Steve Jackson Games Forums - View Single Post - Building a Fun Spacecraft Combat Paradigm

kreios · 09-07-2016, 10:39 AM

Kinetic Weaponry
Kinetic weapons have a comparatively low accuracy. However, they do not suffer from range modifiers. All in all, their to-hit-modifiers are relative velocity, target SM and sAcc (-8 to -6). A choice of rapid fire and proximity detonation can enhance this.
Since gun salvoes are unguided, they can only hit when fairly close to the target: At 0.5G, each 10-mile hex difference a spacecraft wants to achieve takes ten 20-second turns. Accordingly, a salvo has ten 20-second turns until it is being avoided. From rest, this gives the projectile a range of 20 ten-mile hexes or 200 miles. This is increased linearly by the velocity of the launching spacecraft: If it moves at 20mps, effective range will be 2,200 miles. Still short-ranged, but not completely so.
There is another way to use kinetic weaponry in combat: Use it to produce zones where the enemy does not dare to move out of fear to be hit by a salvo. This is more effective with guns than with missiles, since guns have ten times the shots of a missile salvo. By firing a total of ten salvoes, you're restricting your enemy from every vector they pass through; by doing so you can effectively multiply their required vector change by five. This also increases your effective range by five (more can be achieved with good shot placement against bigger craft that are less manoeuvrable). Note that this is much more effective in Gurps Spaceships since space is assumed to be two-dimensional; in three dimensions, your ten salvoes would only triple the effective range.
Once in the same hex, the gun salvo still has to hit. If we go with the scenario above and a 12cm fixed EM gun (major battery on an SM+6 craft), the relevant modifiers are +10 (SM) -7 (sAcc) -9 (relative velocity) +2 (fixed) for a total modifier of -4. Using the skill-12 gunner, only 25 percent of the shots will hit. That's why proximity detonation is so useful, bringing this up to 75%.
An alternative is to use rapid fire weapons. The same craft can mount a 3cm VRF gun, for an RoF of 100. This decreases damage from 6dx3 to 4d, but provides a +7 bonus meaning that proximity detonation is no longer necessary.

Damage is similar to missiles: A heavily-armoured SM+10 craft with a dDR of 150 and dHP of 150 requires a launch velocity for the 12cm gun of 23mps to ensure destruction, and 6mps to make it probable. That's with proximity detonation, so multiple hits are probable and will ensure destruction even earlier. For the 3cm rapid-fire weapon, it's 113mps to ensure destruction, and 32mps to make it probable. Compared to the 12cm gun, this weapon will hit an additional three times, reducing the effective velocity needed to 46 and 14mps respectively.
Using armour-as-dice, the 3cm-gun at 14mps will do 56d damage, minus the 45d dDR makes penetrating damage of 11d, for 11 to 66 (38.5mean) damage per shot. This means an average four-shot hit is sufficient to reduce the spacecraft to 0HP.

The VRF guns also have the advantage of making interception by point defense basically impossible due to volume of fire; other guns can have their shells intercepted.

Beam Weapons
Available beam weapons are Laser (both normal and UV) and Particle Beams.

Lasers and UV lasers are (2) armour-piercing, and have a longer range, while the Particle Beam is (5) and has shorter range and less accuracy.
An exemplary major battery on an SM+10 spacecraft mounts a 3GJ beam weapon. An UV laser does 3dx10 (2) dDmg with a range of 7,000/20,000 miles. A particle beam does the same damage except for the (5) armour piercing, at a range of 1,500/5,000 miles.
The UV laser can penetrates 60/210/360 dDR (min/mean/max); the particle beam 150/525/900 dDR. They penetrate 30/105/180 and 90/315/540 respectively hardened dDR. Even at its half-damage range, the particle beam penetrates more armour than the UV laser. Looking at the armour, an SM+10 design can be assumed to have a dDR of 150-200 at its front hull; an example would be the Riguang SDV (SS8:31). Against these, the UV laser has only a 5% chance to penetrate; a particle beam 95%! On average, the latter is doing 55dDmg, meaning three hits are sufficient to reduce the Riguang to 0xHP. That sounds good.
Using armour-as-dice, the 3GJ UV laser can penetrate up to 60d armour (30d hardened), the particle beam 150d (90d hardened). The former is two hardened armour systems on an SM+10 spacecraft, the latter six. As in the example above, spacecraft will be able to withstand UV lasers, but not particle beams. Against the Riguang, the 3GJ particle beam will do 15d penetrating damage, for 15-90 (mean 52.5) damage. An average of three shots are required to reduce it to 0HP. At the particle beam's 1/2d range, hit chance is 12 + 2(fixed) -7 (range) + 10 (SM) -3 (sAcc) = 14, for a hit chance of 90%. At the 1/2dmg-range, damage is only 1d-3 (since armour and damage cancel out). Hit chance is reduced to skill-11, or 62%.
The Riguang does not mount a 3GJ particle beam, but a 300MJ RF one. This decreases damage to 3dx5(5), and range to 700/2,000 miles. This reduces penetration against hardened targets to 45/158/270. However, the Rcl of 1 makes multiple hits very likely; this may be worth it. With armour-as-dice, and against itself, it never does more than 1d-3 penetrating damage, making it not worth it.

Summary: UV lasers are useful due to range, but a military craft of your size is going to be pretty much immune to it. Some space forces may choose to distribute their craft allowing you to fire on the flanks and rear of the enemy (which will not be armoured as much; you have to put your stuff somewhere!) and use the superior range of UV lasers; the other alternative is mutual annihilation with particle beams.

AKVs
Using Transhuman Space as an orientation, an AKV (i.e. a possibly kamikaze spacecraft, armed mainly with kinetic weaponry) might be useful. Assuming said AKV is SM+6 (30dHP), with five nanocomposite armour systems in the front hull (total dDR 50) plus one 3cm VRF EM gun (4d). Our target is a three-armour-systems (150dDR) SM+10 (150dHP) spacecraft.
As seen above, if the enemy spacecraft is armed with an UV laser, it should be able to kill the AKV in two or three hits at 7,000 miles, and several more shots out to 20,000 miles. A particle beam is overkill; it should destroy every AKV in just one hit yet its range is too low to be really effective.
This suggests the AKV has to attack from 20,000 miles, for which it requires a velocity of 40mps and firing a spread of ten salvoes. It is a suicidal attack, of course; yet trading one, or ten, 100t AKVs against one 10,000t enemy spacecraft should be worth it.

Summary
All in all, there are three weapons available to the enterprising spacecraft: Missiles are hard-hitting when they hit, but are intercepted in numbers too great to make sense; the alternative x-ray warheads are intercepted less often (but still in quite some numbers), but require a few warheads to cripple most craft. Kinetic weaponry is devastating yet can be intercepted; RF/VRF weapons should therefore be chosen which do less damage, but do so more consistently. For beam weapons, the choice against combat spacecraft is probably the particle beam, which has the shortest range but is ignoring most armour. AKVs carrying kinetic weaponry are good against softer targets, but die easily against specialized combat spacecraft.
Spacecraft will aim to be armoured against UV lasers (and take care to only present their front to the enemy), which leaves particle beams as the weapon of choice. Engagement ranges are up to 5,000 miles.

09-07-2016, 10:39 AM	#3
kreios Join Date: Jul 2013	Re: Building a Fun Spacecraft Combat Paradigm Kinetic Weaponry Kinetic weapons have a comparatively low accuracy. However, they do not suffer from range modifiers. All in all, their to-hit-modifiers are relative velocity, target SM and sAcc (-8 to -6). A choice of rapid fire and proximity detonation can enhance this. Since gun salvoes are unguided, they can only hit when fairly close to the target: At 0.5G, each 10-mile hex difference a spacecraft wants to achieve takes ten 20-second turns. Accordingly, a salvo has ten 20-second turns until it is being avoided. From rest, this gives the projectile a range of 20 ten-mile hexes or 200 miles. This is increased linearly by the velocity of the launching spacecraft: If it moves at 20mps, effective range will be 2,200 miles. Still short-ranged, but not completely so. There is another way to use kinetic weaponry in combat: Use it to produce zones where the enemy does not dare to move out of fear to be hit by a salvo. This is more effective with guns than with missiles, since guns have ten times the shots of a missile salvo. By firing a total of ten salvoes, you're restricting your enemy from every vector they pass through; by doing so you can effectively multiply their required vector change by five. This also increases your effective range by five (more can be achieved with good shot placement against bigger craft that are less manoeuvrable). Note that this is much more effective in Gurps Spaceships since space is assumed to be two-dimensional; in three dimensions, your ten salvoes would only triple the effective range. Once in the same hex, the gun salvo still has to hit. If we go with the scenario above and a 12cm fixed EM gun (major battery on an SM+6 craft), the relevant modifiers are +10 (SM) -7 (sAcc) -9 (relative velocity) +2 (fixed) for a total modifier of -4. Using the skill-12 gunner, only 25 percent of the shots will hit. That's why proximity detonation is so useful, bringing this up to 75%. An alternative is to use rapid fire weapons. The same craft can mount a 3cm VRF gun, for an RoF of 100. This decreases damage from 6dx3 to 4d, but provides a +7 bonus meaning that proximity detonation is no longer necessary. Damage is similar to missiles: A heavily-armoured SM+10 craft with a dDR of 150 and dHP of 150 requires a launch velocity for the 12cm gun of 23mps to ensure destruction, and 6mps to make it probable. That's with proximity detonation, so multiple hits are probable and will ensure destruction even earlier. For the 3cm rapid-fire weapon, it's 113mps to ensure destruction, and 32mps to make it probable. Compared to the 12cm gun, this weapon will hit an additional three times, reducing the effective velocity needed to 46 and 14mps respectively. Using armour-as-dice, the 3cm-gun at 14mps will do 56d damage, minus the 45d dDR makes penetrating damage of 11d, for 11 to 66 (38.5mean) damage per shot. This means an average four-shot hit is sufficient to reduce the spacecraft to 0HP. The VRF guns also have the advantage of making interception by point defense basically impossible due to volume of fire; other guns can have their shells intercepted. Beam Weapons Available beam weapons are Laser (both normal and UV) and Particle Beams. Lasers and UV lasers are (2) armour-piercing, and have a longer range, while the Particle Beam is (5) and has shorter range and less accuracy. An exemplary major battery on an SM+10 spacecraft mounts a 3GJ beam weapon. An UV laser does 3dx10 (2) dDmg with a range of 7,000/20,000 miles. A particle beam does the same damage except for the (5) armour piercing, at a range of 1,500/5,000 miles. The UV laser can penetrates 60/210/360 dDR (min/mean/max); the particle beam 150/525/900 dDR. They penetrate 30/105/180 and 90/315/540 respectively hardened dDR. Even at its half-damage range, the particle beam penetrates more armour than the UV laser. Looking at the armour, an SM+10 design can be assumed to have a dDR of 150-200 at its front hull; an example would be the Riguang SDV (SS8:31). Against these, the UV laser has only a 5% chance to penetrate; a particle beam 95%! On average, the latter is doing 55dDmg, meaning three hits are sufficient to reduce the Riguang to 0xHP. That sounds good. Using armour-as-dice, the 3GJ UV laser can penetrate up to 60d armour (30d hardened), the particle beam 150d (90d hardened). The former is two hardened armour systems on an SM+10 spacecraft, the latter six. As in the example above, spacecraft will be able to withstand UV lasers, but not particle beams. Against the Riguang, the 3GJ particle beam will do 15d penetrating damage, for 15-90 (mean 52.5) damage. An average of three shots are required to reduce it to 0HP. At the particle beam's 1/2d range, hit chance is 12 + 2(fixed) -7 (range) + 10 (SM) -3 (sAcc) = 14, for a hit chance of 90%. At the 1/2dmg-range, damage is only 1d-3 (since armour and damage cancel out). Hit chance is reduced to skill-11, or 62%. The Riguang does not mount a 3GJ particle beam, but a 300MJ RF one. This decreases damage to 3dx5(5), and range to 700/2,000 miles. This reduces penetration against hardened targets to 45/158/270. However, the Rcl of 1 makes multiple hits very likely; this may be worth it. With armour-as-dice, and against itself, it never does more than 1d-3 penetrating damage, making it not worth it. Summary: UV lasers are useful due to range, but a military craft of your size is going to be pretty much immune to it. Some space forces may choose to distribute their craft allowing you to fire on the flanks and rear of the enemy (which will not be armoured as much; you have to put your stuff somewhere!) and use the superior range of UV lasers; the other alternative is mutual annihilation with particle beams. AKVs Using Transhuman Space as an orientation, an AKV (i.e. a possibly kamikaze spacecraft, armed mainly with kinetic weaponry) might be useful. Assuming said AKV is SM+6 (30dHP), with five nanocomposite armour systems in the front hull (total dDR 50) plus one 3cm VRF EM gun (4d). Our target is a three-armour-systems (150dDR) SM+10 (150dHP) spacecraft. As seen above, if the enemy spacecraft is armed with an UV laser, it should be able to kill the AKV in two or three hits at 7,000 miles, and several more shots out to 20,000 miles. A particle beam is overkill; it should destroy every AKV in just one hit yet its range is too low to be really effective. This suggests the AKV has to attack from 20,000 miles, for which it requires a velocity of 40mps and firing a spread of ten salvoes. It is a suicidal attack, of course; yet trading one, or ten, 100t AKVs against one 10,000t enemy spacecraft should be worth it. Summary All in all, there are three weapons available to the enterprising spacecraft: Missiles are hard-hitting when they hit, but are intercepted in numbers too great to make sense; the alternative x-ray warheads are intercepted less often (but still in quite some numbers), but require a few warheads to cripple most craft. Kinetic weaponry is devastating yet can be intercepted; RF/VRF weapons should therefore be chosen which do less damage, but do so more consistently. For beam weapons, the choice against combat spacecraft is probably the particle beam, which has the shortest range but is ignoring most armour. AKVs carrying kinetic weaponry are good against softer targets, but die easily against specialized combat spacecraft. Spacecraft will aim to be armoured against UV lasers (and take care to only present their front to the enemy), which leaves particle beams as the weapon of choice. Engagement ranges are up to 5,000 miles.