile coming in at a conventional mach 5 with a 2000lb payload of c-4 ish material on 500m airburst?

My guts tell me b... but slower missiles are quickly becoming subject to interception technologies.
 
I'm looking for a little more than mach 20. Forget propellant. Any kind of engine would just slow it down. And c4 isn't all that good an explosive. You're only calling for a single ton bomb. Hell, they had better than that in WWII.
 
I'm just thinking of the stuff that we already put on rockets. A heavier rocket with a 5 ton payload or more could always be mocked up.

We should just work on James Bond earth crust bombarding shockwaves that can be focused under enemy nations to cause spontaneous volcanoes and earthquakes. Let mother nature work for us for a change.
 
unclehobart said:
I'm just thinking of the stuff that we already put on rockets. A heavier rocket with a 5 ton payload or more could always be mocked up.

We should just work on James Bond earth crust bombarding shockwaves that can be focused under enemy nations to cause spontaneous volcanoes and earthquakes. Let mother nature work for us for a change.
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It's been done
 
I don't think you guys fully understand the forces involved. Five tons is a speck of dust. At 8 km/sec (about mach 20) it works out to around .04 kilotons. Pretty puny on a nuclear scale. The Tunguska comet or meteor is estimated to have been 100,000 tons and the energy released anywhere from 10 to 20 megatons for comparison. :shrug:
 
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