Diffiulty getting to space on KSP vs IRL

[Tortoise]

I've been wondering,

Why is it so hard to make an efficient rocket that can get to far places in stock KSP, than IRL?

In KSP you see people launching rockets with 4 large orange fuel tanks and mainsnail engines externally attached as boosters. Then the normal rocket would have like 4-5 stages. Just to go to duna or something.

IRL its just 2 boosters and a 2-3 stage rocket.

Whats the deal with that? I'm looking to make cool,realistic, and efficient rockets. Not just keep struggling to make a good rocket.

[The Jedi Master]

It's bigger than it looks, and it has more stages than it looks. It's actually a lot harder to get into space in real life than in KSP.

[Pursuedtank]

It takes more Delta V to get anywhere in real life than it does in the game, however, in general rockets have a greater efficiency than in the game.

[Pecan]

Have you read the several threads about how powerful the ARM parts are compared to the rest of stock KSP?

Part of the problem you might be seeing is that some people think mainsail engines must be good because they are late in the career tech-tree. Other people do believe in, or prefer, 'moar boosters'. "Cool", "realistic" and "efficient" are all possible - but what you might think is 'realistic' almost certainly isn't what someone else thinks is 'cool' (and vice versa), while 'efficient' is about KSP physics, not some myth from "a long time ago in a galaxy far, far away"

(My own foible is I prefer plausible SF to ancient history and can't understand why, for instance (not you), so many people think the best way to go to KSP's Mun is with 60-year-old Earth technology)

[joekidd1992]

All's I know is those 4 orange tanks that I just started using get me where I want to go and in one big hurry, mister!

[m4v]

Rockets and fuel tanks are underpowered in KSP compared with IRL, Kerbin isn't as big as Earth.

[GoSlash27]

I've found the opposite to be true. I can get stuff accomplished with a whole lot less in KSP than it would take IRL. You've just got to engineer for efficiency.

An ascent stage that's bigger than it needs to be requires a descent stage that's *much* bigger than it needs to be. Add them together and that's a gargantuan injection stage that requires a behemoth to get it in orbit.

If you design for efficiency (like they do IRL) everything becomes much more manageable.

[merendel]

Geting to space in KSP is realy easy even on the low tech nodes. If we started out with a decoupler I could easily do a mun flyby (a landing and return might happen but its iffy) on the first mission. I could still do it with improvised decouples, AKA overheating SRB's, but thats a real design PITA, easier to just do a suborbital to get a couple nodes first.

I also think its a bit silly that your compairing the SLS, a heavy lift platform, agianst a pile of the smallest SRB's in the game. Thats kind of like haveing a 5 year old throw the first pitch at a baseball game and then be dissapointed he couldnt even get the ball over the plate when its so easy for the profesional pitcher. not even remotely comparaible in terms of ability/design. Those little SRB's are at best for giveing a launch vehicle with low initial TWR a boost off the launch pad to get it heading to space. Nobody uses a huge cluster of them to launch 100ton payloads for any reason other than laughs. Heck you dont even need 100t lift capacity to go anywhere in the kerbin system. the ARM parts are a much closer comparison to the SLS and most people will tell you that those parts make nearly any mission trivialy easy.

[SkyRender]

Just because the old "MOAR BOOSTERS" mantra is inefficient doesn't mean that you cannot build efficient rockets in KSP. Scott Manley occasionally demonstrates that craft of absurdly small part count can make it to space just fine.

[jwenting]

can get to space in KSP with a one man capsule and a tall SRB, plus 4 of the small ones for the initial kick off the pad. Won't be able to steer and enter orbit, but would have the dV to do so (the parabolic orbit tops out at over 500km).

[problemecium]

"Moar boosters" is actually kind of a relic from the days when we didn't have big 2.5-meter parts to launch our interplanetary ships with. In those days (and even more so before docking was a thing), if you wanted to build something functionally similar to the SLS it looked more like a giant bundle of asparagus stems. Hence "asparagus staging".

It's entirely possible to build something that looks AND functions like the SLS... in modern KSP. People simply choose to make ships out of piles of SRBs for entertainment value.

[Brotoro]

Real Life rockets are MUCH larger than KSP rockets. Below is a graphic I made comparing the size of a Saturn V to the size of my Mark Twain rocket that I used in my original round of missions to explore all the bodies in the KSP system.

[maccollo]

Why is it so hard to make an efficient rocket that can get to far places in stock KSP, than IRL?

It's the other way around. In real life you can't just make a 15 ton stage that will go from LEO, to low lunar orbit, to the lunar surface, back to lunar orbit again, go to some captured asteroid and finally back to Earth.

You absolutely cannot make a stage that will go from LEO, to the surface of Mars and then back to Earth.

In KSP you see people launching rockets with 4 large orange fuel tanks and mainsnail engines externally attached as boosters. Then the normal rocket would have like 4-5 stages. Just to go to duna or something.

KSP components are generally balanced around using 2-3 stages to get to orbit with serial staging, just like in real life. However, because this balance is achieved by increasing the structural mass fraction instead of reducing the ISP there is a lot of payload fraction that can be gained by dropping tanks and engines earlier.

Because we have magical fuel lines that allow us to do just that with no downside at all, there is no reason not to add a few extra stages.

Basically people use many many stages because the system is exploitable, just like air hogging.

Edited May 22, 2014 by maccollo

[SkyRender]

...And I've been wondering, why is it so easy to make a SSTO in KSP,

while SSTO from Earth has never been performed?

dV = v(e)*ln(m0/m1)

That's why. We call it the Tsiolkovsky rocket equation, and it basically says that the fuel you carry to propel yourself also has to be propelled in order to be used. This results in a very unfavorable exponential curve wherein you end up using more fuel to push the mass forward the further you want to go. The simplest counteraction to this problem is to include components that are separated along the way, thus reducing the "dead weight" factor of lugging around empty fuel stages.

The other reason is that, while KSP does do its best to balance the model to resemble Earth rockets, the fact remains that the Earth is around 6 times bigger than Kerbin. Low-orbital velocity around Kerbin is a sprightly 2,150m/s or so, while around Earth it's closer to 7,660m/s. Even if KSP's parts didn't have a mass greater than osmium (the densest material known to man, incidentally), they would still not fare that much better than Earth rockets in trying to reach 7,660m/s with a single stage.

[DrDam]

To make things simple , the Earth's minimum velocity of orbitation are 7.9km/s ... for kerbin that are about 4.5km/s ? and that's doesn't deal with the velocity loosed by the atmosphère of Eart

[Deathsoul097]

To make things simple , the Earth's minimum velocity of orbitation are 7.9km/s ... for kerbin that are about 4.5km/s ? and that's doesn't deal with the velocity loosed by the atmosphère of Eart

LKO velocity is ~2.3Km/s

LEO velocity is ~7.5Km/s

Drag and Gravity losses on kerbin amount to about 2.2Km/s stock, and about 1.2Km/s with a more realistic drag model. (FAR)

Drag and Gravity losses on earth, comes to ~1.9Km/s.

So, it's between 3 and 5 times harder to get into earth orbit than KSP.

Just to put this into perspective, you could use the real Saturn V in KSP to go to, land on and return to kerbin from Eeloo, with boatloads of fuel to spare. Whereas your standard Jool rocket in KSP could barely get you into LEO...

[Rjhere]

I could write a whole essay on this since things are changed very much from reality. One thing noone have mentioned yet is the fuel tanks.

In KSP the tank weighs 1/9th of what the fuel weighs, the external orange fuel tanks for the shuttle had a ratio of 1:30. IRL fuel tanks have much more omph than in KSP. From my experience, I'd say theyre almost equally difficult, except that IRL you need alot more velocity, which I personally find to be more fun.

If you follow the link in my signature, I had found almost 50 mods to make KSP more realistic, although it is HIGHLY WIP, but you get somewhat the idea of how it's like.

[magnemoe]

I've found the opposite to be true. I can get stuff accomplished with a whole lot less in KSP than it would take IRL. You've just got to engineer for efficiency.

An ascent stage that's bigger than it needs to be requires a descent stage that's *much* bigger than it needs to be. Add them together and that's a gargantuan injection stage that requires a behemoth to get it in orbit.

If you design for efficiency (like they do IRL) everything becomes much more manageable.

With the STS parts its trivial to make an good looking SSTO rocket who takes 18 ton into orbit and land back on pad.

Put landing legs on an 25x4 entinge stuff fuel tanks on top, probe then separator and an 18 ton tank or other cargo, add fuel until TWR is 1.4, 4 solar cells and a battery, some braking parachutes makes landing easier.

Try doing this in real world.

My version of the STS would have two recoverable boosters, main stage a longer version of the SSTO, estimate 30 ton to orbit, probably closer to 50 if disposable and two stages.

Still the reusable version could do an Mun landing and return, it would probably drop an drop tank or 3rd stage before landing on Mun,

[cantab]

I'd credit a few factors:

Low TWR engines making it harder to build tall rockets.

Coupled with An aerodynamic model that encourages high launch TWRs.

The tanks having such poor mass ratios encouraging dropping them quickly.

No failure rates on parts and no real penalty for complexity, allowing players to use a gazillion stages.

OP fuel lines allowing whole fields of asparagus.

Above all else, though, credit an effort by many players to maximise payload fraction, part count, complexity, looks and realism be damned.

[Hodo]

KSP vs Real Life...

1 mod pack will answer that for you, Realism Overhaul.

The difference is about 60-66% from KSP to Real life.

Kerbin's atmosphere effectively ends at 69.1km, Earth 104km.

Delta Velocity for orbit around Kerbin-2.3km/s roughly. Earth 9.4km/s.

I have used both RO and stock KSP size. The most successful rocket I had in the RO was a copy of the Ares V rocket, with a 19m SRB first stage, with a 150s burn time. I could push it to an altitude of around 70-80km before I had to drop it and go to the second stage.

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[Creature]

From what little experience I have with RO, I'd say that conceptually it doesn't matter whether you're designing a rocket for stock or RO and I think this is where the KSP really has hit the mark. With RO you need more dV but it's also easier to come by. The engines are way stronger when it comes to thrust and generally you need a lot bigger rockets but the parts are very different as well.

When you have the ability to freely stretch the tanks to any size, the only thing limiting you is what kind of engines you have available. If you upscale the engines, you can upscale the payload similarly both in RO and stock. However in stock KSP you're also heavily limited by the tanks and this is at least in my opinion very very well balanced. Unrealistic if you start to factor in densities and stuff, but leads to a good simulation. Everything else is just numbers on a screen.

But none of this has any meaning towards real life engineering where things are difficult, expensive and very often involve hundreds/thousands of hours of boring, hard work. Also in real life we're not artificially limited, in KSP you can only do things that the programmers allow you to. So in short, you can't compare real life to computer games.

[Michaelo90]

Getting to orbit in KSP is really easy if you know what you're doing. With good piloting, you can build a 2 part (the new liquid fuel booster and a probe core) SSTO that can take a 2t payload to orbit.

[LABHOUSE]

There ARE mods that fix this.

http://forum.kerbalspaceprogram.com/threads/59207-0-23-5-Realism-Overhaul-ROv5-1-Modlist-for-RSS-5-7-14