When not running, the blades are only a few inches above the bubble. As they spin up, they also lift up, maybe 9" or so above the bubble. When flying, there's no concern (after getting used to them) about the blades hitting the bubble, and you do not have to fly it any differently than those with the blades much higher. They actually offer more stability in hover work, as there is less pendulum effect. However, I'd still prefer higher blades. I've knocked my head on these many times during pre-flights.