I've been looking for an explanation of exactly what roles the various electronic components play in our Inspires, and I ran across this safety tip after a crash. (It is #9, but the whole page is pretty good.) "The first thing to do is throw a towel over your copters propellers (Propellers may start spinning unexpectedly)." Seems like a good idea. This is the page: http://copter.ardupilot.com/wiki/introduction/safety-multicopter/ HG2G is a reference to Douglas Adams series of satirical novels from the 80's "Hitchhikers Guide To The Galaxy"