Let me tell you what. The velocity that a prop half can be thrown from a prop spinning over 13,000rpm can, and will surely kill someone if it hit an eye, stomach, or kneck. By all means it will kill if it travels the perfect trajectory to it's target. These are not toys be very very careful. Starters are easy.
That is foolish saying it won't kill on these boards. There are kids who read this site very often. Don't be making them any more daring than they already are please!
Not saying your unsafe; saying kids are unsafe.