New post on the Apogee website announces release of Rocksim 10 next month. There are a couple of things mentioned there. One is that the upgrade will be free to current users. Anyone who uses or doesn't AND who has more than just "every day computer" user experience care to comment with their thoughts, opinions etc? I am not asking for an Open Rocket comparison. I have had Rocksim for about 10 years and rely on it heavily for design and motor selection. I have done my share of very successful scratch designing and building different high power rockets that I otherwise would not have been able to do. I really enjoy it and like it very much.