First, thanks Mike I called Matt Spade, we had a great conversation and I learned a lot! He sends his greetings and best wishes to everyone. The answer is 3/32" or .09375. Matt started with 1/16" and found that 3/32" worked better. For all those developing missiles, one piece of valuable info is that a missile will work very different when launched from underwater than in plain air. "In plain air a missile will appear to be very disappointing, while launched from underwater will work amazingly!"
Best to All, Ed
Just one more wire!