The KSP wiki presents an interesting table of terminal velocity in Kerbin's atmosphere preceded by an useful advice:
Note: this table is useless with KSP version 1.0 and later, see the explanation in the answer below.
You can save fuel by being close to your terminal velocity during ascent. Lower velocity wastes delta-V on gravity, higher is wasted on air resistance:
| Altitude (m) | Approx. terminal velocity (m/s) | |--------------|------------------------------------| | 500 | 105 | | 1,000 | 110 | | 2,000 | 120 | | 3,000 | 130 | | 5,000 | 160 | | 6,000 | 180 | | 7,000 | 200 | | 8,000 | 220 | | 10,000 | 260 (remember to start your turn!) | | 13,000 | 350 | | 15,000 | 425 | | 16,000 | 470 | | 32,000 | 2250 |
But this table is more than a year old, it doesn't take into account the new Aerodynamics features added with version 1.0 (released on April 27th, 2015). I'm looking for an updated version of this table for KSP v1.0 and later.
According to Philipp:
With the new aerodynamic model, determining the optimal and maximum speed for a given altitude are quite non-trivial because it greatly depends on how aerodynamic the vessel is as a whole. Also, the orientation of the vessel now matters.
Source: How fast should I be going through Kerbin's atmosphere during launch?.
you will have a hard time getting even close to terminal velocity in most flight phases. So just go for maximum thrust.
Source: What role does terminal velocity play in a rocket launch?
Does non-trivial means impossible? Can terminal velocity can still be estimated for a common spaceship?