FD has put magic thrusters on all ships.

Any legal combination of thrusters and ship will develop enough vertical thrust to leave the surface of any body, even if the gravity is high enough to overwhelm the main thrusters when the ship is in a vertical position.
Leaving the surface of an extremely high-g world with low thrusters and no boost using the usual method of jumping to supercruise will fail, as you need to accelerate to a high enough speed to engage the drive, while having the ships trajectory at around 50-60 degrees from horizonal, and D rated thrusters just can't do it. Departure requires one of two approaches: Either maintain the ascent via vertical thrusters until you are in orbit, which can be over 100 km, and take many, many minutes, then jump to supercruise or hyperspace. Alternatively, select a system within your jump range that is as close to the horizon as possible, use the vertical thrusters to get out of mass lock at 2km altitude, and then jump out of system.
CMDR
grnbrg.