This is not a faint-of-heart predator! I think he is a member of the Clubtail family and possibly a species called, Dragonhunter. But beyond that 'possible' ID, I can't venture. Even though I have always found dragonsflies magical and have three books on the subject, I still know very little about them. However, everytime I see a new one, I want to dive more deeply into reading about them.
Of the Clubtails, my Stokes, Beginner's Guide to Dragonflies says: "The clubtails are one of the most diverse and challenging groups of dragonflies in the world....for many closely related species, even a good look at all of these features will not suffice; only an in-hand examination of anatomical features will permit certain identification. Even experts must let many pass simply as "clubtail species."
Having read that, I know my limitations. But I can readily say he was gorgeous! When he was whirling around in the turbulence, I found myself primed to duck if he came my way. This made me laugh. I've never had that reaction to a dragonfly before. This guy was more like a helicopter!
Note added June 18: This dragonfly was in the 3 inch range, almost double the size of more common dragonflies. I was delighted to receive a postive ID confirmation from Martin Hagne of Weslaco, TX, who agrees this is a Clubtail Dragonhunter. Read his interesting note in the comments section.
And before I leave the subject, if you haven't already discovered Amila's blog, Gallicissa, pay it a visit. Not only is Amila an expert guide for birders, but he loves dragonflies and has created a wonderful pond in his Sri Lankan backyard where he studies dragonflies and other critters and posts beautiful macro images.