As far as I have read, the F3A brake on the modern controllers will allow the prop the turn, but not to windmill, what will hapen is that the prop starts ackting as a huge plate, slowing down the plane a lot. I understood that with the newer hacker controlers you can actually control the bracking with your throttle stick.

This is also what happens on a fourstroke, the windmilling of a fourstroke is much less then with a 2-stroke.

Winfried