the ion engine is way too OP

[Levelord]

7 ion engines, which fit nicely to the bottom of the lander, and 10 small sets of foldable solar panels. The only thing that feels like spamming is the amount of science stuff in the science version of the lander.

This is an earlier version that didn't have enough batteries, so the command module had to assist in killing horizontal speed:

http://www.cs.helsinki.fi/u/jltsiren/ksp/ion_mun_2.jpeg

This is the final version that can land easily on its own:

http://www.cs.helsinki.fi/u/jltsiren/ksp/ion_mun_4.jpg

I'm still not saying that it's overpowered. I'm saying that the update changed the nature of the ion engine so much that it's no longer believable.

I really like your lander design. I'm just not convinced with other people's points that the engine should be reverted because of immersion issues at the expense of how to practically intergrate it into the game. If we go along the lines of immersion we could very well add jet engines to the list (for the way intakes work) and nuclear engines (nuke engines are not meant to work at all in atmosphere, yet people use it to land on Duna and on SSTOs).

I managed to build an ion mun lander recently using 8 engines, but the descent was quite painfully slow (felt like descending with RCS) that I still don't see anyone taking this seriously. Especially for the same people who found the original ion engine burn times excrutiatingly painful to wait for.

I can see a Mublin approach using a shallow descent profiler to land but the lengthy burns is also probably why people don't use a low TwR lv-909 landers often enough even though it potentially is more efficient.

Compared to the current ARM lifter engines that completely outclasses the mainsail and skipper engines by miles (effectively rendering them obsolete, which I find is an legitimate balance issue), I find that other people picking on the ion engine as an overpowered engine a big joke as it in no way has its buffed advantages outweigh the advantages of using conventional engines.

Edited April 10, 2014 by Levelord

[cantab]

(nuke engines are not meant to work at all in atmosphere, yet people use it to land on Duna and on SSTOs).

I don't think this is correct. Two versions of the NERVA were tested on the ground, both making sustained firings. I believe that even on the ground they had higher Isp than chemical rockets, and the low sea level Isp in KSP was done to balance them.

[quasarrgames]

In my opinion, ion engines are perfectly fine the way they are, but maybe they should be higher up on the tech tree. Maybe we could have a low-level electrical propulsion engine that is the same as the pre-0.23.5 engine in the same place as the new ion engine is now, and the new ion engine could be closer to the end of the tech tree. Maybe we could also have another electrical engine at the end of the tech tree with EXTREME efficiency and even less thrust than the old ion engine. (i really want near-future tech in ksp, but that's just my opinion )

Also, maybe we should have some kind of way to time warp while burning. I know the devs said they wouldn't do this, but it seems like it would be simple enough to just squeeze into .24 or.25 or something.

[Red Iron Crown]

Jouni, that lander design is really interesting. Whether the new ions are overpowered or not, it's cool to see them being used in new ways.

[Levelord]

I don't think this is correct. Two versions of the NERVA were tested on the ground, both making sustained firings. I believe that even on the ground they had higher Isp than chemical rockets, and the low sea level Isp in KSP was done to balance them.

They can fire, but I doubt they can lift payloads in atmosphere based on thermal energy alone and the nuclear waste would be disasterous.

[boomerdog2000]

I'm happy with the change. Now the ions are finally usable. If we have to sacrifice a bit of realism for gameplay I'm fine with that. Not a lot of point in having an engine you're never going to use (looking at you M55).

[NERVAfan]

I'm happy with the change. Now the ions are finally usable. If we have to sacrifice a bit of realism for gameplay I'm fine with that. Not a lot of point in having an engine you're never going to use (looking at you M55).

I think the main point of the M55 is if you have a rocket that is a bit too heavy for a single Mainsail (or the bigger engine, now) but doesn't need a full 3 mainsails. It saves part-count over putting in extra side tanks with "in-line" engines or using the smaller radial engine (24-77?).

At least that's the only time I've ever used it.

Maybe it's also for heavy landers?

[NERVAfan]

They can fire, but I doubt they can lift payloads in atmosphere based on thermal energy alone

I don;t understand why not? Do you mean it would overheat?

I thought the problems with ground-launch NTRs were low TWR and nuclear-phobia.

and the nuclear waste would be disasterous.

What nuclear waste? A solid core NTR like the NERVA does not emit radioactive materials, it emits plain hydrogen (or water or whatever, but that gives you less Isp) that is merely heated by the nuclear reactor (thus "nuclear thermal"). If radioactive stuff is coming out the exhaust something is very seriously wrong (that's how I unerstand it anyway). EDIT: apparently erosion of the reactor elements can cause this problem. But again it's a problem -- an NTR is NOT supposed to do this!

I've heard of a gas-core NTR that would emit uranium, as would an Orion drive or nuclear-salt-water-rocket (a Robert Zubrin concept which is basically an Orion without the pusher plate and with a continuous nuclear explosion rather than a series of nuclear bombs). But not a NERVA style NTR.

EDIT: here's a pretty in-depth description of different NTR types. (The person who wrote this posts here as nyrath)

http://www.projectrho.com/public_html/rocket/enginelist.php#ntrsolidcore

Edited April 10, 2014 by NERVAfan

[cantab]

I'm happy with the change. Now the ions are finally usable. If we have to sacrifice a bit of realism for gameplay I'm fine with that. Not a lot of point in having an engine you're never going to use (looking at you M55).

I've used it. As mentioned, it's suitable for augmenting a Mainsail. It won't make the Isp any worse, and it's one part versus at least three if you want to radially mount a regular engine (engine itself, fuel tank or similar to mount it on, and fuel line to run it off the main tank).

With the Mark 55 and for that matter the 24-77, you're "paying" for the convenient form factor. Unfortunately it's too big a price for landers where they'd otherwise be good. I wouldn't mind seeing their vacuum Isp's buffed, but with relatively low TWR to take account a bit of the weight savings by not needing radial attachment structure. (Actually the 24-77 has *high* TWR if Wiki figures are right: Excluding ARM engines, it's 3rd after the 48-7S and the Mainsail.)

[Levelord]

I don;t understand why not? Do you mean it would overheat?

I thought the problems with ground-launch NTRs were low TWR and nuclear-phobia.

What nuclear waste? A solid core NTR like the NERVA does not emit radioactive materials, it emits plain hydrogen (or water or whatever, but that gives you less Isp) that is merely heated by the nuclear reactor (thus "nuclear thermal"). If radioactive stuff is coming out the exhaust something is very seriously wrong (that's how I unerstand it anyway). EDIT: apparently erosion of the reactor elements can cause this problem. But again it's a problem -- an NTR is NOT supposed to do this!

I've heard of a gas-core NTR that would emit uranium, as would an Orion drive or nuclear-salt-water-rocket (a Robert Zubrin concept which is basically an Orion without the pusher plate and with a continuous nuclear explosion rather than a series of nuclear bombs). But not a NERVA style NTR.

EDIT: here's a pretty in-depth description of different NTR types. (The person who wrote this posts here as nyrath)

http://www.projectrho.com/public_html/rocket/enginelist.php#ntrsolidcore

I think ground launch NTRs have such a low TwR that they can't lift payloads out of the atmosphere Earth or Mars, and yet NERVAs on Duna can. That's besides the point, I'm not arguing about the NERVA engines being overpowered and not conforming to real life and whatnot.

I'm using NERVAs as an example of an engine that is pretty much in the same boat as ion engines as far as realism is concerned, since those people want to argue about the realism side of things. Those two engines don't conform to their real life counterparts and are purely made to fit into the game of KSP, it's unique scale of bodies and the physical laws in the game.

It's been established that the ion engines have an increased fuel consumption to compensate for the increased thrust, effectively normalizing the dV. They are capable of landing on low gravity bodies, but still cannot replace the usefulness of already conventional rocket engines for landing and takeoff. The final point of realism is questionable, since KSP is not Orbiter, but that alone is still not a justification for a nerf. All in all, I am going to have to side with SQUAD on this decision because it's balanced the ion engine very well against the other list of engines we can use. The ARM heavy engines on the other hand, I feel are a bit over the top in terms of the iSP and TwR and they either need to buff up the Mainsail to compensate, or nerf the heavy lifter.

Edited April 10, 2014 by Levelord

[NERVAfan]

I'm using NERVAs as an example of an engine that is pretty much in the same boat as ion engines as far as realism is concerned

I don't think it's even vaguely comparable realism-wise, though. The NTRs work more or less like NTRs; their thrust-to-weight isn't THAT great (about 6 to 1). I think the atmospheric Isp was lowered to make liquid fuel engines more competitive, but still... they more or less act like they should.

The ion engine doesn't act anything at all like a real ion engine. It didn't even before 0.23.5, really, the ability to land on bigger bodies with it just makes it more blatant now. A real ion engine in KSP would be a thrust-during-timewarp thing. There's not even much point calling this thing an ion engine because it's nothing like one... it's more like a VASIMR, and even then, it has way too low power requirements for thrust.

EDIT:

the thing that bothers me is that we use ions for Hohmann transfers in KSP, but that is fundamentally different from how they are used in real life (not just balanced differently). I get it; gameplay, but low thrust is kind of the point of ion engines. The PB-Ion shouldn't be NERVA-lite, why not just ditch it and put in a 'Ant Jr." or some such?

Yeah, exactly.

Edited April 10, 2014 by NERVAfan
added quote

[KASASpace]

What I really do not get at all is this:

Before 0.23.5, people were complaining how the Ion engine needed a buff,

But how afterwards, in 0.23.5, someone is now complaining that it's OverPowered?

[Levelord]

The ion engine doesn't act anything at all like a real ion engine. It didn't even before 0.23.5, really, the ability to land on bigger bodies with it just makes it more blatant now. A real ion engine in KSP would be a thrust-during-timewarp thing. There's not even much point calling this thing an ion engine because it's nothing like one... it's more like a VASIMR, and even then, it has way too low power requirements for thrust.

I've addressed this point in an older thread before the update about ion engines. You either enable time warp thrust, or you buff up the engine, because in their current state back then, they weren't practical in the game. Since the game cannot support warp-thrusting, they went for the second option. The reason why we used Hohmann transfers in KSP is also because of the time warp limitations. So I can see why the engines were changed to make up for the game engine's shortcomings.

So you want the engines to be nerfed back to their exact real life counterpart. What then? Still doesn't solve the problem of Hohmann transfers and still doesn't solve the timewarp problems and people won't use the ion engines except for those who can afford a whole day of burning. The buff is a solution to a lot of gameplay problems, your suggestion solves nothing and doesn't encourage any use of the engine except for the hardcore of hardcore people with unreasonable amounts of time.

Edited April 10, 2014 by Levelord
spelling

[KerikBalm]

"You either enable time warp thrust, or you buff up the engine,"

I want time warp thrust. A "Physics-lite" warp - no calculating structural loads, moments of inertia, etc etc.... just the normal on rails physics + F=MA calculations (note that on rails warp already supports draining resources, such as electric charge).

Buffing the engine makes it the least realistic engine in the game

FWIW I used the ion engine before the buff, as a "utility" module, not main propulsion, IRL hall effect thrusters are often used for station keeping and fine tuning orbits.

That is what I used Ion engines for - orbital adjustments, getting into exact kerbostationary orbits, fine tuning my interplanetary trajectories, etc . (although, I don't use mechjeb, which I hear allows you to get pretty precise burns and trajectories).

It wasn't too bad as primary propulsion for a tiny probe core+ 1 ion tank.

And you are still very very wrong about hohmann transfers with real life Ion Engines for most purposes.

* There is no such thing as capture kicks for interplanetary trajectories - you either complete your burn, or go sailing off into heliocentric orbit.

* Perapsis kicks only work until you get to escape velocity. You can't perapsis kick out to jupiter's orbit with an ion engine. You can perapsis kick to get out of Earth orbit, and then you're in a heliocentric orbit, and you can perapsis kick (from the perapsis of your heliocentric orbit) to get your apopasis out ot Jupiter orbit - but that is not a hohman transfer, not even close.

* once you get your apoapsis out to jupiter orbit's, you still won't be able to do a single orbital insertion burn, and it will keep flinging you off, or you'll end up diving into its atmosphere. Even using aerobraking is probably not possible, because it won't have the thrust to circularize at the apoapsis.

You don't need to do a 100% brachistichrone trajectory (indeed, as you get closer to the halfway time point, you get less and less value for additional expended propellant - but with such extremely low TWRs, the trajectory will much more resemble a brachistichrone than a hohman.

LV-Ns are realistic enough.

Ion engines could give us a very different but still realistic spaceflight experience, if we had on rails thrusting. That is what I want. I want that other type of trajectory available to us.

I don't want a super-duper-lulz-look-at-my-dV-that-I-get-to-use-to-do-standard-hohman-transfers-like-I-did-with-the-LV-N-but-I-Sit-at-the-computer-longer engine

[Technical Ben]

NTRs are as powerful as normal rockets AFAIK with some (lots in some cases) additional weight. But the weight can scale, so they are worth it for launches. Oh, quickly looking at the wiki, it says some are lighter as your fuel systems are simpler and payloads can be larger. Wiki/google knows all:

http://en.wikipedia.org/wiki/Nuclear_thermal_rocket

and http://en.wikipedia.org/wiki/Spacecraft_propulsion puts it's TTW just below liquid/solid with more ISP. So not "better" but it is a possible choice, as it is in KSP (liquid is better, but a single NTR in KSP is a simpler design, so the small loss of DV or thrust is no real concern to most).

[boomerdog2000]

What I really do not get at all is this:

Before 0.23.5, people were complaining how the Ion engine needed a buff,

But how afterwards, in 0.23.5, someone is now complaining that it's OverPowered?

Right, the people that didn't like it before are now happy and quiet. The ones that liked doing 3 or 4 hour burns are now vocal.

[jmiki8]

Gameplay>Realism

[Jouni]

NTRs are as powerful as normal rockets AFAIK with some (lots in some cases) additional weight. But the weight can scale, so they are worth it for launches. Oh, quickly looking at the wiki, it says some are lighter as your fuel systems are simpler and payloads can be larger. Wiki/google knows all:

http://en.wikipedia.org/wiki/Nuclear_thermal_rocket

and http://en.wikipedia.org/wiki/Spacecraft_propulsion puts it's TTW just below liquid/solid with more ISP. So not "better" but it is a possible choice, as it is in KSP (liquid is better, but a single NTR in KSP is a simpler design, so the small loss of DV or thrust is no real concern to most).

They may not scale up for larger engines. The biggest nuclear reactors ever built have been something like 4 GW thermal, while rocket engines go way beyond that. According to the Wikipedia, the power output of Saturn V first stage was about 162 GW, or 32.4 GW per engine.

[karolus10]

I like new ions trust, but their energy requirements is rather silly if You can use few batteries to provide enough electric power for lunar landing... that's how I feel about it.

I would even give their old specific impulse back, but make them use adequate amount of power.

Edited April 10, 2014 by karolus10

[Technical Ben]

They may not scale up for larger engines. The biggest nuclear reactors ever built have been something like 4 GW thermal, while rocket engines go way beyond that. According to the Wikipedia, the power output of Saturn V first stage was about 162 GW, or 32.4 GW per engine.

But no one is talking about liquid Saturn V engines for Luna/Muna or Mars/Duna landings and take offs. So that's a strawman if an argument against them in game. In game, they are rather much like their real counterparts. Not as powerful as liquid engines, but more than enough for actual flight on small planets (up to 30:1 TWR) in real life and in game. If it could ever be done for an earth launch would depend on both size and how much you can "spam" them. Of cause we can do so in sandbox mode.

[makinyashikino]

Honestly, people need to relax about this. Nobody is pointing a gun to your head forcing you to use the new Ions. If you are, great good for you. If you aren't because they are too OP, then either A) Don't use them or Limit their thrust. If you're complaining that you could use them in a lander or land on other bodies with them, then DON'T USE THEM TO LAND ON OTHER BODIES THEN. People are getting very passionate over something very simple. Obviously it's not realistic, but nothing in the game is realistic, Kerbin is not even as big as Earth's moon, aerodynamics allow for perpetual motion machines. Orbital Decay doesn't exist, etc. If you seriously have a problem with the way other people are enjoying their single player game, then you have a mental disability.

[NERVAfan]

I don't actually mind the increased thrust, as such... it lets you do the same stuff faster, and from that perspective it's a good thing. But it's a step away from the fix I would like: thrust-during-timewarp, low-thrust ion engines.

I've addressed this point in an older thread before the update about ion engines. You either enable time warp thrust, or you buff up the engine, because in their current state back then, they weren't practical in the game.

Well, I didn't think that was the case, they worked fine for me... for niche applications, yes, but they're niche anyway since LV-Ns can get you everywhere in the scaled-down Kerbol system.

There's not much point in having ion engines in the game, given that scaled down system and the availability of LV-Ns, unless you get to use the different kinds of trajectories real ion engines use.

Since the game cannot support warp-thrusting, they went for the second option.

But it can, it's been done in mods (Orbit Manipulator Series and -- I think -- KSP Interstellar's solar sails).

"You either enable time warp thrust, or you buff up the engine,"

I want time warp thrust. A "Physics-lite" warp - no calculating structural loads, moments of inertia, etc etc.... just the normal on rails physics + F=MA calculations (note that on rails warp already supports draining resources, such as electric charge).

Buffing the engine makes it the least realistic engine in the game

Ion engines could give us a very different but still realistic spaceflight experience, if we had on rails thrusting. That is what I want. I want that other type of trajectory available to us.

I don't want a super-duper-lulz-look-at-my-dV-that-I-get-to-use-to-do-standard-hohman-transfers-like-I-did-with-the-LV-N-but-I-Sit-at-the-computer-longer engine

Exactly. Not only is the time warp thrust engine more interesting, the current ion engine is kind of out of line with the other engines. The KSP solar system is scaled down, but the physics is all pretty much realistic allowing for simplifications (except the atmospheric drag model which I hope is still a placeholder). The planets may be "too small", but their surface gravity is still right for their mass and radius, etc. The rockets mostly work like real-world rockets ... simplified, of course (only one kind of liquid fuel), and they're too heavy because of the scaled down system, but things are pretty close to right.

And then you have the ion engine way off by itself in totally-unrealistic-land. It shouldn't even be called an ion engine.

(The old ion engine had this problem too, though. Again, my only real complaint is that the change seems to make us less likely to get a real ion engine.)

[KerikBalm]

Am I th only one whom is reminded of the pro-ARM arguments on this thread?

Strawman arguments of "why do you care how other people play" and "if you don't like them, don't use them"

[Himynameisjake]

Have you ever had to sit through 20min of 4x physwarp transferburn?

Neither have I and that's the problem here. It simply takes too long to go anywhere with the old stats, so people don't use them.

I did, it was fantastic. Check it out from my grand tour (in my sig).

[Northstar1989]

They may not scale up for larger engines. The biggest nuclear reactors ever built have been something like 4 GW thermal, while rocket engines go way beyond that. According to the Wikipedia, the power output of Saturn V first stage was about 162 GW, or 32.4 GW per engine.

You're right- nuclear reactor designs large/powerful enough for ultra-heavy lifters like the Saturn V haven't ever developed before. That doesn't mean they CAN'T be developed- just because something hasn't been bothered with doesn't mean it is impossible...

Of course, at the weight and power levels of a heavy lifter, you're MUCH better off just building a really, really big array of smaller nuclear reactors (existing designs, instead of developing an entirely new one for space) on the ground near a launchpad, and beaming the thermal rocket power for a thermal receiver (essentially a big heat-exchanger) via microwave beamed-power.

And no, I'm not just talking about a strategy you can use in KSP-Interstellar: this exact plan has been proposed in real life. The rectennas (no, that's not a typo) necessary for microwave-based wireless power transfer have been around since 1964, the means to produce the necessary microwaves at high efficiency and low cost since 2005 with breakthroughs in gyrotrons...

In fact, the first demonstrated use of a rectenna was in aerospace- with the powering of a small model helicopter by microwave beamed-power in 1964...

http://en.wikipedia.org/wiki/Beam-powered_propulsion

Regards,

Northstar

P.S. If you didn't see my hyperlink in the article, I've actually used an array of really, really large of ground-based fission reactors (4.5 GW thermal power EACH- with pebblebed reactors, a next-generation technology currently in development) for microwave-powered launch vehicles in KSP already. I used 18 GW of ground-based reactors (raw thermal power) which generated around 5.4 GW of electricity, which equated to around 1.8 GW of power reaching the receiver over a distance of 5.4 km at sea-level (the microwave beamed-power system simulated in KSP-Interstellar is short-wavelength, as longer wavelengths require much larger receivers- even if they are much less affected by atmosphere).

http://forum.kerbalspaceprogram.com/threads/57509-Kerbin-and-Beyond-a-Maturing-Space-Program?p=1184839&viewfull=1#post1184839

It's true, I did assist the launch vehicle with four heavy (Novapunch2) aerospike engines; as well as 8 smaller radial boosters in the launch shown- but the technology is perfectly viable in KSP as well as in real life (in real life, proposed thermal receivers for thermal rockets are MUCH cheaper than rocket engines...) And with more thermal power, one could easily scale a 3.75 meter thermal receiver like that (which would be even larger in real life due to KSP's 64% scale) to use at least 10-12 GW of beamed power (which would equate to upwards of 30 GW electrical generation capacity on the ground- more electrical generation than some small countries, so the greatest challenge would be acquiring funding to build such a large array of nuclear reactors...)

Edited May 31, 2014 by Northstar1989