Most realistic way to *MOD* Kerbin to mimic Earth?

[Northstar1989]

After trying to calculate impact damage from a predicted asteroid impact with Kerbin, and starting a thread about how gigantic Kerbals are; I got to thinking- what would be the most realistic way to scale up Kerbin to mirror Earth?

I started a thread about this earlier under "General Discussion", but somehow it ended up getting moved by a mod to "Suggestions and Development Discussion", and then closed by another mod- as this is on the list of things to not suggest be implemented in the stock game.

To any moderator reading this, let me be VERY clear: this is about how to MOD the stock game to reflect the real solar system (using mods such as "Real Solar System", or new ones not yet invented). This is *NOT* about implementing it in any way, shape, or form into the stock game maintained by Squad. Therefore, it is NOT appropriate to close this thread, as it is NOT suggesting these changes be made to the stock game (I am well aware of the reasoning for it in the stock game).

I can see several (potentially equally valid) lines of thought here on how to achieve the desired effect with modding:

(1) Scale up Kerbin to the real-world parameters of Earth, like is done in the classic version of the "Real Solar System" mod configs... This sets orbital velocity (which is then much higher, though gravity acting on spacecraft remains the same, due to the greatly reduced curvature of the larger planet) and atmospheric height to the correct values, but leaves the interesting problem that all KSP parts are meant to be at approximately 64% scale of their real-world counterparts, and the Kerbals themselves are approximately 40% the size of humans...

However, this makes it virtually impossible to build rockets that perform on par with their real-world counterparts (without a procedural parts mod), as, in extremely over-simplified terms, the Delta-V of a rocket is essentially determined by its burn-time: which is determined by its height (ignoring variances in ISP for a moment), whereas the height-limit of a rocket is (for structural/stability reasons) essentially determined by its width... Since KSP parts are only to 64% scale, in a real world-sized game, it is impossible to build rockets as large and effective as could be achieved with comparable real-world technology.

(2) Scale up Kerbin by a 1:6.4 scale ratio (as is currently done in a popular alternative config version of "Real Solar System"). This preserves the relationship between the size of KSP parts, and the size of the planetary radius- but sets the Delta-V to orbit as much lower than in the real world, due to the shorter atmosphere and reduced planetary curvature... Still, these values would seem to be best-balanced, and lead to the most similar performance of KSP rockets to the real technologies they are miniatures of- as the performance of a rocket is heavily influenced by the relationship between its burn-time (and thus height) and the Delta-V to orbit..

(3) Scale up Kerbin by an approximately 1:4 scale, so as to preserve the relative size of an individual Kerbal vs. the planetary radius. While it doesn't make a tone of sense from a game-balance perspective, it does from a realism perspective: it might seem more plausible that Kerbals (if they are supposed to emulate humans) simply build relatively larger rockets compared to their body-size than humans, than that Kerbals are smaller compared to their planet than humans (which would be the effect achieved with either of the other scale-ups...)

One thing is clear between all the options. Kerbin DOES need to be made larger in order to create more realistic (and also, coincidentally, harder) game balance. The question is, by how to most realistically achieve it with mods (as Squad has declared they will NEVER change the scale...)

I'd like to hear what you guys all have to say about the issue. I'm guessing you'll all lean towards (1)- simply setting the parameters to real-world values: but as I've stated, that creates major problems with Kerbal rockets only being to 64% scale. With such a re-scaled planet, you are forced either to have unrealistically restrictive limits placed on rocket size (from an engineering perspective- economic/financial costs be darned) that prevent them from performing as well as comparable real-world technology; or you install mods that let you build at a real-world scale (such as Procedural Parts), but then have the opposite problem instead- 6.4 tons of payload in things like electronics and orbital labs can do all the same things that would require 10 tons in real life... (thus meaning Kerbal rockets then essentially out-perform real world rockets with mods allowing 100% scale rocket-construction).

Regards,

Northstar

Edited May 18, 2014 by Northstar1989

[Northstar1989]

By the way, I'm afraid some of you may still not end up understanding what I mean by 64% scale rockets under-performing 100% scale rockets- so let me give an example:

Say you have a simple rocket that is a fuel tank 2.5 meters wide and 6.4 meters tall (for a total volume of 125.6 cubic meters) with an engine underneath that consumes 1 cubic meter of fuel per second, producing 1000 kN of thrust (these numbers are arbitrary- to have a standard for comparison). This is the KSP-scale rocket.

Now let's say you have another simple rocket that is a fuel tank 3.90625 meters wide and 10 meters tall (for a total volume of 479.12598 cubic meters) with an engine underneath that consumes 2.441 cubic meters of fuel per second, producing 2441 kN of thrust (this engine has precisely the same thrust per square meter of area on the bottom as the first one).

The first rocket of the two is a precisely 64% scale version of the second. It has the same ration of height to width. The same ratio of thrust to cross-sectional area. And the same ISP. Yet, it will have a shorter burn-time for the engine than the 100% scale rocket (125.6 seconds vs. 196.3 seconds), and thus in vacuum, a reduced Delta-V... It's only advantage is that it would produce more thrust per cubic meter of fuel stored- and thus might have a higher TWR...

It doesn't take a genius to figure out the larger rocket probably has the advantage of the two, at least if both rockets start from orbit...

Lifting off from the surface of Kerbin/Earth, things get a little more complex due to aerodynamics and drag- but since Real Solar System and other re-scales don't change the actual gravity exerted by Kerbin/Earth (only the density of the planet), only the planetary curvature (and thus, speed necessary to achieve orbit) and atmospheric height (which effects the minimum stable orbital height, as well as time spent in-atmosphere, experiencing drag) are actually altered...

But, since the 100% scale rocket is taller relative to its mass, it out-performs its 64% miniature aerodynamically, and will experience less drag relative to its mass in a FAR-like aerodynamics system (I can only assume anyone playing with RSS would play with FAR as well) and thus will ascend through that higher atmosphere with relatively less issue...

The question then remains- which is the more "realistic" re-scale then: a 1:10 re-scale that brings Kerbin up to approximately Earth-size (and atmosphere heights and planetary curvatures), or a 1:6.4 re-scale, which maintains the ratio of the size of equivalent rocket technology to its real-world relationship with planetary radius, but consequently still has a lower atmosphere height and higher planetary curvature (and thus decreased orbital speed) than real-world Earth?

Regards,

Northstar

P.S. At times like these, I just wish Squad had given us an Earth-sized planet and real-world sized rockets to begin with, instead of messing around with a 10% scale planet and 64% scale rockets... (which, in stock game, drastically out-size real rocket technology in size comparison to the planetary radius)

P.P.S. I am quite clear on their reasoning for not doing so (quicker rocket launches), however- let me be VERY clear to any moderator reading this, I am NOT suggesting a change, only voicing a bit of discontent in a post-script here...

[Superfluous J]

I believe the easiest way is to use the RSS (Real Solar System) mod, along with DRE (Deadly Re-Entry) and FAR (Ferram Aerospace Research).

If you're curious how it works I suggest checking out

.

EDIT: I see you know about RSS. I skipped over the disclaimer as I'm not a moderator

Do you know about regex's 6.4:1 project? May be exactly what you're looking for.

Edited May 18, 2014 by 5thHorseman

[Pecan]

THE way to mod KSP to mimic Earth is:

No.

I can't do it.

Woody Allen was asked if he was like the neurotic, much-troubled characters he often portrayed. In reply he said "I don't have lots of problems, I only have one. The only problem I have is that I'm not someone else"

Orbiter is realistic-ish.

There are probably a lot of ways to simulate 60-year-old technology from a different universe.

Which doesn't help; but are you sure you want to start from here?

[undercoveryankee]

If you want to combine KSP's snap-together rocket building with real-scale speeds and distances, my preference would be to combine RSS with something like Real Fuels that scales your tank and engine masses to realistic values.

[Geschosskopf]

After trying to calculate impact damage from a predicted asteroid impact with Kerbin, and starting a thread about how gigantic Kerbals are; I got to thinking- what would be the most realistic way to scale up Kerbin to mirror Earth?

Play Orbiter, not KSP.

[Vanamonde]

Since this thread is clearly about mods and not the stock game, it will not be innappropriately closed. It will, however, be appropriately moved to Add-on Affairs, where mod maters are discussed.

[cantab]

I don't think you can simply rescale Kerbin and have a very realistic experience, because the stock parts aren't just uniformly above or below real life. The rocket engines are underpowered and the tanks too heavy, but then the jets are overpowered and the fuel lines are godly. The stock aerodynamics are draggy but they let you make crazy moves without losing control or destroying your rocket, while the EVA packs can get you literally anywhere if you've enough patience.

[Guest]

what would be the most realistic way to scale up Kerbin to mirror Earth?

IMO you can take two approaches:

1. Mirror Earth, as you say. Just rescale Kerbin to match Earth's average radius, move it to Earth's semi-major axis, scale everything else up by the same factors. You may to fudge a bit in order to ensure realistic values for other planets.

2. Kerbol has a temperature, according to the Wiki, the matches a K-type star, so rescale Kerbol to match a nice K star, move Kerbin smack dab in the middle of the habitable zone, then rescale everything else's SMA by the same factor. You then have some choices to make as to how to scale the planets, but at least you have an okay starting point.

It's interesting to note that, if you take approach #2, scaling up Kerbin's SMA by 6.4x actually places it in the habitable zone for a K type star. This is the approach I will be taking with future version of 6.4:1 Kerbin for RSS (currently Kerbol uses G2V stats) even though the planets will be scaled up to match 6.4x their original and the densities altered to retain their current gravities.

Another thing I've personally been considering is running a ton of iterations of Accrete on K class stars until I find something approximating the Kerbin system, but Accrete doesn't do well with moons so I'm a bit out of my league once the planets have been arranged. Also, time and energy.

[Northstar1989]

Play Orbiter, not KSP.

I prefer KSP's snap-together rocket building- I just want it to be a bit more realistic.

As I understand it, Orbiter only allows you to re-create real life missions... I have no interest in a game that so limits my creativity...

Regards,

Northstar

[cantab]

Orbiter allows you to do anything that's within the capabilities of the craft. It's just that making more capable craft is considerably harder than in KSP, being more akin to making a parts mod for KSP.

[Northstar1989]

I believe the easiest way is to use the RSS (Real Solar System) mod, along with DRE (Deadly Re-Entry) and FAR (Ferram Aerospace Research).

Deadly Re-entry has nothing to do with actually having a realistic planet. It does implement a re-entry heat system, but that's an entirely separate issue...

If you're curious how it works I suggest checking out

.

I wanted to barf after watching the first video. Lorenzo clearly doesn't remember how to play KSP anymore (SRB's in the upper stages, seriously?), and it's extremely annoying...

EDIT: I see you know about RSS. I skipped over the disclaimer as I'm not a moderator

Do you know about regex's 6.4:1 project? May be exactly what you're looking for.

I was aware of the 1:6.4 re-scale config for RSS (I mentioned it in the OP), but not his campaign system. Once again, not really relevant to having an actually realistic planet though.

If he can get the alternative launchpads working, however, I might still look into it so as to set up permanent alternative launch sites in the mountains and at different latitudes, so as to allow high-altitude launches and launches directly into inclined orbits... Once again, though, his campaign system is not really relevant to the thread topic...

Regards,

Northstar

[Northstar1989]

Orbiter allows you to do anything that's within the capabilities of the craft. It's just that making more capable craft is considerably harder than in KSP, being more akin to making a parts mod for KSP.

It's not really a standard part of the game, as I understand it. I'll stick with KSP, rather than wasting more hardisk space for such a restricted and unimaginative game, thank you very much...

I don't mean to be abrasive- but I don't even see why anybody would actually *like* Orbiter. The game has nothing truly creative about it- it's just an attempt to re-create history exactly as it happened more or less... (with all the mistakes we've made in real life) The system for designing *new* rockets and mission is vastly inferior to KSP.

Regards,

Northstar

Edited May 19, 2014 by Northstar1989

[NathanKell]

Well, I'm surprised Realism Overhaul hasn't been mentioned yet, since it exists to make 100% real scale, real mass parts for an RSS install.

My main goal for the last, ooh, almost a year now, has been to make a KSP-Orbiter fusion. While I do think you're wrong about Orbiter (there are *tons* of user-made vessels for it, only a small portion being real, most being near-future, imaginary, what-ifs, etc; and you can basically create any mission plan you like, just like KSP) it *is* a far more limited sandbox than KSP in terms of construction and in terms of actual activity in space other than flight.

So yeah. RSS is part of that mission, but part and parcel with RSS (due to exactly the issues you mention regarding square-cube rule, etc) comes Realism Overhaul.

And regarding alternate launchpads--have your *tried* RSS 6.1? It's been working for weeks, and manually doing it has been working since *February*.

[Northstar1989]

Well, I'm surprised Realism Overhaul hasn't been mentioned yet, since it exists to make 100% real scale, real mass parts for an RSS install.

The problem I can foresee with that, is it assumes you're only playing with stock parts...

I play with a lot of mods that add their own fuel tanks and engines, such as KSP-Interstellar (adds a set of methane-burning engines and methane fuel tanks), NovaPunch2 (adds a whole set of larger-diameter engines and fuel tanks, as well as some unique landing legs, command modules, and reaction wheels), NearFuture mod (adds several futuristic propulsion systems, as well as solar panels, etc.), and B9 Aerospace (adds a variety of spaceplane parts and airplane/spaceplane engines)

My main goal for the last, ooh, almost a year now, has been to make a KSP-Orbiter fusion. While I do think you're wrong about Orbiter (there are *tons* of user-made vessels for it, only a small portion being real, most being near-future, imaginary, what-ifs, etc; and you can basically create any mission plan you like, just like KSP) it *is* a far more limited sandbox than KSP in terms of construction and in terms of actual activity in space other than flight.

I already find stock KSP to be too limited of a sandbox, without things like In-Situ Resource Utilization (aka. "Resources"), budgets (*yet*), or missions/contracts (once again, *yet*). Therefore, Orbiter doesn't appeal to me at all.

So yeah. RSS is part of that mission, but part and parcel with RSS (due to exactly the issues you mention regarding square-cube rule, etc) comes Realism Overhaul.

I'm leaning towards simply using a 1:6.4 scale-up when I start my next Career game (it will be a good point to add in and remove mods...) There are simply too many things which I can't imagine it having accounted for...

Aside from mod parts, there's also the issue of resource production and consumption rates, for instance. Larger rockets should consume resource (for instance, electricity for ion engines- which should be consumed 2.44 times faster for an engine with a 64% larger radius) at a faster rate, yet unless they scale up the corresponding production rates as well (for instance, electricity production from solar panels would also need to increase 144%, to correspond with a 144% increase in panel area- 56.25% more across both length and width of the PV rectangles to bring them from 64% to 100% scale)

And, to return to mod parts, what about mods that introduce procedural parts, but set hard limits on their maximum size- for instance StretchyTanks? (I don't know if you removed some of those limits in StretchSYB's or Procedural Parts)

The more I think about it, the more a 1:6.4 scale-up sounds easier and more realistic...

And regarding alternate launchpads--have your *tried* RSS 6.1? It's been working for weeks, and manually doing it has been working since *February*.

When I checked the thread about the 1:6.4 scale-up campaign, it said something about the alternate launchpads spawning atop 2 km high cliffs due to not spawning at normal terrain height. I would certainly not consider this to be fully "working"...

Regards,

Northstar

[Northstar1989]

Well, I'm surprised Realism Overhaul hasn't been mentioned yet, since it exists to make 100% real scale, real mass parts for an RSS install.

Annndddd, I went and checked the Realism Overhaul release thread linked to in your signature...

Stock parts are 64% of real-world scale, but your new size system lists "0.5m, 1m, 2m, 3m, etc." How is REDUCING the size of already smaller-than-reality parts bringing them up to 100% real size?

If anything, you've only made the problem WORSE, by making the parts smaller than they already were (assuming the 0.625 meter parts were scaled down to 0.5 m, the 1.25 m to 1m, etc...)

Regards,

Northstar

[Accelerando]

Play Orbiter, not KSP.

How dare somebody propose to modify some aspect of their copy of a game you like to suit their enjoyment. It's completely inconceivable that changing the character of the gameplay to be harder and more complicated would make it more fun to people who enjoy difficulty and complexity.

on topic, Realism Overhaul doesn't just assume you're playing with stock parts, as there are rescales and tweaks for novapunch, KW, etc... and it definitely works with stretchy tanks

true Interstellar should have a rescale + tweak as well

and, on the subject of orbiter, if it's so unimaginative and unpalatable then what is any flight sim? the point is that you live through the joy of the mission, which requires some roleplaying yeah, so indeed KSP is a more visceral experience as you more directly express your own desire in your creation. orbiter has a place though, as long as you love the history, or the fun of flight.

[NathanKell]

Northstar1989: Wow, it would really help if you actually read all the opening posts, maybe even (gasp) tried stuff out, and didn't jump to (wrong) conclusions.

Had you done so, you would have seen that RO supports a *ton* of mod parts; that the 0.5m/1m/etc refers to *node* sizes, not part sizes (the Saturn V 5-engine part is in fact 10m in diameter); that far from not supporting them, Realism Overhaul requires StretchyTanks or Procedural Parts so you can have propellant tanks exactly the size you wish; and so forth.

Further, you would have found that rather than using some simplistic scaling algorithm, RO gives solar panels exactly the W/M^2 they should have (based on a judgment about their technology level), that the RealEngines version of engine configs gives engines real performance (looks like an F-1? Has the stats of an F-1), that RO scales the Mk1 pod into the Mercury it resembles, down to its mass, battery capacity (and use rate in watts), etc., and so forth.

Edited May 21, 2014 by NathanKell

[Guest]

The more I think about it, the more a 1:6.4 scale-up sounds easier and more realistic...

Uh... I specifically made that config file because I wanted a bit less realism than RSS Earth.

When I checked the thread about the 1:6.4 scale-up campaign, it said something about the alternate launchpads spawning atop 2 km high cliffs due to not spawning at normal terrain height. I would certainly not consider this to be fully "working"...

It really depends on how the launch sites are defined. If you want to try your hand at defining some, be my guest; they take some fine tuning. I have the exact same issues with RSS Earth when creating a new launch site and it really has nothing to do with the mod itself, but KSP.

BTW, chill, people are trying to help you out here. If something doesn't fit your needs there's no reasons to get all bunched up about it.

[Hodo]

I can say this.

I played with Realism Overhaul, RSS Real Earth system, AJE jets, FAR, DRE, Engine restarter/ignitor, and a whole slew of other mods including real fuels, and such. Most of the mods I used and still use are in my sig. You can go to 95% real or to 60% real or less if you are so inclined. There is no reason to come off as a pretentious prick.

If you want full hardcore as close to 100% as you can so you can prove to yourself that you are not a complete useless waist of carbon, then so be it, don't let your self doubt and loathing rain down on others.

And most importantly, have fun.

[Northstar1989]

Uh... I specifically made that config file because I wanted a bit less realism than RSS Earth.

Perhaps, but as it turns out on more careful investigation, for rockets, the more important parameter is their size relative to the planetary radius.

Without doing any re-scaling of the rockets, you get more realistic gameplay, in terms of balance being like in real-life with a 1:6.4 scale-up, than with a 1:10 scale-up.

I say *with rockets* because the velocity curves of the jet engines in the game being what they are, spaceplanes will drastically outperform their (theoretical) real-world counterparts even while rockets perform much the same as in real-life in a 1:6.4 scale-up...

Regards,

Northstar

[NathanKell]

Uh, no, the most important parameter is ballistic coefficient, since that's (one of) the things that's messed up in stock KSP, and that's why trying to use real masses with not-real surface area will break.

Also, check my post at the end of the last page, you might have missed it.

[Northstar1989]

Uh, no, the most important parameter is ballistic coefficient, since that's (one of) the things that's messed up in stock KSP, and that's why trying to use real masses with not-real surface area will break.

Also, check my post at the end of the last page, you might have missed it.

Yeah, it appears I did miss a few posts. I'm not sure how- though I think part of the problem might have been having so many tabs open at once (I've been doing a *LOT* of background reading on the efficiency and mechanics of jet engines in real life- of which I previously knew almost nothing. Luckily, I'm a huge sponge for information, with my sky-high IQ... If only that applied quite so well to social skills...), as well as an anti-virus scan, a calculator application, and an annoying pup-up or two in separate windows...

I now know that (surprisingly) the stock engines are actually quite realistic- real world turbofan engines really do act like they have ISP's in the tens-of-thousands (29,000 m/s effective exhaust velocity is the generic figure for a turbofan engine on Wikipedia: the stock turbojet acts like it has an effective exhaust velocity of 40,000 m/s), due to all the inert air they accelerate through them- but I managed to miss quite a few relevant posts on my own thread...

Regards,

Northstar

[Northstar1989]

How dare somebody propose to modify some aspect of their copy of a game you like to suit their enjoyment. It's completely inconceivable that changing the character of the gameplay to be harder and more complicated would make it more fun to people who enjoy difficulty and complexity.

Hey, lay off Geschosskopf. He's growing to become a good (virtual) friend of mine, even through the course of arguments about the feasibility of interplanetary colonization, and the fate of humankind... And, I rather respect his work on the Flying Duna Challenge (even if I can't agree with *all* his judgments- like disqualifying one of my spaceplanes from SSTDABK for an in-flight refueling while on escape trajectory from Kerbin), and the Kethane Traveling Circus... It doesn't hurt he's kicked a few reputation points my way either...

on topic, Realism Overhaul doesn't just assume you're playing with stock parts, as there are rescales and tweaks for novapunch, KW, etc... and it definitely works with stretchy tanks

Not precisely. It says right on the release page for Realism Overhaul that the compatibilities for quite a few of those mods are "partial"...

It also turns out it requires quite a few other mods- including one in particular that I have some issues with, and refuse to play with until it's fixed, "Advanced Jet Engines" mod- which makes the MAJOR mistake of nerfing jet engine ISP, even though it turns out it's actually quite (surprisingly) accurate/realistic... (the TWR's on the other hand, are insanely OP'd)

true Interstellar should have a rescale + tweak as well

My favorite mod of all time. One more reason for me not to use Realism Overhaul.

and, on the subject of orbiter, if it's so unimaginative and unpalatable then what is any flight sim? the point is that you live through the joy of the mission, which requires some roleplaying yeah, so indeed KSP is a more visceral experience as you more directly express your own desire in your creation. orbiter has a place though, as long as you love the history, or the fun of flight.

Flight Sim's aren't really to my tastes either- and I simply can't understand why anyone would play them.. I was always a kid who grew up playing Legos. These days, I enjoy games like KSP and Minecraft- not a game where everything's already been planned for you ahead of time...

Regards,

Northstar

[Northstar1989]

Uh, no, the most important parameter is ballistic coefficient, since that's (one of) the things that's messed up in stock KSP, and that's why trying to use real masses with not-real surface area will break.

I've dedicated quite a bit of discussion to that already. Although I'm not an engineer in real-life (I'm a biologist), and had to just look up "ballistic coefficient", it's precisely what I was describing all along... The problem is, 64% scale rockets have a lower ballistic coefficient than real-scale rockets, due to their not being as tall/long...

http://en.wikipedia.org/wiki/Ballistic_coefficient#Formula

It can be clearly seen right in the second version of the formula: ballistic coefficient is proportional to body-length times density. A 64% scale rocket is 64% as tall, while having the same density (in theory- in reality, KSP densities are also all messed up...)

Also, check my post at the end of the last page, you might have missed it.

Indeed I did. I'll take a look.

Regards,

Northstar