The Walkera 4 doesn't have enough energy to be a serious issue, unless you're unlucky enough to get hit in a bad spot.

I've flown mine into me several times... Once under full throttle, right into bare shins. A hazard of flying in a very small area inside.

Well, it hurt a LOT, but a little scratch and a tiny bead of blood the size of a pinhead.

Of course, that was at hover power. Maybe under full throttle with a bigger battery it would have been a little worse.

On the other hand, I keep right away from the AluSEF even with it's plastic blades. Let alone woodies.

David