Let the Mun Mining begin!!

[MPDerksen]

I have finally progressed from rescuing the stranded, collecting science (the tree is basically complete) and have the start of my Duna Station.  

I accepted a mission to move 2,200 units of ore into LKO.  My probe, in Mun Polar Orbit has collected both the low-rez and the high-rez scans of Mun.  I've picked my landing spot, (directly below my KMSS, Kerbal Munar Space Station)

 and I'm ready to build my mining lander.  Since I need to bring Ore back, not fuel, I wasn't going to put a converter on it at all.  Just solar panels and radiators.  If I want to do this in a single trip, I need 1 large, and 3 small holding tanks.  I was going to use a triad of smaller drills.

This is certainly "first attempt".  I have a fully fueled mass of 18 tons, and around 3,400 vac dV with the 3 sparks.  However, on lift off, I'll have 2,200+ units of ore.  

Question #1:  assuming I get this landed where I want it, and fill it with ore, will I be able to transfer off Mun and to LKO?  I don't know how to calculate how much dV I'm going to actually need.  Happy to aero brake.  Note that I have a docking port on top so I could refuel at the space station.

Question #2:  do i really need the surface scanning module?  Once I land, I'm probably just going to mine where I am, right?  I assume the module is more helpful for rover style miners?

Question #3:  I need about 3,400 dV to move to LKO, and another ~1,000 to get this into the equatorial orbit at Mun.  Or should I plan on a stop at the gas station I have circling Mun before I attempt to land, and then I can use the dV built into the lander as a transfer stage?

Thanks for the help.  This continues to challenge and engage me.

Michael

[bewing]

13 minutes ago, MPDerksen said:

This is certainly "first attempt".  I have a fully fueled mass of 18 tons, and around 3,400 vac dV with the 3 sparks.  However, on lift off, I'll have 2,200+ units of ore.  

You may want to swap out the little drills for big ones, and you may want to add at least a command seat for an engineer. The speed increase for the mining will be huge.

13 minutes ago, MPDerksen said:

Question #1:  assuming I get this landed where I want it, and fill it with ore, will I be able to transfer off Mun and to LKO?  I don't know how to calculate how much dV I'm going to actually need.  Happy to aero brake.  Note that I have a docking port on top so I could refuel at the space station.

It takes maybe 700 m/s to get to Mun orbit, and another 300 to get to a decent Pe on Kerbin for aerobraking. But I'm worried that you won't have enough thrust to get off the ground. You're on the hairy edge for minimum liftoff thrust.

In the editor you can also fill ore tanks, temporarily. Then you will be able to get the dV for the craft with full ore tanks. Then empty the tanks again.

13 minutes ago, MPDerksen said:

Question #2:  do i really need the surface scanning module?  Once I land, I'm probably just going to mine where I am, right?  I assume the module is more helpful for rover style miners?

As you said, the surface scanner is only barely useful if you can move around. It serves no purpose at all for a stationary mining base.

13 minutes ago, MPDerksen said:

Question #3:  I need about 3,400 dV to move to LKO, and another ~1,000 to get this into the equatorial orbit at Mun.  Or should I plan on a stop at the gas station I have circling Mun before I attempt to land, and then I can use the dV built into the lander as a transfer stage?

You're going to need another thousand to land. So yes, I suspect you'll need to refuel.

However, pay close attention to your contract. If the contract is asking for a NEW station in LKO with ore onboard, then you can't dock to anything except brand new ships during your entire mission, or the contract will fail.

 

[MPDerksen]

5 minutes ago, bewing said:

You may want to swap out the little drills for big ones, and you may want to add at least a command seat for an engineer. The speed increase for the mining will be huge.

It takes maybe 700 m/s to get to Mun orbit, and another 300 to get to a decent Pe on Kerbin for aerobraking. But I'm worried that you won't have enough thrust to get off the ground. You're on the hairy edge for minimum liftoff thrust.

In the editor you can also fill ore tanks, temporarily. Then you will be able to get the dV for the craft with full ore tanks. Then empty the tanks again.

As you said, the surface scanner is only barely useful if you can move around. It serves no purpose at all for a stationary mining base.

You're going to need another thousand to land. So yes, I suspect you'll need to refuel.

However, pay close attention to your contract. If the contract is asking for a NEW station in LKO with ore onboard, then you can't dock to anything except brand new ships during your entire mission, or the contract will fail.

 

Just put a lander can with an Engineer on top of the probe core?

Assuming no change in fuel, would a single Poodle be better?  TTW is calculated how?  Maybe learning this would help me.

I use far more than 300dV to return from Mun.  Can I ask you to use crayons to draw me a picture of a better way to do the transfer?  

My station tank is actually empty right now, so I would orbit a small tanker, dock with it in LKO, transfer both to Mun, and NOT dock the tanker to the KMSS until after the lander is up, refueled and back in orbit.  Once the ore is in LKO, I intend to send up a converter as the hub of a new station, and use that tanker in-system.  Here is the mission:

[bewing]

1 hour ago, MPDerksen said:

Just put a lander can with an Engineer on top of the probe core?

That would work.

1 hour ago, MPDerksen said:

Assuming no change in fuel, would a single Poodle be better?

Yes, that would get you a small boost in engine efficiency, and a huge boost in thrust.

1 hour ago, MPDerksen said:

  TTW is calculated how?  Maybe learning this would help me.

You need to go to the wiki and see what the surface gravity is for your liftoff. Your TWR  is the number of newtons of thrust in your engine, divided by your ship's mass in kg times the surface gravity acceleration.

So if your craft is 20 tonnes, that's 20000 kg. The Mun's gravity is 1.63 m/s^2. So you need 32.6 kilonewtons from your engine to achieve a TWR of 1.0. Which isn't enough to get you off the ground.

1 hour ago, MPDerksen said:

I use far more than 300dV to return from Mun.  Can I ask you to use crayons to draw me a picture of a better way to do the transfer?  

You want to be in the lowest convenient orbit around the Mun when you leave -- to take the most advantage of Oberth.

The Mun has enough orbital velocity to have a Pe of 11,400km -- to return to Kerbin, you want your final Pe to be a lot lower than that. So you need to kill most of your orbital velocity from the Mun. So you need to exit the Mun's SOI going backwards along the Mun's orbit.

In this example, I'm in a 15km orbit over the Mun. The maneuver node is pretty good, but not quite the most efficient possible -- because the lines are not quite parallel.

 

1 hour ago, MPDerksen said:

My station tank is actually empty right now, so I would orbit a small tanker, dock with it in LKO, transfer both to Mun, and NOT dock the tanker to the KMSS until after the lander is up, refueled and back in orbit.  Once the ore is in LKO, I intend to send up a converter as the hub of a new station, and use that tanker in-system.  Here is the mission:

OK, good. It's not a station contract, so you can refuel all you like.

Depending on how you play the game, though -- sometimes it's fun to maximize your profits by following the contracts to the letter, but violating their spirit. So you may want to note that the vessel that mines the ore doesn't have to be the same vessel that ends up in orbit around Kerbin. It also doesn't have to be the same ore. And you don't have to get it all the way to LKO to complete the contract. All you need to do is get the ore just barely out of the Mun's SOI. Or mine the ore on the Mun, don't launch it, and launch a craft with 2200 ore from KSC into LKO.

 

 

[MPDerksen]

well that escalated quickly!!!

3 big drills = way more solar arrays, and radiators.  Then I added the required RCS (and tanks) so I could dock and refuel.  2,400 units of ore is a full 24 tons, bringing the Mun lift off to 52 tons.  Now I'll need a bigger engine too.  All this just for Mun, not even interplanetary.  Gonna do some math you mention above, but start with the basics and move down.

Edited May 1, 2019 by MPDerksen

[Kryxal]

4 hours ago, bewing said:

That would work.

Yes, that would get you a small boost in engine efficiency, and a huge boost in thrust.

You need to go to the wiki and see what the surface gravity is for your liftoff. Your TWR  is the number of newtons of thrust in your engine, divided by your ship's mass in kg times the surface gravity acceleration.

So if your craft is 20 tonnes, that's 20000 kg. The Mun's gravity is 1.63 m/s^2. So you need 32.6 kilonewtons from your engine to achieve a TWR of 1.0. Which isn't enough to get you off the ground.

You want to be in the lowest convenient orbit around the Mun when you leave -- to take the most advantage of Oberth.

The Mun has enough orbital velocity to have a Pe of 11,400km -- to return to Kerbin, you want your final Pe to be a lot lower than that. So you need to kill most of your orbital velocity from the Mun. So you need to exit the Mun's SOI going backwards along the Mun's orbit.

In this example, I'm in a 15km orbit over the Mun. The maneuver node is pretty good, but not quite the most efficient possible -- because the lines are not quite parallel.

 

OK, good. It's not a station contract, so you can refuel all you like.

Depending on how you play the game, though -- sometimes it's fun to maximize your profits by following the contracts to the letter, but violating their spirit. So you may want to note that the vessel that mines the ore doesn't have to be the same vessel that ends up in orbit around Kerbin. It also doesn't have to be the same ore. And you don't have to get it all the way to LKO to complete the contract. All you need to do is get the ore just barely out of the Mun's SOI. Or mine the ore on the Mun, don't launch it, and launch a craft with 2200 ore from KSC into LKO.

 

 

That ejection burn is more efficient than you think ... by the time you reach the ejection point, the Mun will be further along in its orbit.  If you drag the node along the orbit and the AP and PE go down, you're improving the efficiency.

Also of note, you only have to mine 2200 from the Mun, nowhere does it say the mining craft has to be able to store it all.  Still, I usually build with ISRU and do a refuel on landing ... means you have LOTS of delta-v to work with!

[MPDerksen]

41 minutes ago, Kryxal said:

That ejection burn is more efficient than you think ... by the time you reach the ejection point, the Mun will be further along in its orbit.  If you drag the node along the orbit and the AP and PE go down, you're improving the efficiency.

Also of note, you only have to mine 2200 from the Mun, nowhere does it say the mining craft has to be able to store it all.  Still, I usually build with ISRU and do a refuel on landing ... means you have LOTS of delta-v to work with!

I don’t know what ISRU is.  Please explain. Is that a converter?  Doesn’t that add even MORE weight to my craft?

Regardless, I need to get 22-24 tons from the surface, up to Munar orbit.  So it need to be in a craft that can lift that, plus itself.  I’m a little baffled how people “dock” on the ground to transfer   

[bewing]

1 minute ago, MPDerksen said:

I don’t know what ISRU is.  Please explain. Is that a converter?  Doesn’t that add even MORE weight to my craft?

Regardless, I need to get 22-24 tons from the surface, up to Munar orbit.  So it need to be in a craft that can lift that, plus itself.  I’m a little baffled how people “dock” on the ground to transfer   

Yes, it's a converter. Yes, it adds more weight -- but the point is that you have a huge amount of fuel available at that point, so you can have a really big engine and you don't have to worry about weight anymore.

The easy way to dock on the ground is with a klaw on the nose of a rover. You just drive up and bump the klaw into any flat surface. That gets you docked. And then if you have the settings set nicely, you can do trasfers.

The hard way is with carefully matched docking ports. Once again, you have one on the nose of a rover, but the rover needs to have some method to raise and lower the nose. You drive up and get the nose aligned horizontally, then either raise or lower the nose -- maybe while inching forward at the same time. Hopefully your docking ports will dock when they get really close.

 

[MPDerksen]

I love the idea of landing from the station, making up some fuel and bringing it back to the station for refueling outbound craft. 

In that case, I would need to land with empty fuel tanks rather than ore canisters. 

I'll make enough on this mission to justify the learning experience. 

[MPDerksen]

I think I have this ready to go, but thought I would double check with the hive mind. 

If I only have fuel in the orange, central tank for landing, I have 1286dV.  (I can always bring more if you think I'll need more to get from my low orbit to my site).  It is sitting at 25.6 Ton for lift off and transfer to Mun.  Very do-able.
Doing the math from the Wiki, like Bewing suggested, My Poodle has 250.0 kn in vac.  Once I have a full load of fuel and Ore, the ship will mass 87 Ton.  250kn/(87T x 1.63m/s2) = 1.76.  I'll get off the ground for sure.  I'll have 2094m/s  to get this back into LKO to complete the mission.

Extras:  I have a spot for an Engineer (I have an extra one doing nothing with 2 stars).  I have a few lights, just in case I need to land later in low light.  I need to add RCS, but do have a Docking Port Jr. on top for future transfer.  I have enough solar and cooling to run everything full speed.

Am I good to go with a lifter and test the mission?  

[bewing]

Sounds good to me.

[MPDerksen]

A quick add.  I built a lifter, and didn't have nearly enough dV to get as far as I'd like, but got it into a stable low Mun orbit.  When I tried to dock, my RCS was all wonky.  I could only go on 1 axis, not both.  I'll have to redo it.  With the lifter I have, I'm going to need to send up a fuel run to have enough to land and then proceed.  I really don't understand why I have so much trouble putting on enough boosters to get where i want to go.  I've followed various Tutorial, but when i try to do it myself I run low, constantly.  my dV is in over the required range, and my launches and captures are also reasonable.

Edited May 2, 2019 by MPDerksen

[MPDerksen]

Took a few Quicksaves to get it landed (this thing is fairly bulky).  We're settled near enough my desired spot and chugging away.  With 2 drills, my Resources tab says (--0.29).  Looks like a fair amount of time warping.  I'm also going to fuel up while I'm here.  That's kinda the point, right?  So I could get the Ore into orbit, then convert it to make fuel to get back to Mun for another load.  

so how do people get complex stations on the surface for mining all assembled?  Put them together in orbit and then land all together?  Or is there a surface construction technique I haven't run across yet?

Michael

Edited May 3, 2019 by MPDerksen
Picture added

[Snark]

On 5/1/2019 at 10:45 PM, MPDerksen said:

I really don't understand why I have so much trouble putting on enough boosters to get where i want to go.

How do you mean, "boosters"-- do you mean during the ascent-from-launchpad phase?

There are a lot of ways to build & fly an inefficient ascent-- it might be a problem with the rocket design itself, or it might have something to do with the ascent path you're following.  Could you post a pic of your complete craft as it looks ready-to-launch, with boosters and all?

What's your TWR on the launchpad?  Also, what does your ascent profile look like, i.e. what flight path to orbit?  For example, when you hit 300 m/s, how high are you and what angle from vertical are you tipped at?

1 hour ago, MPDerksen said:

so how do people get complex stations on the surface for mining all assembled?  Put them together in orbit and then land all together?  Or is there a surface construction technique I haven't run across yet?

The game doesn't have any super great options for surface assembly.  Myself, I tend to just not build big complex stations on the surface.  I put my infrastructure in orbit, and send down a combined miner-refiner to pick up supplies and shuttle them back to orbit.

Assembly in orbit is a thing one can do, yes.  It's also possible to assemble stuff on the surface by fiddling with docking ports, though I myself generally never do that because I find docking on the surface to be an incredibly tedious hassle that sucks fun out of the game for me.  (Other people have had success doing it, but either they're better at finicky surface-maneuvering fiddling than I am, or else they're more patience.)

If you're amenable to mods, KIS has a handy way of building surface bases, using "connector ports".  This is a small, reasonably lightweight, radially attachable thing that you put on your craft.  Land two craft on the surface within a couple dozen meters of each other, with connector ports facing approximately towards each other.  Then send out an EVA kerbal and do some right-clicking on the ports, and bingo, you have a decent-looking "pipe" connecting the two craft and now they count as one.  When done, just use an EVA kerbal again to disconnect them.  I've done some base-building using KIS, and found it to be fun, un-tedious, and decent-looking.

[MPDerksen]

I start my gravity turn at about 5K, trying to get to 90 degrees by 20K.  Once my Ap gets to about 80, I kill thrust until I get close to that, then thrust "sideways" (not sure of the correct term) to circularize at about 90-100K.  I can post a picture of my most common lifter when I get back to the game.  

Watching a few videos about the Klaw, and I had NO idea that an engineer could take a part, and move it to another location.  That's simply HUGE!!  I built my Mun Station before I had unlocked the largest solar panels.  So my science lab nearly runs out of juice before completing the transfer.  If I'm not crazy, I can send up some panels, and EVA my engineer to place them on the station?  (oh,  it's the KIS mod and I have no idea how to install those yet)

Back to the topic of this thread.  I have no where near enough monoprop on my miner to efficiently dock back with my station.  Once I load it up, it needs a huge amount to make directional changes.  I have 6 RCS packs on each side, for a total of 12.  Did I put them in the wrong location?  (another job for the engineer?)  Do I just need to convert some of the ore to Mono while I use it up?  I got $533K for completing the mission, but I had to ditch the craft if I can make some changes to keep it usable.

MD 

Edited May 8, 2019 by MPDerksen
did some homework.

[MPDerksen]

Since I like to add pictures to keep my posts fun, (but don't have another of my miner) here is a shot of my science lander on it's first trip to Ike.  It's kinda relevant, since the miner refueled it to transfer from Mun to Ike....

[bewing]

3 hours ago, MPDerksen said:

I start my gravity turn at about 5K, trying to get to 90 degrees by 20K.

That's very very late to start, and too early to end. You want to start your gravity turn either right off the pad, or within a few hundred meters of the ground. You should be able to lock SAS to prograde within 10 seconds. Your prograde should drift to 45 degrees off vertical by 8km to 10km altitude.

3 hours ago, MPDerksen said:

 Once my Ap gets to about 80, I kill thrust until I get close to that, then thrust "sideways" (not sure of the correct term) to circularize at about 90-100K.

Yeah, thrusting towards the horizon is correct once you get close to your Ap. Many people find it useful to place a prograde maneuver node at the Ap, so they know when to start the circularization burn and how big it should be.

3 hours ago, MPDerksen said:

Back to the topic of this thread.  I have no where near enough monoprop on my miner to efficiently dock back with my station.  Once I load it up, it needs a huge amount to make directional changes.

 

I think the point is that RCS is only useful for making tiny changes for heavy craft. You may want to swap for vernors (they are much more powerful), or else you will need to learn how to do a lot more of your docking maneuvers with your main engine.

If you work at it, you can do your entire docking with your main engines, and then you don't need any RCS on your craft at all.

[MPDerksen]

20 minutes ago, bewing said:

That's very very late to start, and too early to end. You want to start your gravity turn either right off the pad, or within a few hundred meters of the ground. You should be able to lock SAS to prograde within 10 seconds. Your prograde should drift to 45 degrees off vertical by 8km to 10km altitude.

Yeah, thrusting towards the horizon is correct once you get close to your Ap. Many people find it useful to place a prograde maneuver node at the Ap, so they know when to start the circularization burn and how big it should be.

I think the point is that RCS is only useful for making tiny changes for heavy craft. You may want to swap for vernors (they are much more powerful), or else you will need to learn how to do a lot more of your docking maneuvers with your main engine.

If you work at it, you can do your entire docking with your main engines, and then you don't need any RCS on your craft at all.

I mis-spoke.  The NavBall is still a bit of a mystery to me.  I just launched another refueler.  The ball says, "90", but it's at 45 degrees, in the 90 degree from north direction.  And I usually only wait until 5K with really top-heavy craft.  On most, I start the turn once I hit >100m/s.  I never thought to use the Prograde SAS button.

Totally side question:  I am running v1.6 through Steam, and thought I had installed Kerbal Alarm Clock in the correct folders, following the install guide.  I don't see the button for it anywhere on the screen.  Some advice there would be great.

[MPDerksen]

last add to this thread:  I sent up a refueller with a Klaw (more for testing than out of need).  Plugged it into the top of my Miner, and then navigated it back to the KMSS as a single craft.  I practiced using only the Poodle on the Miner to get as close as possible for docking.  Yeah, that was super easy once I actually tried.  Only used RCS to fine tune and kill the last 2m/s.  Then docked the Refueller at the same station.  

Now the unfortunate part:  Once I had the Miner ready to go again, I landed in a hot spot, filled up the fuel tanks, (liquid and mono) as well as 3K units of Ore.  I used a huge % of it just go get back to the station.  But I was able to add a fair amount back to the Station.  I just don't get as much per trip as I would have liked, since it takes SO much dV to get all the ore off the surface (but then I just convert it in orbit and put it into the fuel tanks that have drained on lift off.)

[radonek]

On 5/9/2019 at 8:59 PM, MPDerksen said:

Now the unfortunate part:  Once I had the Miner ready to go again, I landed in a hot spot, filled up the fuel tanks, (liquid and mono) as well as 3K units of Ore.  I used a huge % of it just go get back to the station.  But I was able to add a fair amount back to the Station.  I just don't get as much per trip as I would have liked, since it takes SO much dV to get all the ore off the surface (but then I just convert it in orbit and put it into the fuel tanks that have drained on lift off.)

I don't think that lifting ore off Mun surface is very economical. I would go for surface ISRU and lift up processed fuel. If you want orbital processing, Minmus is a place to go.