How to Build a Small Wind Tunnel

Making the Tunnel

• 1

  Cut a rectangle in the side of a 4-foot length of metal heating duct with shears, 1 foot from the end of the duct, about 7 inches long and 5 inches high.

• 2

  Cover the rectangle with a piece of clear acetate 8 inches by 6 inches in size to make a window in the duct. Tape the edges of the acetate to the metal using duct tape.

• 3

  Screw a hook to the top of the duct centered to the window. Screw a second hook to the bottom of the duct directly below the first hook. These will be used to suspend any item being tested in the wind tunnel.

• 4

  File down the ends of the hooks protruding from the metal, or bend them using a pair of pliers, so they do not snag on anything that moves through the wind tunnel.

Making the Diffuser

• 5

  Open a cardboard box that is at least 2 feet high and will fit over the end of the duct when put on its side.

• 6

  Cut 2 inches from both ends of a box of drinking straws with a table saw.

• 7

  Remove the covers from the ends of the box so you can see through the straws.

• 8

  Spread some white glue to the sides of the boxes and place them in the box.

• 9

  Repeat this process until the bottom of the box is lined with a honeycomb of straws. Use loose straws to fill in the gaps.

Assembly

• 10

  Fold the top flaps of the cardboard box over the sides and tape them down using duct tape.

• 11

  Turn the cardboard box on its side and open the bottom of the box. Slide the bottom flaps of over the duct.

• 12

  Tape the box flaps to the duct using duct tape so there are no gaps for any air to escape.

• 13

  Place a small electric fan in the box. Alternatively, put the assembly on a table and put the head of a floor fan against the opening of the cardboard box.

• 14

  Tie two strings to a model plane. Hang the plane from the top hook in the wind tunnel with one string. Secure the plane in place by tying the other string to the bottom hook.

• 15

  Turn on the fan and begin testing your small wind tunnel.