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Old 04-14-2018, 05:15 PM   #1
Michael Thayne
 
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Default [Spaceships] Missile shield vs. ramming: two questions

I'm trying to figure out how to build a space combat paradigm where large warships make logical sense, as opposed to being the result of mindless aping of naval warfare. Not that we don't want to ape naval warfare, we just want to do so in a thoughtful way. Here "large" = SM+9 at a minimum, or ideally SM+10 or higher.

The basic problem here is that cost scales with volume, while damage, armor, and HP scale with length. The main thing that large warships have going for them is that (1) they can potentially have enough DR to be immune to beam attacks from smaller ships (2) they can have beam weapons powerful enough to penetrate such armor on enemy craft. Unfortunately, this logic doesn't apply so much to kinetic attacks, because kinetic attacks can do incredible amounts of damage, especially when using the tactical combat rules where you aren't arbitrarily limited to a scale-based velocity.

The missile shield design switch from Spaceships 3 seems essential here, to stop large warships from being missile bait. But what about ramming? A couple things are unclear to me. First, if your RoF is higher than the number of ramming ships, do you get one hit per ramming ship, or one hit per point of RoF, which can be divided freely among attacking ships? I can't quite tell from the wording of the rule ("Beam weapons that are assigned to point defense may therefore automatically hit a number of incoming ballistic weapons (or ramming spacecraft) up to their maximum rate of fire.")

Second, would it be reasonable to use the "missile shield" rules not just for beams but also missiles? It seems like this could be extremely helpful, because (1) dedicated suicide drones can have very heavy frontal armor, enough to bypass point-defense guns designed for unarmored missiles and (2) by the standard rules, a point-defense gunner has a minimum 5% miss chance. Point (2) means an SM+10 warship (weighing in at 10,000 tons) can easily be destroyed by a swarm of a dozen or so SM+4 drones (10 tons each).
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Old 04-14-2018, 07:16 PM   #2
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Default Re: [Spaceships] Missile shield vs. ramming: two questions

Range.

You need a large objective to focus a beam at great distance, which in GURPS Spaceships means a powerful weapon, which requires a large ship. So build go with TL 10 or TL11 and build SM +12 warships with 100 GJ spinal UV or X-ray lasers. Fit each one out with a tertiary battery of thirty 1GJ very-rapid-fire UV lasers for RoF 3000 missile defence.

Then stand off at 100,000 miles and plink with the Big Gun. Any warhead or fire platform will cop hell while closing.
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Old 04-14-2018, 07:37 PM   #3
Michael Thayne
 
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Default Re: [Spaceships] Missile shield vs. ramming: two questions

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Originally Posted by Agemegos View Post
Range.

You need a large objective to focus a beam at great distance, which in GURPS Spaceships means a powerful weapon, which requires a large ship. So build go with TL 10 or TL11 and build SM +12 warships with 100 GJ spinal UV lasers. Fit each one out with a tertiary battery of thirty 1GJ very-rapid-fire UV lasers for RoF 3000 missile defence.

Then stand off at 100,000 miles and plink with the Big Gun. Any warhead or fire platform will cop hell while closing.
One issue here is that VRF beams have 1/100ths of the output of regular beams, so those won't be 1GJ VRF beams, they'll be 10 MJ VRF beams. So those guns won't be very useful against a well-armored drone. Devote most of your front hull to hardened nanocomposite, and it will be difficult to impossible to so much as scratch the drone.

As for the big gun, that can be overwhelmed by sheer numbers. The big gun might have a range of 50,000 miles. With TL10 or TL11 drives they can easily travel at speeds in excess of 25 MPS. At that speed, the big ship will have less than one hundred 20-second turns to destroy incoming drones. So 100+ drones will overwhelm the big gun. They'll add up to a mere 1% of the tonnage of the monster ship.

Look at the Nightgaunt dogfight drone in Spaceships 4 to see now this is done in detail. If you tone down the armament, you can give them a fifth front armor system for extra protection against the little guns.

Last edited by Michael Thayne; 04-15-2018 at 08:41 AM. Reason: Typo'd "Spaceships 8" instead of "Spaceships 4"
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Old 04-14-2018, 08:08 PM   #4
Fred Brackin
 
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Default Re: [Spaceships] Missile shield vs. ramming: two questions

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Originally Posted by Michael Thayne View Post
One issue here is that VRF beams have 1/100ths of the output of regular beams, so those won't be 1GJ VRF beams, they'll be 10 MJ VRF beams. So those guns won't be very useful against a well-armored drone.
You can use Particle Beams in the tertiary battery for that (5) armor divisor. Keep the UV Laser in the main battery for the range though.

If you're really worried about those drones add a tertiary battery of missiles too. They'll kill drones easily.

Mostly I agree with Agamemos. Range kills in normal space/hard science combat.
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Old 04-14-2018, 09:56 PM   #5
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Default Re: [Spaceships] Missile shield vs. ramming: two questions

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If you're really worried about those drones add a tertiary battery of missiles too. They'll kill drones easily.
For an SM+12 ship, even if you use the Smaller Systems rules, the missiles will still cost $1M a pop, almost as much as a Nightgaunt drone. You're better off using a fighter screen.

More importantly, though, you still have a 5% miss chance with each shot by RAW. Hence why I asked if it would be reasonable to get rid of that minimum miss chance as a house rule.
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Old 04-14-2018, 11:39 PM   #6
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Default Re: [Spaceships] Missile shield vs. ramming: two questions

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Look at the Nightgaunt dogfight drone in Spaceships 8 to see now this is done in detail.
Can you give be a page reference on that, please? Acrobat Reader text search in my copy of Spaceships 8 doesn't show up "nightgaunt", "dogfight", or "drone".

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One issue here is that VRF beams have 1/100ths of the output of regular beams, so those won't be 1GJ VRF beams, they'll be 10 MJ VRF beams.
So they will. My mistake. What about using a secondary battery of rapid-fire improved lasers? Ten weapons each RoF 20, 300 MJ? Improved lasers are penetrating (2), but AKVs probably have hardened armour. 3 d-dice × 5 should penetrate dDR 51, and damage an SM +6 AKV with five frontal systems of hardened nanocomposite. Range S/L, so you're getting effective damage out to 2,500 miles. A drone with 20 mps of delta=v is going to take at least 125 seconds to cross that, which is 6 20-second turns during which the defence gets 1,200 shots?

And if the thing that launches this salvo gets within 200,000 miles it can gloomily contemplate 100 GJ of x-rays: 2 d-dice × 50 burn* sur (5), after which the ship gets to used the big gun for 500 twenty-second turns of defensive fire against KKVs with 20 mi/sec of delta-v.
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Last edited by Agemegos; 04-15-2018 at 12:49 AM.
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Old 04-14-2018, 11:59 PM   #7
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Default Re: [Spaceships] Missile shield vs. ramming: two questions

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Can you give be a page reference on that, please? Acrobat Reader text search in my copy of Spaceships 8 doesn't show up "nightgaunt", "dogfight", or "drone".
It's on page 15...of Spaceships 4, not 8.
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Old 04-15-2018, 12:36 AM   #8
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Default Re: [Spaceships] Missile shield vs. ramming: two questions

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It's on page 15...of Spaceships 4, not 8.
Spaceships 4 is the one I didn't buy :(
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Old 04-15-2018, 12:56 AM   #9
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Default Re: [Spaceships] Missile shield vs. ramming: two questions

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Originally Posted by Michael Thayne View Post
One issue here is that VRF beams have 1/100ths of the output of regular beams, so those won't be 1GJ VRF beams, they'll be 10 MJ VRF beams. So those guns won't be very useful against a well-armored drone. Devote most of your front hull to hardened nanocomposite, and it will be difficult to impossible to so much as scratch the drone.

As for the big gun, that can be overwhelmed by sheer numbers. The big gun might have a range of 50,000 miles. With TL10 or TL11 drives they can easily travel at speeds in excess of 25 MPS. At that speed, the big ship will have less than one hundred 20-second turns to destroy incoming drones. So 100+ drones will overwhelm the big gun. They'll add up to a mere 1% of the tonnage of the monster ship.

Look at the Nightgaunt dogfight drone in Spaceships 8 to see now this is done in detail. If you tone down the armament, you can give them a fifth front armor system for extra protection against the little guns.
For the moderate-weight 'big ship' classes, RF is more suitable than VRF for anti-strike-craft duty.

VRF beams at 10 MJ are still good against (unarmored) missiles and shells, but 100 MJ is much more the thing for punching big ugly holes in small but somewhat hardened vessels. (Even there, against SM+5 or +6 with hardened armor a laser won't cut it.)
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Old 04-15-2018, 06:00 AM   #10
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Default Re: [Spaceships] Missile shield vs. ramming: two questions

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Originally Posted by Michael Thayne View Post
As for the big gun, that can be overwhelmed by sheer numbers.
You asked two questions. I'm sorry that I was not more clear about which one I was answering where.

"Why build big ships?" you asked, and listed some points about armour ratings and beam weapon damage. You didn't mention range, but it can be significant. Big ships carry big objective mirrors and can therefore focus a weapon at ranges where a smaller ship cannot effectively return fire. In GURPS Spaceships that effect makes a tactical difference up to a 100 GJ UV laser or X-ray laser, for which you need an SM +12 ship with a spinal mount or SM +15 with a major battery. That's another reason to build ships larger than SM +9.

You also asked about defending such large ships against missiles and ramming. Though holding the launching ships beyond X range with the Big Gun is a start on that, you're right that the Big Gun can be swarmed. So I suggest a point defence with high rate of fire, and the use of the "Missile Shield" setting switch. Details remain to be worked out: perhaps a weapon system split into three SM +11 systems: one SM+11 tertiary battery of thirty VRF improved lasers (improved UV lasers at TL 11) for dealing 3D damage to each of 6,000 unarmoured warheads/turn out to S/L range, one SM +11 secondary battery of 10 RF UV lasers (improved at TL 11) dealing 2D×5 (2) to each of 100 (200 at TL 11) SM +4 or smaller fighters or KKVs per turn, out to L range, and a medium battery of three RF UV or x-ray lasers doing 6D×5 (2 or 5) to each of three cheeky pests per turn that have armour on them, out to range L, and useful fire against light targets trying to close from beyond-X to L. It's not immune to everything, but any swarm of warheads or KKVs launched from beyond the range of its Big Gun is going to have to run a hell of gauntlet, especially if you keep down to limited superscience in drive performance.

If attackers build KKV with massive plugs of hardened armour on their front sections, deploy large ships in pairs, or with escorts, that can pour rapid fire at the sides of closing KKVs.
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