[Ultra-Tech] What does the TL10 battlefield look like

[AlexanderHowl]

I am not sure they are really that expensive compared to their utility. At 1,000 km, they are beyond the range of anything but the most specialized ground weapons, and they can be taken out by orbital missile strikes.

[Michael Thayne]

Originally Posted by AlexanderHowl

I am not sure they are really that expensive compared to their utility. At 1,000 km, they are beyond the range of anything but the most specialized ground weapons, and they can be taken out by orbital missile strikes.

When I say "ginormous long range lasers in high orbit, I'm talking about situations where they're high enough up, and have long enough range, that a single-digit number covers the vast majority of the earth 24/7. At 1,000 km, you still need a large constellation to get good coverage of the planet's surface, because the horizon still significantly limits what you can target. A weapon in an equatorial orbit will be able to hit targets roughly from 30 degrees north latitude to 30 degrees south latitude.

If, on the other hand, you want to be able to cover from 60 degrees north to 60 south from an equatorial orbit, your altitude needs to be around 4,000 miles, and your lasers range needs to be almost 7,000 miles. In the Spaceships system, this calls for a 3GJ laser, which costs $50 million dollars and weighs 450 tons. The complete platform probably costs much more than that—there's launch costs, powering the thing, and of course the cost of defenses (the platform is going to be an eggshell armed with a hammer regardless, but you don't want to be a complete sitting duck).

I'm not saying there are no circumstances in which something like that would get built, but it's a bit like building massive battleships just to provide fire support on the shore.

[AlexanderHowl]

Well, the designs that I was imagining would have sufficient delta-v for interplanetary travel (at TL10), so they could simply move to a different orbit when required. A TL10 fusion rocket would give them 60 mps of delta-v, which would be more than enough for them to change orbit a dozen times. When required, they could retreat to L4/L5 for resupply and return in a couple of days. I would personally use a small group of SM+4 AKVS for defending the platforms from attack, but that is just my preference.

[Michael Thayne]

Originally Posted by AlexanderHowl

Well, the designs that I was imagining would have sufficient delta-v for interplanetary travel (at TL10), so they could simply move to a different orbit when required. A TL10 fusion rocket would give them 60 mps of delta-v, which would be more than enough for them to change orbit a dozen times. When required, they could retreat to L4/L5 for resupply and return in a couple of days. I would personally use a small group of SM+4 AKVS for defending the platforms from attack, but that is just my preference.

Even if you can do change of plane maneuvers, I'm not aware of any way to get a weapons platform to pass over a particular point on the Earth's surface more than once a day, if that location isn't on the poles or equator. There's geosynchronous orbits, of course, but then you're looking at needing a terrajoule laser to hit at that range.

[AlexanderHowl]

Well, a SM+10 tertiary laser is 100 MJ, which possesses a maximum range of 10,000 miles (16,000 km). It is only dealing 5d(2) damage at that range, but that is sufficient to punch holes in soft targets, and it does give it the option to engage soft targets from MEO. At an orbit of 10,000 km, it could reach any target on a hemisphere, as it covers a radius of over 12,000 km. If you had a network of twelve such platforms, you could quite easily support any battle with four of them.

[Michael Thayne]

Originally Posted by AlexanderHowl

Well, a SM+10 tertiary laser is 100 MJ, which possesses a maximum range of 10,000 miles (16,000 km). It is only dealing 5d(2) damage at that range, but that is sufficient to punch holes in soft targets, and it does give it the option to engage soft targets from MEO. At an orbit of 10,000 km, it could reach any target on a hemisphere, as it covers a radius of over 12,000 km. If you had a network of twelve such platforms, you could quite easily support any battle with four of them.

10,000 miles is for UV lasers. Spaceships doesn't exclude UV lasers from being used for ground fire, but that seems like an omission—Ultra-Tech caps their range at 1 atm at 500 yards. If you go by the letter of the Spaceships rules, I agree orbital lasers become more viable. I think Ultra-Tech is more realistic though. My understanding is that near-UV isn't going to be totally useless in atmosphere, but visible wavelengths are strongly preferred, such that UV lasers being used to fire on ground targets from orbit should (at a minimum) probably have to contend with more than the 20 dDR from atmosphere that infrared lasers have to contend with.

[Michael Thayne]

Originally Posted by Fred Brackin

What tanks? The ones with DR 2100 on every facing that survived the 100mm missiles?

Even if you build such a monster you're just giving your enemy an excuse to iuse micronukes. After that escalation you need DR 42,000.

I could probably find more uses for cyborg cavalry horses. They at least could be used to breed your improved robot mules.:)

I'm going to return to his point. I think TL10 equivalents of main battle tanks probably have 1200 DR on the front, but it's electromagnetic armor so it gives 3600 DR vs. shaped charges. On the top/sides, you have 900 DR to protect against SEFOP (and the side-attack missiles which I suppose would be built if a tank designer were ever dumb enough to make side armor weaker than top armor). Fred seems to assume top attack with HEAT will be easier to pull off at TL10 than it is at TL8, but I'm not sure why. I'd be interested to hear him make that case, though.

Playing around with some of the optional rules for Spaceships from Pyramid #3/34 makes me think this is feasible—though a more rigorous approach would involve taking Vehicles 3e and tweaking the assumptions for consistency with 4e. And the result should have similar survivability in a TL10 threat environment to an M1 Abrams in 2018. Great powers might plan to use mininukes against such tanks in the event of WWIII, but as long as mininuclear proliferation is kept under control, that won't be an issue for the 22nd century version of Operation Desert Storm or whatnot.

[AlexanderHowl]

No, S/L is the range category for 100 MJ lasers, and that translates to a range of 3000/10,000 miles. As for orbital missiles attacking targets, the average damage for an orbital strike would be around 6d×35 Ddamage (5 mps), which would deal an average of 7,350 points of normal kinetic damage. A tank is nothing more than missile bait at that point.

[Michael Thayne]

Originally Posted by AlexanderHowl

No, S/L is the range category for 100 MJ lasers, and that translates to a range of 3000/10,000 miles.

This is another "huh" for me. It turns out there's a big discrepancy between beam ranges in Spaceships and Spaceships 3. The former follows a 3-10 progression for beam range, while the latter follows a 2-5-10 progression for beam range. A side-effect of this is that big beams have much shorter range under Spaceships 3. Which numbers you use look like they could be a very big deal.

As for orbital missiles attacking targets, the average damage for an orbital strike would be around 6d×35 Ddamage (5 mps), which would deal an average of 7,350 points of normal kinetic damage. A tank is nothing more than missile bait at that point.

5 mps assumes your missile isn't slowed down at all by reentry. I've heard claims that kinetic weapons fired at Earth's surface could impact at Mach 10 (~2 mps), but not higher than that. Furthermore, the Chinese are claiming Mach 10 for the DF-21, which is a surface launched ballistic missile. The real problem, though, is that hitting a tank requires a very small CEP, which may not be achievable with the sort of weapons we're talking about even at TL10.

[AlexanderHowl]

I imagine that the accuracy of missiles will be much higher at TL10 than TL8, as they would have improved computing, designs, and materials. When it come to reentry, there are more than a few methods to maximize velocity, most of which revolve around creating a dart like shape for the warhead. As it stands though, the basic rules is Spaceships are what I would use for such a scenario, which suggests some very destroyed tanks.