I created a KSP forum account just to tell you this. Your applet is beautiful. I just downloaded it and ran some tests simulations. I absolutely love it. If I could suggest any feature I'd like to see next (and it may already exist without my having discovered it yet) it would be the ability to input a flyby trajectory, rather than an orbit, so that simulations of flyby scenarios can be linked (i.e. a calculated flyby trajectory can be input into another flyby simulation). Thanks for the app. I'll definitely be using it.
