RSS minimum altitude?

[Perotis]

What is the minimum altitude to get into orbit of Earth in Real Solar System?  The Dv map shows that 250km is "low orbit" but in game 140km is "in space"

[Phineas Freak]

You answered your question. The minimum "in-space" altitude is 140 km and anything after that is also space. DV maps set this altutude to cover a wide range of parking (or not) orbits as an average value.

[VikingStormtrooper]

At h = 140 km, the orbital velocity required to have a circular orbit is v = 7814 m/s. However, in order to get there you need to provide a higher delta V because of air drag, gravity losses, etc.

[Gaarst]

In practice, an efficient and low TWR launch will always put you in an orbit higher than 200km, close to 250.

To get a lower orbit, you'd either need more powerful upper stage (not really a thing in real life, but you are free to do it if you don't mind the added dry mass of a bigger engine), or a less efficient ascent profile (circularising way after apoapsis or burning in the outward radial direction).

Edited January 30, 2017 by Gaarst

[ColKlonk2]

It's stated somewhere in the real world that atmospheric effects go up to around 2000 km, from there it's categorised as space (vacuum).

But for the purposes of KSP RSS ... 140Km it is.