Leif Ristroph and colleagues at NYU are designing tiny paper aircraft and making them fly using a pot, a speaker and a bunch of straws. When the subwoofer plays a low-frequency tone, it pushes the air above it up and down, which is funneled through the pot and straws, creating a flow of pulsing air. The system simulates flapping flight by taking the flap out of the wing and putting it into the air. Ristroph explains what his aircraft are teaching him about stable flight.