Space Combat Mechanics Guide
by visage

Starships versus System Ships versus Orbitals

Starships are the default for ship stats. Hull size for hull size, orbitals cost 60% of the AUs and get 150% of the space, System ships cost 75% of the AUs and get 133% of the space.

Armor, Shields, and Hit Points

Things that get shot at by default have Hit Points equal to their space. For some reason, ships have space available equal to one less than their listed space; the amount of damage to distroy a hull with a listed space of 200 is 200 points, but you can only put 199 space of stuff in the hull. Fighters have HP equal to their base space, which is 66% of the space the interceptor form takes up and 33% of the space that the SCF form takes up; this is entirely dependent upon the weapon type of the fighter. Missiles have HP equal to the space a single missile takes up (without counting in the +1 per-rack surcharge; I have not tested whether armor piercing warheads have more HP, though I assume that they don't).

The number of armor points a ship, fighter, or missile has is based on its armor type and armor thickness. Armor for fighters and missile always has the same "thickness." Armor also has a deflection value, established by armor type and modified by thickness. Armor never takes up space, regardless of its thickness.

Shields have three combat-relevant stats, apart from their size and cost. Each shield technology has a stopping percentage (StpPow), a number of shield points (ShdStr), and a recharge rate (Recharge), and except for the Damper Field they all default to consuming 5% of the hull space of the ship they're on (so shielding an Orbital takes up more space than shielding a Starship). Shield generator sizes modify the shield points, the recharge rate, and the space, but don't change the stopping percentage. Missile and fighter shields have their own shield generator "size."

Note: Shields and armor for fighters and missiles don't take up space. Their cost "*= .33" seems to be interpreted as just 0.33 AUs, and is affected by chassis.

How damage is applied to a target:

1) Take a particular weapon hit (so, a volley from 2 LFG's that fire 5 times each time they fire would go through this 10 times).
2) First, apply the effects of shields.

• The shield absorbs a fraction of the damage equal to its stopping percentage.
• Subtract that fraction from the shield points remaining on the shield.
• The remainder, plus any absorbed damage that was in excess of the remaining shield points, is passed on to the next step.

• If the amount of damage remaining is less than or equal to the deflection value, the remaining damage is wasted. If shields were damaged, display a blue number equal to the number of shield points lost.
• Take a random number between 0 and 1.
• If the random number is less than the ratio of the remaining armor to max armor, the remaining damage hits the armor: subtract that many armor points. Display a yellow number equal to the amount of damage that hit armor.
• If the random number is not less than the ratio, go on to the last step.

In actuality, you only display damage per-volley, based on the furthest penetration achieved by that volley.

Note: the shield recharge rate is misrepresented in game as the number of shield points regenerated per 5 seconds; the actual rate is per second.

Note: Armor piercing doesn't (shield penetrating does).

Direct Fire Weapons

Accuracy: The change to hit at or below the minimum range (AccDisSt) for a DF weapon is the listed maximum accuracy for that weapon. The chance to hit scales down linearly to 60% of the maximum value at the maximum range (AccDisEn); beyond this range the weapon will refuse to fire. So, a weapon with an accuracy of .7, or 70%, has a 42% chance of hitting at its maximum range. Some weapons (Stellar Converter, Mauler) have their minimum range set to just under their maximum range so as to produce an effect of no dropoff in accuracy. Having an accuracy of greater than one (once accounting for range dropoff) is treated like having an accuracy of 1.

Damage Dropoff: Most DF weapons don't do their maximum damage when they hit their target. There are two elements to this.

First, there's a range-based reduction. At or under a weapon's minimum range for damage purposes (DmgDisSt), this reduction is zero; the Base Damage is equal to the weapon's maximum damage (NearDamg). The Base Damage scales down linearly from there to the minimum damage (FarDamag) over the course of twice the weapon's listed maximum range for damage purposes (DmgDisEn). Thus, the Base Damage for a weapon is its minimum damage at 2*DmgDisEn + DmgDisSt; the default weapons set always has the maximum range for accuracy and damage the same, so the actual minimum Base Damage for a weapon is close to the average of the minimum and maximum damage, shifted towards the maximum damage based on the relationship between the minimum range and the maximum range.

The actual damage done is the Base Damage reduced by a random factor. To determine the random factor, take the smaller of the Base Damage and the damage delta (DmgDelta) stat. Multiply this by a random number from between 0 and 1. Subtract the result fro the Base Damage to determine how much damage is actually dealt.

By default, the damage delta stat is equal to the difference between the maximum and minimum damage stats.

Mass-classsed weapons (Mass drivers, Rail guns, and the like), have their minimum range for damage set to be just under the maximum range for damage, so they have no dropoff due to range. Furthermore, they have their damage delta set to 0, so there is no randomized reduction.

Mounts change all of the stats mentioned above except for the damage delta stat. Thus, mounts with larger multiples on the damage stats (e.g. the Spinal series) suffer much smaller proportional reduction in damage dealt from the random factor. (Obviously, mass-classed weapons don't benefit from this effect.)

Note: The code is capable of handling cases with stat configurations that are far from the defaults. DmgDelta can be much larger than the NearDamg; FarDamag can be larger than NearDamg; AccDisEn does not have to be the same as DmgDisEn; etc. These cases all behave as described above.

Weapon Stats: Range and damage weapon stats, as well as DmgDelta, are discussed above. Other weapon stats:

• FireDlay: Seconds between weapon fires.
• Multfire: How many times the weapon fires when FireDlay has elapsed. All Multfire shots hit the same target.
• ShldPen: When hitting shields, the shield's stopping percentage is multipiled by this value; lower is better.
• ArmrPier: Has no effect.

Mods: Weapon mods are capable of altering: MultFire, the four range stats, FireDlay, the two damage stats, size, DmgDelta, and ShldPen.

IF Weapons

All default missiles have 95% accuracy at all ranges, regardless of what you change about their range stats; they always do max admage, similarly regardless of what you change about their range stats. They have ShldPen and ArmrPier stats, but I haven't tested the former and assume that the latter doesn't work (based on DF armor piercing not working).

The rate of fire displayed in the ship design screen is not the actual rate of fire, but the multiplicative modifier to the warhead's rate of fire, which are all 45 seconds by default. The number of racks you have is the number of missiles you fire in a volley; the number of missiles per rack is the total number of volleys you can fire. The space a missile rack takes up is proportional to 1 plus the number of missiles in it.

Once you have the tech for missile armor and shields, they are installed by default on all missiles in new designs, but the checkboxes aren't selected. To turn them off (not that you'd want to outside of testing game mechanics), you have to select then deselect the checkboxes.

The combat AI will happily launch missiles before having a target for them, in which case they'll circle around the launching TF until a target is detected. I believe that missile launchers will not launch a second volley until the first has at least acquired a target (perhaps even until the first volley is gone).

Fighters

As far as I know, the following fighter stats have no in-game effect: ShieldDmg, MaxShrnk, MinFactr, MinimSize, HullDMod, ArmrPier, DamagCap.

Fighters have HP equal to the base space, the amount they take up before the *=1.5 multiplier for Interceptors or the *=3.0 multiplier for SCFs is applied. The only difference between SCFs and Interceptors is that SCFs take up twice as much space and get a 40% increase in max damage and a 20% increase in min damage.

Damage calculations for fighter weapons are handled in the same fashion as for direct fire weapons. However, all fighter weapons are listed with 3000 minimum range, and almost all fighter combat happens under that distance.

The combat AI will happily launch fighters before having a target for them, in which case they'll circle around the launching TF until a target is detected.

I have noticed no difference between SCF AI and Interceptor AI. It's conceivable that Interceptors will occasionally deign to shoot at missiles and fighters while SCFs won't.

It is commonly reported in these forums that Interceptors will not participate in planetary bombardment, but SCFs will.

Modding Note: I've found the following fighter weapon stats to be not modifiable by the fighter chassis: Armor points, DmgDelta, DmgDisSt, MultFire. This makes me strongly believe that the only stats that fighter chassis can affect are the ones it alraedy does (size, damage, and cost).

ECM/ECCM/Sensors/Cloak

Sensors and ECCM multiplicatively reduce the OffTgtRg stat. ECM and Cloak multiplicatively increase the DefTgtRg stat. Cloak also increases the Cloaking stat.

None of this has any impact on weapon accuracy.

Apparently, this only affects visual detection. All my tests on the subject have been far too noisy to draw any conclusions. Da_Blade has claimed on these forums that a QS developer has told him that there should be a deterministic visual detection radius and that the randomized behavior is a bug.

Assuming Da_Blade's information is correct, this is my ex recto theory as to how this is supposed to work. If I'm correct, the shipbuilding AI's as broken on this subject as it is on every other. Every theory I've come up with that bears any resemblance to the tech stats and various descriptions is fairly broken as a game mechanic...

Warning: Completely ex recto speculation follows
a) There is a base detection radius inside which you would by default see anything. Target size may very well frob this (i.e. "leviathans are easier to see than lancers").
b) Sensors increase this radius multiplicatively.
c) When a ship is attempting to see a target, their radius for that purpose is reduced by the ECM and Cloak of that target.
d) That ship's ECCM will counteract the effects of the cloak and ECM, but will not increase the effective detection radius beyond the base detection radius.
e) If any ship on a side in combat can see a ship in a taskforce, that entire taskforce is visible to all ships on the detecting ship's side.
Warning: Completely ex recto speculation precedes

Shipbuilding AI

What the autobuild will pick for you, and thus what your AI opponents use.

Armor and Shields
Class 0: No armor, no shields. Colony and Outpost ships are Class 0.
Class 1: Minimal armor, minimal shields. The AI will take your highest tech armor and best shields and put them in the smallest mounts available (usually "very light" armor and "small" shield generators). IF, CV, Recon, and Transport are Class 1.
Class 2: Maximum armor, mediocre shields. For armor, you'll get the highest tech in the heaviest form available. For shields, you'll get your highest tech in the Standard generator. Point Defense ships are Class 2.
Class 3: Maximum armor, maximum shields. LR, SR, and Planet Destroyer ships are Class 3.

Note: "Highest Tech" above actually means "furthest down the listings in TechTables." Since the Damper Field is listed after all other shields, it will be chosen preferentially over all other shields. Changing its position in the sequence will change the preference.

ECM/ECCM/Cloak

If a ship is marked Stealth, it'll put the best cloak available on. (Presumably, "best" once again means the one furthest down the TechTables listing.)

LR, SR, and PD ships get one copy of a sensor or an ECCM. I have not noticed a pattern as to which of sensors or eccm are chosen, but the AI seems to only use the weakest one available.

Recon ships seem to get maxed out on thet highest tech of ECCM available.

Weapon and Mount choices

I've not investigated anything about the decisionmaking process of picking which Planet Destroyer weapon to mount on a Planet Destroyer ship. Each of SR, LR, and PD ship-types are listed in TaskForceRules as trying to optimize a particular characteristic (NearDamg, AccDisEn, and FireDlay, respectively). For simplicity, I'm going to talk about the decisions based on SR/LR/PD. I've not found another stat that you can plug in there that will work (including FarDamag, which is listed as what IF TF's are supposed to optimize) for DR autobuild choices.

I've not been able to determine what controls whether the autobuild AI will include mods available for a weapon when it decides to use that weapon. It seems to usually be pretty happy to add mods to a weapon if they're available, and it seems to often take those mods into account when making weapon-choice decisions. This is an area I should test more. My hypothesis is that it will strip away size-increasing mods to get smaller weapons to look at if it can't fit the full thing into the space available, but will otherwise preferentially add all mods.

Point Defense ships: For the type of the primary weapon, it picks the weapon with the smallest FireDlay (in general, every weapon except the New Orion weapons has the same FireDlay of 2.5 seconds). From any ties there, it chooses the weapon with the highest base tech level. From any ties there, it picks the weapon lowest on the TechTables list. It uses the available mount highest on the list in TechTables. Once it has stuffed as many of those in as it can, it will try to fill in the remaining space by going down its list of "best PD weapons" and finding the best one that will fit at least one weapon in.

Long-Range ships: For the type of the primary weapon, it picks the weapon with the highest AccDisEn. From any ties there, it looks like it prefers the weapon with the smallest InfoWeap number (the order weapons are listed in the weapons table). For the mount, it selects the mount furthest down the TechTables listing (since TechTables lists the PD, then Light, then Standard, then the Heavy Series, then the Spinal series, it will only pick Heavy series mounts for LR ships if there are no Spinal mounts available). It then tries to fill the rest of the space as listed in PD ships, above.

Short-Range ships For the type of the primary weapon, it picks the weapon with the largest NearDamg. I haven't been able to determine what governs choices between ties in this case. It follows the same scheme for weapon mount choice and secondary weapons as it does for LR.

Indirect-Fire ships It takes the largest warhead you've got and puts it on the chassis furthest down TechTables. It then fills in space with PD nukes. I haven't yet tested how it decides to use PD nukes; I assume the PD chassis is selected as the first listed in TechTables, nukes are probably chosen as the first warhead listed in TechTables (and if there were lower-listed warheads with smaller space, they'd presumably be used in any case where the PD nukes wouldn't fit). It builds 5-missile racks.

Carriers It selects the fighter weapon listed last in TechTables, and fills the carrier with SCFs of this type. It then fills the rest of the space with Laser Interceptors. Predictably, the SCF/interceptor choice is made by position in TechTables, and it's also the case that Lasers are chosen as padding also because of their position in TechTables.

Engine Speeds

Colony ships, Transport ships, and Outpost ships get autobuilt with 60% of their max speed. IF ships get autobuilt at 80% of max speed. Everything else gets full system engines.

PD bug

At least until the code patch is out, there's a severe problem that ships usually fail to acquire the first inbound volley of missiles and/or fighters before they hit/start firing. The best workaround that's been found is to make sure that every ship you want to have firing PD has a missile rack with missiles remaining.

Some people have claimed that loading up your PD ships with sensors and ECCM will fix this; I've found minimal improvement using this method compared to using the missile workaround.

Data Appendix - Click here

Other useful tables by visage:

Damage efficiency of weapon/mount combinations at maximum range: http://web.mit.edu/munch/www/moo3/fardammetric.html

Damage efficiency of weapon/mount combinations at 50% of maximum range: http://web.mit.edu/munch/www/moo3/middammetric.html

Percent damage done at maximum range, by weapon/mount: http://web.mit.edu/munch/www/moo3/fardropoff.html

Percent damage done at 50% maximum range, by weapon/mount: http://web.mit.edu/munch/www/moo3/middropoff.html