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I'm currently setting up a (Kethane) refueling station at Minmus. My idea is that you can show up at Minmus with empty tanks, load them up, and then do the return drop to Kerbin and as you're swinging around you do the interplanetary burn.

The way I see it, it's a "free" 1000 (or so) delta-V head start on the journey. I mean, you still have to spend that delta-V getting to Minmus but then you fill up the tanks while there so you're starting ahead of the curve.

I'm probably totally wrong for some reason that I can't conceive of, but it seems fun and novel (for me) and I love the idea of slingshotting off of Kerbin to get somewhere.

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I'm currently setting up a (Kethane) refueling station at Minmus. My idea is that you can show up at Minmus with empty tanks, load them up, and then do the return drop to Kerbin and as you're swinging around you do the interplanetary burn.

The way I see it, it's a "free" 1000 (or so) delta-V head start on the journey. I mean, you still have to spend that delta-V getting to Minmus but then you fill up the tanks while there so you're starting ahead of the curve.

I'm probably totally wrong for some reason that I can't conceive of, but it seems fun and novel (for me) and I love the idea of slingshotting off of Kerbin to get somewhere.

Not a bad idea. The only fly in the ointment - and it's not a big one - is that you'd have to wait an entire minmus orbit to get a proper orientation to fling you from Kerbin in solar retro/prograde.

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I'm currently setting up a (Kethane) refueling station at Minmus. My idea is that you can show up at Minmus with empty tanks, load them up, and then do the return drop to Kerbin and as you're swinging around you do the interplanetary burn.

I'd suggest to place it in Kerbin orbit at about the Minmus level. Delivering the fuel from Minmus shouldn't be a problem (just takes longer to approach but that's what time warp is for), it will allow easier approach for any craft coming from out of Kerbin SOI and easier planning of departure. Higher warp speeds too, maybe.

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That's not accurate. Interplanetary is about total speed, not just breaking SoI. You lose the Oberth effect at higher altitudes. Which is why I ALWAYS depart from a 75km parking orbit.

The Oberth effect is only relevant if you're not refueling before the actual injection burn. A ship full of fuel in a higher / faster orbit will need less dV to get on an interplanetary trajectory.

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The Oberth effect is only relevant if you're not refueling before the actual injection burn. A ship full of fuel in a higher / faster orbit will need less dV to get on an interplanetary trajectory.

I believe that to get interplanetary from high circular orbit it takes less fuel to drop to highly elliptical low-periapsis orbit and burn at periapsis than to burn straight out from where you are.

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I'm currently setting up a (Kethane) refueling station at Minmus. My idea is that you can show up at Minmus with empty tanks, load them up, and then do the return drop to Kerbin and as you're swinging around you do the interplanetary burn.

Another option is always the Mun. More gravity but no inclination change, easier to encounter and you've already spent 800 m/s dv. Minmus is only 200 or so after that right?

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A good place for a station is 100km. If you have craft that can't get too high, a lower altitude is good for docking. A higher altitude allows for easier rendevouzing so you don't accidentally dip back down below 70km during manuver node experimenting. The higher the orbit, the more delta-V it will take to get to it.

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Not a bad idea. The only fly in the ointment - and it's not a big one - is that you'd have to wait an entire minmus orbit to get a proper orientation to fling you from Kerbin in solar retro/prograde.

That's not a HUGE deal, as you don't *have* to make your burn at periapsis. You can do it anywhere along the 180 degree line around Kerbin closest approach without *too* much loss of Delta-V. And from way out at Minmus you can pretty easily set your approach to Kerbin on either side of the planet without using too much fuel. I'm actually planning on doing it with a tug to see how that goes.

I'd suggest to place it in Kerbin orbit at about the Minmus level. Delivering the fuel from Minmus shouldn't be a problem (just takes longer to approach but that's what time warp is for), it will allow easier approach for any craft coming from out of Kerbin SOI and easier planning of departure. Higher warp speeds too, maybe.

That's a really good idea and a caveat I didn't think about when setting this up on Minmus. That makes using a tug an even better idea. Tug it into proper equatorial Kerbin orbit, then tug it into the "big drop.", and then send the tug back to Minmus for the next mission. Thanks for pointing that out!

Another option is always the Mun. More gravity but no inclination change, easier to encounter and you've already spent 800 m/s dv. Minmus is only 200 or so after that right?

The problem with Mun is twofold, though neither is probably that big a deal. First, it costs more to get away from, though that could be mitigated by putting the refueling station in a higher orbit. Of course that would mean less fuel per shuttle load from the surface but again, not a huge deal. Second, it costs more to deorbit because you're going faster in relation to Kerbin, so either the ship would use more fuel or you'd need a bigger tug. And if you had to reverse the orbit that'd be even worse. In Minmus orbit, it's not nearly so bad. And third, which I just realized... I'm bored with Mun :) I've been there too many times. Minmus is still fresh at least by comparison. Also, every step is just easier on Minmus because of the lower gravity.

Most of this is all theory, of course. I'm currently in the "collect fuel" stage of the operation. I've successfully brought up one orange tank's worth of fuel and hope to have 5 when I launch for Moho. Eventually I should design that ship, too :)

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