Best Ore ISRU Architecture for Jool

[LameLefty]

So while I wait for Squad to get a handle on the suddenly-fragile/explosive landing gear in 1.4.2, I've put my Career save on hold and I've been experimenting with designs and concepts for a Laythe colony with an associated Ore miner/refinery infrastructure in the Jool system. I've got a Jool window coming up and I want to send a flotilla of missions to establish a permanent presence there.

At first glance, Vall looks ideal to support a Laythe base. It's in the same plane as Laythe; it's close in terms of dV, and there's no atmosphere to complicate precision landing or cause ascent drag losses. Howver, it does have relatively high gravity for a planetary moon, and I've found that the gravity losses incurred in both landing and return to orbit are eating up all or nearly all of the Ore I can recover with a reasonably-sized rover. By that I mean, after I've refined all the Ore into LfOx to refuel the lander, I've got nothing left; this is using unscrewed equipment - if I understand correctly, have an Engineer available "on site" so to speak can increase the efficiency. Is that correct?

By contrast, a mining lander and refinery operation on/around Pol costs next to nothing in dV to land and return to orbit; the downside is that there's a fairly high dV cost to haul the fuel back to Laythe. Pol's orbit is inclined relative to Laythe's and it's pretty far out from Jool.

I'm sure that some folks out there have explored these trades in great depth and can provide some pointers.

Thanks.

[Cpt Kerbalkrunch]

If you're adept with spaceplanes, Laythe itself can make for a self-sufficient system. Jet engines are high-effiency, so you can overcome the atmospheric losses with comparatively low cost to orbit. As an added bonus, you won't need to travel anywhere.

With all that, I still prefer Pol (not a spaceplane guy). To me, Val's gravity negates it's usefulness, as you said. With Pol, on the other hand, you can make your fuel shuttle as large as you want to. And although you'll use a lot of it on the transfer, you'll have plenty to spare. You can also aerocapture at Laythe to save some Delta V. And on the way back, the ship will be much lighter; making the transfer cheaper. And, as you no doubt already know, it costs almost nothing to land on Pol.

I like Bop as well, and have an operation there, but my refueling setup on Pol has served me well for a long time. You'll get plenty of opinions on this subject (as with anything else). So it really comes down to personal preference. I think Pol works the best. Others will say somewhere else. About the only thing you won't hear is Tylo. Nobody's that crazy. 

Edited April 5, 2018 by Cpt Kerbalkrunch

[AeroGav]

I did a Jool 5 mission about a year ago.

I had a very large Mk3 cargo space plane with a bunch of liquid fuel in its wings and strakes, and nerv engineers.

It used droppable whiplash boosters and drop tanks to get out of Kerbin with sufficient delta V to reach the Jool system without assists.

Inside the cargo bay was a chemically fuelled Tylo lander with a small IRSU rig.   The lander could actually reach the ground and mine when it was inside the space plane if i retracted the landing gear.

First stop was Laythe.     Used the aforementioned "drill through the floor of the mk3 cargo bay" trick to fill up.   Jettison remaining jet engines on the climb out of Laythe - they aren't going to get used any more.

Next stop you want somewhere low grav like Pol or Bop.    Land spaceplane intact and fill up.  The low gravity of these moons mean you arrive at next destination with almost full tanks.

After that, I'd recommend  Val.      Undock in low orbit and bring the IRSU lander down on its own.      The trouble with landing the whole plane, is that on NERV engines it won't have the TWR to get out of the moderate gravity with full tanks, which makes fuel tight for the next stop.      After you've planted flags and the lander has refilled its tanks, re dock with the spaceplane.  It will easily have enough fuel to take you to the next destination, which should be the remaining unexplored low gravity moon (Pol or Bop)

Again, land intact here and brim everything off.    Our next destination is Tylo and we're going to need to arrive here with as much fuel as possible 

In low Tylo orbit, undock the lander and fly it down to the surface.  I set mine up  so it could jettison the IRSU gear on the surface and not have to carry that back to orbit.     After rendezvous with the space plane,  I jettisoned the lander's engines and fuel tanks but docked its crewed bits back to the space plane, since i thought my little guys might appreciate all the habitat volume they can get on the long journey back.   

Finally, hope the space plane has enough delta V to plot a journey home again.  We can't refuel again, after leaving our IRSU behind on the surface of Tylo.

Sadly,  I hosted my images from this mission on Photobucket and they are no longer accessible, but the youtube vids still exist.

I flew the craft again recently and verfied the space plane side of things still works well 

https://kerbalx.com/AeroGav/Steven-Tylo

Droppable fuel tanks to get out of Kerbin.      The Whiplash pods come off soon after as well.

   

In LKO,   airplane's cavernous interior on display..

[boccelounge]

Thanks for both the question, and the answer.  I've currently got a refinery operation en route to Jool, including two landers-- one designed for Mun, one for Minmus.  I'm going to test them on Vall and Pol, respectively...  but I'm already pretty sure we'll set up the operation at Pol.

[bigcalm]

In my last playthrough and this one too, I went for the refuelling setup at Vall, though Pol was always a consideration.  Its highish gravity well means that you need extra large vessels to do Vall efficiently.  Anyway, pros and cons.

Laythe:  Pros: Can do it using an ISRU plane which is nice and air breathing and efficient.  Great location.  Cons:  Can't automate landing a plane with MechJeb ; Using a plane will mean each refuelling trip takes ages;  Designing a heavy ISRU plane that can land easily on Laythe is not a trivial task and you're more likely to crash it.

Vall:  Pros: Best location in the Joolian system;  Can be automated with MechJeb; Flattish.  Cons: Highish gravity well means larger engines, larger fuel tanks to make it efficient and thus pushing the thing out to Vall in the first place can be fiddly.

Tylo:  Pros: None ; Cons:  HUGE gravity well means HUGE vessels to make it work.  I wouldn't even attempt it.

Bop:  Pros:  Low gravity well;  Cons: Worst location in the Joolian system due to the inclined orbit.  Very hilly.

Pol:  Pros: Lowest gravity well;  Cons: It's a long way out meaning transit to the other moons takes a long time.  Very hilly.

 

[LameLefty]

Thanks for everyone's comments and insights. I have no desire to do a formal Jool 5 challenge but it's nice to hear how it can be accomplished. 

Rather, I simply want to role-play a permanent research base/colony on the surface of Laythe and exploration of the other Joolian moons with as little propellant shipped in all the way from Kerbin. Nice to see my general first-blush impressions were correct in that orienting things around resources from Vall is going to require a lot more work/effort/vessel mass for a given amount of prop, as opposed to doing the same from Pol. 

Another insight I had the other night, though I failed to mention it, is that using nuclear engines for my mining lander is pretty useful; I get much higher ISP as opposed to LFOx, and the lander itself can be lighter and/or more efficient for the same mass of propellant since it's not using oxidizer on each round-trip, only liquid fuel. Linuxgurugamer, among his many dozens of abandoned mods he maintains, has resurrected and maintains Porkjet's "Porkworks" pack which includes some nifty NTR rockets, as well as those from Kommitz's "Nucleonics Ltd.". Kommitz's parts, in particular, have been a part of my KSP experience since probably 0.25 or earlier. LOVE those engines. Linuxgurugamer has balanced these parts' mass/ISP and they really make a great addition to any late-Career game.

As a result, I'm going to try to design an architecture around a Pol-based orbital refinery/tank farm with a high-capacity mining lander that I'll set down on the highest concentration of Ore I can locate in a reasonably flat, reasonably equatorial region of Pol. The orbital tank farm module will be able to separate from the refinery module and periodically make a milk-run (also on NTR power) back to Laythe to refuel a crewed shuttle to the surface base and/or whichever moon I have vessels around that need propellant.

Anyway, thanks again.  

 

[bigcalm]

9 hours ago, LameLefty said:

Thanks for everyone's comments and insights. I have no desire to do a formal Jool 5 challenge but it's nice to hear how it can be accomplished. 

Rather, I simply want to role-play a permanent research base/colony on the surface of Laythe and exploration of the other Joolian moons with as little propellant shipped in all the way from Kerbin. Nice to see my general first-blush impressions were correct in that orienting things around resources from Vall is going to require a lot more work/effort/vessel mass for a given amount of prop, as opposed to doing the same from Pol. 

Another insight I had the other night, though I failed to mention it, is that using nuclear engines for my mining lander is pretty useful; I get much higher ISP as opposed to LFOx, and the lander itself can be lighter and/or more efficient for the same mass of propellant since it's not using oxidizer on each round-trip, only liquid fuel. Linuxgurugamer, among his many dozens of abandoned mods he maintains, has resurrected and maintains Porkjet's "Porkworks" pack which includes some nifty NTR rockets, as well as those from Kommitz's "Nucleonics Ltd.". Kommitz's parts, in particular, have been a part of my KSP experience since probably 0.25 or earlier. LOVE those engines. Linuxgurugamer has balanced these parts' mass/ISP and they really make a great addition to any late-Career game.

As a result, I'm going to try to design an architecture around a Pol-based orbital refinery/tank farm with a high-capacity mining lander that I'll set down on the highest concentration of Ore I can locate in a reasonably flat, reasonably equatorial region of Pol. The orbital tank farm module will be able to separate from the refinery module and periodically make a milk-run (also on NTR power) back to Laythe to refuel a crewed shuttle to the surface base and/or whichever moon I have vessels around that need propellant.

Anyway, thanks again.  

 

1. There's also some different nuclear engines available in the NearFuture mod - they're balanced, just tend to be larger thus saving on part count more than anything else.  The only issue I've had with nuclear engine powered ISRUs is the engines are really long and it's fiddly to arrange the craft around them so that they have lowish centre of mass and won't tip over when you inevitably land on a steep slope.  This will happen to you on Pol - there's very little flat terrain around so plan accordingly.

2. Bear in mind you will likely need a small amount of oxidiser - for your SSTO planes at Laythe, so don't forget the ability to transport it around.

Sounds like you've got a great mission planned out ahead of you - apart from the vessels to Laythe (your primary objective), you're going to need the ISRU setup at Pol - one Lander, one orbital refinery and fuel dump, and one tanker and these can likely be sent in a single package.  Good luck!

[AeroGav]

4 hours ago, bigcalm said:

2. Bear in mind you will likely need a small amount of oxidiser - for your SSTO planes at Laythe, so don't forget the ability to transport it around

@LameLefty to be honest I would certainly use a liquid fuel only SSTO design for Laythe.   All my designs are in fact heading that way,  even LKO cargo lifters,  but it's especially easy on Laythe since orbital velocity is only slightly higher than air breathing max speed and the upper atmosphere remains thick enough to run jet engines until only some 15km below the boundary of space.

It also means your refuelling infrastructure can standardise around a single fuel type and makes the transport of the SSTO from Kerbin to Jool system much easier.   A chemical SSTO typically only has around 1000dV worth of oxidizer tankage, so would need refuelling multiple times to get to Laythe.

Have a look at this thing,  it could probably do a job for you -

https://kerbalx.com/AeroGav/MK1-Griffon-Deep-Space-Crew-Shuttle

11 seats, docking port,  3000dv in lko liquid fuel spaceplane.   If refuelled in orbit, would have nearly 6000 delta v for the trip to Laythe..

[LameLefty]

I’ve actually tested a few lander designs for Pol already. I’ve been doing some form of ISRU, usually at Minmus and/or Ike since fooling around with Kethane back in 0.21 or so. I’ve got good designs with top-mounted engines and low-mounted prop tanks and drills. I’ve been testing similar designs using the Cheat Menu to get them into orbit around Lathye, Vall and Pol.

Once the LT-2 exploding landing legs issue gets worked out, I’ll be continuing my Career and getting missions en route from Kerbin.