How does the Xenon engine work?

[Kurbus]

The title pretty much explains it. I've strapped a regular fuel tank (didn't work, obviously), a Xenon tank, a Xenon tank and a battery, and nothing worked. It made a sound when i launched it, though! So can anyone give me a basic idea of how the Xenon engines work?

[Kerbart]

With very, very little thrust. It probably worked, but if you have a large vessel you won’t notice anything. You’ll need a fairly light ship and even then acceleration will be in the tenths of one g.

[Kurbus]

Just now, Kerbart said:

With very, very little thrust. It probably worked, but if you have a large vessel you won’t notice anything. You’ll need a fairly light ship and even then acceleration will be in the tenths of one g.

I had a small ship. It was just a Stayputnik, a single Mk1 fuel tank, and the Xenon tank and battery.

[DerekL1963]

13 minutes ago, Kurbus said:

I had a small ship. It was just a Stayputnik, a single Mk1 fuel tank, and the Xenon tank and battery.

Do you mean the MK1 fuselage?  That holds Liquid Fuel, a Xenon engine needs a Xenon tank.  And a battery isn't going to provide near enough power, the Xenon engine will suck it dry in relatively short order.  You'll need solar panels and/or a PB-NUK.

Also, a Xenon engine isn't strong enough to launch from anywhere except maybe Pol or Bop - you'll need to put it into orbit first.

[Orbital_Decay]

Ion engines are weak. Comparatively quite weak actually. That's because they aren't supposed to be what gets you to the stars. Rather they are what pushes you around while your in space.  

Real-world examples of ion engines are mounted on "lightweight" spacecraft. NASA has an article on the topic. I can't out-science NASA so here it is: https://www.nasa.gov/centers/glenn/about/fs21grc.html. 

The long and short of it is that you will never take off with an Ion engine. You can, however, use one at your "end stages" and use them to keep your spacecraft/ satellite/ probe moving or to keep something in an orbit you like. Just be aware that it is really weak, so you should only use them on small objects. 

Helpful?

Edited August 6, 2020 by Orbital_Decay

[bewing]

Ion engines don't do a darn thing until you are out in vacuum.

[Streetwind]

^---- this.

You need to read more of the part rightclick info, @Kurbus. That would have told you the required fuel type plus electricity consumption even without trial and error. It would also have told you the difference between sea level Isp/thrust and vacuum Isp/thrust.

Ion engines work by pumping so much energy into an otherwise inert gas that it ionizes into a plasma. Then, that plasma is accelerated to extremely high speeds via an electric field, which is what produces thrust. However, plasmas are by their very nature extremely thin and light affairs. Have you ever stood facing a blizzard and gently exhaled through your mouth? That's about what happens when you attempt to create a plasma jet inside an atmosphere. Which is to say, nothing happens. Nothing at all. It doesn't work.

Once you are in the vacuum of space, however, a plasma jet works just fine. And then you have the single most fuel-efficient engine in the game on your hands, by a big margin. Still, plasma continues to be thin and light, so the thrust is pretty low. In KSP, it's actually still about two thousand times stronger than IRL

[s_gamer101]

I highly recommend to get familiar with the TWR display. TWR means thrust weight ratio. It must be larger than one, otherwise your craft won‘t be able to take off vertical (planes can take off with a smaller TWR because they have wings).

[Snark]

On 8/5/2020 at 9:37 PM, Kurbus said:

The title pretty much explains it. I've strapped a regular fuel tank (didn't work, obviously), a Xenon tank, a Xenon tank and a battery, and nothing worked. It made a sound when i launched it, though! So can anyone give me a basic idea of how the Xenon engines work?

Short answer:

• It needs only xenon fuel.  No regular fuel required; don't bother adding a regular fuel tank.
• It needs a lot of electricity, so have plenty of solar panels.
• It needs to be in a vacuum.  Don't try to use it until you're in space.

[Singhnaut]

ion engines are either for sats or deep space probes, don't use under a sphere of influence (unless it is the same pull or less than kerbin's). it can use either electricity or xenon, once one runs out, it usually switches to the other (real life is different, as @Orbital_Decay posted). I recommend using it once you get to the hard core stuff.

[Spricigo]

57 minutes ago, Singhnaut said:

it can use either electricity or xenon, once one runs out, it usually switches to the other

That's not how the stock ion engine works, it uses both electricity and xenon gas at the same time to operate. Maybe you are referring to some modded engine you have?

Also, the "don't use under a sphere of influence" sounds strange, since all celestial bodies, including the sun have one. (Just the case that the Sun's is for all practical purposes infinite). Maybe it is the case that under higher gravity one will have bigger losses with an ion engine but the Isp (and consequently potential deltaV budget) is so much better that it become a very manageable issue anyway, the real problem is that with very long burns it become difficult to be precise (not to mention the risk of being bored to death)

 

[Fierce Wolf]

Be sure to add LOTS of solar panels, the vessel might fare well near Kerbin, but if the mission is towards the outter planets you will see that panels generate less electricity. Also, be prepared to spend a couple of minutes in real time accelerating the thing!

[Singhnaut]

15 hours ago, Spricigo said:

That's not how the stock ion engine works, it uses both electricity and xenon gas at the same time to operate. Maybe you are referring to some modded engine you have?

Also, the "don't use under a sphere of influence" sounds strange, since all celestial bodies, including the sun have one. (Just the case that the Sun's is for all practical purposes infinite). Maybe it is the case that under higher gravity one will have bigger losses with an ion engine but the Isp (and consequently potential deltaV budget) is so much better that it become a very manageable issue anyway, the real problem is that with very long burns it become difficult to be precise (not to mention the risk of being bored to death)

 

I know they both use the different propellants at the same time, its just that it uses barely any electricity until you run out of xenon. What I meant is that you can, it just not super close, and like I said, if it is the closest you can get but has a stronger gravitational force than kerbin, then it is basically just extra weight. The one exception is if you are on a high orbit of kerbol.

On 8/5/2020 at 8:37 PM, Kurbus said:

The title pretty much explains it. I've strapped a regular fuel tank (didn't work, obviously), a Xenon tank, a Xenon tank and a battery, and nothing worked. It made a sound when i launched it, though! So can anyone give me a basic idea of how the Xenon engines work?

do you know how to throttle up? On PC, you would hold shift until throttled. (I had the same problem once).

[Snark]

Just a little reminder, folks, that this question was asked three months ago.  So additional discussion is all well and good, but it's likely that the OP has gotten things sorted out by now. 

13 hours ago, Fierce Wolf said:

Be sure to add LOTS of solar panels, the vessel might fare well near Kerbin, but if the mission is towards the outter planets you will see that panels generate less electricity. Also, be prepared to spend a couple of minutes in real time accelerating the thing!

Ions are gonna have trouble out at Jool and beyond; there's just so little sunlight available.  If you're going out to Duna or beyond, yeah, you're gonna need to spam a lot of panels.

Where ions really shine is for missions to the inner solar system, especially Moho.  The sunlight's so bright down there that you don't need many panels; plus, Moho missions need tons of dV, and that's precisely what ions are good for.