Engineers Best railgun modification?

[Punchdrunk]

I know that you can get -40% heat with super penetrator and feedback cascade or the fuel-use extra, but what primary engineering do you go for?
Sturdy reduces heat, does this stack with the 40% above, for super- cool rails?
Is there a better option?

I'm wondering if 4 rails on my FDL is now viable, if I use a huge Beam laser with thermal vent? I was thinking sturdy rails with super-pen and 1 feedback cascade...

 

[Cmdr Ultra]

Sturdy reduces heat, does this stack with the 40% above, for super- cool rails?

Its does stack.

 

[Nero Tacitus]

Firstly, yes; Sturdy mods stack with the -40% thermal load from the 3 experimentals, but it stacks multiplicatively, not additively, so a G5 will reduce the heat by 58%, not 70%.

4 rails can work on an FDL, I tried the setup, without the thermal mods, a while ago and while the heat was a problem, halving it would definitely make them spammable. Your distributor may have a hard time supporting all 4 with a beam on top of it though, I'd recommend coupling the rails with a huge multicannon instead, this will also allow you to pick up corrosive.

As for mods, it depends on your average engagement distance usually. Most people run Long Range mods on their rails due to their 1KM fall-off, however the FDL is incredibly fast and so can usually dictate the range at which it engages. For the FDL, I'd personally go with lightweight for the distributor reduction and to maintain the best flight performance. For RES/CZ farming however, you'll need to synthesis or return to base often as rails burn through ammo surprisingly quickly.

 

[Bob Lighthouse]

I only use long range with superpen or feedback.
Rails work great with a little distance.

Feedback has a higher firing rate than superpen due to the reload time.
So despite the dps hit off the top it tends to win out in the end.

That combo will drain your capacitor quickly and I'd say it's probably still going to get a bit hot when you fire the rails.
2 c2 + 2 c1 rails will drain a fully modded 3.0 Corvette's PD, even at 4 pips.

 

[Cmdr Ultra]

I built a 7 rail FGS and have an NPC fly it.
He never misses. I fly the fighter. The heat stacking stops him cooking the ship.

 

[Bob Lighthouse]

I'm wondering if 4 rails on my FDL is now viable, if I use a huge Beam laser with thermal vent? I was thinking sturdy rails with super-pen and 1 feedback cascade...

I just tried 4 c2 G5(3.0 max values) LR feedback rails on my G5 FDL (max 3.0 charge enhanced PD w super conduits).
With 2 pips it was overheating in two shots but it still had some capacitor.
It's probably a little better with sturdy but I'm thinking you can still find better options.
By the time you'd want to use the thermal vent, you won't have any PD left.
I've been thinking about trying the c1s tbh.