usnraptor wrote:
GT (Global Tribunal) Source (gt_source.zip) has an X15.PT
Looking in the pt file, the X15 flight envelope at 1g tops out at 352,000 ft.
When testing it just now, it topped out at 268,000 feet and airspeed instantly went to -44 knots and stalled.
3,600 knots is structural limit speed
Two throttle settings: 100% and afterburner; can't shut down engine though it goes through fuel quickly.
The real deal X-15 had a throttleable rocket engine so that setup isn't too realistic
Have you tried increasing engine thrust and fixing the throttle so you can keep your speed above 268000 ft?
Also later X-15s carried huge external tanks for more rocket fuel...
I just checked it out for Cent; then deleted it.