I don't do flop shots unless I'm in the greenside bunker. I use my normal full swing but have an open stance. this makes that ball fly higher. the higher I need the ball to go the more I open my clubface and the more open I leave my stance. I also make sure that the ball if foward in my stance as I want to strike the sand before the ball. the longer I need the ball to fly the further back in my stance I have the ball.