Building tetrahedral kites – activity – teachengineering storing electricity in water

Do you know how a plane flies? Believe it or not, it is all because of the unique shape of the airplane’s wings. Bernoulli’s principle states that as the speed of a moving fluid increases, the pressure within the fluid decreases. As the plane flies, the air traveling over and under its wing is considered a fluid. The wings of the plane are designed so that the top of the wing is curved while the bottom of the wing is flat. This creates a longer distance for the air on top of the wing to travel than the air on the bottom of the wing. Since the air on top and bottom of the wing must travel from the front of the wing to the back of the wing at the same time, the air on top of the wing must travel faster to make up for the longer distance traveled. Now applying Bernoulli’s principle, because the air on top of the wing is traveling faster, it decreases the pressure on top of the wing. Because there is a lower pressure on top of the wing and a higher pressure on bottom of the wing, it creates an unequal force on the wing causing it to lift, thus allowing the plane to fly.

In today’s activity, you will apply this mechanism of flight to designing tetrahedral kites. Working in teams of four, you will build a tetrahedral kite following a specific set of instructions and using specific provided materials. You will use basic processes found in many manufacturing systems – cutting, shaping, forming, conditioning, assembling, joining, finishing, and quality control – to manufacture a complete tetrahedral kite within a given time frame. Pay attention to your team’s efficiency, the quality of the finished kite and the time limit. Testing of the kites is simple, we will time how long it stays in flight.

industrial engineering: A branch of engineering dealing with the optimization of complex processes or systems. It is concerned with the development, improvement, implementation and evaluation of integrated system. The term originally applied to manufacturing, but has grown to encompass any methodical or quantitative approach to being efficient in how a process, system or organization operates.

Bernoulli’s theorem states that as air passes below a wing, air also passes above it. The air on the top of the wing moves a longer distance over the curved surface of the wing, thus it moves faster reducing the pressure above the wing. The air below the wing moves more slowly causing the air pressure below the wing to be larger than the pressure above the wing. It is the change in relative pressures above and below the kite that allows the kite to lift.

Kites were the first flying devices ever made by humans. The word "kite" comes from a bird in the hawk family known for its grace in the air. Kites come in a wide variety of shapes and sizes and have been used for many purposes throughout history, although today, kite flying is done largely for recreation. See Figure 1 for an example of a tetrahedral kite, the type that students will be manufacturing in the activity.

• Assemble the kite. Begin with the bottom layer. Arrange three pyramids side by side so that they only touch by one corner and the front of each is a covered panel (all of the covered panels should lie in a plane). The other covered panel should be lying flat on the table. Knot the pyramids at the points where they meet. Arrange two pyramids behind those three so that the front covered panels of the two new pyramids faces the same direction as the front three. The back corners of the front three just meet the front corners of the two behind. Knot the two pyramids at all points that touch. Attach one more pyramid to the back corners of the row with two, again facing the covered panel forward. Be sure that all knots are secure!

• Add the second layer of pyramids. Arrange two pyramids side by side (make sure the covered panels are on the bottom and front). Knot them to each other. Align the bottom corners of these two with the peaks of the front five pyramids on the bottom layer. Knot these two pyramids to the bottom layer. Arrange and attach a third triangle behind the two you just attached. Be sure that all knots are secure!

• Start a stopwatch as soon as you let go of your kite (or when your partner lets go), and then stop the stopwatch when the kite touches down on the ground. This will be a "fair test" as long as the wind does not change too much. Groups may see improvement in flight time as they modify and improve their kite design.