Thanks again for your Help, you can see the Result here if you want:
www.againstgravity.de (choose Testlevel)
When hitting LMB the ship will rotate towards the Mouse Cursor and give thrust relative to the distance ship/cursor.
It's best to place the cursor over the ship, press and hold LMB and then move the mouse up slowly to get a feeling for the controls.
While LMB is pressed you can throw bombs with RMB.
While LMB is released you can shoot lasers towards the cursor.
What do you think?