Creating and Testing Lift With a Homemade Wind Tunnel

Have you ever wondered how airplanes fly? How the wings work? How the shape of the wing affects lift? I have, which is why I built a wind tunnel to test diferent wing designs. In this Instructable, I will show you how I buillt my wind tunnel, as well as how I kept up with my experiments.

Safety: Get assistance from an adult to use a saw to cut the various parts for the wind tunnel and wing mount. Make sure that your hands are well clear of the saw at all times. Keep hands away from the moving parts of the blower while it is on.

· Four pieces of Plexiglass

· One blower

· Power adjuster

· Weather station with anemometer

· Flexible clear plastic sheeting

· One bungee cord

· Two hose clamps

· One dowel rod

· One block of balsa wood

· One strip of balsa wood

· Small screw-in hook

· Fishing line

· Eight small metal brackets to secure corners of tunnel

· Metal bracket to secure plastic sheeting to tunnel

· Wooden block – 2.5”x1”x0.5”

· Wooden block – 8”x1.5”x0.5”

· Metal wire covering

· Spring scales

· Epoxy glue

· Stickers to label wings

· Spray paint

Glue the pieces of plexiglass together into a rectangular prism and secure with small metal brackets on the corners. Next, put tape in the middle of the top and bottom of the box to help prevent the plexiglass from breaking during drilling.The tape is removed after drilling is complete. Drill small holes in the center of the top and bottom of the plexiglass box, being careful not to break or crack the plexiglass. Slowly drill bigger and bigger holes until you eventually drill holes big enough for a section of dowel rod to fit snugly through each hole, though you won’t yet insert the dowel rod.

Next, attach fan to end of wind tunnel. Use flexible plastic sheeting to connect the front of the fan to one end of the tunnel. Secure plastic to the fan with a bungee cord and to the tunnel with a metal bracket. You may also want to add straws behind the fan in order to straighten the airflow, as the fan blade can cause turbulence.

Cut two small pieces (each about 2 inches long) off the dowel rod. Next, drill a hole the same size that you drilled in the plexiglass in the center of each small wood block. Then drill two smaller holes on each side of the big hole to put piano wire very snugly into. Make sure the holes in one block align with those in the other block. Next, glue a piece of dowel rod into each wood block. Put piano wire through the smaller holes on one of the blocks, making sure that the wire is pointed the opposite direction than the dowel rod. Put the piano wire in the corresponding holes in the other block. Then, insert the dowel rod sticking out of the bottom of the larger wood block in the hole previously drilled in the bottom of the wind tunnel. Secure block to bottom of wind tunnel with epoxy. After that, screw small hook into lower wood block between the piano wires. Insert the dowel rod sticking out of the top of the smaller wood block in the hole previously drilled in the top of the wind tunnel.

Make five different shapes of wings out of balsa wood. I used a power sander to shape the airfoils(the shape of a wing) In each wing, drill two vertical holes that are the same distance apart as the piano wires on the wing mount. Make sure the holes are just large enough that the piano wire can move easily through the holes. I lined the holes with very small plastic tubing to ensure that the wing can easily glide up and down the wire, as well as making sure the wing maintains the correct angle of attack(the angle of which a wing is pointed). Make sure that the angle at which the holes are drilled is the same in all wings; otherwise, the wings would be angled differently in the wind tunnel and would give you inaccurate information. Now, make a very small hole in each wing between the two holes previously made for the piano wire. This will be used to run fishing line through for the weight test. Diagram credits to http://en.wikipedia.org/wiki/Lift_(force)

Remove the smaller, top wood block from the piano wires by lifting the dowel rod which is protruding from the top of the wind tunnel. Slide one wing onto the piano wires and then lower the small block of wood back onto the wires. Make sure the curved upper surface of the wing is up and that the thicker side of the wing is directed toward the wind source. Next, place the anemometer at the open end of the tunnel, opposite the fan. Turn on the fan. Now, measure the wind speed as the wing begins to rise. Measure the wind speed at which the wing maintains its altitude. Repeat the test two more times with the same wing by turning off the fan, restarting the fan, and measuring wind speed as described in the previous steps. Now remove the wing from the wing mount and place a different wing on the wing mount. Repeat the testing process for each wing. Make a chart that shows the shape and results of each wing. Compare the results for each of the five wings.

Remove the smaller, top wood block from the piano wires by lifting the dowel rod which is protruding from the top of the wind tunnel. Slide one wing onto the piano wires and then lower the small block of wood back onto the wires. Make sure the curved upper surface of the wing is up and that the thicker side of the wing is directed toward the wind source. Place a spring scale at the open end of the tunnel, opposite the fan, with the hook facing toward the wing mount. Tie a loop in one end of a piece of fishing line, and hook it onto the spring scale, run it
through the hook on the lower wood block of the wing mount, and thread it through the small hole in the middle of the wing. Secure it with a knot and tape. Turn on the fan. Measure the amount of weight the wing can support in grams by using the spring scale. Repeat the test two more times with the same wing by turning off the fan, restarting the fan, and measuring wind speed as described in previous steps. Remove the wing from the wing mount and place a different wing on the wing mount. Repeat these steps for each wing.

After you have finished your testing, compare the results of the wings and determine which wing can produce the most lift. In the future, maybe try adjusting the angle of the wings and see how that affects the lift produced by a wing. Thanks for reading!