Lift Heli-paper above your head as shown in the diagram, then drop it.

What's Going On?

You have made the type of "wing" used by helicopters. It is called a horizontal rotor. The shape of your rotor causes it to twist due to uneven drag on the paper surface. The rotor begins spinning and this reduces the pressure above the "wing". The pressure underneath the spinning rotor is greater and pushes up, allowing the helicopter to drift slowly down rather than falling quickly. Real helicopters lift up when the motor spins the rotor at tremendous speeds.

What Else You Can Do

Put a paper clip over the folded part. See if it changes the flight pattern.

Click here for Heli-Paper Pattern