How fast are you climbing and at what angle?
i climb quite steep until like 6-7km altitude and then i angle down to perhaps 5 degrees and make sure that i’m above 1300km/h at that point, then i climb REALLY slow and letting the increase in speed be the thing that generates lift and NOT aiming upwards with the nose more than like 2-3 degrees once you get to above 8km altitude.
Edit:
it wasn’t even a challenge to get to 16km using what i wrote above.
