Advice on refueling/tankers?

[Ralstemar]

I have finally managed to set up a mining/refinery on minmus, with capability to dock to Clamp-o-tron Sr. and all is going well there (took me forever to actually land it because of part counts and a dogwater cpu though lol). And am looking to set up a "gas station" of sorts in low to mid kerbin orbit where most of my craft  tend to be parked.

This poses a question. How would I go about making a tanker capable of taking large amounts of fuel from minmus, to LKO? Recovery and funds are not an issue as this is a sandbox run. Thus far my best idea is to just haul a bunch of empty tanks into space, with seperate stages/sections with full tanks for actually moving the vessel. But at what point does the TWR/DV just become unacceptable for something like this? Or is there a better way?

Additionally, any input regarding the "Gas station" would also be appreciated!

[Vanamonde]

Getting it from Kerbin will be the challenge. Once it's flying around Minmus it won't need much thrust. However, once full of fuel it might be hard to maneuver. Pack lots of SAS. 

[18Watt]

I prefer to refuel in orbit of Minmus, it seems to be simpler.  However, I agree that it is slightly more convenient to refuel in LKO.  While I no longer do that, here is what I used to do:

You will need a tanker which can go from Minmus to LKO and back to Minmus.  One consideration is part count.  Even with a good computer it's still a good idea to keep part counts low, if you can.  With that in mind, you want to use the biggest fuel tanks available.

For engine efficiency, the Nuke engines are an obvious choice.  However, the Wolfhound engines also have a really good ISP, so those are a good choice as well.  If you go with Nuke engines, use enough of them that burns are not excessively long.  I do not recommend Ion engines.  The burn times are way too long, and they can not be refueled (in stock KSP).

In order to transfer the fuel to ships in LKO, you will need to dock.  So one of the ships will need good docking maneuverability.  I suggest you make the refueling vessel docking-capable- long -range ships are difficult to make maneuverable sometimes.  So put a lot of RCS ports on the refueling ship, and don't make it excessively long.  There are Vernier thrusters which use standard LFO, but work as RCS thrusters.  The advantage to those is you don't need a second fuel source, just standard LFO will work.  Or just use standard RCS thrusters, but don't be stingy with them.  I also like to put a lot of reaction wheels on big refueling tankers.  You will likely be docking with your refueling tanker while it's heavy, so you'll need a lot of control.

Finally, you need to decide on a strategy to get fuel from the surface of Minmus to LKO.  I suggest not worrying about efficiency from the surface.  Minmus' gravity is so low that it doesn't really cost much to haul extra equipment to orbit.  So here are a few strategies:

• Tanker has a complete ISRU setup on board:  Drill(s) and Converter.  Yes, that's a lot of weight to drag all the way to LKO and back, but it's easy, and only requires one docking maneuver.
• You could have a dedicated ship to deliver ore or refined fuel to your Tanker in Minmus orbit.  That requires at least one extra docking maneuver each time you do a fuel run.  It's more efficient, but takes a lot more patience doing extra docking maneuvers.
• There are more ways to set the operation up, which would add efficiency, but probably add extra docking maneuvers.  Yes, docking is fun, the first hundred times you do it.  But eventually it gets a little grindy.

Good luck!