Ion drives?

[magnemoe]

Done more testing with ion engines, they have an sweat spot for around 1 ton probes, large solar panel, 2-3 xenon tanks probe, control an medium battery, isa and kertane mapper.

This give 4-6Km/s dV. Next step down is ant engine and oscar tanks but it would give you less than 1000 m/s and is only good for adjusting orbit.

Going up in size you TWR drops from 0.2 who is livable and fast downward against 0.1 and below. So if you want to bring an lander or more gear you will fast be better off with an LV-N and a 4-6 ton craft.

As solar panels and engines is most of your weight, adding more will not improve things much.

[Tw1]

Ion engines are very high tech, and thus expensive.

The LV-N is not exactly cheap either, at 1700. Twice most of the other engines.

Edited April 28, 2013 by Tw1

[ruiluth]

Ion engines aren't the expensive part, they're just electromagnets. The expensive part is the xenon, which is extremely rare (on earth at least). They're not real high tech either; the Soviets were using ion drives on their satellites in the 70s. The cost of nuclear engines is a moot point because the KSP nuclear engines don't work like real ones at all; real nuclear engines don't burn liquid fuel or oxidizer, they just shoot mass out like an ion drive.

[Mihara]

My particular problem with ion drives as implemented is the fact that they consume so much electric charge. I don't really have the play time to manually perform numerous small maneuvers, but as long as I can sic MechJeb on executing a planned one-hour maneuver and turn on physical time warp, it's ok.

The problem is that I haven't been able to figure out the amount of batteries and solar panels which would allow such a probe to actually complete such a maneuver -- either they run out of juice halfway through it or the build mass snowballs until it loses it's delta v advantage over LV-N. Which renders ion-only probes pretty much unusable in practice despite how tempting they are.

[LordOrio]

They are slow becase they are slow in real life to.

All engines in ksp are same speed like real life so there are your answer to your qesten

[DMagic]

Another part of the problem with energy usage is that the in-game description is wrong. It says they use 12 energy / sec, when they really use about 14.5.

It can also be difficult to estimate how much energy your panels will produce in a non-ideal orientation and at different distances from the sun. At Jool they produce half the energy they do around Kerbin, but at Duna it's only decreased to something like 0.9 times the normal energy. Around Moho they produce something like 3 or 4 times as much energy.

I never worry much about batteries though. Just put 1 or 2 and let the solar panels take care of the energy. Ion engines consume so much energy that you would have to add a huge amount of mass in battereis to complete a large burn in the shadow of a planet. So you just have to be careful about timing.

[KerbMav]

Almost a pity, that the only system in the game (as of now) that makes real use of the energy part of the simulation is not really that useful.

OK, only yesterday I had to quickload a probemission because I forgot to extend at least one of its solar panels - wondering why I couldnt even switch off SAS ...

[Mihara]

Another part of the problem with energy usage is that the in-game description is wrong. It says they use 12 energy / sec, when they really use about 14.5.

It's not that it's wrong, it's that it's misleading. It's 12 energy per the given quantity of xenon used rather than second. The actual consumption depends on current specific impulse and throttle level instead.

[Themohawkninja]

I just used an ion drive pointed straight up to give me traction for a rover on Gilly. There's a fun, and innovative purpose!