ねことイルミネーションでも見てすさんだ心を癒そうぜ Helicopter Physics Series - #4 They're Gyroscopes - Smarter Every Day 48 ttp://www.youtube.com/watch?v=eTjGTxSevHE The Helicopter Speed Limit - Helicopter Physics Series - #7 - Smarter Every Day 51 ttp://www.youtube.com/watch?v=_pbdwueqGp4