Highest Kerbin orbit?

[Wanderfound]

I'm sure that this information is easily available somewhere, but my Google-fu is failing me.

What's the highest possible stable Kerbin orbit? I feel like setting up a maximum-altitude refuelling station for interplanetary spaceplane trips.

Edited September 7, 2014 by Wanderfound

[Taki117]

Technically you can do it at the SoI boundry (84 159 286 m) but I don't recommend it. You lose a lot of Oberth if you go out that far. If you want a refuel station I'd say about 200km is about the upper limit (Unless you have some reason to go higher)

If you don't know, the Oberth Effect is where the use of a rocket engine when travelling at high speed generates more useful energy than one at low speed. MEaning that if you burn closer to the gravitational body you are orbiting (And therefor moving faster around) you will save some amount of dV.

[mhoram]

A while back there was a discussion about ideal altitudes for refuelling stations with some charts.

See

http://forum.kerbalspaceprogram.com/threads/75542?p=1072850&viewfull=1#post1072850

and following posts.

[Laie]

What Taki said: you want a pretty low periapsis for the oberth effect. I like to refuel at 120km+ just for the sake of time warp. I also have employed tugs to dock with the interplanetary vessel and undock after reaching a high Kerbin apoapsis. They don't ever leave Kerbin SOI, they only provide the fuel (and some thrust) for the first 800m/s or so, then return to LKO.

[Pecan]

As well as the fuel-efficiency, consider the TIME. If you are in a very high orbit your orbital period will necessarily be very long - which means you could entirely miss a transfer window because you're in the wrong part of your orbit to make the burn. Of course, you could just make the burn anyway, using much more deltaV, but then you lose any putative fuel-efficiency from the high orbit anyway.

Not being able to burn when you want to will even be apparent from Mun altitude so all in all, you're spending more deltaV to get there, losing any benefit from Oberth effect and (probably) losing any benefit of an efficient, timely, transfer window. Getting high isn't worth it, just say no.