ORIGINAL: LearjetMech
I also heard it was a bird! But as mentioned earlier, they have about a 90 sec hover limit. I believe the engines are water with possibly methonol injected for cooling during hover. And I think the tank capacity is roughly 90 sec. Could be wrong though!
If they have a 90 second timelimit then the guy at last year's Dayton Airshow needed a complete overhaul of his engine after his display, which included 3, over 4 minute hovers including 2 short field takeoffs. Unfortunately that's all he did except for 1 high speed pass into a high G break.