What you’ll need
- Paper, e.g., from an old brochure, magazine or print paper
- A ruler
- Two coloring or felt-tipped pens
- Paper clips
- Optional: sycamore seeds
How to do it
Initially, the helicopter falls towards the floor. But suddenly it starts to rotate around its own axis and spirals slowly towards the floor. The double samaras of the maple tree also rotate the same way. If you have some, why not give it a try?
What's the secret?
A real helicopter flies because it has a motor that turns its rotor. Due to the shape and movement of the rotor blades, the air pressure above the rotor blades is lower than the pressure below them. When the helicopter’s rotor turns, this generates lift which allows the helicopter to fly.
Your helicopter does not have an engine to make the “paper rotor” rotate, so it works the other way around. It drops to the ground because of the force of gravity. As it falls, the air presses against the rotor blades. As the rotor blades are offset, this causes your helicopter to rotate around its longitudinal axis. In fact, a better word than helicopter would be “dropcopter.”
The way in which sycamore seeds* fly is similar: First, they fall downwards, seed first. Then suddenly they lie flat in the air and start to rotate around their own axis. How does this help the sycamore seed? Because it has such an ingenious design, it takes longer to fall to the ground and has more chance of being carried by the wind. The more places the seeds land on, the higher the probability that some of them will germinate and new trees will grow.