The_Cat_In_Space

'Dawn' engine. Useful or useless?

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As you are aware, In Kerbal Space Program there exists the IX-6315 "Dawn" Electric Propulsion System, commonly known as the Ion engine. It's small, and produces low thrust, but has incredible fuel efficiency. Is it useful, or useless?

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Probes mainly. Things that like to explore deep spaces, and maybe touch down on the occasional tiny moon/asteroid.

Also could be used on a comm net satellite.

Most people tend to use nukes for bigger craft. 

Basically, if it's small and in deep space for long periods, go ion.

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2 hours ago, The_Cat_In_Space said:

Is it useful, or useless?

Try it. If you find it fun, then it's useful. Personally, I find it fun and love making small probes, Duna planes, and Mun landers with it.

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Weeeeeeeelll, I mean you could use it for large interplanetary craft.  At least for the inner planets...probably be well into the law of diminishing returns by the time you get to Dres, though.

EV-5%2002A_zpsqvqwiy1z.png     EV-5%2004_zpspdz4seva.png

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Will use them for my Grand Tour...

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I find it useful for the lighter stuff on Jool 5 trips. And EXTREMELY useful for those "rescue ____ in low solar orbit" missions where you need 10s  of km/s of delta-v (and get oodles of power from solar panels).  

However, I have not found it all that useful for small robot probes.  The delta-v demands for such missions are usually low enough that it's easier/cheaper to just go with chemical rockets, start small and use lots of stages.

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50 minutes ago, Raptor9 said:

Weeeeeeeelll, I mean you could use it for large interplanetary craft.  At least for the inner planets...probably be well into the law of diminishing returns by the time you get to Dres, though. 

(Picsnip) 

Those are some gorgeous engine pods, Raptor. love.gif

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My Grand Tour, which used no ISRU taught me to love them.

They're quiet, run very efficiently, cool blue glow, and have the capability to reach anywhere and land almost anywhere.

I have a Ion Lander design that can land on Vall and take off, on battery power alone.

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1 hour ago, Xurkitree said:

They're quiet, run very efficiently, cool blue glow, and have the capability to reach anywhere and land almost anywhere.

Are these arguments in some particular order? Noise levels more important that efficiency? Or cool blue glow more important than efficiency? :cool:

In any case I am a big fan of the Mainsail’s roar! 

In addition these humorous remarks I have very little input to this thread. I think I only used Dawn once and haven’t unlocked it in my current career yet. I am interested in using it more though, once I unlock it, so it’s nice to hear other people’s opinions. 

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*Duna ION plane (using engine plate with seats in fairing is very aerodynamic)
Probes.
*Very fast interplanetary crew vessels (using 100x physical timewarp in bettertimewarp mod)
*Assist on some SSTO's. Some of mine have ISRU and require 35EC generation for drill and ISRU, consequently that static EC generation can service for 4 Dawns. So if your SSTO has ISRU you could asswell add 4 Dawns at the back of it. I try to balance Dawn ION engine burn time with Nerv LV-N burn time to effectively increase the total Dv when combining both engine modes. A LV-N/Dawn combo can make for a effective *850-900ISP engine mode (depending on amount of Dawn vs LV-N motors)
*You could use ION as RCS by adding each vector to a action group (larboard facing ION to action group 2 and fwt facing ION to action group 1.
*You could use ION on rovers to quickly accelerate and to push them back to the ground on low gravity environments.
*Be a lifter on many worlds like Gilly, Eeloo, Moho, Vall, Bop, Minmus, Mun, Dres, Ike and *Duna (*using a fairing/aerodynamic shell design)
Of course you are supposed to use a lightweight (OKTO2, Toroidal tank, Command seat, solar panels and a battery for most those worlds)
*Act as a hybrid engine. I have a MOHO orbiter that uses Ant's and Dawns to land and orbit Moho on a 4.2Ton design for 3 crew (otherwise it would be a 6.5Ton design using only LFO)
*You can stack Dawn ION engines without one blocking the thrust of any Dawn engine within that stack. You don't have to build wide to increase thrust by adding parallel stacks but your dawn engine can be in between another Xenon fuel tank within a single stack if you so desire.

 

 

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useful everywhere - batteries and RTG for the outer plannets

Eeloo for 4.29 ton? 

kD6XJ5e.png

ion vacuum craft under the fairing

or larger with TAC-LS

oU16gmp.png

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if you get get the thrust to weight ratio at a comfortable amount then they can be very useful, then again you can't refuel xenon tanks so there's also that. depends on the situation/mission

actually the best way i can describe ion engines is: the amount of fuel of you have is the amount of patience you have

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I once took a look at ion engines. The dV is excellent, but I can't figure out how you're supposed to actually use these things without attaching so many batteries that they can't even leave Kerbin's SOI without using up so much xenon that they can't brake at their destination.

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Posted (edited)

oky9oIM.png        Long March has one ion engine (and ridiculous dV)

0JZdTvX.png       Gossamer Anisoptera has nine ion engines

BgMr8F4.png       Omega has thirty two ion engines

 

It's a kind of arithmetic progression, you see...  (note my avatar)

 

Edited by Hotel26

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Starting to use the fuel cell array really opened up a lot of fun with the Dawn engine.  The fuel cell array fully powers two ion engines, and it takes hours to burn through a tiny LfOX tank.  It's also great because combining oxidizer engines like ant or twitch can vastly increase thrust which covers the greatest weakness of the Dawn.  The hybrid is great for suicide burns and landings.  And sometimes you need to capture from a hyperbolic orbit, but your maneuver node is in an eclipse.

Solar power is only good enough in the inner solar system.  RTG's must have been nerfed since a previous version.  It takes 10 RTG's to keep one Dawn engine firing continuously.  

As a prior user mentioned, battery power alone can be sufficient for most moon landings.  But this leads to a low thrust vehicle that must start it's suicide burn from many kilometers up.  The fuel cell array/hybrid is way more powerful. 

 

 

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6 hours ago, Fraktal said:

I once took a look at ion engines. The dV is excellent, but I can't figure out how you're supposed to actually use these things without attaching so many batteries that they can't even leave Kerbin's SOI without using up so much xenon that they can't brake at their destination.

Attaching batteries is actually counter productive beyond a certain point.

Better to go with 1-2 batteries and the lightest  power generation/collection you can come up with.

 

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Except how are you supposed to even leave Kerbin's SOI if your batteries ran out barely more than a fifth into the maneuver node burn?

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Posted (edited)
2 hours ago, Fraktal said:

Except how are you supposed to even leave Kerbin's SOI if your batteries ran out barely more than a fifth into the maneuver node burn?

You obviously split the burn into many smaller burns. I do this all the time with ions(and other low twr craft such as with nukes sometimes). It also makes the oberth effect better as you are not burning far away from kerbin but make every burn close in. And when doing my "standard" gravity assists (especially with multiple assists chained after one another) the orbits far in the future get hyper sensitive to what you burn right now, so sometimes an ion engine at 0.5% limiter and minimum throttle is sometimes too much.

Overall the ion engine is my all time favourite in the stock game, and i have recently discovered the mod near future propulsion among others wich adds many more ion Engines of different sizes and power requierments.(instantly became one of my favourite mods obviously)

Edited by Eriksonn

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5 hours ago, Fraktal said:

Except how are you supposed to even leave Kerbin's SOI if your batteries ran out barely more than a fifth into the maneuver node burn?

You add more batteries. They're very mass efficient. You can make an ion craft comprised of payload+fuel and engines+Solitary power source like and RTG+Batteries and go a long way. If you run out or the burn is large, split it up or start eariler.

uZqmGJR.png

This is the Hummingbird Mk3. Ion Powered, but can land on the 2nd largest Vacuum body ingame on battery power alone.

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5 hours ago, Fraktal said:

Except how are you supposed to even leave Kerbin's SOI if your batteries ran out barely more than a fifth into the maneuver node burn?

Solar panels! Stick them on, put batteries on as well, and you won't run out!

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10 hours ago, Fraktal said:

Except how are you supposed to even leave Kerbin's SOI if your batteries ran out barely more than a fifth into the maneuver node burn?

Only use one engine. Don't even attempt to have a reasonable TWR. Don't even try to insert to or transfer from LEO.
Transfer from 300-500km orbit instead. A less-efficient transfer is acceptable with an Isp of 4000. Even 300km up, you'll want to split the transfer into two or three burns, but it's still better than trying to do a split burn to Moho from 70km orbit with a TWR of 0.05.

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Play around with real ion engines from RSS and you will feel stock IONs are so OP their insane.  Only reason I don't use them is ISRU is more powerful and more playable.  My exploration vehicle could land and SSTO everywhere except Eve.

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