Yep, that's a big graph.


X axis is escape velocity (kps), Y axis is thrust (kN), labels show range of added non-propellant mass in tons, per thurster, assuming tin droplet radiators. Drives are grouped based on reactor technology they are used with. Colours denote type of reactor technology (fission is red, fusion is blue, etc.), with symbols separating drives into individual compatibility groups, see legend to the top right.

In more human terms:
Generally, the further up a drive is, the more agile it is in combat, and the further right a drive is, the further it can take you across the solar system. In addition, under under the name of each drive, you can see the possible range of extra mass added to the ship because of reactors and radiators. Note that the scales are logarithmic, so the distance between two grid lines is actually a ten-fold increase. A Firefly Torch is more than 10 000 times more fuel-efficient than the starting drives, not 4 times.

The numbers, what do they mean?:
The added non-propellant mass is based on the best and worst reactor a given drive can be combined with (in terms of mass/power output ratio) and the tin droplet radiator (125 tons / GW) -- so your added non-propellant mass per thruster will be somewhere in between the two numbers, with variation based on the radiator used.


The drives in the top right will add considerable non-propellant mass to your ship, This is highly counter-productive, as the extra radiator mass will in some cases negate most mass advantages afforded by the increased fuel efficiency. Instead of 50% ship weight in fuel, you're hauling 50% of ship weight in radiators.

Generally speaking, you should consider what weight class of ships you want to build, and aim at a drive tech tree that will yield drives with good mileage without increasing mass (and construction cost) by an order of magnitude.

For example, I may have mocked the Firefly Torch previously, but if your intended solution to the alien menace is a massive flying brick with enough armour to ram tier 3 space stations out of orbit, the radiator mass of the firefly torch will likely seem quite negligible compared to the overall mass of the ship, making Firefly the best choice for the job.

On the other hand, this chart has made me appreciate fission-based drives more, since it's hard to find any other drives that provide that much thrust without turning your patrol ship into a ball of radiators. I can see this being great for agile planetary defenders.

Other than that, antimatter drives seem to strike a very good balance, but good luck getting your hands on them anytime soon.

Also, low non-propellant mass even at lower tech levels is probably also why magnetic confinement fusion exists.

Finally, keep in mind that one important thing; this chart does not show is the number of research points required to reach a given drive, or the probability that you'll even be able to research it in a given run. You'll have to figure it out on your own, and I strongly recommend making sure you'll have a backup plan in case the game screws you out of the perfect drive you were aiming at.

That's it. Hope you found this helpful.


The data used for this graph is from CrimsonLionDC's spreadsheet of ship drives and should be valid for v.0.3.35. This means that the credit for most of the hard work and all of the typos goes to CrimsonLion. Cheers mate.

I did some basic checking to see if the calculations line up, but if you spot something wrong that isn't (1) a typo, or (2) overlapping labels on drives nobody cares about, feel free to complain.