Many years ago Fat Cat attended Space Camp for Educators. While there he met some amazing teachers from all over the country and learned many things about flight, rockets, and space. He wanted to learn more and started taking flying lessons to help quench that thirst for knowledge. To this day we can see him watching the huge jets coming in for a landing by our house as he wonders, "How in the world does that huge thing stay in the air?" We know he knows but he asks any ways. How do we know he knows? Well we were silly enough to ask one day. Here is what we found out.
A quick history of flight can be found in our other instructable.
Step 1: Materials
Roll of toilet paper
Stick or piece of dowel rod
A leaf blower! That's right a leaf blower!!!
Step 2: Leaf Blower!
Plug in blower, switch it on, and point it upward. Gas powered should be outside, the fumes can harm you. Electrical is great for inside or out. Use caution when operating either type of blower.
Carefully put the ball in the stream of air. Observe the ball floating in the stream of air. Gently move the blower from side to side. The ball will seem to float with "nothing" under it.
Try floating other light weight objects with different shapes in the air stream. Does one shape work better then others? Try two or more objects.
Step 3: Flying Toilet Paper!
Flying Toilet Paper!
Start up the leaf blower. Gas powered should be outside. Electrical is great for inside or out. Use caution when operating.
Just hold a roll of toilet paper in the stream of air and watch the paper take off! Be sure to hold the toilet paper roll on a long stick (piece of dowel) in order for it to spin fast and unroll the paper. Aim the flow of air across the top of the roll.
Air rushing over the top of toilet paper exerts less pressure than air from under the toilet paper. So the relatively greater air pressure beneath the toilet paper supplies the upward force, or lift, that enables the roll to fly.
Now replace toilet paper with wing and roll with plane! You just learned Bernoulli's Principal and an explanation of airplane flight!!!
These activities are great examples of Bernoulli's Principle. Bernoulli, an 18th century Swiss mathematician, discovered that the faster air flows over the surface of something, the less the air pushes on that surface resulting in lower pressure. The air from the blower flows around the outside of the ball. The air flows evenly around each side. Gravity pulls the ball downwards while the pressure below the ball from the moving air forces it upwards. This means that all the forces acting on the ball are balanced and the ball hovers in mid-air. As you move the blower you can make the ball follow the stream of air. Bernoulli's Principle says that the fast moving air around the sides of the ball is at a lower pressure than the surrounding stationary air. If the ball tries to leave the stream of air, the still, higher pressure air will push it back in. So, the ball will float in the flow no matter how you move. Bernoulli's Principal is the same principle that allows heavier-than-air objects like airplanes to fly.*
*Modified from http://www.stevespanglerscience.com/