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## Activity

If so instructed by your teacher, print out a worksheet page for these problems.

Explanation:

After becoming familiar with the way in which FoilSim demonstrates the factors that affect lift, you will be expected to make a device to demonstrate low levels of wind speed. You will be guided through creating a stand, a balancing arm, and a uniform airfoil. Once these are completed, experiment using changes in weight to determine a scale and measuring device for wind speed.

Step 1. The Stand

• You should obtain an empty soda pop can and a spring operated clothes pin.
• If your clothes pin does not have holes in the pinch part, the area where you put your fingers, you must put a piece of masking tape doubled over on each edge. There should be approximately 2 cm. of tape protruding from each end.
• With a pair of scissors, cut out a small notch in each of these tape pieces. This becomes the holder for your straight pin.
• Place the clothes pin on the turned up tab opener of your pop can. Make sure it is perpendicular to the top of the can.
• Add water to the can to keep it from falling over when air is blown across the foil.

Step 2. The Balancing Arm

A. The Weight Pan:
• Glue the Weight Pans Pattern to a piece of manila file folder.
• Cut out each pan. Cut on all solid lines and remove the dark triangles from each corner.
• Fold along each of the dashed lines.
• Glue a toothpick or short piece of skewer onto the pan along the axis. Let dry.
• Fold up the sides of the weight pan and glue each triangular flap. Allow to dry.

B. The Airfoil:

• Do not glue the Airfoil Pattern to a piece of manila folder. Cut out the paper pattern.
• Using the point of a pencil, make a small hole at dot A on both sides of the foil. The hole should be slightly smaller than your straw so that as it slips through, it is held snugly.
• Fold along the dashed fold lines.
• Gently bend the paper so that Trailing Edge C aligns with Trailing Edge C. Tape together.
• Mark your straw at 3 cm and 10 cm from the left end.
• Gently place the straw through your Airfoil at dot A to the right and left. The left side of your Airfoil should be on the 3 cm mark.
• Put a drop of glue in each end of the straw and attach each weigh pan. Make sure the pans are level one to the other.
• Put a pin through the 10 cm mark perpendicular to and level with the weight pans. There should be an even amount of pin on each side of the straw.
• Place the pin in the clothes pin holder. If you have done everything correctly, the straw should dip toward the side with your airfoil.

• Into the pan on the high (light) end of the straw, place or attach paper clips until the Airfoil is just about to "lift off."
• If one paper clip is not enough and two are too much, you may use small pieces of tape placed on the pan to balance your straw mechanism.

Step 4. The Testing

• With the wing level with your mouth, blow a horizontal stream at the Leading Edge of the wing section. The wing section should lift off and cause the pan on the other side to "bottom out." Try to keep a steady stream of air so that your wing and pans are level. If you have to blow hard, the wing section is not balanced properly and you may need to add more weights.

Step 5. The Assessment

As designed, the wing device demonstrates that blowing air across the wing generates enough lift to overcome its small amount of unbalanced weight. Small masses can now be added to the weight pan on the Airfoil side. It should be possible to quantify the amount of lift generated by blowing air across the wing.
• Using a blow drier on low setting, determine the mass that your Airfoil will lift. You do this by adding weight to the Airfoil side pan until you have an easy leveling process.
• Add one more mass beyond the level position. This confirms that you had the maximum weight lift for that airspeed.
• Record the maximum mass in grams that your foil could lift.
• Increase the drier speed to the middle level and continue collecting your data as you did before. Record.
• Finally, increase the drier to its top speed and collect your data. Record.
• Graph these three points.

Data Table:

 Trial 1 (Mass in g) Trial 2 (Mass in g) Trial 3 (Mass in g) Low Speed Middle Speed High Speed

Step 6: The Analysis

1. Based on your observations and your data, what do you think will happen as you increase the mass and not the airspeed?

2. Based on your observations and your data, what do you think will happen as you increase the airspeed and not the mass?

3. What do you predict will happen if you blow across the Trailing Edge of the wing section?

4. List other wing shapes that you think might work better and tell how you would test your predictions.

Related Pages:
Standards
Worksheet
Lesson Index
Aerodynamics Index

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