Algodoo

The beacon should be stationary or going at a low speed.
Change the density of the red circle to change the power
Controls:
1 - Toggle missile

Variables used (if you want to use it in another scene):
scene.my.pos = [0,0];
scene.my.mspd4 = 0;

Explanation: http://www.algodoo.com/forum/viewtopic.php?f=18&t=2543