1. Do they stack?
2. Do they do more damage than corrosive?
3. Do they do more damage than no experimental effect at all?
I can honestly say i saw much difference between 2 incendaries and one corrosive and one g4 with no experimental effect.
I put two medium incendiary MC on my FDL and its cooking my ship
Before i spend a utility slot on a heatsink launcher i want to make sure its worth it, otherwise i will jsut convert one to corrosive.
There have been quite a few changes to how incendiary effects work since they were introduced and I described the changes to incendiary multicannons in detail in this post:
https://forums.frontier.co.uk/showt...s-Incendiary?p=5427275&viewfull=1#post5427275 It might be worth reading if you want to sort out how they were changed over time to what we currently have.
Despite being a projectile weapon they currently inflict thermal damage and basically function like an ammo-dependent energy weapon. They are essentially very similar to the plasma repeaters on the SLFs.
To answer your questions:
1. Yes, each effect is applied individually so you only get the incendiary effects on weapons that have been modified. The mod applies to the weapon itself, it's not a damage "buff" effect like the corrosive rounds.
2. The incendiary rounds do more damage to shields and less damage to hulls compared to corrosive multis because their damage type has changed due to the incendiary modification. However, the corrosive damage buff (which weakens the target's hull resistance) applies to all damage inflicted, meaning that it "stacks" on top of the existing thermal weapon damage from incendiaries. This means that having a single corrosive multicannon hitting the target will increase the damage output of your incendiary multis against hulls.
3. The base damage type is changed from kinetic to thermal so the main effect is that the damage is much better against shields and much lower against hulls. The incendiary modification also applies a ROF penalty of -5% so they would do less damage due to that penalty but the more important issue is the change in damage type.
It's worth noting that the major advantage of incendiary multicannons over lasers is the much better damage dropoff and maximum range compared to laser weapons. Comparing an incendiary muticannon to an efficient beam laser, the incendiary multicannon doesn't have damage dropoff until 2 km and has a maximum range of 4 km while the beam laser has damage dropoff staring at 600 m and has a maximum range of 3 km. This means that you can deliver effective damage at a much farther range with incendiaries. You can also snipe at a larger target and stay outside the effective damage range of laser turrets while still delivering effective damage with the incendiary multis. The main disadvantage of course is the need for ammunition but in terms of both alpha damage and sustained dps an incendiary multicannon will generally outperform laser weapons (at least until you run out of ammo).
Regarding your FDL, yes, it has heat issues with incendiary multis. The solutions are to either improve the powerplant thermal efficiency (with a low emissions mod), use heatsinks (which the FDL can carry plenty of due to having 6 utility slots) or timing your fire to allow the ship to cool down. In the prior engineering system it was also possible to roll a large number of incendiary mods to generate ones with reduced thermal load secondary effects which also helped substantially. My FDL currently uses all of those strategies in order to run a full set of overchanged mutlis which is great fun to use and obliterates shields but will still eventually overheat the ship with sustained fire.
