Any sense in using Ion engines?

[ROXunreal]

I've read that Ion engines only make sense in very small probes, if even there. Are there any other applications for them? Is there a benefit to sticking a lot of them to a bigger (not BIG) ship? What are the approx burn times required for say, an Eve or Duna transfer?

[jman508]

well what some people have done with ion probes are do flybys of every planet.

but yeah unless you like 10 day transfer burns don't use ions on anything larger than something the size of a mainsail engine.

[Thomas988]

I use ion engines so little I even forget they're in the game. Whenever I try to use them I end up adding more mass to the spacecraft from solar panels than the rest of the craft. The only practicality I see with the ion engines is for really, really, really, small probes or rovers, given that the pilot has the patience of a rock.

[jman508]

what i would LOVE to see implemented

YES SQUAD LOOK AT ME I NEED YOUR IMMEDIATE ATTENTION

are engines with an isp of 500 because its either something under 340 iso or about 800 and its annoying.

because with somewhat with more thrust than the nuclear engine but less isp would make spaceplanes a bit easier.

there really isn't any middle grounds when it comes to effeciency.

[FlyingPete]

I have a 1-man plane on Eve that's powered by six ion engines. There's no oxygen so jets are out, but these work really well as an alternative. They're useful on SSTOs as well as long as you can get suborbital while within the atmosphere- then all that's needed is a slight nudge to push the periapsis out of the atmosphere.

[Skorpychan]

Not that I've found. I've tried attaching a bunch of ion-propelled probes to a mothership, but they just take ages to get anywhere. And the mothership always has tons of DeltaV left with a nuclear engine.

Maybe for tiny-launch satellite contracts, but they're so damned expensive THAT isn't worthwhile.

[Reactordrone]

They're great for the inner solar system. The increased power from the solar panels lets you burn the engines continuously with fairly small battery banks but they are really only meant to be a satellite/probe engine.

[cantab]

The main problem with using ion engines on larger ships is the lack of larger xenon tanks. A cluster of engines isn't too bad, but if you need three or four tanks per engine the part count goes way up. Numerous mods have larger xenon tanks though; MRS includes a couple though they still aren't mega-big, while Near Future has some huge tanks along with a range of mod ion engines, solar arrays, and nuclear reactors.

Also keep in mind that for ships large enough to justify a nuclear engine, you would need to be specifying a lot of delta-V for ions to be worthwhile instead.

[Fearless Son]

I can think of a couple of applications:

* Probes that you park in orbit but intend to move to different orbits around the same body later. They do not need to go far so the low thrust is not an issue, and the endurance will really help. This is especially true of small "parasite" probes that you mount on larger spacecraft and deposit at other planets (like a trip to Jool with a few different probes to leave by its moons.)

* Extremely light landers (three tons or less) you might put on low-gravity and atmosphere-free bodies, like Minmus, Pol, Gilly, or maybe Ike. The extra endurance you get from the ion engines is useful here because you can go hopping about the surface from one biome to another to take samples. You might be able to fit some of the smaller scientific instruments on it too, like seismic and temperature scanners.

* Low-velocity, high-lift spaceplanes on planets with no-oxygen atmospheres. Eve is a good example of this, since the thick atmosphere means you get great lift, but jet engines will flame out and rocket engines chew through fuel and overheat quickly there.

* Self-imposed challenge.

[tsotha]

I can't even figure out how to use them in probes. I can always come up with a design that performs better using a 48-7S. By the time you add on multiple relatively heavy Xenon tanks and solar cells, the promise of crazy amounts of dV slips away.

They say you can make ion spaceplanes that can actually get to orbit from EVE, which is something. I've never tried it.

[Laie]

I've read that Ion engines only make sense in very small probes, if even there. Are there any other applications for them? Is there a benefit to sticking a lot of them to a bigger (not BIG) ship? What are the approx burn times required for say, an Eve or Duna transfer?

The downsides of using ion propulsion on heavier vessels: a) part count, xenon fuel is incredibly expensive.

That's good reasons not to use them, but not exactly chiseled in stone. There may be circumstances where you absolutely want a lightweight vessel, with utter disregard for cost and part count. In that case, ions are there for you. Burn times to Duna or Eve? Seven minutes are doable, 15-20 minutes more likely. The good news is that you can usually run them at 4x physics warp.

[Streetwind]

In stock KSP, ion drives are somewhat outclassed by higher-thrust engines simply because the thing they do really well (stupidly high dV) is not in great demand. The stock Kerbal solar system is so small, you don't even need a LV-N to get around.

Playing with larger configs (3.2x, 6.4x or full scale Real Solar System), you'll quickly notice that a.) you're going to need way more rocket to get out of Kerbin's gravity well, so you have less rocket left to go interplanetary with; and b.) going interplanetary costs more as well; and c.) going interplanetary takes a lot longer, unless you invest even more dV to shorten the transfer.

Suddenly, high dV engines become very interesting options, even if the TWR is somewhat small. (Though it is still extremely high... compared to a real NSTAR ion thruster, the stock PB-ION generates over 22,000 times more thrust!)

[rynak]

I use ion's a lot, but not the stock ones. Stock ions are an example of "so realistic that it's useless".

So yeah, i guess the answer to the question is "No".

[Spheniscine]

I've used them for contracts to put satellites in low solar orbit ; the combination of high ∆v requirement and extremely efficient solar panels make ion engines an obvious choice.

Other than that though, I'm always paranoid of having to do maneuvers during eclipses, and you need 12 RTGs to constantly power an ion engine, which is too heavy to be practical. I suppose batteries would work, but I don't know how many I'd need.

Edited January 23, 2015 by Spheniscine

[Heagar]

I had build once - for test purposes - an spaceplane consiting of one jet fuel tank, an advanced jet engine, two intakes, four xenon containers and two ion-engines. I found it funny, that this little thingy was able to go to mun, minmus and return to kerbin in one launch.

So, for small systems an ion engine is a good choice in my opinion. For example:

• if you want to do a "grand tour" (visiting every (outer) planet in one mission) assisted by slingshots around the planets an then go interstellar like voager
  
• if you use any life-support mod, you can use a ion powered unmanned spacecraft to deliver the goods for a spacestation/base and return to kerbin.
  
• 
  

[juanml82]

I had a light utility rover/lander craft with two ion engines to use at Minmus. It was fun to use.

But other than that... they don't really have much use. You could make a single stage to Laythe spaceplane, for instance, but the incredibly long burn times will make that boring, as it can take hours to complete the burn.

I think ions require a change in gameplay so they can be used when the ship is on rails (ie, not in focus) and a different system than maneuver nodes is also implemented for them. That way, you can create a maneuver or some sort which will make the ion engines burn for in game months at a time (as in real life ion engines), making your spaceship in LKO move to its destination while you aren't commanding it.

Of course, that can make them THE interplanetary engine for anything that's not too heavy or, maybe nerfing solar panels output, going beyond Dres. Probably as in real life.

[Commander Jebidiah]

I use ion's a lot, but not the stock ones. Stock ions are an example of "so realistic that it's useless".

So yeah, i guess the answer to the question is "No".

Your wrong about ions being so realistic.

The ions in ksp are extremely unrealistic, a real ion engine has a about 1000x less thrust than in game and can take weeks of continuous running to complete a meuneuver.

[tsotha]

Yeah. Realistic ion engines would be impossible to use in the game unless you could accelerate on to prograde on rails. They you could set an alarm in KAC and either warp until the burn is done or do something else in the meantime.

[GoSlash27]

I can't even figure out how to use them in probes. I can always come up with a design that performs better using a 48-7S. By the time you add on multiple relatively heavy Xenon tanks and solar cells, the promise of crazy amounts of dV slips away.

Remember that solar panels and batteries are massless if you do it right.

They say you can make ion spaceplanes that can actually get to orbit from EVE, which is something. I've never tried it.

We've tried to do that, but so far no success (all stock). I've had good success using ions to do all sorts of crazy stuff, but that doesn't necessarily make ions the "best" option for a job.

Ions are ideal for smallish missions that require insane amounts of DV. Anywhere you can use another engine, you probably should.

Best,

-Slashy

[Kesa]

I use ion's a lot, but not the stock ones. Stock ions are an example of "so realistic that it's useless".

So yeah, i guess the answer to the question is "No".

I've used them for contracts to put satellites in low solar orbit ; the combination of high ∆v requirement and extremely efficient solar panels make ion engines an obvious choice.

Other than that though, I'm always paranoid of having to do maneuvers during eclipses, and you need 12 RTGs to constantly power an ion engine, which is too heavy to be practical. I suppose batteries would work, but I don't know how many I'd need.

Radial batteries are masseless (at least the smallest one), so don't count! also, once you're no longer in LKO, there are not so much eclipses.

I can't even figure out how to use them in probes. I can always come up with a design that performs better using a 48-7S. By the time you add on multiple relatively heavy Xenon tanks and solar cells, the promise of crazy amounts of dV slips away.

They say you can make ion spaceplanes that can actually get to orbit from EVE, which is something. I've never tried it.

Your probes may be really heavy, because for any minimalistic probe under 2000 m/s, I find that a lv 1 is better than a 48-7s. I almost certain that Ion engines perform better than 48-7s for interplanetary, mass wise (but maybe not cost wise).

Try to make the Lightest possible probe with dV requirement for a trip to EEloo or Moho and capture, I think they will appear to be the engine to use.

[FleshJeb]

I have to make myself NOT use ions on everything...

[kahlzun]

I have an emergency return system for my kerbals, which I used on my "Eve Rocks" challenge.

Because ion engines were nerfed, and now only need 8 power, you can supply that with 2 1x6 panels now at Eve or closer to the sun, and adding an extra .7 tons to the pod (including a chute) gives it >6k dV. That's enough juice to get a Kerbal home from ANYWHERE.

I've used a little bit of fuel in that shot, it started with about 6808 dV.

Interestingly enough, still enough TWR to land on many moons. A barebones version can almost land on the Mun (TWR 1.08)

Edited January 24, 2015 by kahlzun

[Empiro]

I haven't had much use for Ion Engines in regular KSP. I don't have the patience for those extra long burns, and there's just not that much need for so much delta-V.

[UnusualAttitude]

They're very useful for many contracts in career games.

"Put a probe with a materials bay in low Kerbol orbit"... ie: you need 10km/s or more dV. You can even deploy one from a spaceplane for only the cost of fuel (and the xenon, ouch):

Burn times...? Tens of minutes... Chill out, have a beer ;-)

... or for taking multiple crew reports/temperature readings above/below 9,123.6m from a low polar orbit of Mun, with a self-imposed rule of always taking crew accommodation with you for missions of long duration:

As always, it depends on your style of playing.

[kStrout]

Remember, ion engines are powerful tools in the hands of the patient.