I have a similar one passed down from my Grandfather, he was a bomber pilot and traded badges with a German pilot after the war ended (so the story goes). It was made of a silver metal (aluminium?) and the eagle looked as if it was pouncing on something rather than standing upright spreading its wings, the swastika also had spaces between the leg things that stick out instead of being on a shield like yours. Maybe that rules out it being a Luftwaffe badge (or it could even be an earlier/later/different rank version, but apart from that I can't help you except point you towards this subreddit http://www.reddit.com/r/Whatisthis/