At one point Dave King wrote: I have a small spreadsheet I use for ballistics, it's small enough to run on a Palm computer. I have a spreadsheet that does Coriolis and I imagine that with a little time I can add this "spin drift" Yaw of Repose item too. Perhaps I could just build a small program in Visual Basic to do all this and put it out here on the site. I would require some technical assistance for the items I've not dealt with in the past. What's others thought on this software issue? Dave, What kind of spreadsheet are you talking about?? What all does it do? I might be able to help you with it. MIGHT!!