ISRU noob needs help...

[MaverickSawyer]

Alright, I have a confession to make... I have been playing KSP for a touch over 7 years now, and there are few things that are able to make me sit back and go, "Wait... how... WHUH??"

In-Situ Resource Utilization is one near the top of the list.

I mean, I understand how to get the drills to work and gathering ore, and that you feed that into the converter to get fuel, oxidizer, and monoprop. I just... I have never been able to make heads or tails of the idiosyncrasies of the systems.

Here, an example...

That's two stock mini drills, three stock RTGs, and a pair of radiators from ProbesPlus to keep the drills cool, btw. But, I set this up just outside physics range of the base. I started the drills with the first tank in place, drove off to go get more parts, came back, and everything had quit. Is that normal? Should I have built the rig inside the physics bubble of the base?

Also, I'm currently babysitting that rig with my engineer, and the radiators, at startup, spiked to nearly 60% cooling, and are now closing in on 50% and still going down, albeit slowly. Is that also normal?

Basically, I need some advice from people with some experience running ISRU. I'm very confused.

[Aegolius13]

I don't have exact numbers at hand (and not sure if the wiki is current), but three RTGs does not sound like nearly enough juice for two mini-drills and three radiators. 

I've had some weird results as well with leaving drills to run outside of physics range.  It can work, but doesn't always seem to.  I think someone said at one point you have to leave them for a certain amount of in-game time before the mining registers, but not sure.

I wouldn't worry too much about radiator numbers - the more important question is whether your drills are able to hold steady at their ideal temps.  If you had just landed, the radiators might have also been rejecting extra heat from your engines or something like that.  Loads could also vary depending on whether your ship is in the sun vs. shade. Or it could be a quirk with the mod you're using. 

[bewing]

Yes, radiator spikes on startup are normal. As Aegolius said, the rest of your craft has heat in it when you start, and the radiators automatically go to 100% load until all that residual heat is gone. Radiators are smart, and automatically go to 100% and never go over during normal operation. So you don't have to worry about them.

Note that drills and converters have a special kind of heat -- "core heat". They also have the standard two kinds -- skin and internal heat. The core heat is what makes them run efficiently. When you turn them on, they are supposed to quickly ramp up their core heat to the optimal temperature. If you don't have sufficient cooling, then they will immediately start to overheat (the temp increase after that point is slow).

When you are outside physics range of a craft, it goes "on rails". Drilling and ore conversion get switched to a mode called "background processing" for on-rails craft. Background processing gets updated once every 6 hours. If you return to the craft within that first 6 hours, or get back within physics range, then the last batch (up to 6 hours worth) of processing gets erased, and the drills and converters get retroactively shut off. They will also shut themselves off if they run out of EC. So it's best if you just start the drilling/conversion process and then switch away from the craft. Don't come back (or back in range) for 6 hours.

 

 

[MaverickSawyer]

1 hour ago, Aegolius13 said:

I don't have exact numbers at hand (and not sure if the wiki is current), but three RTGs does not sound like nearly enough juice for two mini-drills and three radiators.

It ran perfectly fine, actually. I ran the numbers before I launched the supply mission with the parts in it, and it wasn't running out of juice or anything.

1 hour ago, bewing said:

Yes, radiator spikes on startup are normal. As Aegolius said, the rest of your craft has heat in it when you start, and the radiators automatically go to 100% load until all that residual heat is gone. Radiators are smart, and automatically go to 100% and never go over during normal operation. So you don't have to worry about them.

Note that drills and converters have a special kind of heat -- "core heat". They also have the standard two kinds -- skin and internal heat. The core heat is what makes them run efficiently. When you turn them on, they are supposed to quickly ramp up their core heat to the optimal temperature. If you don't have sufficient cooling, then they will immediately start to overheat (the temp increase after that point is slow).

I did check the core heat rejection requirements of the drills against the radiators... it was more than adequate with one, but I ran a second one, because Murphy.  

They're fixed units, but I made sure to orient them to be parallel to the sun's path. Being on the equator on a body with no axial tilt makes this quite easy.

1 hour ago, bewing said:

When you are outside physics range of a craft, it goes "on rails". Drilling and ore conversion get switched to a mode called "background processing" for on-rails craft. Background processing gets updated once every 6 hours. If you return to the craft within that first 6 hours, or get back within physics range, then the last batch (up to 6 hours worth) of processing gets erased, and the drills and converters get retroactively shut off. They will also shut themselves off if they run out of EC. So it's best if you just start the drilling/conversion process and then switch away from the craft. Don't come back (or back in range) for 6 hours.

Aha! So THAT's what happened. Good to know. I parked it far enough away to be outside of physics range,, but close enough to be a few minutes drive via rover... but also for an extra 1% of ore concentration. I don't think it's worth it, so I'll be setting up the new one much closer to the base, so I can keep a closer eye on it... and to keep the Kraken at bay. He smashed the rig I had been working on, and upon reloading the quicksave, it was completely and utterly gone.  Darnedest thing I've seen in a long time...

[Loren Pechtel]

RTG's are weak, it takes a lot of them to keep things powered.  For your money there are two other options that work better:

1)  Fuel cells.  Yes, they'll burn up some of your take but it keeps things running during the dark time.  (Note that this is only an option if you have a refinery on the craft set to produce fuel and oxidizer.)

2)  Big batteries.  They're heavier to lift but don't consume any fuel.  Obviously you must have enough solar to charge them up.

Nuke is overkill for a simple mining base.

[Laie]

On 2/6/2019 at 5:59 AM, Aegolius13 said:

I don't have exact numbers at hand (and not sure if the wiki is current), but three RTGs does not sound like nearly enough juice for two mini-drills and three radiators. 

On 2/6/2019 at 8:03 AM, MaverickSawyer said:

It ran perfectly fine, actually. I ran the numbers before I launched the supply mission with the parts in it, and it wasn't running out of juice or anything.

Some things about powering ISRU that I learned:

• drills will always run at full power. If there's not enough electric charge, they will shut down. Then you have to drop out of warp in order to turn them on again.
• converters will automatically pause if they don't have enough input resources. If there's some (but not enough) energy or ore coming in, they will quickly alternate between on/off and, for all practical purposes, run at (e.g) 20% load.
• Both can run faster when a skilled engineer is present, and will require more power as well. So a vessel that used to work fine with a two-star engineer may be underpowered when the engineer earns a third star.

BUT: all of that goes out of the window on sufficiently high timewarp: at 10k and 100k, the fastest two settings in stock, the game only checks if a power source is present, no matter how feeble, and then keeps everything running. That way, you can run a large rig from a single RTG, or a small fuel cell.

You still need enough power / battery capacity to transition from zero to high warp. If the machinery runs out of juice before the 10k warp level has been reached, the drills will shut down.

 

[MaverickSawyer]

Thanks again for all your help... I've repositioned the rig next to the base and left it alone for a while after building it... Gotta admit, it's working quite well!

It's working a heck of a lot better than I'd anticipated. Shipping out the refinery parts now, so I'll see how that goes. I am using the 1.25 meter version, due to the smaller size of both the part and of the operation at present. I understand that it'll shut down after a while, as I noticed that it needs 100kW of cooling... but max core transfer is 75kW.  I'm just glad I'm not expecting to do very large fuel loads right now.