Question on refueling efficiency using Kethane Mod

[Jouni]

A Kethane refinery in Kerbin orbit is basically useless, because it's not hard to get massive amounts of fuel into low orbit from KSC. One around Mun or Minmus has a little utility, but not much since outbound flights are usually better off maximizing the Oberth Effect to leave from low Kerbin orbit. My main use for a Minmus base has been as a depot for INBOUND flights, where a ship coming back from Jool or Duna might not have quite enough fuel left to get back to Kerbin.

These are both playstyle issues. If you set limits on what kind of rockets you can build, refueling ships with fuel launched from Kerbin can be slow and tedious. Similarly, if you restrict the use of ridiculous aerobraking (or the tools required to reliably do that), it can be easier to return to Minmus than to LKO from an interplanetary mission.

[Spatzimaus]

If you set limits on what kind of rockets you can build, refueling ships with fuel launched from Kerbin can be slow and tedious.

And what kind of "limits" are you referring to? Part count? Total mass? No other mods?

The fraction of mass that reaches orbit isn't any lower for a giant rocket than it is for a small one. As long as your machine can handle the frame rate, it's not hard to put a thousand tons of fuel into orbit in a single launch, and that's enough to top off any fuel depot you can think of. (Granted, it's easier to just use that thousand tons of fuel as a depot in its own right, and not bother docking it with a station.) Heck, my 300-ton mobile refinery can fly to Jool and still have a third of its fuel remaining, so even if you don't want to use Kethane it's not hard to send fuel supplies to the other planets, as long as your manned follow-up vessels will be kept small.

Right now, you need a large-part mod like KW Rocketry to make this sort of depot practical, although apparently larger parts are going to be added in upcoming versions of the core game. Using KW I've got a 12000-ton SSTO rocket booster that can easily lift a thousand tons, with no staging or complex maneuvers necessary, so it's actually EASIER to lift those big payloads than it would be to try something made with small parts. (And as an SSTO, it'll do just fine once we get an economy.)

But back to the original point. It's far, far more tedious to try transporting Kethane from Mun or Minmus down to a station in low Kerbin orbit. That's a big part of why I don't bother with too much Kethane refining in Kerbin's SOI, except as proof-of-concept tests of my designs. But for Jool, Eve, and Duna I have networks of fuel stations, refineries, and rovers that make it easy to use small vessels. I've got an SSTO spaceplane that I've flown to a lot of different moons and planets, since it's easy to refuel on-site from my far larger depots.

Similarly, if you restrict the use of ridiculous aerobraking (or the tools required to reliably do that), it can be easier to return to Minmus than to LKO from an interplanetary mission.

I almost never aerobrake, although there's nothing "ridiculous" about it given how often NASA's rovers have used similar methods. If anything, we should be aerobraking more in KSP than we are; the current interface doesn't do a good job of telling you what your trajectory will be after a pass through a braking medium, but the tools NASA has would do this far better.

But back to Kerbin. In the absence of the Deadly Re-entry mod, the delta-V needed to drop from a Minmus orbit down to Kerbin's surface is so small that it's almost never a good idea to stop at Minmus, and you're just better off dropping straight down to Kerbin instead. Now, that "almost" is still enough of a window that I do keep a depot around Minmus, plus a couple emergency recovery vessels, but they rarely get used.

[SuperBigD60]

These are both playstyle issues. If you set limits on what kind of rockets you can build, refueling ships with fuel launched from Kerbin can be slow and tedious. Similarly, if you restrict the use of ridiculous aerobraking (or the tools required to reliably do that), it can be easier to return to Minmus than to LKO from an interplanetary mission.

The aerobraking doesn't really get that ridiculous until you either start talking about returning from Jool, or using sub-optimal transfer windows.

I agree with the other stuff, though. Launching fuel from KSC can be almost as tedious as mining it, anyway.

[Brotoro]

...My plans are to haul raw Kethane from Minmus to an orbital refinery around Kerbin. Mostly so I can refine it into whatever products I need most at that moment; LFO, monoprop, or xenon...

You can convert methane into xenon? What alchemy is this?

Then again, I guess it's strange to be able to convert KH₄ into fuel and oxidizer…or monopropellant. It all seems odd to me.

[Jouni]

And what kind of "limits" are you referring to? Part count? Total mass? No other mods?

Anything someone may consider interesting. I personally like rockets that look like rockets and don't have too many boosters. With stock parts, that means that I can't get more than about 1.5 orange tanks worth of fuel to orbit in a single launch. Other people may have other restrictions for their rocket designs.

I almost never aerobrake, although there's nothing "ridiculous" about it given how often NASA's rovers have used similar methods. If anything, we should be aerobraking more in KSP than we are; the current interface doesn't do a good job of telling you what your trajectory will be after a pass through a braking medium, but the tools NASA has would do this far better.

By some stricter definitions, aerobraking is always ridiculous, unless you are using Deadly Re-entry and FAR. Others may assume that everything except dedicated atmospheric landers will be destroyed, if re-entry flames show up. There are many ways to play the game.

[Superfluous J]

You can convert methane into xenon? What alchemy is this?

Then again, I guess it's strange to be able to convert KH₄ into fuel and oxidizer…or monopropellant. It all seems odd to me.

No, you can convert kethane to Xenon. And it's the same alchemy that allows a planet 1/10th the radius of Earth to have Earth's surface gravity. i.e., it's a video game

[WafflesToo]

You can convert methane into xenon? What alchemy is this?

Then again, I guess it's strange to be able to convert KH₄ into fuel and oxidizer…or monopropellant. It all seems odd to me.

It's done with Voodoo magic. I believe it requires the bones of a chicken and incense made from the petemoss gathered from the north face ofthe cliffs in the Southern hemisphere.

[Brotoro]

No, you can convert kethane to Xenon. And it's the same alchemy that allows a planet 1/10th the radius of Earth to have Earth's surface gravity. i.e., it's a video game

That just requires supposing some unknown, very dense state of matter can exist -- and since it can be limited to down deep in the cores of the planets, I wouldn't have to deal with the weirdness of the material.

[Brotoro]

It's done with Voodoo magic. I believe it requires the bones of a chicken and incense made from the petemoss gathered from the north face ofthe cliffs in the Southern hemisphere.

Oh! Chicken bones and australian peat moss. This all makes sense now.

[OgreMagi]

Kethane mining is a no brainer, you can get fuel easier from lower gravity moons on any planet in the kerban system, you don't have to launch a ship from kerban to refuel ect ect ect.

Mun vs Minius Mun is closer less time but higher gravity slightly less efficient need more fuel to make orbit., Minius lower griavity but longer travel times and I much higher delta v to get there from kerban

What I did was as follows,

To get larger and larger craft in orbit I began to see that sending them up with less than a full load of fuel when launching from kethane made it much easier. By having a loaded tanker of fuel in orbit it was much easier to get a larger craft there.

So I build a single stage lander/miner and placed it in orbit at the MUN, with rather large kethane tanks and a small converter. then I have several remote fuel tankers that move between kerban and the mun,

I can in 1 day game time land the miner, mine, launch and orbit the MUN and still wait on the tanker to arrive. then dock with the tanker, covner the kethan and send it back to kerban, and even save fuel by using aerobraking to get it into orbit.

I have a space station but I found it is easier to have the fuel tankers stay in orbit and rendezvous with ships as they launch from kerban.