The helicopter
You might be able to get our helicopter in the air, if you pedal really hard. The blades of the helicopter have the same shape as airplane wings. But how can you get a helicopter to fly?
Helicopter blades are designed as tilted aircraft wings. They have a gently rounded top, meaning that the air stream moves faster when the propeller blade starts moving. Air with a higher speed has a lower pressure, which means that the air beneath the propeller blade pushes it upwards and creates a lifting force on the helicopter. If you pedal really fast, you can create a lifting force of about three kilos. Nobody has managed to create a helicopter that can lift off using muscle power.