Shambling zombie thread about ion engines

[Gestahl]

I like that ion engines exist but seriously these things have practically no use in 1x speed, other than some guy said he uses them for traction on ground vehicles

[JoeDaTomato]

İlk olarak Technicalfool tarafından gönderildi:

Wow, that's an epic-level necro. Ion thrusters (and the game in general) have changed significantly since 2013.

As far as using ion thrusters in a Duna lander is concerned...
https://www.youtube.com/watch?v=Ee59XkEufjA

I was watching that video not even half an hour ago.

[RoofCat]

İlk olarak Technicalfool tarafından gönderildi:

Wow, that's an epic-level necro. Ion thrusters (and the game in general) have changed significantly since 2013.

As far as using ion thrusters in a Duna lander is concerned...
https://www.youtube.com/watch?v=Ee59XkEufjA

Battery solutions (weeks of charge, minutes of burns) are indeed the way you play Ion going higher. Batteries are very light in KSP. And then "distributing" payload to multiple Dawn engines you can indeed even lift there...
or simply use this Terrier (because single Dawn engine does cost 8000$ and sucks in flight)
http://steamcommunity.com/sharedfiles/filedetails/?id=815826304

Anyway, we have noticed necro status, but the first question waking up this zombie sounded kind of legitimate additional one - to use the old cadaver as good as creating a new one.

İlk olarak Oskar.io tarafından gönderildi:

Would strapping more than one ion thruster work to make it go faster? Or would that be stupid?

[Gestahl]

I watch DasValdez and EJSA from time to time, and I never seem to see ion engines come up. I guess I'd still like to see something faster than 4x physics warp when you're out in deep space with no gravity or atmosphere to worry about. Would be cool to have loooooong burns for craft using a single ion to set up an encounter.

[Chibbity]

Just use a bunch of ion engines?

You can get a respectable TWR pretty easily, like at least .50.

I think the Better Time Warp has a lossless physics mode for faster physics time warping? Idk, I haven't used it much; it's still in beta and quite buggy.

[Gestahl]

Ions weigh / cost sort of a lot for their thrust though, realistically you could push a fairly large mass with smaller numbers of them given enough time, would be neat to have the option of longer burns than are practical with 4x physics warp.

[Chibbity]

İlk olarak Gestahl tarafından gönderildi:

Ions weigh / cost sort of a lot for their thrust though, realistically you could push a fairly large mass with smaller numbers of them given enough time, would be neat to have the option of longer burns than are practical with 4x physics warp.

I guess it would be a neat option?

Still...even if it was; I'd rather brute force it with more engines, but maybe I'm just impatient? Your time is valuable too after all.

You could check this out? It's still a WIP though.
https://forum.kerbalspaceprogram.com/index.php?/topic/120404-wip13-persistentthrust-v109/

[Astronaut]

Once I was using ion engines and I had to do a burn that was a few hours and I had not discovered physics warp yet so I was just staring at the screen and gave up.

[Astronaut]

Moar boosters!

[RoofCat]

İlk olarak Chibbity tarafından gönderildi:

Just use a bunch of ion engines?

You can get a respectable TWR pretty easily, like at least .50.

I think the Better Time Warp has a lossless physics mode for faster physics time warping? Idk, I haven't used it much; it's still in beta and quite buggy.

except weight used in thrust to weight ratio is local unit
Weight: 9.81kN on Kerbin = 2.94kN on Duna = 0.491kN on Minmus
for the same thing with exactly 1t mass

Which means you can have TWR=4 too. With a single Dawn. On vacuum Minmus. Just neither on Kerbin nor Duna.
And then considering there is "no gravity" in orbital space and thus no weight, there is no limit to that TWR. Even 0.05/0 is still infinite huge.

Having more Dawns you can rather easy reach TWR=1.5+ on Duna. It's just still slow and expensive.
On Kerbin though there is no way to reach TWR>1 which is needed for vertical launch with Dawn. Since engine alone has 0.25t *9.81=2.4525kN weight, while the thrust is limited to 0.05kN ASL. Even if there were vacuum on Kerbin surface, it would be just 2kN thrust - still not enough to counter and lift 2.4525kN.
And then due to extremely low ASL thrust value and drag on top of that you can't build horizontaly launched TWR<1 planes either. Also ASL Dawn engine basically just wastes all the fuel with Isp as low as 100 (compared to 4200 in vacuum).

[Chibbity]

İlk olarak RoofCat tarafından gönderildi:

İlk olarak Chibbity tarafından gönderildi:

Just use a bunch of ion engines?

You can get a respectable TWR pretty easily, like at least .50.

I think the Better Time Warp has a lossless physics mode for faster physics time warping? Idk, I haven't used it much; it's still in beta and quite buggy.

except weight used in thrust to weight ratio is local unit
Weight: 9.81kN on Kerbin = 2.94kN on Duna = 0.491kN on Minmus
for the same thing with exactly 1t mass

Which means you can have TWR=4 too. With a single Dawn. On vacuum Minmus. Just neither on Kerbin nor Duna.
And then considering there is "no gravity" in orbital space and thus no weight, there is no limit to that TWR. Even 0.05/0 is still infinite huge.

Having more Dawns you can rather easy reach TWR=1.5+ on Duna. It's just still slow and expensive.
On Kerbin though there is no way to reach TWR>1 which is needed for vertical launch with Dawn. Since engine alone has 0.25t *9.81=2.4525kN weight, while the thrust is limited to 0.05kN ASL. Even if there were vacuum on Kerbin surface, it would be just 2kN thrust - still not enough to counter and lift 2.4525kN.
And then due to extremely low ASL thrust value and drag on top of that you can't build horizontaly launched TWR<1 planes either. Also ASL Dawn engine basically just wastes all the fuel with Isp as low as 100 (compared to 4200 in vacuum).

Sure? The TWR will obviously go up or down depending on which SOI you are in.

I don't think I ever mentioned taking off from Kerbin on ions though?

I only used .50 as an example number because for me personally; that's a reasonable TWR which won't result in 2 hour burn times and TWR in Kerbin SOI is a good default example situation. I'd be willing to go as low as like .20 but I draw the line there.

[Astronaut]

There was a guy who built an ion engined plane that actually flew. It needed help on takeoff, though.

[RoofCat]

İlk olarak Astronaut tarafından gönderildi:

There was a guy who built an ion engined plane that actually flew. It needed help on takeoff, though.

you mean flying like using lifting force from wings or flying like being thrown on a ballistic trajectory? :)
The problem with atmosphere is its drag and horrible impact on Dawn thrust and Isp. The higher you go, the more speed you need to keep flying. Although drag gets lower after some point, it is still quite high on Kerbin. Drag acts just like any force - kN, just opposite to your movement direction. Wings add to that drag.
The video above used stored kinetic energy to escape atmosphere high enough to have enough time to gain velocity in thin air and vacuum until reaching apoapsis. For a plane to fly - that should be really hard for Dawn. Not claiming there is no way some bright dude may have figured out something I can't see yet, but it smells fishy in respect to flying. You could use even Whiplash to create a short vacuum jump and activate Xenon high enough, but it is not exactly flying like a plane and you may have to drop everything once geting there. For example having like 2 small fins at 40km+ doesn't count as plane. There is no air to hover on with wings as small. It's just ballistics from that point on.

[Astronaut]

Well, he had a rover launch it to gain some speed, and after that the plane flew on ion engines and it used lift to fly. Well, actually several people, now that I actually take a look.
Here's the vid I originally saw: https://www.youtube.com/watch?v=tMiD-eAng3M

[RoofCat]

İlk olarak Astronaut tarafından gönderildi:

Well, he had a rover launch it to gain some speed, and after that the plane flew on ion engines and it used lift to fly. Well, actually several people, now that I actually take a look.
Here's the vid I originally saw: https://www.youtube.com/watch?v=tMiD-eAng3M

did you watch the whole video? As it is rather a fail. Just a gliding with climb possible within some altitude range. He couldn't launch from ground nor reach space nor any considerable speed for ballistic curve with this. And then those engines blowing into each other did look strange too. Doesn't Dawn have minimal exhaust range too?

Don't get me wrong, I'm actually curious about a working solution within stock game possibly without shenanigans like that catapult in the one posted by Technicalfool. Although that one was funny too.

[Astronaut]

Well, it's still a PLANE.