I sadly have no real midgame experience yet, but a 2k Fleet and only 286 MC feels a bit low unless you really know what you´re doing.

Regardless of dV, it probably wouldn´t have the biggest chances at actually fighting an alien station with lots of ships present.

By the way, do Aliens still come to LEO or just turtle up in their stations?

If all you want is some exotics to later on build the actually strong ships capable of taking out multiple stations and 50+ ship fleets with low casualties, then maybe just baiting some Aliens to come to LEO can work.

Aliens take into consideration the Fleet strength in a planetary system and (at least the Planet-Sun)-Lagrange Points aren´t considered part of the planetary system.

Which means that building a shipyard on one of those points, then sending your defense fleet to that shipyard can sometimes bait an Alien Fleet to come visit LEO.

If that happens, send your fleet back to LEO, refuel and intercept. Then it´s a question of:
-Do the Aliens accept the fight (they often do if they have more fleet power), if yes, great.
-If they don´t accept the fight, what´s a lot more important to succesfully engage is not dV, but having a high combat acceleration, 4g if possible.
-And of course, can you beat what comes or not.

There´s a lot that can go wrong with this approach:
The Aliens can land more councilors if you don´t successfully engage and destroy, or worse they destroy your fleet and if you don´t have battlestations, most likely your stations too.
So I strongly recommend saving first.

First of all, make use of transfer planner. Just set up a transfer from where you are building your fleet towards base you want to attack and see how much time your ships will take. Different people and different situations call for different definition of a "reasonable" amount of time.
I think that for asteroids/Jupiter offensive operations low-single-digit month transfer time is what you should aim for. Which translates into >10 mG cruise acceleration and around 250 dV for your ships.
The earliest drive that can give you such results on a battleship hull is Deuteron Polywell with HCF2. The problem with it is that it uses metal as a propellant. Which means that it does not make use of your water mines and is almost unupgradeable.
If you are willing to wait for He3 tier your best options are either Tokamaks (Helion Torus + T4) or Hybrids (Helion Plasmajet + HCF3). Tokamaks come a bit earlier and are actually less fuel hungry, while Hybrids are lighter and less "out of the way" in the tech tree (assuming that you want to swap to ICF in the endgame).

Also, using tankers does not make much sense when you can simply take an platform kit with you, build a base at your destination and repair/refuel ships in place.

To start off, you're going for objectives not complete alien annihilation. Things such as stopping an alien carrier, saving a station (or crippling the fleet going after it), establishing a beachhead in a planet, removing alien settlements or colonies, that kind of stuff.

Don't worry about individual battles so much but about your economy. You're not just fighting with ships but also shipyards and mines.
As it's a war -not a movie- you're going to be losing ships, maybe even stations.
You can also use the other factions, your direct competition will provide you with space assets while the 'ideologically adjacent' (resist-destroy) will hopefully draw alien aggro - and their fusion torpedoes.

Originally posted by LorDC:

Also, using tankers does not make much sense when you can simply take an platform kit with you, build a base at your destination and repair/refuel ships in place.

Best usable advice so far thanks!
Cause it's simple as. i will do so.

You going to want to expand your economy more and your fleet more.

Baiting aliens by moving fleets in and out of planetary systems is a good trick early on.

Having A fleet is not enough your going to need multiple fleets and a mining economy big enough to out produce the aliens, this means colonizing beyond the asteroid belt.

You will want to consider how to get enough volities to pay for lots of armor for bigger fleets. This usually means looking at colonizing one of the volitie rich jovian moons which means sending a colonizer and a fleet to protect your initial space station as it builds your construction modules, ship yard and battle stations for that you will need to commit at least a 4k fleet to just sit there for the long term.

Went over some basic ship designs in this other post.

https://steamcommunity.com/app/1176470/discussions/0/4407417835482261039/

As for ∆V, it varies greatly based on ship purpose, stage of game, and the drives you have.

Early game pure defensive ships don't need much more that 2-3∆V and are never intended to leave their system.

Mid game combat fleets using those fission drives only need enough to get to Jupiter or the asteroids, which is like 40 or so. Anything more is overkill for inner-system travel but nowhere near enough for outer-system traversal. Or you use the very slow drives but can get large ∆V values for colony ships. You basically have to trade off between range versus combat fighting.

By the time you get to the late game drives is when you can sort of "do it all" while reaching to the outer Solar system.