Non-Nuclear Interplanetary

[DunaRocketeer]

It's all ions for me!

[Rusty6899]

I normally try to pick the right engine for the mission. If you're going to Jool or Moho, you'll probably be wanting nukes, as it would take a lot of fuel to give a normal liquid fuel engine enough delta-V.

The solitary stage might be cheaper for liquid fuel engines, but the mass of all that extra fuel would be expensive to get into orbit.

[MalfunctionM1Ke]

I know for a fact that you can reach Duna and Eve pretty easily without an LV-N. But anything beyond thats becomes more and more a pain

Good luck with the Ion-Engine then, just kidding

But If you want to turn this thread on its head and you want to go full-scale-Nuclear, check out this Mod. But I dont know if it still works

http://forum.kerbalspaceprogram.com/threads/28428-Orion-aka-Ol-Boom-boom

[Red Iron Crown]

Nukes for me if I can get a TWR of 0.5 or more without a ridiculous number of them, Poodles or KR-2Ls otherwise. Ions are too low thrust for my tastes, I only use them for specialized applications.

[radonek]

If nuke cant save you more then about 2t of fuel, you are better off with LV-909, because it is that much lighter. Otherwise (read: anything interplanetary too big for xenon) LV-N is better choice.

[lazarus1024]

I abuse NERVAs like no-one's business. I really shouldn't, but I do. Generally anything over around 25t (ship mass, not payload mass) and I tend to reach for a NERVA(s).

Then again, a lot of times once I start getting in to that mass range, I am often buidling or using a re-usable tug. My common designs are a pair of NERVAs on the end of a 1.5m jumbo tank, with a bi-coupler to a docking port. For bigger loads I'll go with a quad adapter with NERVAs and fuel tanks. Then if I need more fuel for a mission, I'll launch up a fuel section to go between the drive and payload sections and jettison fuel tanks as I go. To counter act the ridiculous burn times, if I have the ability, on the end of the ship, attached to the payload section, I'll often have a Skipper with a large 2.5m fuel tank and whatever fuel is left after everything has been assembled and topped off. I'll burn that till it is empty, flip the ship around and then burn with the NERVAs.

Ideally at some future point, it would be nice to see KSP have a couple of options, a "vaccum only" chemical engine that has terrible atmospheric ISP, but awesome vaccum ISP (like 240-260s sea level and 430s space) with a thrust in the 75-120 range and maybe 1-1.5t. Then an "electrical" drive engine, like a VASMIR that is pretty light, like 1-2t and either 1.5m or 2.5m and can produce 30-75 thrust, but uses a prodigous amount of power. To go with, the option of a fairly heavy (maybe 4-8t), but huge electrical output (100 units a second?) nuclear power plant that can feed the drive at full output. Or you can do lots of RTGs, or big solar panels, or lots and lots of batteries or some combination if you want. Also stick some of that stuff even higher up the tech tree so that they are ultimate "end game" engines.

Edited December 17, 2014 by lazarus1024

[Hodo]

On all of my SSTOs I tend to use one of three engines for space.

SABRE-S/M Or Rapier (same engine different sizes to me), but those craft very rarely leave Kerbins orbit.

LV-1N or its larger brother from the KSPX mod that is 2.5m and weighs in at 6tons and creates 150kn of thrust, those are for all of my interplanetary SSTOs.

And then the Aerospike for anything that is interplanetary but within the 3km/s d/V.

[sedativechunk]

I built a vessel capable of doing the entire "Jool 5" challenge, although I haven't done a formal submission of this I did complete the entire quest. My ship is capable of about 25,000 m/s and it uses 16 nuclear rocket engines. If you are doing deep, interplanetary missions, the best route is to use nuclear engines. Other engines just aren't quite as efficient I have found. Maybe for Duna or shorter trips other engines work nice, but for the bigger voyages where you need to preserve fuel you want those vacuum efficient nuclear engines.

As an orbit breaking engine, however, I use four skipper engines on big ugly orange tanks. They are a hassle to get into orbit attached to a ship, but for efficiency and power they do very well for breaking the orbit of Kerbin. I mostly use the nuclear engines for orbital insertion and maneuvering to my destinations. This dramatically cuts the time it takes to leave orbit.

The close contender IMO is the aerospike. I prefer it on landers because of it's fuel efficiency. All in all, i don't really use the LVT-45 too much. It's awkward length makes its difficult to incorporate on a lander and it's efficiency isn't quiet as good as a nuke engine.

[Guest]

Use skippers, they're fun.

[moogoob]

For most purposes, the 48-7S is actually the most efficient chemical engine. The Vacuum Isp isn't exactly stellar, but their low weight and high TWR more than makes up for it. Of course, the LV-909 should also suffice if you want to avoid absurd parts counts.

Truth. My biggest fail ever: Trying to put a satellite into LKO with a 48-7S-powered upper stage. Ran out of power on the circularization burn (sun was directly behind me, and I failed to bring any batteries at all) and the engine just kept firing. My final apoapsis was somewhere around Dres.

EDIT: Thinking about it a bit, I think it has something to do with mass ratios - nukes do bigger on larger vessels where the ratio of engine to other stuff is still rather low versus a small craft where the engine is a massive portion of the rocket by mass. That said my standard SpaceM Interstellotron is just a probe core, solar panels, one striped size 2 tank and a nuke pushing a small (8 ton at most) payload, and I've tried all sorts of engines and have to say that even with the weight of the nuke it still gets the best delta-v by 25% at least.

Edited December 19, 2014 by moogoob
adding stuff