Dear Fu-Kwun,
thank you for your help with astroblaster applet. I try to learn from the code, how you create rather mass ratios...I would like to show advantage of this idea. If we set m2:m1=1,66, m3:m2=2, m4:m3=3, (for k=1) lowest three balls are in the rest after the collisions (see dialog window, or switch off auto scale) and height of the throw is greater than in case of constant mass ratio = 2.