#What engines are best for when?

10 messages · Page 1 of 1 (latest)

manic ledge
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I don’t have very much experience in ksp1 or 2 and the furthest I’ve gotten is to the mun, I’ve landed on it like twice. I know that some engines are better for getting out of the atmosphere, and some are better for getting out of orbit, and some are better for use in the vacuum of space, but I don’t really know which is which. I do know that the description on the item gives a hint, but some look so similar to me that I don’t really see a benefit with on vs the other.

I think I’d be able to figure it out if I could see the delta V of each stage when in the VAB, but it doesn’t show until I’m on the launchpad. Any hints on what engines are best or how to get more delta V out of my rocket?

split pike
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Well, one of the ingame tutorials talks about the four classifications of engines that the game uses 🙂

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Launch/booster engines are for getting off the pad through raw power. Orbital engines are great upper stages or lander engines due to a mix of good efficiency and small profile. Sustainer engines try to straddle the gap. And deep space engines come with large bells for maximum fuel efficiency in a vacuum.

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Each engine will tell you its category in the subheader directly below the name.

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As for how to get more dV? Bring more fuel and less not-fuel. Sounds dismissive, but: it really is all about that, unironically.
Most of the time, you're not choosing your engine by comparing which one gives you the most dV for a given stage. Because then you may find that the engine you select will have the wrong size, or really anemic thrust, or is physically so long that no landing leg in the world will let you fit it between your vessel and the ground. Engines are more often than not chosen by mission requirements first, dV yield second.

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And if the mission requirements prescribe your engine, then the Isp part of the rocket equation becomes a constant, and only the mass fraction of your fuel load matters for how much dV you have. Nothing else affects it.

verbal jacinth
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TL:DR- you want good TWR during launch, and high ISP once you leave atmo

leaden plover
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isp is king. You want the most isp you can get without sacrificing something else. But everything comes with a cost.

The engines with the highest isp in vacuum either

  1. loose most/all their thrust and isp in atmo
  2. are so heavy that a lighter, less "efficient" engine is better(on smaller crafts)
  3. have so little thrust that they can't lift a lander off most surfaces(this is the ion propulsion)
leaden plover
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Many of the larger engines are for getting different payload sizes to orbit from a surface with atmo. You can ignore them for vacuum transport, landers, etc.