How high to orbit

[JackBush]

What altitude must a ship reach to orbit Kerbin?

Edited October 10, 2015 by JackBush

[SanderB]

Ideally 75km to save time, you can fast forward at 50x from 70km and up. If you go for 70.01km, you'll have to wait the full coast to apoapsis at 4x instead of 50x.

[peachoftree]

I usually go for a 125 km orbit for 100x time warp, you don't have too build things too much bigger to achieve it

[capi3101]

Both Ap and Pe need to be up above 70,000 for low orbit and both Ap and Pe need to be up above 250,000 for high orbit.

[CalculusWarrior]

Kerbin's atmosphere ends at 70 km up, which must be exceeded in order to orbit without being tugged back down by atmospheric drag, but to actually reach orbit, remember that you need to be going at least 2200 m/s (at 70 km altitude) sideways in order to 'miss' the planet entirely and stay up. If you burn straight up and reach 70 km, you're just going to fall right back down again.

[Reactordrone]

You need to be above the atmosphere (70km) and doing about 2300m/s around it. Orbiting is all about obtaining enough horizontal speed that the path that you're following due to the gravity of the planet, never intersects the surface (or in this case, also the atmosphere).

ETA-ninja' d

[nekogod]

You can orbit at any altitude as an orbit is not a function of height but of speed.

To orbit a body without hitting it you must travel in parallel with the ground (perpendicular to gravity) fast enough that the ground curves away from you as fast as you're falling.

The higher you are the lower this speed is.

The atmosphere ends around 69.9k meters up and you will need to be above this to have an orbit that does not decay due to friction with the air.

[cantab]

70 km is the minimum, any lower and you'll be in the atmosphere and pretty quickly be brought back down.

I'd rarely recommend such a low orbit though. Somewhere in the 80-120 range is good for most purposes.

[Starwhip]

With the new aero it's actually fairly difficult to get to an 80 kilometer orbit, simply because it's tricky to pitch over enough to get a lot of orbital velocity before your apoapsis is at the mark.

I try for 80 out of habit, but 100 kilometers is probably easier.

[Tex_NL]

Incredible how people can give the nearly exact same answer four days after the question has been answered.

[Alshain]

Incredible how people can give the nearly exact same answer four days after the question has been answered.

It's 70k. No need to thank me.

[Pecan]

With the new aero it's actually fairly difficult to get to an 80 kilometer orbit, simply because it's tricky to pitch over enough to get a lot of orbital velocity before your apoapsis is at the mark.

I try for 80 out of habit, but 100 kilometers is probably easier.

[it's 70km, just in case no-one's mentioned that yet ^^]

If you can't pitch-over enough to establish an 80km, let alone a 70km, orbit you've got too much engine power and you're climbing too fast. (Or, of course, you have too many stabilising fins and have made a rocket that just won't turn).