Hi everyone I'm Chesscube! You maybe wondering how to fire missiles in sandbox mode, specifically the build and fly mode. I discovered the solution by accident and it is really simple. All you have to do is attach a missile to a pylon like normal. Then set the pylon to the appropriate group. So if you set it to group 1 and then while you're flying click group 1. that should fire the missile. If it doesn't work, try setting your missile to armed group 1. I hope this helped. Have fun and happy flying!