reactor size ?

[Booze]

playing survival star system and building a ship to leave planet. all large block and hydrogen powered. not sure about the reactor. large or multiple small reactors?

[Drahull]

I don't remember the numbers but 1 large is better than 9 smalls, ofc if you have enough room to build 1 (or multiples) large.
Why ? More efficient and you CAN'T build 9 smalls together (3x3) because of their ports.
But if you don't have the necessariy space (for example, a looonnnng flat ship), you can still go for smalls ones.

[Karmaterrorᵁᴷ]

I its hydo powered you wont need much. Id go with a few smalls. I tend to use large on ships with many ion/atmo thrusters :)

[Legas]

Small.

Large Reactor is abolutely overpowered, very heavy and able to power huge walls of ion thrusters or charging several Jump Drives.
For anything else you're hauling dead weight since you won't be using 1% of it's maximum output.

Large becomes worth it when about 20 small reactors aren't enough to power your grid.

[profitX10]

Weight is the real issue with reactors, if you have 10 small reactors, and you have a good place to put it, go 1 large you will save weight and components(But lose a lot of redundancy)... If you have 5 small reactors, and they power everything, stick with them.

[Baratheon79]

Like a few others have said/implied, it depends heavily on the the design of the rest of your ship. Like Karmaterror said, if your ship uses mainly hydrogen thrusters, you're not gonna need as much power. In that case, you're better off going with a few small reactors to save on weight (or add more hydrogen tanks for more fuel capacity).

In my game, my base ship is powered by two large reactors, but I've got a large number of ion thrusters, as well as 4 refineries, 4 arc furnaces, 4 assemblers and 2 jump drives. I've also got enough batteries to run every system on the ship for a couple of hours on battery power alone (in the unlikely case that I run out of fuel, or something happens to one or both of my reactors). But this ship is basically a mobile base, designed to carry everything I need on board. Something to just get into space would be much more basic, and wouldn't have anywhere near the same power requirements.