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Old 10-02-2017, 10:13 AM   #31
Fred Brackin
 
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Default Re: [Ultra-Tech] What would naval warfare at TL10 look like?

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Originally Posted by Anaraxes View Post
The SM-3 LEAP warhead is designed to have about 130 MJ of energy at impact, or 31 kg of TNT equivalent, and itself masses about 23 kg. An 8000 kg solid tungsten rod, a la Project Thor, isn't going to be discomfited in the slightest by something that tiny. You could set off 31 kg explosions next to it all day without bothering it.
The explosion wouldn't be "near" the Thor-ish thing. It would be on the _nose_ of it.

It would be a bigger explosion too as the front of the orbit-to-ground thing will also explode when it hits something solid. The figure used back in the day for Thor had it exploding with a force equal to 10x its' own weight in TNT.

It's not just an explosion more than 10x what you were considering it's the very much unscheduled course correction. The Thor-thing should not only miss what it was targeted at it probably loses stabilization too. It would at least try and fly sideways and probably tumble end over end.

A thing that can explode like 10x its' weight in TNT has a lot more KE in its' mass than it has structural strength in its' molecular bonds.
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Old 10-02-2017, 10:20 AM   #32
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Default Re: [Ultra-Tech] What would naval warfare at TL10 look like?

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Originally Posted by Fred Brackin View Post
The Thor-thing should not only miss what it was targeted at it probably loses stabilization too. It would at least try and fly sideways and probably tumble end over end.

A thing that can explode like 10x its' weight in TNT has a lot more KE in its' mass than it has structural strength in its' molecular bonds.
In particular, at those speeds once it starts to lose its orientation and yaw, it will begin to "pancake" and disintegrate. This gives you a nice explosion up in the air, with the occasional fragment of tungsten raining down onto the ground below.

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Old 10-02-2017, 10:30 AM   #33
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Default Re: [Ultra-Tech] What would naval warfare at TL10 look like?

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Originally Posted by Fred Brackin View Post
It's not just an explosion more than 10x what you were considering it's the very much unscheduled course correction.
A "solid tungsten rod" wasn't going to hit anything in particular anyway. Given that a little tumble may be enough for it to break up and burn in the upper atmosphere, even "the ground" isn't a sure thing.

Seriously this has always been one of the big criticisms of orbital bombardment ideas - hypersonic flight through the entire depth of an atmosphere, with all the variable forces that entails, is not conducive precision targeting. By the time you add enough guidance and stabilization and course correction capacity to guarantee you can hit the right city, never mind a smaller target, you've added all the expensive parts of a missile. Assuming you can even do it at all without slowing down to the point your kinetic energy isn't any higher than said missile, which you may not be able to. Count the propulsion stuff you need to move it into the desired orbit before "launch" and you've way exceeded the fuel or energy requirements of said missile too.
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Old 10-02-2017, 10:31 AM   #34
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Default Re: [Ultra-Tech] What would naval warfare at TL10 look like?

A single large projectile could very well be intercepted or miss but you really dont need 80 tons of TNT to kill most ships while it might be useful against naval facilities and the like. A hundred projectiles at 8 tons of TNT or a thousand at 800 kilograms should do a lot better. Intercepting such an attack should be considerably more difficult and likely very expensive.

Personally I'd say ships will only be used for transport with possibly occational submarines for mobile nuclear deterrents and possibly to hunt transports and submarines. Mostly because a single "cheap" drone aircraft can kill any ship and any equal enemy will be able to saturate any resonable point defense. Most of the actual fighting over seas will be done by aircrafts or space based military with some form of drones doing a lot of the land fighting especially outside densly populated areas.

Last edited by exalted; 10-02-2017 at 10:42 AM.
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Old 10-02-2017, 11:17 AM   #35
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Default Re: [Ultra-Tech] What would naval warfare at TL10 look like?

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I don't think everything will go full-on submarine. The physical and psychological standards for submariners are much higher than those of the surface ships, so what you gain in stealth you'd lose in overall eligible manpower. At some point someone will say "our Navy is under-manned because our standards are too high", at which point the reason those standards are in place will surface when people not suited for sub service gets assigned to one and flip out for some reason or other, which will raise some (probably very public) questions as to why the standards were lowered in the first place(!).
That is not at all the case at TL 10 even without volitional AIs. In fact, Dedicated and Non-Volitional AIs would be superior to Volitional AIs for most submarine crew related tasks since they can have higher IQ for the same Complexity.

Even without using AIs at all, you could greatly reduce the number of crew with automation.
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Old 10-02-2017, 03:49 PM   #36
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Default Re: [Ultra-Tech] What would naval warfare at TL10 look like?

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Originally Posted by johndallman View Post
Maneuverable reentry vehicles have been built and successfully tested. The technology is not like other air vehicles, but it works. The US did not adopt them in the early 1980s, but that doesn't prove that they won't be in use at TL10.
That vehicle has already finished reentry by the time it maneuvers, and does those maneuvers at a speed significantly slower than orbital velocity. In fact, it's speed is comparable to the hypersonic missiles I mentioned, but with a high, obvious flight profile. It's also essentially the same idea as the DF-21D I mentioned, which puts the same idea into an anti-ship role.

Coming in at full orbital velocity is going to be a bit more limiting on maneuverability.

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Originally Posted by Anaraxes View Post
The first point isn't true, nor follows from the second.
It doesn't follow from the second because you misquoted me by clipping off half the statement. Not cool.

You seem to be presenting this scenario as if someone is setting off a bomb nearby a stationary rod, but that's about as far from the scenario as we could get. The rod isn't stationary; it's closing at near-orbital velocity, upping the energy of the impact by roughly 4 to 10 times, depending on when the intercept occurs (The rod is going considerably slower at impact than during reentry) and the angle of impact (Likely to be head-on if we're talking about a ship defending itself). Further, this isn't just a random explosion nearby; this is a kinetic impact directly on the surface of the rod with a significant directional component. With the minimum speed for a head-on intercept, we're talking mach 20-25, close to the velocity that you get from a HEAT jet. This isn't some simple proximity detonation, and it's not distributed randomly (The LEAP is a unitary warhead, not some package of multiple smaller projectiles). It's going to be a single focused impact point leaving a sizable hole or crater on the surface of that reentry vehicle.

Get a solid head-on impact during reentry, and you stand a good chance of blowing the entire head off that rod.

Needless to say, these are things you really don't want during reentry. Hell, you don't want it when hypersonic. It very likely leaves the vehicle uncontrollable during reentry, if not tearing it apart through aerodynamic forces. If it does survive and regain control, it would have burned a great deal of energy, which, combined with impaired aerodynamics from the impact, might easily leave it unable to maneuver onto its target.

But even that isn't the end of it. If it's got terminal self-guidance (And it needs guidance to have any chance of hitting a mobile target 10+ minutes after launch), then it needs to see the target, and that means vulnerable sensors that really don't respond well to mach 20+ impacts.

So yeah, the reason I said it having a kinetic kill warhead didn't provide any benefit here is because it makes no meaningful difference in the outcome. A kinetic intercept at these velocities is devastating, even against another kinetic-kill vehicle.

And yes, you can scale up bigger and bigger until you find something that would survive just through sheer mass, but I was imagining we were talking practical tactical weapons that might be employed against ships. You're obviously not going to stop a moon, but you'll stop reasonable threats. Even the thor project is already getting a bit silly for anything other than strategic mass-bombing and hardened-target strikes against a nation without suitable air/space defense.
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Old 10-02-2017, 04:04 PM   #37
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Default Re: [Ultra-Tech] What would naval warfare at TL10 look like?

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Originally Posted by mlangsdorf View Post
Is it? In WWII, you needed 1000 lbs of HE hitting the underside of the hull to reliably kill a 2000 ton destroyer, but 3 hits from Hedgehog projectiles, at 30 lbs each, could kill a 700 ton U-boat. Water is only armor when the enemy is using saturation attacks to compensate for stealth; if the enemy can manage to get an explosive into contact, than water is a force multiplier for him Water also complicates the PD for the sub, because the sub's blue-green lasers are only effective out to 150 yards. Versus a supercavitating torpedo approaching at 100 yds/s, that only gives the sub 1.5 seconds to destroy it. It's not impossible, but it's a lot tighter than the 10+ seconds PD gets on the surface against Mach 10 missiles.
Looked up the reasons why, and you may be right. Submarine hulls need to withstand pressure, and even small dents can lead to nasty feedback loops. On the other hand, AI may solve that for you. If can you build a submarine that doesn't have atmospheric pressure humans on board, you can build much tougher subs. I don't know if that's politically feasible, but it is at least technically so.
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Old 10-02-2017, 04:43 PM   #38
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Default Re: [Ultra-Tech] What would naval warfare at TL10 look like?

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Originally Posted by exalted View Post
A single large projectile could very well be intercepted or miss but you really dont need 80 tons of TNT to kill most ships while it might be useful against naval facilities and the like. A hundred projectiles at 8 tons of TNT or a thousand at 800 kilograms should do a lot better. Intercepting such an attack should be considerably more difficult and likely very expensive.
Small hypersonic projectiles have a lot more trouble punching through the atmosphere than big ones.
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Old 10-02-2017, 05:14 PM   #39
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Default Re: [Ultra-Tech] What would naval warfare at TL10 look like?

One thought, presumably the TL 10 landscape will include more undersea habitation, mining fish farms and so forth. Floating islands could also exist depending on the setting. Navies acting in a support role for undersea infantry operations would presumably be a function.
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Old 10-03-2017, 10:30 AM   #40
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Default Re: [Ultra-Tech] What would naval warfare at TL10 look like?

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One thought, presumably the TL 10 landscape will include more undersea habitation, mining fish farms and so forth. Floating islands could also exist depending on the setting. Navies acting in a support role for undersea infantry operations would presumably be a function.
There is a lot of setting dependence in any military force. For instance a lot of TL 10 settings have an interstellar component, and the stuff you need on colony worlds where the navy's primary job is stopping the colonists (all of whom are Terran Federation citizens) from pirating each other's "exotic spice" shipments, which move by locally manufactured sailboat, is pretty different than the one you want on the post-Greenhouse Earth where everybody lives in underwater domes belonging to hostile city-states.
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