I've been flying my P2V for 6 months and have never had anything like this. This afternoon, during an otherwise uneventful, compass-calibrated, GPS locked flight of my P2V, with the copter at 175 ft altitude and approximately 200 feet away, with an unobstructed line of sight view, i suddenly lost camera signal, and telemetry, but had flight control; then 5 seconds later the aircraft dropped tumbling from the sky into a dense forest. It is lost & I really doubt we'll ever find it. 1) What happened? 2) this has really made me think about safety. If it had fallen on someone, it could have been a problem.