Space Infrastructure

[Baker]

Hi everyone I'm quite a few hours into KSP. For me the harder missions now involve large numbers of tourists to the Mun or trips to distant planets. Its occurred to me recently that solving missions with a single bigger and more complicated ship is sub-optimal. (Sub-optimal from a resource perspective and my own fun. :) ) What I need is a "space infrastructure": relays, refueling bases, mining and processing facilities, ships designed for refuel and certain parts of the voyage, etc.

So I need to get a lot of stuff into space. And it seems necessary to build reusable lifters and large, composable craft and bases. That's where I'm having some problems. I've attached below pictures of my medium and large lifters. As well as one "mothership" part and my tech tree.

Here are my problems:

• The large lifter uses those beauty Mammoth engines. It's also so heavy that it's tough to get back to Kerbal's surface safely. I'd like to get similar lift with less weight. Any ideas?
• Because of the huge engines the heavy lifter lacks finesse in orbit. Its tough to do precise maneuvers for rendezvous and docking. It would be nice to attach Twitch engines and use just those for fine-tuned docking maneuvers. But I don't know how to "turn off" the Mammoth and use a smaller engine. How can I improve maneuverability and add finer-grained thrust control for a lifter so it can possibly dock itself?
• Because of heavy lifter control problems, I generally decouple my mothership parts and give them mono propellant and controllers to dock themselves to the other parts. But some of those parts (Such as my S3-14400 fuel tank) are so damn big that mono propellant can barely move them. The big tank has fuel so it could also use Twitch engines but the backbone (pictured below) only carries mono propellant. Any suggestions on how to design my mothership parts to facilitate easy docking in orbit? Or is this all solved with improved control of the lifter so it can do the docking itself?

Thank you!

Heavy lifter:

Medium lifter:

One piece of my "mothership" (the backbone):

My tech tree:

[bewing]

3 hours ago, Baker said:

But I don't know how to "turn off" the Mammoth and use a smaller engine.

All engines have an "Activate/Deactivate" button in their context menus. So you get to orbit, right click on each engine, and click the "Deactivate" button. You can also do this with an action group, to turn off all the Mammoths at the same time.

If monoprop and RCS thrusters are not providing sufficient oomph, then you might want to consider using Vernors instead. They eliminate the need for monoprop, which simplifies your craft design -- and they have quite a lot of thrust.
 

[Adenosine Triphospate]

3 hours ago, Baker said:

relays, refueling bases, mining and processing facilities, ships designed for refuel and certain parts of the voyage, etc.

Wow, thats a pretty big undertaking for career mode when the tech tree isn't fully unlocked! To be honest, I don't deem these really necessary (nor really exciting in my opinion, except for all the rendezvous with refuelling ships) and really just overcomplicates things if you're only going to the mun. By all means, if you find it fun to plant satellites and use ISRUs then go ahead, its just that I personally wouldn't, I'd stick to a more simple approach, like an ordinarily staged rocket.

As for the lifter, its seems, ermm, big! If you want more dV, don't be afraid to just build taller, just as long as it has a TWR more than 1 (this could make it harder to land, although I'd just add more parachutes and let it gently tip over). Having four mammoths seems more than necessary for whatever payload that large size fairing could hold. I'd recommend perhaps just using one mammoth which saves weight. If you really need more power, strap some (like maybe six kickbacks) to the side and just stage them off. They're pretty cheap, so no big loss.

However, I don't recommend keeping the lifter stage in orbit once its done its job! Once the payload is delivered, just de-orbit and land it. I can't imagine how annoying it would be to have to do orbital manoeuvres with a mammoth. The payload (mothership I think in this case) should have its own engine to do low dV manoeuvres in orbit, perhaps a spark or twitch as you mentioned. Don't lug around that enormous mammoth longer than you need to!

I understand that you want to recover the entire lifter, however, you may want to consider going back to good old staging? Its far more efficient, so overall you'll need less parts and fuel, as you don't carry those heavy lower stage rockets, which you may only need to use one of (instead of four) if you decide to stage. You'll also have a smaller ship in orbit, so its easier to control  Yes, it will cost more, but sometimes the reduced stress is worth the extra kredits.

 

[Incarnation of Chaos]

Spoiler

4 hours ago, Baker said:

Hi everyone I'm quite a few hours into KSP. For me the harder missions now involve large numbers of tourists to the Mun or trips to distant planets. Its occurred to me recently that solving missions with a single bigger and more complicated ship is sub-optimal. (Sub-optimal from a resource perspective and my own fun. ) What I need is a "space infrastructure": relays, refueling bases, mining and processing facilities, ships designed for refuel and certain parts of the voyage, etc.

So I need to get a lot of stuff into space. And it seems necessary to build reusable lifters and large, composable craft and bases. That's where I'm having some problems. I've attached below pictures of my medium and large lifters. As well as one "mothership" part and my tech tree.

Here are my problems:

• The large lifter uses those beauty Mammoth engines. It's also so heavy that it's tough to get back to Kerbal's surface safely. I'd like to get similar lift with less weight. Any ideas?
• Because of the huge engines the heavy lifter lacks finesse in orbit. Its tough to do precise maneuvers for rendezvous and docking. It would be nice to attach Twitch engines and use just those for fine-tuned docking maneuvers. But I don't know how to "turn off" the Mammoth and use a smaller engine. How can I improve maneuverability and add finer-grained thrust control for a lifter so it can possibly dock itself?
• Because of heavy lifter control problems, I generally decouple my mothership parts and give them mono propellant and controllers to dock themselves to the other parts. But some of those parts (Such as my S3-14400 fuel tank) are so damn big that mono propellant can barely move them. The big tank has fuel so it could also use Twitch engines but the backbone (pictured below) only carries mono propellant. Any suggestions on how to design my mothership parts to facilitate easy docking in orbit? Or is this all solved with improved control of the lifter so it can do the docking itself?

Thank you!

Heavy lifter:

Medium lifter:

One piece of my "mothership" (the backbone):

My tech tree:

 

#1- Why does your lander have 4 engines in the first place? You apperently have the ability to dock and NERVA engines. So make yourself a Space Tug, shoot it up into LKO and rendevous it with the "Lander" for your contracts. This saves you money on the transfer stage (Your only cost is fueling it now) and makes the lander the only stage you need to recover and it goes from needing to carry enough fuel to go from LKO>Mun>Insertion burn> Circularize>Land>Ascend>Escape>LKO>Decend>Land. To only needing enough fuel to Land>Ascend>Rendevous>Decend; which can also be done with much more efficient engines now with much less weight. And you still recover the lander!

#2- Honestly i hate to say this but your solution is not really in the stock game; there's plenty of mods that add reaction wheels for 2.5M parts and beyond which make this a cakewalk. But assuming the stock game is your only option; don't fuss around with RCS and just make sure you have enough reaction wheels to keep these parts stable at the very least; then left-click your engines and find the "Thrust Limiter" and set it at about 10-20. Then target your docking ports and do the dance; and save often so when you muck it up it's not a complete waste of time.

But tbh i think you're building wayyy too big and the mass is just running away from you; meaning more fuel and more engnes which means more mass AHHHHHHAAAAHHH. 

Like i haven't seen contracts in the stock game where the number of tourists is over 4; which means that even if your lander parts don't have the capacity making multiple trips with the lander is an option. 

[Zhetaan]

1 hour ago, bewing said:

All engines have an "Activate/Deactivate" button in their context menus. So you get to orbit, right click on each engine, and click the "Deactivate" button. You can also do this with an action group, to turn off all the Mammoths at the same time.

@Baker:  I wanted to place some extra emphasis on this point.  Using an action group is a quite popular way of controlling engine clusters, because they allow one to activate or deactivate, for example, the air-breathing engines versus the rocket engines on a spaceplane while under power.  Doing it one at a time can cause asymmetric thrust.

Another important point is that if your mothership will include any landers or transfer craft, then you absolutely will want to employ this method to control which engines fire when you want to go anywhere.  Common control schemes include setting separate action groups for each vessel's engines, or a universal engine shutdown/abort command, followed by individual groups to activate a craft's engines--or however, you may want to do it, really.

1 hour ago, Adenosine Triphospate said:

Having four mammoths seems more than necessary for whatever payload that large size fairing could hold. I'd recommend perhaps just using one mammoth which saves weight. If you really need more power, strap some (like maybe six kickbacks) to the side and just stage them off. They're pretty cheap, so no big loss.

I agree with this sentiment; four Mammoths is an immense lifter.  I'd expect that on something designed to return from Eve, perhaps.  But your best option for this may well be to build cheaper.  Other possibilities for weight reduction include reducing redundancy (let the payload's batteries power everything) and shipping tanks empty (set up ISRU first and bring fuel from the Mun or Minmus).

Depending on how you want to do things, you may benefit from shifting the monopropellant carriage to stations rather than taking two long-form Mark-II fuselages full of it from place to place.  In other words, only carry enough monopropellant on the vessel to match velocities (assuming you need that much), and instead use a docking tug or similar contrivance (or set of contrivances; you can put one on each end if you like) to bring the vessel in to dock.

On the other hand, you can avoid the need for gigantic manoeuvres with three amazing words:  detachable crew modules.  You can transfer large numbers of crew to stations or wherever by use of a passenger module that operates as a shuttle (whether or not you use a tug).  Moreover, the undocked engine/tank combination then becomes available for a tanker to refuel.

[Geschosskopf]

7 hours ago, Baker said:

....What I need is a "space infrastructure": relays, refueling bases, mining and processing facilities, ships designed for refuel and certain parts of the voyage, etc.....

Wow, that's an ambitious project ;).  Sounds like a lot of challenging fun to build all that.

However, for practical purposes you really don't need all that.  The KSP solar system is very small.  This makes having a refueling infrastructure within the Kerbin system not worth the time, money, and hassle of setting up and running.  It will never pay for itself and you'll spend most of your time fiddling with it instead of flying missions.  Refueling infrastructure is only of practical value at other planets, and then only if you are planning major, long-term missions or permanent colonies there.

Relays are essential (if you have their options enabled) but fortunately can be done quite simply.  This old guide is still pretty useful for that:

https://forum.kerbalspaceprogram.com/index.php?/topic/148995-relay-networks-in-12/

 

[steuben]

Part of the fun for such projects is spreadsheet work, <forceful bro voice>Cause. Spreadsheets. Are. The. Bomb. Yeahh!!</forceful bro voice>

I know that reusable lifters are kind of the cool thing. They have their place. But, you may want to look at your tonnes to orbit and compare the cost of a single shot lifter versus relative to your reusables. IRL there are other factors that change some of the costs for each design philosophy, but they are poorly modeled in KSP.

If you want to get really ambitious you can add a third axis of game time to fly it.

What's the mass of the modules that you are lifting? I've used four mammoths, but I think I was lifting around two hundred tons.

 

 

[Baker]

On 6/13/2019 at 2:54 AM, steuben said:

What's the mass of the modules that you are lifting? I've used four mammoths, but I think I was lifting around two hundred tons.

200 tons?! Oh boy it sounds like I've over-designed again. My heaviest mothership part is a full S3-14400 fuel tank, with some light stuff attached to it. It weighs only 80 tons. Sounds like I need to scale back the engines.

On 6/12/2019 at 10:23 PM, Zhetaan said:

@Baker:  I wanted to place some extra emphasis on this point.  Using an action group is a quite popular way of controlling engine clusters, because they allow one to activate or deactivate, for example, the air-breathing engines versus the rocket engines on a spaceplane while under power.  Doing it one at a time can cause asymmetric thrust.

Another important point is that if your mothership will include any landers or transfer craft, then you absolutely will want to employ this method to control which engines fire when you want to go anywhere.  Common control schemes include setting separate action groups for each vessel's engines, or a universal engine shutdown/abort command, followed by individual groups to activate a craft's engines--or however, you may want to do it, really.

Yeah OK I was not using action groups for any of my craft. I understand how important this becomes with larger craft. Will study up and use. Thank you!

[Baker]

On 6/12/2019 at 10:14 PM, Incarnation of Chaos said:

  Reveal hidden contents

 

#1- Why does your lander have 4 engines in the first place? You apperently have the ability to dock and NERVA engines. So make yourself a Space Tug, shoot it up into LKO and rendevous it with the "Lander" for your contracts. This saves you money on the transfer stage (Your only cost is fueling it now) and makes the lander the only stage you need to recover and it goes from needing to carry enough fuel to go from LKO>Mun>Insertion burn> Circularize>Land>Ascend>Escape>LKO>Decend>Land. To only needing enough fuel to Land>Ascend>Rendevous>Decend; which can also be done with much more efficient engines now with much less weight. And you still recover the lander!

OK OK this is an interesting idea. Seems you're suggesting a space taxi system. One craft to deliver a payload (detachable crew as @Zhetaan says), the tug to move it to the Mun or wherever, and a lander to bring it to the surface. Do I understand that right?

 

On 6/12/2019 at 10:14 PM, Incarnation of Chaos said:

#2- Honestly i hate to say this but your solution is not really in the stock game; there's plenty of mods that add reaction wheels for 2.5M parts and beyond which make this a cakewalk. But assuming the stock game is your only option; don't fuss around with RCS and just make sure you have enough reaction wheels to keep these parts stable at the very least; then left-click your engines and find the "Thrust Limiter" and set it at about 10-20. Then target your docking ports and do the dance; and save often so when you muck it up it's not a complete waste of time.

But tbh i think you're building wayyy too big and the mass is just running away from you; meaning more fuel and more engnes which means more mass AHHHHHHAAAAHHH. 

Like i haven't seen contracts in the stock game where the number of tourists is over 4; which means that even if your lander parts don't have the capacity making multiple trips with the lander is an option. 

But I do have a contract in stock with six tourists to the surface of the Mun. This is difficult for me. It basically means I need to land a mk2 lander and a hitchhiker storage facility. Put those two things together and the 1500 delta v required to descent and return from Munar orbit and now I have a tall, awkward craft. And it requires refueling at a mun orbit base. And that's why I'm pursuing infrastructure that allows me to refuel.

Of course I could just make a bigger lander, use drop tanks, launch it from kerbal with big engines and lots of reaction wheels. But my assumption is that the infrastructure, using reusable components and vessels purpose-built for a small part of the journey, is more cost efficient. But @steuben has me wondering if that assumption is correct. Maybe I'm just doing this because I like complexity.

 

[bewing]

39 minutes ago, Baker said:

But I do have a contract in stock with six tourists to the surface of the Mun. This is difficult for me. It basically means I need to land a mk2 lander and a hitchhiker storage facility. Put those two things together and the 1500 delta v required to descent and return from Munar orbit and now I have a tall, awkward craft.

Well, not necessarily. I would do it as an MK1 capsule, on top of a MK1 crew cabin, with two more MK1 crew cabins as nacelles. That gives you a short little squatty (and very lightweight) non-awkward craft for landing and kerbin reentry. You just have to be very careful about reentry heating, because the crew cabins are delicate.

Edited June 15, 2019 by bewing

[Tonka Crash]

13 minutes ago, Baker said:

But I do have a contract in stock with six tourists to the surface of the Mun.

They don't have to go on the same trip to complete the contract. You can do them is more manageable groups.

Personally I like building up the infrastructure. I eventually try to get to the point that the only fuel I pay for is to get out of Kerbin's atmosphere. 

Another option is to build a dedicated Mun lander you leave in Mun orbit. Rendezvous with it for each trip to the surface. One launch to boost it to Kerbin orbit. The dV for it's normal mission should be around what you need to get it into Mun orbit from Kerbin. Stick a probe core on it for so it can operate uncrewed.

Design your tourist taxi to go from launch pad to Mun orbit and back to reentry. For each Mun landing take the fuel to top off the lander. The smaller the lander the less fuel it needs per trip. Dock with the lander, transfer fuel and tourists. 

Eventually I'd want a refuelling station, so I could quit lifting fuel from Kerbin for Mun landings.

[Baker]

40 minutes ago, bewing said:

Well, not necessarily. I would do it as an MK1 capsule, on top of a MK1 crew cabin, with two more MK1 crew cabins as nacelles. That gives you a short little squatty (and very lightweight) non-awkward craft for landing and kerbin reentry. You just have to be very careful about reentry heating, because the crew cabins are delicate.

I guess I'm bumping up against my understanding of the game with that. I tried as you suggest. The MK1 capsule on the MK1 crew cabin is easy enough. But there are no "attach points" on the side of the crew cabin to allow anything on its side. I've tried adding cubic struts, which will attach. But the additional crew capsules won't attach to them. Exactly how do you attach two additional crew capsules to the side of the first?

[FleshJeb]

44 minutes ago, Baker said:

Exactly how do you attach two additional crew capsules to the side of the first?

Attach a couple of the pointier nose cones and put the cabins on them. Close the other cabin node with another cone--Lighter or the same. Autostrut: Grandparent on the side cabins.

[Incarnation of Chaos]

2 hours ago, Baker said:

OK OK this is an interesting idea. Seems you're suggesting a space taxi system. One craft to deliver a payload (detachable crew as @Zhetaan says), the tug to move it to the Mun or wherever, and a lander to bring it to the surface. Do I understand that right?

 

But I do have a contract in stock with six tourists to the surface of the Mun. This is difficult for me. It basically means I need to land a mk2 lander and a hitchhiker storage facility. Put those two things together and the 1500 delta v required to descent and return from Munar orbit and now I have a tall, awkward craft. And it requires refueling at a mun orbit base. And that's why I'm pursuing infrastructure that allows me to refuel.

 

a MK3 command pod with a docking port and enough fuel can get you > 3K Delta-V; then you can just make multiple trips with a nice compact lander. The only issue becomes getting all 6 back down to kerbin; you have to choose between making the "Tug" heavier with more space for tourists. Or docking a return module after entering LKO.

[Epicdreamer]

On 6/12/2019 at 11:36 AM, Baker said:

But some of those parts (Such as my S3-14400 fuel tank) are so damn big that mono propellant can barely move them. The big tank has fuel so it could also use Twitch engines but the backbone (pictured below) only carries mono propellant. Any suggestions on how to design my mothership parts to facilitate easy docking in orbit?

With fuel the S3-14400 is a beast, but without it gets quite controllable.

I usually send up interplanetary motherships, or modules for a mothership, empty. Makes controlling them a lot easier. Once assembled in orbit I refuel the mothership in one or a few refuel launches. Might not be the most cost/time efficient, but then again, sending up near empty modules makes that you can send more stuff in one launch. The first module doesn't need any control, apart from SAS and a reaction wheel. As long as its attitude is stable. I do provide the rest of the modules with (detachable) controls (monoprop/thrusters)...or send up a spacetug to assemble the mothership in orbit. And for the bigger, heavier modules....patience will help. Moving slowly is moving as well.

 

[bewing]

7 hours ago, Baker said:

But there are no "attach points" on the side of the crew cabin to allow anything on its side. I've tried adding cubic struts, which will attach. But the additional crew capsules won't attach to them. Exactly how do you attach two additional crew capsules to the side of the first?

As FleshJeb said, you can start some nacelles by radially attaching some nosecones. Or you can start with fuel tanks -- almost all fuel tanks are radially attachable. Or Structural Fuselages. Then attach the Crew Cabins either ahead or behind any of those radially attached thingies. To get the nacelles into the proper locations, you will likely have to use the Move gizmo in the editor.

 

[Aegolius13]

On 6/14/2019 at 6:59 PM, Baker said:

But I do have a contract in stock with six tourists to the surface of the Mun.

For missions in this passenger range, I'm a big fan of using the Mk 1-2 capsule as a base.  It's got great heat resistance, good torque, etc.  One of my most-used designs is to put an Mk 1 crew cabin on the top, so it looks like a giant flask (appropriate for science missions).  The capsule protects the cabin on reentry, and it's all quite stable.  That's only 5 passengers, but you could probably add a Mk 1 command pod on top.  

Or, if you have Making History, I imagine putting a Pomegranite (3-person Soviet reentry capsule) on top of a Mk 1-2 command module would work pretty well too.  Keeps the center of gravity nice and low.

Eventually, when my headcount inevitably gets out of control, I switch to landers built around the 16-passenger Mk 3 crew cabin.  With fuel/engines on side nacelles and some big landing legs, it's easier than I expected to keep the thing stable.

Edited June 16, 2019 by Aegolius13

[Incarnation of Chaos]

14 hours ago, Aegolius13 said:

For missions in this passenger range, I'm a big fan of using the Mk 1-2 capsule as a base.  It's got great heat resistance, good torque, etc.  One of my most-used designs is to put an Mk 1 crew cabin on the top, so it looks like a giant flash (appropriate for science missions).  The capsule protects the cabin on reentry, and it's all quite stable.  That's only 5 passengers, but you could probably add a Mk 1 command pod on top.  

Or, if you have Making History, I imagine putting a Pomegranite (3-person Soviet reentry capsule) on top of a Mk 1-2 command module would work pretty well too.  Keeps the center of gravity nice and low.

Eventually, when my headcount inevitably gets out of control, I switch to landers built around the 16-passenger Mk 3 crew cabin.  With fuel/engines on side nacelles and some big landing legs, it's easier than I expected to keep the thing stable.

I enjoy a "Barbell" configuration with 2 MK3 pods connected to a 1.25m service bay and one end with a 2.5m docking port; throw some science and/or a probe core in it and now you have 6 crew+ science+ docking. Apply parachutes and a heatshield for easy reentry; simmer at around 2000m/s at ~50,000 km. Best served with a recovery crew with thermal blankets, water and stretchers to get your brave explorers out of the miserable can safely back to KSC.