>>706609I get the feeling the engines don't take into account air resistance or gravity, anyway here's my findings:

Small Engines - AL Block mass is 26 tons

D30 - 49 tons (combined engine plus block it sits in)

Engine - 23 Tons

MN - 25

Fuel - 3kg/s

MN per ton - 0.51 MN

Fuel per MN/T - 5.88kg/s per MN/T (lower is better; how much fuel is consumed per unit of thrust per ton of engine)

NK25 - 56 tons

Engine - 30 tons

MN - 36

Fuel - 3kg/s

MN/T - 0.643 MN

(kg/s) / (MN/T) - 9.33 kg/s

D30S - 45 tons

Engine - 19 tons

MN - 32

Fuel - 4kg/s

MN/T - 0.711 MN

(kg/s) / (MN/T) - 5.63 kg/s

Big Engines - Block mass is 575 tons

RD59 - 875 Tons

Engine - 300 tons

MN - 90

Fuel - 7kg/s

MN/T - 0.103 MN

(kg/s) / (MN/T) - 67.96 kg/s

RD51 - 789 Tons

Engine - 215 tons

MN - 110

Fuel - 7kg/s

MN/T - 0.14

(kg/s) / (MN/T) - 50 kg/s

Most of the problem with the big engines comes from needing the fuckhuge 4-block that inexplicably masses 575(!!!) tons. If instead it massed the same as 4 aluminum blocks (104 tons):

RD59 - 404 Tons

MN/T - 0.223 MN

(kg/s) / (MN/T) - 31.39 kg/s

RD51 - 318 tons

MN/T - 0.346 MN

(kg/s) / (MN/T) - 20.23 kg/s

Which is still 2-4x worse than the small engines, but at least not 10x worse.

Basically, never EVER use the big engines.

Also NK25 is 20% more thrust per ton than D30 for 40% more fuel consumption, choose which you need - more speed or more fuel efficiency.

Math could be wrong or maybe there's a tipping point in mass where big engines are good (I don't think so) but this follows what I see in practice.