For my 4-year-old's birthday party, I built a wind tunnel for her and her friends to "test" the flight characteristics of stuffed animals, balls, toys, and anything else that fit into the 4-inch diameter tube. Powered by an air pump (normally used for a bouncy house), the tunnel was oriented vertically so items could be launched towards the sky. See the video below for some of the tests:

I considered the wind tunnel a total success as it kept a herd of 3-6-year-olds occupied, let them play and discover what items would fly, and simultaneously was interesting enough that all the parents wanted to play, too.

I built the project organically with no more of a plan then wanting to have kids play with a stream of fast moving air. If you don't want to follow along to see what I did specifically for my setup, here's the summary:
  1. Consider cardboard concrete forms for projects that require 12-inch diameter tubes
  2. Desktop fans that fit inside such a tube can't move enough air to be fun
  3. Not only can an air pump from a bouncy air move enough air to fly all sorts of things, but it produces a collimated stream of air; a leaf blower would probably work just as well.

Step 1: Fans Inside a Cardboard Tube Vs. Air Pump

I initially tried powering the wind tunnel with two fans, but they didn't move nearly enough air for us to have fun. The air pump for our bouncy house moved plenty of air, plus it has a giant sticker labeling it as "not a toy". 
The air pump came with this bouncy house from Amazon. Check here for my other mod to the bouncy house, an additional safety net.
Awesome fun!
i hope yr planning on biulding protection screen 4 the air inlet. soo a little one doesnt get sucked in.
There's a screen on the inlet to the air pump, and we didn't set out any small toys or items that could fit through the screen.
Hair can be sucked in there. You might want to build a box around that air inlet to make the chance of a kid bending over to pick up a ball next to it impossible for hair to be sucked in. Great project! You might consider adding a 1.5" to 2" PVC coupler to one of the output pipes so that you can dry fit all kinds of T's & 45° & 90° elbows along with various sections of straight PVC pipe to make all kinds air "plumbing". It would need to be closer to the ground though to be fun for this part.
brilliant!!!!! water play if fun, but I had not thought of wind play. nice work
#1: wow, LUCKY KID! #2. This is a great time to be a kid! The world is just getting more interesting every day. Hopefully now that Instructables is here, more kids can have awesome diy moms and dads and grow up in an Exploratorium at home.
great love it  keep up the great job of being a great dad    to astral-mage  in step 8 photo 3 there is a protection screen  built in the fan itself  for safe use  you have to look close i almost miss it myself lol at me
That is fantastic.
My little nephew will like
That is awesome- my kids would love this!
wekll yes u can do it by, using a gated wheel like the ones used in wheel leaf blowers. hooked up to a battery operated drill.
hey if it keeps the kids an parents happy. go it . i might be uising the idea my self as well.
You are the best dad on the planet.

About This Instructable




Bio: Eric J. Wilhelm is the founder of Instructables. He has a Ph.D. from MIT in Mechanical Engineering. Eric believes in making technology accessible through ... More »
More by ewilhelm:LEGO table with integrated parts bin Custom Wooden Train Track X-crossing Mad Max and War Boy Nux father son costume 
Add instructable to: