the ion engine is way too OP

[Jouni]

The reason why the Merlin engine is good for SpaceX is not that its technical performance is better than older engines. And although it is worth the effort, the positive effect on launch cost is marginal.

The bottom line is that for the time being we're essentially stuck wrt launcher technology.

You are mistaking academic performance with technical performance. Engineering is not about improving arbitrary specifications of products, but improving them in ways that are relevant in the real world. The Merlin is technologically superior to most other engines in use, because it achieves similar performance with a simpler and cheaper design.

[Jouni]

True, we're basically working on commoditizing existing technology.

I always to that in KSP, when I get docking ports in career mode. After that, rockets get demoted to lifting stuff to LKO, and simplicity, maneuverability, and reliability become their main design goals.

[maccollo]

You are mistaking academic performance with technical performance. Engineering is not about improving arbitrary specifications of products, but improving them in ways that are relevant in the real world. The Merlin is technologically superior to most other engines in use, because it achieves similar performance with a simpler and cheaper design.

Well yes, engines can become cheaper by simplifying the design and construction and by using more advanced methods to create them. I think this goes pretty well with later engines being balanced with older engines efficiency wise, but being cheaper per unit of mass.

[LostElement]

Ok, just stop the OP? Just edit the .cfg file for your liking.

[rkman]

You are mistaking academic performance with technical performance.

We have different definitions of those terms.

Engineering is not about improving arbitrary specifications of products

I'm not saying that it is.

I suppose "technical performance" is not the right term for what i mean. I do mean "specifications" - though i'd say those are not arbitrary, since they do affect economical performance.

I refer to 'technical performance' (specifications) because it was claimed elsewhere in this thread that the Merlin is better than older engines because it has lower twr. I pointed out it also has lower Isp, so overall its 'technical performance' is not superior to older engines.

Smart move to basically have one engine to meet thrust requirements for all kinds of lifter stages, makes it more worth it to invest in refinements, and benefits from mass-production.

But it is a marginal improvement compared to the sort of increase in both economical- and technical performance that one would like to have.

I'm pretty confident that any significant improvement is not going to come from economics, business model, free market nor engineering, but from science - if at all. Maybe nano tech materials.

[Hans Dorn]

Lifting stuff with jet engines works remarkably well in KSP. Would this be an option in real life?

Cheers

Hans

[Superfluous J]

...it was claimed elsewhere in this thread that the Merlin is better than older engines because it has lower twr. I pointed out it also has lower Isp, so overall its 'technical performance' is not superior to older engines...

I did an end run around the whole TWR and Isp and actually attached the engines to ships. I could not find an engine or a combination of engines that had both better TWR and better dV than either of the new engines. I did not test the "LFB" engines as they also contained their own fuel so it'd not be perfect.

Using the LV-N I could get better ISP. Using enough of other engines I could get better TWR. But I could never, ever get both to be better. No other engines can say this. They're demonstrably, real-Kerbin demonstrably better than every other engine.

Note: I don't think this is a bad thing, but it's not a matter of opinion. It's a fact: In every single situation where you have mainsails or skippers or poodles*, or groups of 4 of the mid sized engines, you'd be better off simply replacing them with either of the 2 new engines.

*I include Poodles for completeness. Of course they're worse than the new engines. They're worse than the old engines

Edited April 5, 2014 by 5thHorseman

[Jouni]

I did an end run around the whole TWR and Isp and actually attached the engines to ships. I could not find an engine or a combination of engines that had both better TWR and better dV than either of the new engines. I did not test the "LFB" engines as they also contained their own fuel so it'd not be perfect.

Turbojet is still the most fuel-efficient choice for a first stage engine, unless you are lifting very large payloads. It takes some skill to use them effectively, but you can build SSTO rockets with payload fraction over 40% with them. With the new 3.75 m fuel tanks, you can easily use 12 radially mounted turbojets and 6 inline RAPIERs, allowing you to use the simple jet-boosted rocket design for 60-tonne payloads.

[Superfluous J]

Turbojet is still the most fuel-efficient choice for a first stage engine, unless you are lifting very large payloads. It takes some skill to use them effectively, but you can build SSTO rockets with payload fraction over 40% with them. With the new 3.75 m fuel tanks, you can easily use 12 radially mounted turbojets and 6 inline RAPIERs, allowing you to use the simple jet-boosted rocket design for 60-tonne payloads.

While doing my tests I never considered jet engines. I believe this use is considered an exploit (like using landing gear as your "legs" so you can smack into the ground at 50m/s and survive) so ignore the possibility.

However that's more a indication that jet engines are even more OP than the new ones, not that the new ones aren't OP

[Jouni]

While doing my tests I never considered jet engines. I believe this use is considered an exploit (like using landing gear as your "legs" so you can smack into the ground at 50m/s and survive) so ignore the possibility.

It's not as much an exploit than a direct consequence of the fact that the turbojets are broken by design. They produce 50% more thrust than real-world supersonic jet engines of similar size with afterburner on, they are lighter than real jet engines, their fuel efficiency is extremely high (somebody claimed that fuel usage calculations compare both fuel mass and air mass against ISP), and they can be used to fly twice as fast as and at much higher altitudes than their real-world counterparts. Add this to the fact that the "twice as fast" is orbital velocity at Kerbin, and you can reach orbit almost without using any oxidizer at all.

[jwenting]

sigh, as always the same people complaining they weren't powerful enough before they were boosted are now complaining they are "overpowered"...

[Accelerando]

I remember a few years ago a friend of mine asserted that there would never be a space game with Newtonian physics that would gain any form of mass popularity. People wouldn't like that they couldn't swoop around in their spaceships as if they were WW2 fighter planes, and would therefore grow bored. I'm pleased that KSP seems to disprove the notion that space-based realism cannot also be fun. So you can probably tell that I don't care much for the "who cares if it's crazy unrealistic, it's just a game" argument.

oh, don't you even start. i love realism, and i've been arguing that same line of yours that i bolded for ages now. my point in that post however is that if you're going to justify things on grounds of realism in-game, consider that the the game, as it has been, and still is, is to a very small degree realistic with respect to actual rocket flight. much greater than Freelancer or X series for sure, but the fact is that if you're going to talk about how OP the ion engine is compared to how it was in previous releases, the ion engine really hasn't been taken that much further except to cut down wait times. we've been able to use ions to land and ascend from low gravity bodies for ages, and to fly in atmosphere for even longer.

2kN is high thrust now? good luck getting all those panels/RTGs to lift off tylo, man.

granted, it does change the potential span of mission regimes to give ions comparably high thrust to IRL stuff. but in real life with ion engines you have the benefit of not being an actual space program manager, so we can sleep while the things run. even then, in real life deep space probes run on autopilot for the duration of those burns. so low thrust doesn't have to mean babysitting your rocket for 5 IRL hours. are there other solutions to this problem? sure, squad could implement better phys warp, it's been done in mods, up to something like 100x phys warp without incurring major bugs.

but since that isn't happening any time soon i don't see it as any great injury to the game's realism to buff their thrust to ~LV-1 status. they still mass more, and if you factor in the power systems you need and the low mass ratio of the tanks there's more mass still. and we've always been able to land on minmus with them. if being able to barely land on Mun or Ike with them now is the exchange for actually making them useable to players with crappy PCs like myself in the stock game, that nearly chug on KSP to begin with, who can't just leave KSP on and do other things on their computer while waiting for their 5 hour burn to complete, then that's acceptable, personally.

and before anyone asks, "but why don't you read a book while you do it accelerando?" news flash, i'm not always in the mood for reading books/going outside/socializing/doing things that aren't video games when i boot up my computer to start a tour of my own private personal virtual cosmos

Edited April 6, 2014 by Accelerando

[NERVAfan]

I don't think the 5 hour burns are anything like the intended use, mine diving into the sun or going to solar escape velocity from a Kerbin-like solar orbit were not that long and that's way more delta-V than Kerbin to Duna. The trick was to build light, light, light.

But I don't mind the change. (I really wish you couldn't use them to land on things though.) Kerbin system delta-v requirements are low compared to real ones, and unlike real life, KSP has nuclear rockets; the combination of the two pretty much relegates ion engines to a niche role anyway.

I'd prefer super-low thrust (more like .0005 kN) but the ability to thrust during full timewarp -- it's been done in at least one mod so is definitely possible.

Barring that, well, the pre-0.23.5 ion engines were so unrealistic that the current ones aren't really much worse. And they are more accessible/fun. So if thrust-during-full-timewarp is off the table then I'm fine with them.

[NERVAfan]

Yeah, nuclear engines, now those still have a ton of improvements left. The NERVA program didn't come close to maxing that tech out.

However, those aren't launch engines, and we're talking about launch engines here. Not sure you can get a clean NTR to a useful thrust-weight-ratio for launches even with modern technology.

There's no particular reason for them not to be "clean" (assuming we're talking about solid-core NTRs and not open-cycle gas-core ones, which are totally politically and environmentally impossible, and I think are purely theoretical anyway). The exhaust is plain old hydrogen (or steam, or whatever you're using as reaction mass - but hydrogen gives the best specific impulse) not radioactive isotopes. I think the reactor elements are supposed to be under a protective coating.

EDIT: people just tend to be obsessive about radiation, and not realize how high the radiation levels they're exposed to just by living on Earth are, compared to most environmental/pollution type sources (yeah, if you're right in the Chernobyl exclusion zone, that's bad, if you're in a 50s open-air test's fallout zone, that's bad, but... living near a nuclear reactor is not unhealthy.

Fukushima was IIRC a category 9 earthquake plus tsunami -- IE a very major cataclysm in its own right. It's just silly for people living in the US (barring maybe right on the California fault line or in some parts of Alaska) or Europe to use it as any kind of evidence that reactors are unsafe -- if the US East or Gulf Coast or any part of Europe got hit by a cat 9 earthquake and its tsunami*, you'd have MUCH bigger problems than any nuclear meltdown would cause!

*The Atlantic is not completely safe from tsunamis (there was a very destructive one that hit Lisbon in 1755) but they are very much rarer, and Atlantic coast cities are NOT prepared for them, so if a big one happened it would be very, very bad.

Edited April 6, 2014 by NERVAfan

[Jouni]

The problem is with the word "nuclear". People don't believe that nuclear engines can be made safe enough in case the rocket explodes. Whether that's true or not is irrelevant.

[Red Iron Crown]

The problem is with the word "nuclear". People don't believe that nuclear engines can be made safe enough in case the rocket explodes. Whether that's true or not is irrelevant.

As I understand it, a modern medical imaging technique is called an MRI instead of an NMRI for exactly this reason.

[NERVAfan]

As I understand it, a modern medical imaging technique is called an MRI instead of an NMRI for exactly this reason.

I have heard this too.

EDIT: Maybe NASA or whoever needs to change the name of NTRs to something else. Like "High Temperature Thermal Rockets" or "Fission Energy Rockets" or something. Or make one using water as propellant and call it a "Superheated Steam Rocket".

Edited April 6, 2014 by NERVAfan

[Kerbonautical]

I was looking to test out the Ion engine today with a nice new set of probes I launched into space but....I don't appear to have them. I can't really figure that out, I'm playing stock on sandbox and they're nowhere to be found, although they used to be in the game for me.

[Merinsan]

I've done a 90 minute burn before. It sucked big time. I was using nukes for that and a huge payload.

With ion engines it would have taken days. That's not my idea of fun, so I never used them. Now I am having some ideas about using them again, so this change is a good thing in my opinion.

[Hans Dorn]

I was looking to test out the Ion engine today with a nice new set of probes I launched into space but....I don't appear to have them. I can't really figure that out, I'm playing stock on sandbox and they're nowhere to be found, although they used to be in the game for me.

They're hiding in the utility tab, not under propulsion.

Cheers

Hans

[xcorps]

I've done a 90 minute burn before. It sucked big time. I was using nukes for that and a huge payload.

With ion engines it would have taken days. That's not my idea of fun, so I never used them. Now I am having some ideas about using them again, so this change is a good thing in my opinion.

I just built a kethane probe for the Mun and Minmus. I used a probe and nothing but the long girders with 16 ion engines, 8 of the largest solar panels, and 12k in battery storage. I used a nuke to get to the Mun, it ran out of fuel about half-way.

The burn times were very reasonable, even though I borked the launch with unstable lifters and didn't properly transfer to the Mun. I did a terrible transfer to Minmus, had to make like 8 burn of 40+ seconds. I'm scanning minmus now, and I've still got enough xenon to get just about anywhere in the system. The thrust is pretty good. I'm going to put a Lab on the next on and send it to the Sun.

[Dodgey]

sigh, as always the same people complaining they weren't powerful enough before they were boosted are now complaining they are "overpowered"...

Excuse me? Can you please show me the people who have done a complete 180 on their opinion? To assert that the people who wanted to buff them are now hypercritical is just wrong.

[SSSPutnik]

Agreed, I argued weeks ago against buffing them, now I am just expressing my displeasure they got buffed anyway.

[Dodgey]

Agreed, I argued weeks ago against buffing them, now I am just expressing my displeasure they got buffed anyway.

Ok point. My counter argument is that there is always a balance, and such thing as too much power.

[tygoo7]

I prefer the ion engine like this because I don't think its fun and exciting to do a 2 hour burn IRL to Jool.