Bamboo-copter

Let's take a look!

What type of experiment is this?

Experimental procedure and explanation:

• Let us fly a handmade bamboo-copter (though not made of bamboo).
• The first bamboo-copter is a commercially available propeller with an attached shaft. The second bamboo-copter is a blade made of cardstock paper (construction paper).
• Release the copter upward while rotating the shaft, and let it fly.
• When the propeller is rotated, the wind flows downward, and that rebound (reaction) causes the bamboo-copter to float upward.
• Let us take a closer look at this (enlarged view). The wind that hits the rotating propeller is turned by the propeller and it bends downward. At this time, a force called “lift” acts on the propeller in the direction opposite to the force applied to the air to bend the flow. This force acts on all the blades, and the resultant force becomes an upward force, which allows it to fly.
• Blades that rotate in this manner are called “rotary wings” and are used in helicopters and drones. In both cases, the flow drains downward, and the rebound (reaction) generates an upward force.

[Keywords]	Rotary wing, Momentum theory
[Related items]	Jet Propulsion
[Reference]	“The Wonders of Flow”, Japan Society of Mechanical Engineering, Kodansha Blue Backs, P192-197. “Illustrated Fluid Dynamics Trivia,” by Ryozo Ishiwata, Natsume Publishing, P222-223.

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