Cardboard Wind Tunnel

This is a quick, inexpensive, and easy way to create your own wind tunnel. The only thing I had to purchase was the paper straws. This only took me a few hours to build, but ended up being quite durable.

A wind tunnel consists of an air source that is compressed and uniformed that allows for various objects to be tested for aerodynamics and air resistance. The different terms for the parts of the wind tunnel, which I will refer to, are explained in the picture of the completed project.

- Cardboard boxes (one being at last 15inx17in wide, and the other being 5inx5in wide and 1.5ft long)

- Scissors

- 175-200 paper straws

- Duct tape

- Upright fan (I used a 2ft x 2ft fan)

- Ruler and/or measuring tape

- Pencil/sharpie

- (optional) Hacksaw

In this step, use the scissors to cut all the straws in half. The straws will eventually be used in the flow straightener. At this time, also cut the box, which ad contained the straws, in half.

I found that, when cutting the straws, measure one straw and cut it perfectly in half. Then use that straw as a template to cut the others.

(Optional) You can use the hacksaw to cut the straws and the box at the same time instead of cutting them all individually. I found this difficult to do without breaking or damaging the straws, so I didn't do use the saw.

In this step, you are going to tape the cut straws together in groups of twenty. Lay out a strip of duct tape and the place the straws on the duct tape. You will need to do this 18 times.

Take nine groups of 20 straws and tape them together. Tape them by stacking one on top of the other and then wrap the stack around once or twice over with the duct tape. Make sure not to cover any of the open straw ends. After taping the groups together, slide the groups into the straw box that was cut in half.

Stack one of the straw boxes on top of the other and tape them together. If one of the straw groups are sliding out of the box, use double sided to stick them back in.

Take all tape off the box and open the bottom and the top of the box

Put the fan up against one of the open ends of the box. The 17in side of the box should be the base on the table. the 15in sides of the box should be on either side of the fan. Use the flaps on the edge of the box to cover most of the fan. If you need to, cut off excess material on the flaps to make them flush to the edge of the fan.

Tape the box to the top and sides of the fan. For now, it is ok to have the big gaps like I do in the second picture.

Tape the big gaps on the top of the box and fan using strips of duct tape. It might take a few strips to cover the gap, but you want to make sure you are maximizing the amount of area you are covering on the fan while minimizing air loss. Don't forget to tape up any gaps on the bottom of the box too. Sometimes they are only really visible from the inside of the box, so be sure to check this before moving on.

To create the testing chamber, cut out four strips of cardboard that are 5in x 24in. Tape three of them together and tape them to the flow straightener like I did in the pictures above.

Don't forget to tape the inside corners. You can do this using one long strip of duct tape per side. This will prevent any turbulence from arising in the testing chamber.

Cut from the top of one side down, one inch away from the end of the flow straighter. About 6 inches from the previous cut, make another cut down to pull down what will look like a flap. See photos for example.

Take your final strip of cardboard and tape it, on both sides, to the no-window side panel. Then tape the top to the window-side,but dont tape the widnow shut. Remember to add tape to the inside of the testing chamber on the window side.

Take the side flaps of the contraction section and fold them so that they meet up at the edges of the testing chamber. Make sure that the flow straightener is at the beginning of the testing chamber. Look at the first picture for an example of how it should look.

Draw a line from the top corner of the testing chamber to the top corner of the contraction box. See first picture for example. Then cut along that line and remove the piece.

Fold the top flap of the contraction box down. Then, apply tape to where the top flap and side flap of the contraction box meet. See picture for example.

If you have any remaining gaps between the contration box and the tesing chamber, use an extra piece of cardboard to cover the gap. Tape the same way you did in the previous steps. Also apply tape to where the contraction box meets the top of the testing chamber. Finally, tape up any other gaps you may find in the contraction box/testing chamber.

If you want to add accessories, this is the time to do it. I used a flashlight to light up the inside of the testing chamber. I also used the excess cardboard I had to make a small wing that I can test.