Are Ion drives useless ?

[Lohan2008]

Built a 13 ion engine ship to test out how much drive it gets,,,

I could not get enough push to leave Kerbin;

It is too big to use as a tow truck to push/pull parts

What good are they ??

Edited September 24, 2013 by Lohan2008

[carazvan]

They are very good for probe and satellite construction (vehicles with mass under 1t). Basically it's very high deltaV for very low TWR.

To the extreme you can use them for very small ships also (check the Flea Ion in my sig) but those require more patience than most most people have.

[Bobhendly]

Its debatable.. Ion engines have terrible thrust, but are gratuitously efficient, You would have to physics warp to the max to get simple burns don't in a timely matter..

But then again, you cant "On Rails" Warp with engines on.

[Char0093]

They are Useless to an Extent. I've been playing around with them as Orbital Drones to Check out Ike from Duna Orbit.But the burn is still pretty long.It's more of a Patience thing with them if anything.

[AlamoVampire]

Lohan: for a ship like that, ion engines are 100% useless, as that ships mass is far far higher than patience allows. Will it get it done? Yes, if you abuse the snot out the Oberth effect and spend a few days REAL TIME going at it. As someone above said, they are mostly used for high efficiency deep space probes, as they require very little fuel, but a ton of electricity. I think we have a real world Ion Drive probe in space right now, but, its acceleration is not in meters per second, its centimeters per second.

[Lohan2008]

At least I built a ship to test the design; as you can see, it does look pretty.

[steffen_anywhere]

Yeah...As AlamoVampire said, NASA does have an ion powered spacecraft somewhere in our remote solar system, but in fact, the KSP ion engines are actually OVERPOWERED! Yes! IRL, they are a lot less powerful. The things is, though, that NASA Jet Propulsion Labs have the skills to have these engines 'burn' for days in order to achieve a notable result.

[AlamoVampire]

At least I built a ship to test the design; as you can see, it does look pretty.

no denying its a pretty ship, also, unless I missed my guess, its brutal on the FPS? looks to be north of 450 parts?

[carazvan]

Here's an example back from 0.20 of a probe that used an Ion engine and that gave it decent TWR (about as good as you can hope out of them):

[Lohan2008]

Not convinced > 20 minute burn to shape an orbit ?

I am going back to = burn 'til it hurts !!

[wasmic]

Built a 13 ion engine ship to test out how much drive it gets,,,

I could not get enough push to leave Kerbin;

It is too big to use as a tow truck to push/pull parts

What good are they ??

That ship is insanely inefficient. You only get the thrust from 3 ion engines, the rest consume fuel without providing thrust. All the ion engines that point at the ship itself will provide no thrust, leaving you with a thrust that is four times lower than it should be.

[Starwaster]

Built a 13 ion engine ship to test out how much drive it gets,,,

I could not get enough push to leave Kerbin;

It is too big to use as a tow truck to push/pull parts

What good are they ??

they're for small probes. or maybe Gilly or Minmus landers if you're daring

but would you try to install an engine from a VW bug into an Abrams main battle tank?

no.

so dont try to install something with such low TWR on a large station sized ship. thats not what they're about. read up on IRL ion engines.

Edited September 24, 2013 by Starwaster

[Lohan2008]

they're for small probes. or maybe Gilly or Minmus landers if you're daring

thats not what they're about. read up on IRL ion engines.

Sometimes you just want to test the craft/concept limits for yourself.

[capi3101]

Really, it depends on what you want to do. They work well for small probes and I've also heard of folks using them to provide constant, reliable down-thrust for rovers. You're probably not going to be using them for manned missions, though.

[Monkeh]

I'll just leave this here:

http://forum.kerbalspaceprogram.com/threads/50449-JIMO-Jool-Icy-Moons-Orbiter-v1-0

[daffy]

they're for small probes. or maybe Gilly or Minmus landers if you're daring

but would you try to install an engine from a VW bug into an Abrams main battle tank?

no.

so dont try to install something with such low TWR on a large station sized ship. thats not what they're about. read up on IRL ion engines.

I think the point of that ship was to try something out, rather than actually predict an outcome. And now the answer is pretty clear. Cool looking station though.

[Starwaster]

Sometimes you just want to test the craft/concept limits for yourself.

I think the point of that ship was to try something out, rather than actually predict an outcome. And now the answer is pretty clear. Cool looking station though.

And that's great! Experimentation is what the game is about. Except that last in the OP questioning what good ion engines are... sorry I just had to facepalm when I got to that part.

Edit: (not to mention the very title of the thread)

Edited September 24, 2013 by Starwaster

[Anton P. Nym]

I like the spirit of the experiment, but the execution... well, could've been better.

On my end I did make the KSS Sunjammer; a Mk1 command pod on a truss with 4 Gigantors powering 4 ion engines. It worked... it took mighty patience to get anywhere, but it looked like it could roam around cis-Minmar space quite handily. Didn't keep the result, though. I also have a glider probe en route to Eve aerocapture powered by quad-ions, and it has xenon left to use them as kicker engines to extend its glide in that soup of an atmosphere.

In the main, though, ions are most useful for moving little probes long distances. (Cheap, too; I have a Moho orbiter on its way that cost overall less than the first stage of my crewed Mun rockets.

-- Steve

[rodion]

Burn times aren't really an issue in KSP...at worst, you can go get a sandwich and a cup of coffee, or just window KSP and put something else on top, showing only the maneuver progress. If anything, consider yourself privileged to have such overpowered ion engines; each KSP-model ion thruster has over 5,500 times the thrust rating as the one that powered Dawn to Vesta and (en route) Ceres.

[Silverchain]

By my back-of-the-hand calculations the limiting deltav for an ion engine is about 36,000ms-1, which is way higher than you'll get with anything else.

[NFK]

Some realworld ion-engine powered probes. They make 'em pretty small.

http://dawn.jpl.nasa.gov/mission/spacecraft.asp

http://www.isas.jaxa.jp/e/enterp/missions/hayabusa/index.shtml

http://www.esa.int/Our_Activities/Space_Science/SMART-1/SMART-1_factsheet

[lajoswinkler]

They aren't useless if you want to put a probe in an orbit around Kerbol, or if you want to swing near a planet, but any braking to enter the planet's grip... Not really.

It better to strap on a chemical engine on the probe and use it to brake down after detaching from the ion engine.

One of the problems is constant high requirements for electricity. Theoretically, one large panel is enough for one engine, but you can't expect full exposure all the time, so you add more panels, increasing the mass. It's frustrating and slow even under physical acceleration, so I go nuclear.

[-Velocity-]

Burn times aren't really an issue in KSP...at worst, you can go get a sandwich and a cup of coffee, or just window KSP and put something else on top, showing only the maneuver progress. If anything, consider yourself privileged to have such overpowered ion engines; each KSP-model ion thruster has over 5,500 times the thrust rating as the one that powered Dawn to Vesta and (en route) Ceres.

Quoted for truth.

If I remember correctly, the highest thrust ion engine ever created in real life was 3 N. In KSP, the stock ion engine has a thrust of 500 N- so the stock ion engine in KSP has 167 times more thrust than the most powerful ion engine ever created IRL.

However, the ISP is about correct to real life. The very high thrust of ion thrusters in KSP could be seen as a concession to gameplay; we can't enter time compression above 4X with ion thrusters enabled, and no one wants to leave the game running for a week at 4X just to build up like 1000 m/s delta V. Also, the KSP GUI isn't really properly set up to plan really long burns.

HOWEVER, if you are AT ALL concerned about maintaining even a shred of credible realism, you will NEVER use ion-powered aircraft. If you're using an ion propelled aircraft, you might as well be using a mod that makes your aircraft fly via fairy dust. Heck, a fairy dust propelled aircraft would be preferable to an ion thruster propelled aircraft; at least it wouldn't be trying to masquerade as something that's based on real physics. IRL, not only is it impossible for ion thrusters to produce enough thrust to propell an aircraft, but ion thrusters do not work AT ALL in atmospheres- they ONLY work in a vacuum.

I'm guessing that the only reason ion thrusters work in atmospheres right now is the unrealistic way that Squad had ISP set up- right now, ISP just sets fuel efficiency, and thrust is fixed. IRL, thrust is NOT fixed, it is actually less the more dense the atmosphere is, and it is FUEL CONSUMPTION that is fixed. I'm guessing that Squad has ion thrusters work in the atmosphere right now because they don't want you to accidentally activate your ion thrusters and instantly consume all your xenon (as the fuel consumption would be infinite due to the ISP being 0).

Edited September 24, 2013 by |Velocity|

[Anton P. Nym]

HOWEVER, if you are AT ALL concerned about maintaining even a shred of credible realism, you will NEVER use ion-powered aircraft.

Until we get electrically-driven propellors or ducted fans as stock parts, the only way to create an entirely-realistic solar powered ultralight aircraft is to make unrealistic use of ion engines. I'll cheerfully switch over the instant I can.

-- Steve

[Dispatcher]

Ion driven rover probe (compact design and low mass) with a range of about 16 km. Good only for taking photos (F1) or movies, but still a nice predecessor to science or manned mobile rovers: