Wind Car 1 (Spool of Thread Type)

Let's take a look!

Watch the video on YouTube.

What kind of experiment is this?

Experimental procedure and explanation:

• A car that runs from the energy of wind flowing around it is called a wind car.
• In this wind car, a thread is rolled up by the rotation of a propeller. The moving thread turns an axle (an axis of the tires), moving the car forward.
• There are two key factors here. One is to turn the tires in the correct direction so the car moves forward. The other is to make the axle diameter large enough to slow down the rotation of the axle. By slowing down the rotation, the force increases, and when this propulsive force becomes larger than the aerodynamic drag, the car will begin to move forward.
• When the wind car has a payload, it will not move forward if the propulsive force is not large enough. In that case, you can make the car move forward by increasing the axle diameter; this slows the rotation and increases the propulsive force.
• Usually, the wind will push the car backwards because of aerodynamic drag. What this experiment shows is that wind has energy, and by utilizing this energy appropriately, you can make the car move forward against the wind.
• This is the same principle as wind power generation, which also utilizes the energy of the wind.

[Keywords]	wind energy, moment, reduction ratio (gear ratio)
[Reference]	“The Wonders of Flow,” Japan Society of Mechanical Engineering, Koudansha Blue Backs, pp. 118-119 “Illustrated Fluid Dynamics Trivia,” by Ryozo Ishiwata, Natsume Publishing, p. 186 “Children’s Science,” Seibundo-Shinkosha, September 1997, pp. 45-47
[Link]	http://www.kait.jp/nagare/ (Contest is conducted at Wonders of Flow Exhibit Watch “Wind Car Contest” at the right side frame.) http://www.kait.jp/nagare/how-to-make-a-wind-car.pdf (Spool of Thread Type Wind Car.) http://sc-smn.jst.go.jp/(Search under program name “Science Battle,” and select #14 wind car.)