Trying to teach my old man to fly the little ones, he hit me with a Blade SR, a smaller than 250 but close enough size helo. It hurt, didn't cut me, but I had the wood blades on it instead of the more expensive carbon fiber ones. If it was the CF blades I bet it would have sliced me open through me jeans, not to mention a strike in the head....I've flown a lot of 450 size helo's, and the one this guy got clobbered with was even larger. It's surprising to me this hasn't happened more often to be honest, will all the young kids I see flying park flyers and crashing them into all kinds of stuff constantly.