Jool Exploration with Mining

[digger1213]

I decided I want to try and get as much out of the Jool system as possible. For this cause, I have set up a Vall mining base that is capable of producing fuel for anything that can get into orbit around Vall, with the help of a tanker I also sent.

I am in the process of designing a vehicle that can be used to land on the majority of the moons of Jool, maybe excluding Laythe and Tylo, at least until I get refueling stops there.

How much Delta-V should a vehicle capable of refueling in Vall orbit need, for exploration of these other planets? Preferably, it would be a single stage so it would be reusable after refuel. I have currently managed to get a lander that has 5k DV and has enough TWR to land on Tylo, but not Laythe. 5k DV isn't enough to visit Tylo and return to Vall, is it?

[TotallyNotHuman]

According to this Delta-V map here:

And this utility here:

KSP Launch Window Planner by Alexmoon

You will need (assuming you start in a low Vall orbit) 865 m/s to get to low Bop orbit and another 230 to land. For Pol, it's 945 m/s to transfer and 130 to land.

You should have no problems tackling those two moons. Hell, you could probably go Vall -> Bop -> Pol -> Vall without refueling. 5 km/s is plenty when dealing with those potato moons.

Tylo, however, is more difficult. You will need 1,125 m/s to get to low Tylo orbit, and 2,270 m/s to land. 5 km/s will not be sufficient in this case; you want at least 7.5 km/s to have a safe margin.

Good luck on your Jool exploration campaign!

Edited May 8, 2017 by TotallyNotHuman_

[digger1213]

Thanks! If I were to set up a mining base on Tylo, I could probably ferry the engineer back and forth in the lander as well. With that setup, I could probably use the 5km/s lander renewably for Tylo exploration too. And since I will be using Laythe SSTOs there, that will be fine.

Considering this is my first big expedition in the Jool system, or really anywhere other than Duna, I hope it goes well too.  Thanks. 

 

Actually, by the way, that launch window planner often has blank spaces on it where no Delta-V is shown. What happens here? I cannot think of a time where it would be actually impossible to do a transfer, so what exactly are they?

[Snark]

Moving to Gameplay Questions.

3 hours ago, digger1213 said:

If I were to set up a mining base on Tylo

...You could do that, but it's really not a great idea from an efficiency standpoint-- you'll find that engineering it is really hard.

Why?  Because Tylo has such a deep gravity well; orbital velocity is comparable to Kerbin.  Look at it from the tanker's point of view.  It's landed at the fueling station on Tylo.  It fills up its tanks.  Now it has to spend over 2000 m/s of dV just to get to low Tylo orbit... and even then, it can't give all its fuel to the thirsty ships in Tylo orbit, because it has to save another 2000+ ms of dV so that it can land on Tylo again for the next refueling cycle.

So you're looking at close to 5 km/sec of dV flushed down the toilet every time your tanker wants to land or take off... so the only fuel it can effectively transfer has to come after that.  And, since you want this to be a reusable craft (right?), it has to be SSTO-- it can't use drop tanks or stage away things.

So, to pull off a mining base on Tylo, you'll need a craft that's single-stage, and also which has high TWR (meaning you have to lug a lot of dead engine weight, and the really high-Isp engines are hard to use because of low thrust)... and this craft needs to have a dV of over 5 km/sec, and the fuel it can transfer on each engineering cycle will be after subtracting that 5 km/sec of dV.

Designing a craft that can do that is a challenging engineering hurdle.  You're really making life difficult for yourself if you do that.  Just making an SSTO that can land and take off from Tylo, at all, is hard.  Even if you pull it off, you're likely going to have a craft that requires huge, time-consuming amounts of refueling on the Tylo surface, just so that it can deliver a few teaspoons of fuel to Tylo orbit each time.

Even Vall is somewhat challenging (its escape velocity is the third-highest of any vacuum world in the game, after Tylo and Moho), but doable-- you just have to resign yourself to wasting lots of fuel on every landing/takeoff cycle.

Basically, if you're considering a refueling base in the Jool system, here are your options:

• Pol or Bop.  Nice low gravity and escape velocity, very efficient for refueling operations.  But they're located rather inconveniently, so you'd need to be patient (e.g. allow long transfer times, waiting for launch windows, etc.) for exploring the other moons.
• Vall.  Very conveniently located.  However, has an escape velocity that's somewhat inconveniently high, for a vacuum world.
• Laythe.  You can use airbreathing engines for SSTO goodness, and it requires basically zero dV to land since you can aerobrake.  On the other hand, there's a limited choice of land area for placing a refueling base, and even with airbreathing engines, Laythe needs a fair amount of dV to get to orbit.
• Tylo.  Horribly high dV requirements to land and take off.

I think Tylo would be about the worst possible choice you could make for a refueling base.  Any of the others would be a reasonable choice-- they just have different advantages/disadvantages, so it's a matter of deciding which of their advantages/disadvantages work best with your play style.

(For example, I'm an efficiency nerd and am very patient, so I'm biased in favor of Pol / Bop.  And my second choice would be Vall, because I'm totally not a spaceplane guy and therefore I don't fit well with Laythe.  But that's just me, because it fits with my personal play style.  You could make Vall or Laythe work, no problem.)

[Cpt Kerbalkrunch]

Been wondering why you picked Vall for your base as well. I assumed you had a contract for it, or you just liked it's location between Tylo and Laythe. I have refueling operations on Pol and Bop. Even though they're further out (and Bop is inclined), I find I'm able to move a lot more fuel.

I actually do have a very small operation on Tylo, though. Had a very lucrative "mine Tylo" contract that I couldn't resist. Doesn't get much use now. It's mobile, though, so it's at least useful when I have a lander that's going to be low on fuel. If you do have a Tylo base, I think refueling visiting ships on the surface, and return vessels in Tylo orbit (with a good enough fuel shuttle) that just need enough fuel to get home, are about the best you could expect to do with it.

[Spricigo]

3 hours ago, Snark said:

...You could do that, but it's really not a great idea from an efficiency standpoint-- you'll find that engineering it is really hard.

My assumption was that he meant a 2nd mining base on Tylo. Just for departures from Tylo.

Combined with fuel deliveries from Val it may allow for a smaller and more efficient Tylo lander/ascender for the cost of increased infrastructure complexity.

Well, I deploy rovers, lander/ascender, space transports and tankers everywhere I go. But  I don’t suggest to do like me because not everyone have OCD.

 

[Human Person]

It's always good to bring an additional tug or two. Something you can put a bunch of fuel in and park in orbit somewhere. I designed my Vall miner/lander to be capable of merging with on of the tugs. They land together, fill up both their tanks and get back to low Vall orbit. From here on, the still filled up tug separates from the Lander, deliveres fuel anywhere in the jool system and returns to the lander wich has reserverd enough fuel to land the two back on Vall.

The Engines on the tug are attached radially to be able to support the lander during ascend.

Edited May 8, 2017 by Physics Student

[digger1213]

Yeah, I did mean a second small mining base on Tylo just so I can get around there. My one on Vall would be my main fuel mover, and although it is less efficient than Bop or Pol, it is far more conveniently located. Especially because once I get my Laythe SSTO program up and running it would be easier to move fuel to Laythe from Vall than from those far moons.

9 hours ago, Physics Student said:

It's always good to bring an additional tug or two. Something you can put a bunch of fuel in and park in orbit somewhere. I designed my Vall miner/lander to be capable of merging with on of the tugs. They land together, fill up both their tanks and get back to low Vall orbit. From here on, the still filled up tug separates from the Lander, deliveres fuel anywhere in the jool system and returns to the lander wich has reserverd enough fuel to land the two back on Vall.

That's actually a really good idea. Since my lander has a docking port on it that actually doesn't really do anything, top mounted just so I could refuel anything using it in emergencies, I could use it for tug purposes. Although it might be a bit irritating as my lander is a bit on the heavy side.

Actually, if I have the tug land and refuel or use the refuel depot I plan to set up in orbit, it could be an easy way to get stuff into and out of orbit. Ooh, I might send a launch tug next transfer window. Thanks for the idea!

My question still stands though about the launch window planner blank spots, for example looking at transfers from Tylo to Vall. There are a lot of blank spots on it, and I have no idea what they mean.

[Spricigo]

I'm guessing : blank space may be because some other celestial body get in the way?  

There is a lot of.... Transit (forgive me) around Jool

[digger1213]

I thought that there would always be a way to do it, but considering that it doesnt allow for mid-course corrections and it has a set time of transit on the Y axis, I guess I can actually see why. Strange though, considering how I've seen blank spots on my Duna transfers from Kerbin.

Anyway, everything has gone to plan. I set up the base, landed the tanker, the refuel rover, and my lander. I EVA'd the Kerbal into the lander command pod. I took it to orbit. I tried to EVA the Kerbal again.

Hatch obstructed.

God dangit. I find if I spin the ship fast enough at 4x physics warp the parts glitch and separate enough to let the Kerbal EVA out, but that is a massive pain in the backside. I can't do that while landed. It's even more stupid because there is plenty of space for the Kerbal to get in, but once inside they are trapped forever without glitches or docking claws.

Excuse my horrible-looking lander design.

Is there any way I can force the Kerbal out, cheating or not? I will eventually get a replacement lander in here, but until then... well... there is clearly enough space there. I had a quick dive through the Cheats menu, and all of F12, but couldn't find anything. Thanks in advance.

And also, my goal for this is pretty much to get as much infrastructure around every place as possible. That way all I would need is the Delta-V to get to each new place, rendezvous with a fuel depot and continue. As well as checking out loads of anomalies.

Edited May 9, 2017 by digger1213

[Snark]

6 hours ago, digger1213 said:

Hatch obstructed.

It's even more stupid because there is plenty of space for the Kerbal to get in, but once inside they are trapped forever without glitches or docking claws.

If you have a design where they can get in but not out, that sounds like a bug to me.  Have you reported it?