Hey man, I can do you one better.
I have the original 3D Mirc Jetslom jar (yes, it's originally a java game).
This can be decompiled (java decompiler) into source files which you can reference to improve your version.
You can also run it. Don't remember running the jar itself.
Rather I remember extracting it and using appletviewer with game3d.class or maingame.class
mediafire.com/file/rsxysacw5yh9uqq/JSlalom.jar
I noticed your improvements. However, the ship takes a bit of time to appear on the screen and to respond to controls.
Perhaps having the original code will help you solve that.