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Author Topic: Rods from God / "Project Thor"  (Read 3872 times)

Offline Charlesferdinand

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Re: Rods from God / "Project Thor"
« Reply #30 on: December 07, 2018, 12:24:52 am »
Would these tungsten rods lose a lot of their mass through friction by the atmosphere. What are the chances that they break up before they hit the ground.

Also, why rods? Obviously it looks cooler, but ouldn't balls be more convenient and ballistically more effective?
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Offline Orionblamblam

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Re: Rods from God / "Project Thor"
« Reply #31 on: December 07, 2018, 03:01:04 am »
Would these tungsten rods lose a lot of their mass through friction by the atmosphere.

Not if designed correctly. The nose would probably have an ablative cap.


Also, why rods? Obviously it looks cooler, but ouldn't balls be more convenient and ballistically more effective?
[/quote]

Nope. The point is to retain as much velocity as possible, to lose as little of it as possible due to drag. And one simplistic way to look at the drag of ballistic objects is the mass per cross sectional area. So... look at a tungsten rod shaped like a pencil. Each square inch of frontal area might be backed up by ten, fifteen, twenty *feet* of tungsten. A sphere of the same mass would be considerably larger in diameter, with much less mass per cross sectional area. This is related to why bullets these days are relatively long compared to their diameter... and not musketballs.
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Offline LowObservable

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Re: Rods from God / "Project Thor"
« Reply #32 on: December 07, 2018, 03:48:09 am »
Also, when a long rod strikes a solid object, its kinetic energy is concentrated on a small area. Think of an APFSDS tank gun round.

Offline Charlesferdinand

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Re: Rods from God / "Project Thor"
« Reply #33 on: December 09, 2018, 11:56:33 pm »
Also, when a long rod strikes a solid object, its kinetic energy is concentrated on a small area. Think of an APFSDS tank gun round.

Agreed, but that would depend on the accuracy you can expect. So would these projectiles have some kind of steering mechanism, and be something like a guided bomb?
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Offline Orionblamblam

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Re: Rods from God / "Project Thor"
« Reply #34 on: December 10, 2018, 03:35:52 am »
So would these projectiles have some kind of steering mechanism, and be something like a guided bomb?

Yes. Exact mechanisms of both navigation and maneuver is unclear, but presumably they'd be able to get occasional GPS fixes. Given their velocity at the end, it's unlikely that they'd really be up-to-the-microsecond, but they should follow pretty predictable paths. Likely use paddles at the tail for pitch and yaw.
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Offline Brickmuppet

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Re: Rods from God / "Project Thor"
« Reply #35 on: February 16, 2019, 10:27:06 am »

.........

Additionally, the claims that these things pack the punch of nukes is exaggerated to the point of being outright lies. They would hit the ground at less than orbital velocity (how much less is down to trajectory options... if you slow it down only a little bit to get it to de-orbit, it will hit the ground at a relatively shallow angle; if you drop it straight down, then you had to have dumped most of the orbital velocity). LEO circular orbit velocity is about 7,800 m/sec. The density of tungsten is 19.3 grams/cubic centimeter. So a rod 20 cm in diameter and ten meters long would have a volume of 3.14159*(10^2)*1000 = 314,159 cubic cm => 6,063 kg. Having six metric tons whack you upside the head at 7.8 km/sec would be harsh, but is it nuke-like? The kinetic energy is 1/2 M*V^2 = .5* 6063 * 7800^2 = 184,436,460,000 joules (184.4 gigajoules). One metric ton of TNT releases 4.184 gigajoules, so this six-ton rod has the equivalent yield of 44.1 metric tons of TNT, a multiple of 7.35.

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.

An entire Falcon 9 delivers a maximum of 0.13 kilotons of destructive potential upon the enemy using "Thor." Alternatively, you could load up that Falcon Nine with a couple hundred megatons of thermonuclear sunshine.

Davy Crocket's W-54 warhead had a yield of either 10 or 20 tons depending on setting so 44T is technically in tactical nuke territory. However, the W-54 got most of its lethality from the radiation pulse, so the Thor, even given double the blast, is probably less effective. It's probably more deliverable in a high threat environment than a BLU-82(Daisy Cutter) though.

The concept as a whole, associated with something like a re-useable Falcon might give us some idea of what the Chinese interest (mentioned earlier in the thread) might be looking at. Take Mr. Lowther's six ton tungsten rod and increase it by 50% for 9 tons (this is a completely arbitrary figure intended to allow for something small but with a thrust to weight ratio akin to a SPRINT ABM motor)  This weapon needs targeting, quite precise targeting given the guidance challenges during re-entry, so we'll be insanely generous and provide each weapon system with a KH-11 spy satellite= about 12 tons. This is certainly on the high end of targeting needs and budgeting possibilities but it allows us some design margin.

Falcon Heavy can throw 63 tons into low earth orbit. 63-12=51 which leaves 51 tons remaining.
51 tons divided by 9 tons per tungsten telephone pole+de-orbit motor in turn yields 5.667.
This gives us 5 warshots and .667 of 9 tons to add to our design margin.
So we have 5 warshots per launch to LEO.
However, an on call orbital system probably ought to be in Polar, Molniya or SSO orbit so we'll go with 2 shots per launch as an alternative, low end case.

The goal for Falcon Heavy is reportedly 100 launches. One can assume a Chinese equivalent will be similar so 100 launchers give 10 thousand launches which result in 20,000 or 50,000 warshots on station depending on the orbit chosen. In a polar orbit the whole enchilada could be fired at one target in a 24 hour period. Optimistically assuming a firing window of one half hour for each satellite, about 213 shots would be in position over any point on Earth at any time. Optimistically assuming a launch a week per rocket, the USSF or the People's Liberation Army Taikonaut Attack Corps (?) could put this sword of Damocles up in two years or so.

Each shot is, again, equivalent to 2 and a half Daisy Cutters. Any warship, even A Nimitz or Kuzenetsov class, will be ended by a hit from one of these things. Even the lower end figure of 20,000 is a much greater number than there are warships in the world. Sink any one navy and there are enough left over to use against most fixed targets of strategic importance such as RailYards, power plants, Whata-Burgers, air fields, dams, canal locks, munitions factories, command/control centers and even strategically located cloverleafs.

100 rockets, 10,000 launches and their not inexpensive payloads are a massive and, arguably, unrealistic investment but  by no means an impossible one. Given the current downward trends in launch costs facilitated by Mr. Musk, the cost to benefit analysis of this sort of thing with regards to national goals and resources is going to trend in its favor in the future.

Full disclosure: I'm a History Major, not an engineer, so I grimly await having my math checked.
« Last Edit: February 16, 2019, 11:37:59 am by Brickmuppet »

Offline Orionblamblam

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Re: Rods from God / "Project Thor"
« Reply #36 on: February 16, 2019, 12:13:14 pm »

The goal for Falcon Heavy is reportedly 100 launches. One can assume a Chinese equivalent will be similar so 100 launchers give 10 thousand launches which result in 20,000 or 50,000 warshots on station depending on the orbit chosen. In a polar orbit the whole enchilada could be fired at one target in a 24 hour period. Optimistically assuming a firing window of one half hour for each satellite, about 213 shots would be in position over any point on Earth at any time. Optimistically assuming a launch a week per rocket, the USSF or the People's Liberation Army Taikonaut Attack Corps (?) could put this sword of Damocles up in two years or so.


While I'm sure we can all agree that a launch a week for two years of a F9H class booster carrying USSF payloads would be a laudable goal, it would pretty much necessarily cause an arms race... which might or might not be a good thing. As with any satellite, there are chances of something going screwy and the thing falling out of orbit. Usually a satellite coming down results in harmless things like burnt bits of tank landing in the outback or Soviet fissionables scattered across a grateful Canadian tundra, but having tungsten telephone poles belly flopping out of the wild blue yonder could make for some entertaining CNN Personally I think it'd be worth the risk *if* those rods have white stars painted on the side... but if it's a red star, that's not so good.

Launching a *few* of these into orbit makes for an interesting tactical weapon. If the US and China tangle over, say, a Chinese invasion of the Spratleys or Japan, and one side or the other sinks a ship or two with a rod or two... things *may* stay conventional. but if one side has thousands of rounds overhead, they cease to be tactical weapons and become strategic. China sinks an American carrier with one of these from there vast orbital stockpile, chances are fair that the US Navy will respond not with some F-18's dropping JDAMs, but with an Ohio launching a barrage of Tridential howdies.


Quote
Any warship, even A Nimitz or Kuzenetsov class, will be ended by a hit from one of these things.

That might not actually be true. Yes, it seems entirely plausible that getting bullseyed by a rod would result in the rod going straight through the ship... but would it necessarily sink it? Sure, having a hole a yard wide punched suddenly through the middle of your ship is in no sense a good thing, but ships have watertight compartment doors for a reason. Unless the ship *completely* stops the round, then the 44 isotons of yield is to some degree simply wasted. The water below the ship will eventually stop the round, converting its kinetic energy into thermal and generating either a big bubble of steam or a long string of such. Exactly how fast the water stops the round will determine if the ship has to deal with a giant bubble underneath it, lifting the vessel out of the water and snapping its keel, or if the ship will just find itself sailing through a sea of seltzer for a few seconds.

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Offline Brickmuppet

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Re: Rods from God / "Project Thor"
« Reply #37 on: February 16, 2019, 01:31:13 pm »




Quote
Any warship, even A Nimitz or Kuzenetsov class, will be ended by a hit from one of these things.

That might not actually be true. Yes, it seems entirely plausible that getting bullseyed by a rod would result in the rod going straight through the ship... but would it necessarily sink it? Sure, having a hole a yard wide punched suddenly through the middle of your ship is in no sense a good thing, but ships have watertight compartment doors for a reason. Unless the ship *completely* stops the round, then the 44 isotons of yield is to some degree simply wasted. The water below the ship will eventually stop the round, converting its kinetic energy into thermal and generating either a big bubble of steam or a long string of such. Exactly how fast the water stops the round will determine if the ship has to deal with a giant bubble underneath it, lifting the vessel out of the water and snapping its keel, or if the ship will just find itself sailing through a sea of seltzer for a few seconds.

I'd think that the heat would generate a steam bubble breaking the ship's keel, but as you say some testing would be needed to determine if this is in fact the case. Interestingly, the effect you mention might make these things much more lethal in shallow water.

I wonder if a shrapnel round would be practical?

With regard to maintenance issues and satellites tumbling out of orbit, we'll be pessimistic and assume each satellite needs maintenance once a year. In both scenarios above there are 10000 orbital platforms. Divide that by 350 rather than 365 to allow 15 days of leeway per year. That's 28.5 so an orbiting maintenance station would have to go service 29-30 satellites a day. Assume 5 such stations that goes down to 6 and if you have 2 servicing cradles per station you are doing 3 satellites per work area per day which is an 8 hour shift per satellite. Extend the life of the satellites to anything close to that of a KH-11 and you really only need one maintenance platform to keep these things from falling without permission. The maintenance station is vulnerable of course and if the balloon went up any crew would probably have bail out real quick, but having it crewed allows for hands on maintenance and programing during peacetime without relying on remote communications so it MIGHT be less susceptible to hacking in some scenarios.

Also it'd give space force personnel something to do in space.

Offline Orionblamblam

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Re: Rods from God / "Project Thor"
« Reply #38 on: February 16, 2019, 04:19:49 pm »

I wonder if a shrapnel round would be practical?

The purpose of a log made out of tungsten is to punch *deep,* bunker busting and the like. If you want to kill a ship, what you probably want is a round that blows upright around contact. These things would be moving so fast that any bursting system short of an embedded nuke would turn them not into a nice spherical explosion, but sort of a shotgun blast.

But if you have "bursting rounds," they take the place of "bunker busters." More options, but less of what the system is supposed to be best at.


Quote
With regard to maintenance issues and satellites tumbling out of orbit, we'll be pessimistic and assume each satellite needs maintenance once a year.

We'll also be realistic and recognize that sometimes boosters and upper stages don't put their payloads in quite the right orbits. A Thor system should be relatively dense compared to other satellites, even considering associated telescopes, antenna and solar panels, so if it is in the right orbit it should deviate much more slowly due to drag.


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Offline LowObservable

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Re: Rods from God / "Project Thor"
« Reply #39 on: February 17, 2019, 06:21:40 am »
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.

Offline Orionblamblam

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Re: Rods from God / "Project Thor"
« Reply #40 on: February 17, 2019, 12:29:02 pm »
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.
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Offline Dilandu

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Re: Rods from God / "Project Thor"
« Reply #41 on: March 01, 2019, 10:17:27 am »
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.
 

Offline sferrin

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Re: Rods from God / "Project Thor"
« Reply #42 on: March 01, 2019, 10:32:14 am »
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.
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Offline Dilandu

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Re: Rods from God / "Project Thor"
« Reply #43 on: March 01, 2019, 10:57:18 am »


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.

Offline marauder2048

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Re: Rods from God / "Project Thor"
« Reply #44 on: March 01, 2019, 11:57:18 am »
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.