Wednesday, August 21, 2013

Spaceships/JC: Corvettes vs a Strike Carrier Example Combat

So I've decided to start posting combat examples for GURPS Spaceships using the Jovian Chronicles conversions I recently did, more or less in response to a thread on the SJ Games forums asking for turn by turn examples of GURPS Spaceship combat. I started with a bunch of small craft fighting each other and went on to small craft against an escort ship. Now I'm going to try a bunch of escort ships against a strike carrier.
I'm trying to run these examples without any house rules. I'm not doing a perfect job of that, though. One issue is that technically, a single pilot/gunner can't fire two different weapons (GSS1 p53). I don't consider it at all abusive to let the pilot/gunner use both his main weapons and his point defense weapons at the same time, with appropriate multi-tasking penalties, and I didn't notice that rule on my first read through. I'm not about to go back through these examples and add a semi-competent AI gunner, but you can do that mentally if it really bothers you.
Another issue is that multiple identical weapons in a turret mount cannot fire together (GSS1 p57). I didn't notice that rule either. Tripling the number of rolls made for turret attacks is not going to make these examples shorter or easier to read and I doubt it would affect the outcome. Again, you can do it mentally if it really bothers you.
Thanks to the eagle-eyed readers of the forum and on the comments below who pointed out my mistakes. It's a learning experience and I welcome the feedback.

Scenario: The Surprise of the Vigilant

While on routine patrol of the asteroid belt, the JAF Valiant-class strike carrier Vigilant sends most of her strike-fighters and exo-armors to deal with pirates attacking a nomad ship. The Jovian pilots easily deal with the pirates and return to their carrier, except for a pair of Lancer aces who get overexcited and spend all their delta-V reserve. The Vigilant heads after them to prevent them from traveling into interstellar space.

The Vigilant's radar then picks up three new shapes coming around an asteroid: a trio of CEGA Bricriu-class corvettes! The Briks light up their drives and angle for attack vectors while signaling the Vigilant to surrender. The Jovian exo-armors are still rearming and refueling in the hangar and won't be ready to launch for another twenty minutes, but Valiant-class strike carriers are meant to handle themselves in dangerous situations, and the Vigilant prepares to see the hostiles off.

Special Rules and Command Orders

Objectives: The CEGA corvettes want to destroy the Vigilant. The Vigilant wants to destroy the CEGA forces and needs to continue on this course in order to recover her errant strike fighters.

Retreating: The Vigilant may not attempt a Retreat maneuver until she has completed five consecutive Contolled Drifts, Hold Course, Evasive Maneuver, or Closing maneuvers, since she basically needs to get past the corvettes on this path to catch up with her strike fighters.

The Briks are trying to destroy the Vigilant, and while CEGA high command might consider trading the three of them a good deal for one strike carrier, the crews of the Briks don't. After two Briks have had more than half their medium batteries disabled or have been reduced to -0 dHP or less, all Briks can attempt to retreat.  

Opening Turn: The Vigilant is taking a very low acceleration Hold Course maneuver to catch up with strike fighters when the CEGA corvettes appear from behind an asteroid at Long range. Her PDS gunners are taking Aim and Wait (Point Defense). Her captain has just performed Space Tactics to determine what the Briks are attempting.

All of the CEGA Bricrius will act before the Vigilant. The CEGA start off in formation but do not have to maintain it.

Turn Length and Scale: All of the ships have 0.5G of acceleration, and 20 mps of delta-V, but the Vigilant has several Extreme range weapons. The best scale is Standard Scale and the best Turn Length is 3-minutes per turn.  

delta-V reserves: The Vigilant and the Briks all have 20 mps of delta-V reserves. They can spend 0.5 mps of delta-V at 0.5G to get a +1 acceleration bonus or 2 mps of delta-V at 1G to get a +2 acceleration bonus.

The rapid increase in delta-V reflects the doubled fuel consumption for high thrust operations.

Skill Levels and Crew Actions: All ships are fully staffed with professional crew, giving them Skill-14 at whatever they're trying to do. They can perform one of every type of task every turn without multi-tasking penalties, except for Gunnery Tasks, where they can perform 1 Gunnery Task for each of their weapon batteries.  

Other Notes: These are optimized Bricrius, that have swapped the Habitat and Tertiary Weapon Battery from the forward hull with the two KKC Medium Weapon Batteries in the central hull. Their KKCs have slightly worse arcs of fire, but they don't explode as soon as someone fires a missile at them from behind.

Play of the Encounter

CEGA Turn 1: The Briks are starting at long range against a weapon that can blow through their armor and hulls in a single shot and outranges their guns to boot. Closing in on Vigilant is mandatory, and hopefully at short range their KKCs and particle beams can overwhelm the Vigilant.

Bricriu 1 starts off with its captain performing defensive space tactics, resisted by the Vigilant's captain. The rolls are 13 for the Brik and 12 for the Vigilant, so there's no effect. Then the navigator plots a tactical course, rolling 10 against Navigation-14 and providing a +1 bonus to the pilot. The pilot burns 2 mps of delta-V at 1G to get a +2 acceleration bonus and attempts a closing maneuver, rolling against Pilot-14, +2 for acceleration, -1 for handling, +1 for navigation, and getting a 15 against a net 16 (MoS 1). The Vigilant's pilot contests with a 9 against Pilot-14 and a -2 for handling, and wins his roll by 3 and the contest by 2. Bricriu 1 ends up neutral to the Vigilant, at long range with the front hull facing. Should the Vigilant survive this turn of attacks, Bricriu 1 is a likely target of the spinal laser. At this range, Bricriu 1 has no weapons that will reach, and the gunners decide to Aim and Wait on the off chance that the Vigilant decides to close with them.

Bricriu 2 sees no value in hanging out at the edge of space and being demolished by long range fire, and chooses to break formation and try to pincer the Jovians instead. She will also start with defensive space tactics, resisted by the Vigilant's captain. The rolls are 10 for the Brik and 15 for the Vigilant, so Bricriu 2 will get +1 to Dodge this turn. Then the navigator plots a tactical course, rolling 11 against Navigation-14 and providing a +1 bonus to the pilot. The pilot burns 2 mps of delta-V at 1G to get a +2 acceleration bonus and attempts a closing maneuver, rolling against Pilot-14, +2 for acceleration, -1 for handling, +1 for navigation, and getting a 6 against a net 16 (MoS 10). The Vigilant's pilot contests, also with a 6, against Pilot-14 and a -2 for handling, and wins his roll by 6 but loses the contest by 4. Bricriu 2 closes to Short range, with her front hull toward the enemy.

Her gunners open up with the port particle beam battery. They roll a 10 against a base Gunnery-14, +10 for target size, -3 for sAcc, -8 for range, +5 for Rof, -2 for ECM, and succeed by 6 against a net 16. 7 particle beams hit, and the Vigilant tries to dodge with a 12 against a 7, +1 for ECM, +2 for turn length, missing by 2. The beam's AP modifier of (5) is reduced to (3) by the hardening of the Vigilant's armor, so the effective arrmor dDR is 17. d-damage for the 7 shots is 52, 63, 44, 57, 46, 62, and 62, reduced to 35, 46, 29, 40, 28, and 28 penetrating d-damage on locations 2, 6, 6, 4, 6, 4, and 4. Each hit does at least 10% of the Vigilant's 150 dHP and disables the system, so the reserve fuel for the exos in location 2 is disabled, the cargo hold in location 6 is destroyed, half the hangar bay is location 4 is destroyed, the control room is disabled (from wrap-around on the third '6'), and the forward section of the spinal gun is disabled. The Vigilant is also driven to -33 dHP and has to make 7 surge checks against its HT of 13, all of which it passes.

Then Briciu 2's gunners open up with the starboard particle beam battery. They roll an 8 against a base Gunnery-14, +10 for target size, -3 for sAcc, -8 for range, +5 for Rof, -2 for ECM, and succeed by 8 against a net 16. 9 particle beams hit, and the Vigilant tries to dodge with a 15 against a 7, +1 for ECM, +2 for turn length, missing by 2. The beam's AP modifier of (5) is reduced to (3) by the hardening of the Vigilant's armor, so the effective arrmor dDR is 17. d-damage for the 7 shots is 53, 54, 53, 54, 57, 41, 47, 58, 40 which is reduced to 36, 37, 36, 37, 40, 24, 30, 58, 40 (the last two hits are are previously destroyed armor sections) penetrating d-damage on locations 2, 3, 1, 6, 6, 4, 4, 1, 1. Each hit does at least 10% of the Vigilant's 150 dHP and disables the system, so the reserve fuel for the exos in location 2 is destroyed, the other half of the hangar bay is location 3 is disabled, the armor location at 1 is disabled, the core control room is destroyed, the armor location at 1 is destroyed, and the forward section of the spinal gun and the last half hangar are destroyed by wrap-around attacks. The Vigilant is also driven to -371 dHP and has to make 2 death checks and 9 surge checks against its HT of 13, all of which it passes.

Bricriu 2 decides not to fire the KKCs, since the Vigilant's powerful PDS suite is still available and is more than sufficient to intercept the slow-moving attacks.

Bricriu 3 will also break formation to form a pincer on what's left of the Vigilant. He will also start with defensive space tactics, resisted by the Vigilant's captain. The rolls are 11 for the Brik and 10 for the Vigilant, and no effect. Then the navigator plots a tactical course, rolling 10 against Navigation-14 and providing a +1 bonus to the pilot. The pilot burns 2 mps of delta-V at 1G to get a +2 acceleration bonus and attempts a closing maneuver, rolling against Pilot-14, +2 for acceleration, -1 for handling, +1 for navigation, and getting a 12 against a net 16 (MoS 4). The Vigilant's pilot contests, also with a 13, against Pilot-14 and a -2 for handling, and wins his roll by 1 but loses the contest by 3. Bricriu 3 closes to Short range, with her front hull toward the enemy. (Oddly, at this point Bricriu 2 and 3 are at long range to each other, even though they're only at short range to the Vigilant.)

Briciu 3's gunners open up with the starboard particle beam battery. They roll an 8 against a base Gunnery-14, +10 for target size, -3 for sAcc, -8 for range, +5 for Rof, -2 for ECM, and succeed by 8 against a net 16. 9 particle beams hit, and the Vigilant tries to dodge with a 5 against a 7, +1 for ECM, +2 for turn length, succeeding by 5 and dodging all but 2 of the beams. The beam's AP modifier of (5) is reduced to (3) by the hardening of the Vigilant's armor, so the effective arrmor dDR is 17. but the shots hit destroyed armor locations 1 and 2 and the armor stops nothing. D-damage for the 2 shots is 51 and 52, which goes straight to the dHP, reducing it to -483 dHP and requiring another death check, which succeeds with a 12.

Briciu 3's gunners then fire the port particle beam battery. They roll an 8 against a base Gunnery-14, +10 for target size, -3 for sAcc, -8 for range, +5 for Rof, -2 for ECM, and succeed by 4 against a net 16. 5 particle beams hit, and the Vigilant tries to dodge with a 5 against a 7, +1 for ECM, +2 for turn length, succeeding by 5 and dodging all.

Vigilant Turn 1: The Vigilant is a shattered hulk, with her entire forward hull smashed. She can't possibly recover her missing strike fighters without her hangar, and indeed, all her on-board exos and strike fighters were destroyed with the hangar. She could try closing on the luckless Bricriu 1 and pounding it with KKCs and missiles, but the corvette could respond with particle beam fire and destroy the Vigilant.

Results

Overwhelming CEGA Victory, as the corvettes destroyed a high value target without taking any losses.

Conclusion

I wasn't thrilled with the Valiant conversion, because it felt like it was trying to cram too many things into too small a space, but I didn't expect it to go down like that! And I'm not sure what would have helped.

Replacing one of the hangars with more armor would have drastically cut down on the available exo-armors without noticeably increasing the craft's toughness: every shot in the first p-beam blast would have penetrated the armor and most would have disabled a system. Another ECM system might have helped, but not enough.

No, I think the decision to use the Standard scale and 3 minute turns was the problem, turning the nasty but survivable RoF9 attacks from the Briks' turrets into the devastating RoF30 attacks. And the only solution is to back to Close scale and 1 minute turns, which means that the Vigilant can't properly take advantage of her giant spinal laser.

Well, I'm definitely going to revisit this fight, and see how it works out on a closer scale.

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