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Rods from God / "Project Thor"

Orionblamblam

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LowObservable said:
I have heard it theorized, by someone I would regard as an expert, that a shotgun blast on the right scale is exactly what you need against a warship.
It might depend on *when* the blast goes off. If it goes off above the ship, so that there is sufficient time for the hundred or so chunks of hundred-pound slabs of tungsten moving at five kilometers per second to separate enough to get some good coverage of the ship...yeah, it'll make a mess. If it goes off *inside* the ship, it probably won't make a whole lot of difference *to* the ship, though the "exit wound" on the belly of the ship will be bigger. However, even if that action doesn't do much to the ship, by kerploding the rod before it actually hits the water, the kinetic energy of the rod will be deposited into the water a *lot* faster. So you will poke a meaningful hole through the ship and then promptly create an energetic bubble of steam right under the keel.

Not a good day to be in a boat.
 

Dilandu

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Orionblamblam said:
Keep in mind: in order to drop that six ton rod of tungsten on the other guy, you had to expend a de-orbit stage of unknown mass, as well as a whole lot of tons of rocket propellant to boost the system into orbit in the first place. The Falcon 9 Full thrust can put 22.8 tons into orbit (equivalent to 3.75 rods, not counting de-orbit systems...call it three rods), burning through 410.9 tons of propellant in the first stage and 107.5 tons of propellant in the second => 518.4 tons of propellant expended to deliver the equivalent of 3X44.1 tons (132.3 tons) of TNT onto the enemy.
Hmmmmm. Let's assume, that the cost of the whole system would be about 100 millions dollars (50 millions for F9B5 launch and 50 millions for the system itself ). So we have the system, that could within 90 minutes deliver along its orbital path a 130 tons of destructive power.

How much it would cost to deliver the same amount of explosives by conventional means? The cost of modern "Tomahawk" missile, if I'm not mistaken, is about 2 millions dollars (1,82 actually). So the system cost as much as 50 "Tomahawks"... which could deliver to the target about 50 * 0,45 = 22,5 tons of explosives.

* Of course, 50 "Tomahawks" could be used against much more targets, but I must point out, that against well-defended target only a part of those 50 "Tomahawks" would come through. And I must also point out, that 50 "Tomahawks" would not deliver themselves all the way from USA to the target. They needed a carrier vessel - an "Arleigh Burke"-class destroyer, perhaps, or nuclear submarine, which also would cost money. If we use ALCM's instead, we would need enough bombers to carry them.

* Of course, the actual system on orbit would probably cost more than 50 millions, but up until it cost less than the number of "Tomahawks" required to deliver the same amount of explosive power + their carriers, it would be at least partially cost effective.

In short, my IMHO - the "Thor" system is not hopeless. Granted, it is not the system you would call in to destroy the tank column. But it would work great against high-valuable, protected targets, like command bunkers, strategical transport nodes, hardened airfields, ect. For example, something like good ol' "Thor" may be quite a good solution against those Chinese island fortresses in Southern Chinese Sea. To took them out by conventional means, would require quite a lot of efforts. To nuke them, would means a clear escalation to at least tactical nuclear level (and who would benefit more?). But to orbit-strike them with the power of tactical nukes would be both cost-effective, and fairly conventional way.
 

sferrin

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LowObservable said:
I have heard it theorized, by someone I would regard as an expert, that a shotgun blast on the right scale is exactly what you need against a warship.

It would not sink it but it would trash almost every sensor/comms aperture on board.
Back in the day (early 80s) there was a piece of HARM artwork that showed it attacking an old Kresta II class. Presumably, this is exactly the strategy employed.
 

Dilandu

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sferrin said:
Back in the day (early 80s) there was a piece of HARM artwork that showed it attacking an old Kresta II class. Presumably, this is exactly the strategy employed.
I must point out, that HARM would home on radar systems, i.e. would hit the warship around radar antennas. Which means that shrapnel hit is preferable to direct hit, since the probability of hitting tops of masts and superstructures are significantly less than in case of hull attack.
 

marauder2048

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sferrin said:
LowObservable said:
I have heard it theorized, by someone I would regard as an expert, that a shotgun blast on the right scale is exactly what you need against a warship.

It would not sink it but it would trash almost every sensor/comms aperture on board.
Back in the day (early 80s) there was a piece of HARM artwork that showed it attacking an old Kresta II class. Presumably, this is exactly the strategy employed.
Although given HARM's CEP against a moving emitter, I'm not sure they could have employed any other strategy.
 

_Del_

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Reported by whom? I've never seen a credible claim that orbital bombardment tech was real-world tested or even seriously experimented with.
So I never found what I was looking for in DTIC, but there was this from Jane's International Defence Review, Jan 2006, which just popped up from the depths again on this forum, oddly enough:

"One conventional strike option against hardened targets was demonstrated under a "black" or classified programme in 1978-88. Colliquially known as "rods from God" (a term attributed to science fiction writer Jerry Pournelle), it involved placing small space vehicles containing 15-20 long, dense, inert tungsten rods - 6m long and 0.3m in diameter - in elliptical orbits around the Earth. (There is no treaty restricting the use or deployment of conventional or non-explosive orbital weapons.) The vehicles would achieve ultra-high apogees of almost 65,000km and would eject and de-orbit the rods on demand. When something falls in a vacuum from 65,000km it is apt to be moving rather quickly when it hits the ground, and the concept involved impact speeds of 6,000m/s. It was estimated that the sheer kinetic energy impact would be enough to destroy missile silos. According to analyst Barry Watts of the Center for Strategic and Bugetary Assessments: "A total of perhaps USD70-80 million was spent... including test shots against the Kwajalein Atoll from Vandenberg AFB in California. In the end, however, the programme met staunch opposition from Air Force fighter generals who were not interested in seeing SAC develop a non-nuclear global-strike capability. As a result, the programme was terminated."...
 

sferrin

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An 18,000lb rod of tungsten wouldn't need to fall from orbit to kill a silo.
 

SpudmanWP

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The primary purpose of having it in orbit is response time.

Using a single bomber to drop a single rod is not efficient.
 

Orionblamblam

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The primary purpose of having it in orbit is response time.

Response time from orbit could be many hours. Not just the 90 minutes to go around the Earth, but however many orbits it needs to go through to get somewhere over the target. The cross-range on a rod is likely not spectacular, especially if you want to maintain maximum velocity. Optimally you'd want to shed as little velocity as possible, which means that you would want to drop the rod onto a target that is almost exactly in line with the orbital path. And you may want to impart *just* enough delta V to drop perigee down to ground level, which means the rod would come screaming in nearly horizontally.

All this means that if you have a limited number of weapons in orbit, your targets could be days away. So waht you'd want is to have a *lot* of weapons in orbit. Sure, there will inevitably be foreign government complaining and some members of your own public protesting, but you could simply declare that the protestors are "colluding" with the foreign powers...
 

sferrin

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The primary purpose of having it in orbit is response time.

Using a single bomber to drop a single rod is not efficient.
But imagine trying to get a useful number of them up there and moving them around. A silo would be just as dead with a 100 pounds of tungsten hitting the lid at 6 km/sec.
 

SpudmanWP

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If 100lbs is sufficient then make the RfGs 100lbs (+ ablative shielding) , no need for 9000.

If they are only 100lbs, then there can be many more in orbit so the response time is shorter.

I wonder what a RfG could do to a sub a couple of hundred feet below the surface?
 

Orionblamblam

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I wonder what a RfG could do to a sub a couple of hundred feet below the surface?
Realistically? Probably make a loud "bang" well overhead that spooks the crew. Going faster doesn't seem to greatly increase penetration depth... a couple hundred feet of water would probably stop a RfG quite effectively.
 

edwest

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I get the orbit-deorbit part, what I'm still vague on is total impact force.
 

SpudmanWP

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I wonder what a RfG could do to a sub a couple of hundred feet below the surface?
Realistically? Probably make a loud "bang" well overhead that spooks the crew. Going faster doesn't seem to greatly increase penetration depth... a couple hundred feet of water would probably stop a RfG quite effectively.
If there can be supersonic, rocket powered torpedoes.. why not shape the tip of the RfG to do the same thing or is there some gas generation involved?

nm, Googled it and 'answered my own question'. :)
 

sferrin

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I wonder what a RfG could do to a sub a couple of hundred feet below the surface?
Realistically? Probably make a loud "bang" well overhead that spooks the crew. Going faster doesn't seem to greatly increase penetration depth... a couple hundred feet of water would probably stop a RfG quite effectively.
If there can be supersonic, rocket powered torpedoes.. why not shape the tip of the RfG to do the same thing or is there some gas generation involved?

nm, Googled it and 'answered my own question'. :)

Some use gas-generation to supercavitate. Others use shape.



616105
 

Orionblamblam

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I wonder what a RfG could do to a sub a couple of hundred feet below the surface?
Realistically? Probably make a loud "bang" well overhead that spooks the crew. Going faster doesn't seem to greatly increase penetration depth... a couple hundred feet of water would probably stop a RfG quite effectively.
If there can be supersonic, rocket powered torpedoes.. why not shape the tip of the RfG to do the same thing or is there some gas generation involved?

nm, Googled it and 'answered my own question'. :)

Some use gas-generation to supercavitate. Others use shape.



View attachment 616105
Wait. Is that chart actually saying that bullets will travel hundeds of feet in water? Mythbusters would like a word.
 

sferrin

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Wait. Is that chart actually saying that bullets will travel hundeds of feet in water? Mythbusters would like a word.
Mythbusters wasn't using supercavitating bullets. (I saw that episode too. :) )
 

SpudmanWP

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So... Zeus striking at Poseidon can be a thing.

Rods from Gods.. apply named :)
 

DrRansom

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I have a question: what sort of damage would a 1000kg+ rod dropping at 6 km/sec actually do? I haven't been able to find a study on the Rod from God impact damage.
 

DrRansom

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That article is for asteroids impacting at >11km/s and is a collection of scaling assumptions. The impact of a streamlined solid metal rod at hypervelocities should be very different than an asteroid.
 

Mark S.

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Why don't they use Depleted Uranium? Not only is it denser than Tungsten but it's pyrophoric? Sounds like these rods would make a useful warhead for hypersonic weapons..
 

SpudmanWP

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Cost along with "OMG the US is using nuclear weapons in SPACE!!!!!!!!!!"
 

edwest

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That article is for asteroids impacting at >11km/s and is a collection of scaling assumptions. The impact of a streamlined solid metal rod at hypervelocities should be very different than an asteroid.

I guess we'll never know. How would it work at a Scottish pole toss event?
 

edwest

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And everybody knows who Jormungandr is...
 

Forest Green

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I have a question: what sort of damage would a 1000kg+ rod dropping at 6 km/sec actually do? I haven't been able to find a study on the Rod from God impact damage.
0.5 * m * v^2.

500 * 6000^2 = 18GJ = 4,500kg of TNT (roughly), or roughly the same as a WWII Grand Slam Bomb.
 

edwest

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I have a question: what sort of damage would a 1000kg+ rod dropping at 6 km/sec actually do? I haven't been able to find a study on the Rod from God impact damage.
0.5 * m * v^2.

500 * 6000^2 = 18GJ = 4,500kg of TNT (roughly), or roughly the same as a WWII Grand Slam Bomb.

Thanks. Not as bad as I thought.
 

Grey Havoc

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And there’s this wonderful “thing” we have where a person can instantly look up information even on their phone.
Alas, even the best search engines are not what they used to be.
 
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