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Sharpy

For whoever still thinks mining is just a gimmick.

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All these crafts have about 4300m/s of delta-V in the "red fuel". Variants 2, 3 and 4 end up with exactly the same transfer stage configuration before transfer.

Vehicle 2 - not using refueling - costs about twice as much as the recommended variant 4.

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I do something between 1 and 4. I have a space-efficient engine instead of a mainsail as the only engine, and use solids (which are cheap and disposable) for what you use the mainsail in #4 for.

The solids get me 10-20km up and going pretty fast, and then the transfer engine can get me to orbit for refueling, then Minmus for more refueling and an eventual kick out to somewhere else.

It's amazing how much smaller my ships became after I got a Minmus fuel driller set up.

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My designs look similiar. I refuel in orbit only when i need the stage with high thrust to get past duna/dres with acceptable burn times. Sometimes i send the transfer stage separately and dock in kerbin orbit or i send a nuke stage separately out to the planet where i'm going and have it docked there with the lander (that has a pack of probes and scanners for each moon) to slow that down or do all the plane changes and adjustments to set the probes free ...

The lander is isru-capable on low gravity moons or even on duna. My duna and sarnus missions are planned that way, the latter still running. I might have underestimated the delta-v i need in the sarnus system so i sent another nuke stage after them to dock near sarnus and help get rid of all the probes and scanners.

So, yes, 2 is ineffective, and long missions have become much simpler since the isru thingy ... but i'm too lazy (and have too much funds) to recover ... :-)

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Edited by kemde
Too thick to paste in an imgur album link ...

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I do something between 1 and 4. I have a space-efficient engine instead of a mainsail as the only engine, and use solids (which are cheap and disposable) for what you use the mainsail in #4 for.

The solids get me 10-20km up and going pretty fast, and then the transfer engine can get me to orbit for refueling, then Minmus for more refueling and an eventual kick out to somewhere else.

It's amazing how much smaller my ships became after I got a Minmus fuel driller set up.

Yeah, I like your setup, but I must point out you only get amazing results because you pay no attention to the clock. And even then sometimes you pay dearly in dV because you can't hit a window in time due to Minmus' position. Yup, I do follow you on youtube, in case you didn't know already. You build tiny!

You can, however, get the proverbial nine tenths of the dV savings, with much more often launch windows (8.3 times more often, or every six days to any given ejection angle), basing the whole thing in Mun instead. The difference in LKO during the ejection maneuver is about 100m/s, plus 100-200 to leave Mun depending on how high your Munar depot is, compared vs lifting from Minmus and ejecting there like you do for about 300m/s, so the advantage from Minmus, dV-wise is pretty much nonexistant if you factor orbital depots. You pay in worse fuel "gear ratio" (the fuel tankers to supply the orbital depot eat some fuel per kg delivered), and have another craft to fly, of course, but hey, compromise solution. If you launched straight from the ground in both cases Mun would be about 600m/s more expensive for a given ejection on account of the bigger gravity well, but if both places used orbital depots, then the difference is much less, at about a couple hundred m/s. All figures, of course, eyeballed and only approximate.

But there are other metrics that could make the second-best alternative the most ideal. For example, you can supply at the last second some expedition, because the flight time there is a few hours. That is something that can't be measured in numbers, but that I find very useful because all of us forget something at launch. Or it turns out that we added some numbers wrong and we need some solar panels, or something. Plus, I play with KAS+KIS, so orbital outfitting is really cool to do.

Then again, you go much more minimal that I do, of course. And to each their own! But if you have a rugged mission architecture, with built-in dV margins, it's good to put them to use into making your mission planning more convenient. My only 1.0 save is currently at day 21, with a couple million on the bank and Mun and Minmus tamed already (surface base with mining equipment, orbital depot, the works). Now I'm grabbing some 'roids to get the LKO depot going and make surface mining mostly obsolete, with a bit of luck. I anticipate I will need fuel around kerbin much less often from now on, so perhaps stockpiling a few E-classes I will have enough. Sentinels are great to find them! I already have three targets, and a test refinery is going to grab a C-Class in a couple days to practice. Pity I didn't know how you pretty much need an engineer to mine quickly when I built it...

Rune. I also play with life support, so the clock counts when planning missions.

Edited by Rune

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I never really understood this whole refueling thing ... thus never bothered doing it. Now tho, as im planning my first trips to more distant planets/moons, DV is starting to be quite a problem when launching from kerbin.

How does this whole thing work?

As far as i understand it, you build a refinery kinda structure on a planet/moon (ill take Minmus as example since it requires very little dv to lift off and land on it), build a depot in orbit with empty fuel tanks, get a small "reusable" rocket/plane/something that can take the fuel from the refinery and bring it in orbit at the depot.

Then, when launching crafts to other planets from kerbin, you only put enough dv to reach Minmus (the fuel depot) and some empty tanks (as much as you need to complete the trip from minmus to your planet/moon of choice), launch and get to the depot, refuel and be on your way to your death glory ...

Is that how it works?

Can someone please give me some tips for this and how to do it myself?

EDIT: Also, i use LS mods so will that affect me (i assume that if you end up with a large craft that needs a lot of fuel, you would wait a while in orbit around minmus until you produce enough fuel to refuel that craft so ... life support might be an issue, you would need to add more LS stuff on the craft thus making it heavier?).

Thanks!

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Is that how it works?

Can someone please give me some tips for this and how to do it myself?

Edited by kreutzkevic

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There are additional costs in getting that refueling rig into orbit as well, though. Either paying to launch it up there full, or setting up infrastructure to manufacture the fuel. Really it only comes down to one thing: You can pay kerbalbux and launch big rockets, or invest some real time and launch smaller rockets.

Personally, I'd hate to miss out on my big rockets exploding violently upon staging in exchange for staring at Minmus while the fuel bars on my transport fill up, but like everything Kerbal, to each their own.

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You build tiny!

...you go much more minimal that I do, of course.

You spelled "efficient" wrong, and differently each time ;) I build the ship that's needed for the task. Not my fault there are no worthwhile tasks in the game that take larger ships.

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Also, an exercise in overkill and how to run out of funds in the first week. If you are playing career, I'd advise you to watch 5th Horseman's channel instead. Just do the rockets about 50% bigger for a given payload to account for his "expert-flier-but-I-still-run-out-of-dV-becasue-I-cut-things-too-close" syndrome (it's totally a technical term), and you are golden. :)

Basically, once you have fuel stockpiled in orbit, any orbit, you build things with oversized upper stages and lots of SRBs (2+km/s out of the 3.5km/s minimum to escape the ground in the upper stage), then refuel the spent upper stage to use it as a transfer stage. Note that there is no rule as to where to put the depot. But going to Minmus means your launch dV is about 5km/s, while reaching a LKO depot is about 3.5km/s. The most convenient for the mission itself is a depot in low kerbin orbit and leaving form there, but that will mean a complicated mining operation to get the fuel in place. The easiest on infrastructure is to refuel directly on Minmus' surface, but that takes a lot out of the ship to get there in the first place, and Minmus is only on the right spot to launch to a given escape trajectory once every 50 days. Munar orbit is a happy medium, if you know how to do things to keep your energy when you leave the kerbin system, your escape will be about 800m/s cheaper than from low kerbin orbit, and you get launch windows every six days.... but you still need much more dV on the launch vehicle if you don't have a LKO refuelling station.

Also, if you are worried about life support, a trip to Minmus to refuel will eat about 15 days of food, while Mun will be under one before you are on your way. Either way, if you are going interplanetary, pack enough food for a couple years... you might miss a return window or something. Also, 5th Horseman has a nice config file to allow the refineries to produce Mulch to feed your life support systems from ore, I'd advise doing something like that.

And lastly, I will note, that if you really just want to fuel a big mothership on orbit because you couldn't launch it full, SSTOs are probably the most economical way to do it: fuel is dirt cheap, and carrying a small satellite in the bay will allow you to actually earn money doing fuel runs if you pick the relevant contracts. I'm talking something like a 0.5mT probe making about 200-400k√ by completing a couple of contracts every time I launch a Big Red worth of fuel in a Longsword, for absolute peanuts (10k√ in fuel or less? something ridiculous like that). That's about 200k√ positive cash flow, for every Big Red I put up there. And the Longsword isn't even a particularly huge SSTO (though it is efficient, costing ~200k√ itself, which means I can stomach the loss if my cat makes me crash one on landing). But hey, you don't have a handy VAB in Laythe to launch more fuel, so practice for off-world operations. Plus it's cool. ;)

- - - Updated - - -

You spelled "efficient" wrong, and differently each time ;) I build the ship that's needed for the task. Not my fault there are no worthwhile tasks in the game that take larger ships.

Hey, I measure efficiency in percentages, not launch mass! That's being economical (or minimalistic), not efficient. :P Plus, I roleplay a lot my game, and build some things just for beauty's sake... say, like these. No reason my kerbals need to travel in one of these, but I wouldn't go manned outside kerbin without at least one.

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Rune. Note, I consider you rock at what you do. Keep on rockin'! :)

Edited by Rune

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There are additional costs in getting that refueling rig into orbit as well, though. Either paying to launch it up there full, or setting up infrastructure to manufacture the fuel.

Make the rig as big as you see fit. Strap it on top of an SSTO (no reentry) stage that is as big as you like. That stage will be your fuel depot/base. The initial cost is significant, but the returns appear very quickly.

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I never really understood this whole refueling thing ... thus never bothered doing it. Now tho, as im planning my first trips to more distant planets/moons, DV is starting to be quite a problem when launching from kerbin.

How does this whole thing work?

As far as i understand it, you build a refinery kinda structure on a planet/moon (ill take Minmus as example since it requires very little dv to lift off and land on it), build a depot in orbit with empty fuel tanks, get a small "reusable" rocket/plane/something that can take the fuel from the refinery and bring it in orbit at the depot.

There are several design decisions. First, what's your fuel source: Mun, Minmus or asteroids. All with their shortcomings and benefits. Next, where your fuel depot will be, LKO, moon's orbit or surface. Surface is mostly out, but orbits are a decent choice. Next, how to get the fuel there: does the depot land, do you have dedicated "trucks" or maybe the whole rig launches. Next, how and where to process the ore: do you have miner-landers and ISRU in orbit, or do you have a stationary fuel refinery on the surface and just ferry the fuel.

One quite reasonable option is to bring the depot into Minmus orbit, then fetch the fuel with a refinery/local depot from the surface, then bring the big depot full into LKO. Consider the number of docking and precision landing operations needed.

Another - if you have the patience - is to bring a large asteroid into LKO and build a rig+depot around it. It's exhaustible resource, but enormous one.

Then, when launching crafts to other planets from kerbin, you only put enough dv to reach Minmus (the fuel depot) and some empty tanks (as much as you need to complete the trip from minmus to your planet/moon of choice), launch and get to the depot, refuel and be on your way to your death glory ...

Better to keep the depot down there, although that's a personal choice. Try to find a thread that discusses benefits and problems of the various locations. LKO gives you a big Oberth effect boost. Minmus with Kerbin flyby gives you even bigger Oberth effect boost but makes the trajectory quite tricky. Minmus without Kerbin flyby is very costly.

Also, you don't bring empty tanks, you empty them on launch from Kerbin. You don't get rid of the launch stage, just dump the atmospheric engines... if that. Having a pair of mainsails deep in space can be useful at times.

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https://dl.dropboxusercontent.com/u/3152580/sshots/refuel.png

All these crafts have about 4300m/s of delta-V in the "red fuel". Variants 2, 3 and 4 end up with exactly the same transfer stage configuration before transfer.

Vehicle 2 - not using refueling - costs about twice as much as the recommended variant 4.

You have not factored in all of the information. The cost of the infrastructure to mine fuel or deliver fuel to orbit counts. You also assume everyone is after fuel saving, I prefer the sanity of not using the crappy stock system. I'd rather spend more money on they lifter than touch that junk, since I can't get Kethane to work anymore.

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My current manned designs are based on Mk III holding ISRU and ore tanks(plus whatever I need for the mission, like a science lab to hold results from interplanetary missions), with a nuclear based engine on the bottom(Atomic Age nuclear lightbulb to be specific) and i-beam based landing legs(with deployable feet on the end and drills just above them).

I generally have a Klaw on the nose of the cockpit for refueling probes or pod-rescues and used this design successfully in the Kerbin SOI for quite a while before taking it interplanetary.(two ships on their way back from Duna/Ike with a third on it's way there before heading to other planets.

(lots of 'base', 'rescue', and 'I'm already there so I might as well' missions combined with training flights have me with over 30 3-star Kerbals and over 30M funds)

I am not a huge fan of docking, so I just include the ISRU on all my manned flights to make sure my less than ideal flight paths don't leave my Kerbals stranded.

Of course the down-side of this is that my frame-rate is not great. Fortunately it is not so bad that it makes the game hard to play, it just gets very noticeable when I launch my occasional small probe and everything happens so much faster than I expect.

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This sounds like an essay on the benefits of orbital refueling. While this can be done via mining, what's the difference between mining for new fuel and refueling in orbit by launching a fuel tanker? (I know there IS one; I want to know people's findings on how big a difference it is)

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Benefits of mining: You get fuel.

Need anything else?

Time.

If you have a life, your opportunities to play KSP, and how much time you can play for in 1 sitting, are limited. Mucking about with a fuel system in Kerbin's SOI takes a huge amount of time and you make zero forward progress on the actual mission. Remember, refueling is merely a support function, NOT the mission itself. But it can become the only thing you do if you let it. Where refueling bases are worth the time required to run them are at other planets, where you have large, long-term colonies. If you've got to spend time monkeying around with refueling, at least doing it at some exotic location makes it more interesting that anywhere near Kerbin.

But OTOH, there's a quick and easy way to refuel at Kerbin, thanks to Roverdude's UKS mod. Build a mining/refining/storage base on Kerbin just far enough away from KSC so you can launch without loading the base's parts. The base has the Logistics Hub from the UKS mod on it, which abstracts moving the fuel from the base to the ship in LKO via drones (IOW, it magics the fuel up there at the cost of more fuel and a bit of game time). This way, you get the benefits of refueling in LKO without the drudgery of actually having to go through all the trips back and forth to Minmus, the landings and takeoffs, the rendezvous and dockings, which eat up so much of your playing time.

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Benefits of mining: You get fuel.

Need anything else?

Responsibility. By creating an infrastructure you create the obligation to maintain and service it, which could draw immensely upon your attention & concern.

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Given the game what it is, i.e. an open-ended sandbox; does this refueling thing even matter, or is it just a discussion in personal play style?

I play career mode exclusively. My current game has over 35M in funds at ~90% approval. I've never refueled on orbit. I do not have any mining apparatus anywhere. At any given time I have 5-8 missions running concurrently. My rockets are giant, glorious examples of excessive indulgence and they do the job in the black nearly every single time.

In response to the OP's refueling being a "gimmick". IMO, yes, it is a gimmick. A mode of playing fortuitously included by the devs to allow you play the game how you see fit. Without a doubt, many dVs can be saved by refueling on orbit. Good on you for using this to build frugal vessels with razor thin dV budgets. Still a gimmick, though.

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I never really understood this whole refueling thing ... thus never bothered doing it. Now tho, as im planning my first trips to more distant planets/moons, DV is starting to be quite a problem when launching from kerbin.

How does this whole thing work?

As far as i understand it, you build a refinery kinda structure on a planet/moon (ill take Minmus as example since it requires very little dv to lift off and land on it), build a depot in orbit with empty fuel tanks, get a small "reusable" rocket/plane/something that can take the fuel from the refinery and bring it in orbit at the depot.

Then, when launching crafts to other planets from kerbin, you only put enough dv to reach Minmus (the fuel depot) and some empty tanks (as much as you need to complete the trip from minmus to your planet/moon of choice), launch and get to the depot, refuel and be on your way to your death glory ...

Is that how it works?

Can someone please give me some tips for this and how to do it myself?

EDIT: Also, i use LS mods so will that affect me (i assume that if you end up with a large craft that needs a lot of fuel, you would wait a while in orbit around minmus until you produce enough fuel to refuel that craft so ... life support might be an issue, you would need to add more LS stuff on the craft thus making it heavier?).

Thanks!

Well, there are a variety of solutions, but here is one possible system:

You place a refinery on the surface of Minmus, as well as a reusable lander to carry fuel to orbit. You park a tanker (not a depot) in Minmus orbit, refuel it with several launches from the lander (which need not refuel it in a single launch- having a smaller lander saves you on initial setup costs) and then have the tanker return to Low Kerbin Orbit- using the atmosphere to drop the orbit back down over one or more aerobraking passes from a return trajectory (which is EXTREMELY cheap from Minmus- if you eject from Minmus' SOI heading retrograde relative to the moon's orbit around Kerbin...)

If done properly this is actually cheaper in Delta-V than returning to LKO from Munar orbit, due to the weaker gravity-well and much lower orbital velocity of Minmus than the Mun... The tanker can be quite large and designed without the thrust needed to land (it also doesn't need landing-legs, which is another reason to have a specialized lander...) using something like an LV-N for propulsion, for instance.

The tanker meets up with craft needing refueling in Low Kerbin Orbit and refuels it, leaving just enough fuel to return to Minmus to refuel again. The tanker can also double as a tug or transfer-stage, and can be used to haul modules back to Minmus that are too large to refuel in LKO in a single trip... (keeping the two vessels docked reduces the number of transfer and capture-burns you have to make, and allows use of the tankers possibly higher-ISP engines)

This plan can also be carried out with the lander returning all the way to LKO, to reduce the need for rendezvous and docking, but this will be much less efficient in terms of fuel "gear-ratio". By the time the lander even makes Minmus orbit, it will have already emptied a portion of its fuel tanks and you will be wasting fuel moving empty fuel tank mass back to LKO. Additionally, a lander would likely have landing-legs, and would be forced to have higher Thrust than a dedicated tanker (which could actually get away with a TWR less than one on Minmus' surface, as it never lands...)

Regards,

Northstar

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My rockets are giant, glorious examples of excessive indulgence and they do the job in the black nearly every single time.

Allow me to ask: what is your computer configuration (CPU, RAM, gfx card)? Also, what kind of framerates you're getting?

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Given the game what it is, i.e. an open-ended sandbox; does this refueling thing even matter, or is it just a discussion in personal play style?

I play career mode exclusively. My current game has over 35M in funds at ~90% approval. I've never refueled on orbit. I do not have any mining apparatus anywhere. At any given time I have 5-8 missions running concurrently. My rockets are giant, glorious examples of excessive indulgence and they do the job in the black nearly every single time.

In response to the OP's refueling being a "gimmick". IMO, yes, it is a gimmick. A mode of playing fortuitously included by the devs to allow you play the game how you see fit. Without a doubt, many dVs can be saved by refueling on orbit. Good on you for using this to build frugal vessels with razor thin dV budgets. Still a gimmick, though.

KSP is part game, but part simulation. Some people like to design a mission that could actually get funding in real life (yes ISRU *is* something we're developing technologies for in real life). To say your playstyle is superior just because it's easier is... a bit self-indulgent.

Also, and more importantly, not everybody (I'm a prime example) has a computer that can HANDLE a massive, 500-part craft that can carry out something like a Jool grand-tour in a single launch- at least not with KSP's current poorly-optimized program structure. In this regard, for players with weak computers mining is a godsend. Before, I had to launch an entire flotilla of tankers just to refuel a craft in LKO for a large mission, unless I was using a lot of parts mods with 5 meter diameter rocket parts at a bare minimum (or better yet, something like Procedural Parts for 10 meter fuel tanks and Procedural Fairings for multi-engine thrust -plates and interstage-fairings...) Now, I can send ISRU equipment to whatever system I'm headed to, and mine my return-fuel there, massively reducing the size of my vessel in LKO... (I may still have to launch a tanker or two for the largest of missions, where I still can't launch a sufficiently large craft from the ground on Kerbin to make it to Jool or wherever in a single launch without orbital refueling...)

Yes, setting up ISRU systems in the Kerbin system is hardly worth it if you don't have much time to play KSP, though. The example I gave of a simple and efficient LKO refueling-system is still a massive drain on play-time compared to just launching expendable tankers to LKO...

Regards,

Northstar

EDIT: Sharpy hit my thought right on the head w.r.t. not all computers being able to handle "glorious examples of excessive indulgence".

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It's so much simpler to just make your refueling stations to also be miners and refineries. Skip all that hassle of docking, and this thing can be sent to just about anywhere in the kerbin solar system and mine from any moon with the gravity of the mun and lower.

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This sounds like an essay on the benefits of orbital refueling. While this can be done via mining, what's the difference between mining for new fuel and refueling in orbit by launching a fuel tanker? (I know there IS one; I want to know people's findings on how big a difference it is)

Well, to put is shortly, depends on how close to kerbin you are. For keeping a LKO depot stocked, sure, launching from the runway a SSTO tanker is the most economical and efficient way to go. To keep a depot on low Laythe orbit stocked? A very different proposal, you will be better off sending a refinery and tanker there than fuel. All of this, of course, assuming you want a stocked fuel depot in the first place. Which mainly makes sense if you are setting up reusable infrastructure, since it allows you to single-stage the whole kerbol system.

Rune. Places where it actually makes gameplay sense, saving significant launch mass: Tylo and Eve landers. Period.

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Benefits of mining: You get fuel.

Need anything else?

you get fuel, at the cost of time. And if your mining operation isn't very effective you may not get more fuel than you need to run your operation :)

or it may take so much time that you're spending several days mining and refining to fuel a mission lasting a few hours.

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or it may take so much time that you're spending several days mining and refining to fuel a mission lasting a few hours.

If you're looking for cost savings, you also have to take into account how much money you could be earning with the same amount of time.

I think this is the big thing that prevents mining from being a useful game feature rather than just a gimmick (and this has been true of any resource system I've looked at, including my own, not just the stock one). For any given unit of player time, you can advance your space program a lot more through other means.

I realize some enjoy setting up the operation simply for its own sake, and that's totally cool. However, in terms of being a practical gameplay solution to anything other than a handful of problems (the Eve landing/return example mentioned previously being one), I feel it leaves a lot to be desired. The relationship of player-time to in-game resources is a rather sticky problem to deal with for this kind of system.

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