Using the latest svn for fgaddons, it is impossible to take off from AK97 with MiG-15bis. The gears will break before getting high enough speed to take off.
It's not a bug, it's a feature (tm). The MiG-15 detects that the runway is not made of concrete but earth, so the speed limit for gear breaking is much lower. In real life, the MiG-15 requires a concrete or asphalt runway.
If you still want to take off from this airport, disable realistic failures in the Configuration dialog.
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(Sorry for the late reply...)
It's not a bug, it's a feature (tm). The MiG-15 detects that the runway is not made of concrete but earth, so the speed limit for gear breaking is much lower. In real life, the MiG-15 requires a concrete or asphalt runway.
If you still want to take off from this airport, disable realistic failures in the Configuration dialog.