Neat idea, fun game. Some small UI suggestions: (1) since the player will have to restart a lot, put the 'restart' button near the rest of the controls (maybe right underneath the 'Go!' button). (2) As the player gets closer to a successful launch, they'll want to make smaller and smaller adjustments. Consider having each round begin with the previous round's settings... otherwise the player just has to memorize what their setting were last time.