This is a project of mine I have been working on for a while. When i was younger, I visited a science museum and saw a tornado machine. I stood there for literally hours staring at it. A few years later, it came back into my mind and I decided to build a small one. It was pretty much a plastic tube with a computer fan and a few slits in the side, and an ultrasonic fogger. It worked great. Although, I couldn't really interact with it. So I built another one around the same size, but with a gap in the front, and a peice of PVC pipe with a blower mounted to it. I drilled holes down the side of the pipe, and this eliminated the need of a sealed tube or the air flaps in the side.
It was fun, and I won a few awards for it, but recently I decided I wanted to try build something bigger.
I went out and gathered some parts, and built the frame. It's about 1.8 metres high total, producing a tornado around 1.5 metres tall.
It sat as a bare frame for a few months due to lack of funds to complete, but recently I have had the urge to finish it off. Around $200AUD later, I had a neat looking machine that produced a nice tornado!
A few weeks later I decided to buy and Arduino and thought, "Why not use an Arduino to make this thing computer controllable?" So I gathered some parts together, and made my own shield, which is basically a few transistors.
With the help of this forum, I did up some code to control it. This involved reading a command sent over serial, followed by a value.
Each fan was assigned a command. So if I wanted fog, I would send over serial: f, 255 (255 being the PWM value), if I wanted rotation, I did: s, 255 etc.
I played around with this for a while, and thought, "Why not add some LED's?" For the tornado to show up well, it needs to be quite well lit. I bought some 3W RGB LED's and installed them into the top of the machine, and connected them to an Arduino through some FET's I pulled out of an old CRT monitor. These were assigned the commands r, g and b.
Typing all these commands in serial got a bit time consuming, so with the help of a friend, created a program in VB which made controlling the machine much easier. It still uses my original idea of using commands, however.
And there it is! I have purchased a pressure sensor and was intending to incorporate it so I can get a pressure reading from inside the eye, which would in turn help generate a fake fujita scale reading (Just for added fun), however it seems the sensor is not sensitive enough for such a small change in pressure, so back to the drawing board with that one. Anyway, pictures and video's describe much better than text, so here they are 
First tests:
Added some paint, plastic sheeting on the sides (Front remains open), a bucket under an acrylic plate with holes in it for the fog, with 2 ultrasonic foggers and a fan to force the fog out:
What do you do when you have a tornado? Add a house of course! Unfortunately I didn't have any spare cows at the time so I had to leave that out 
The Arduino with my shield all wired up and functioning:
The control application (So far) :
LED's and top exhaust (updraft) fan (Funny how it looks like the power cord is in the fan ):
And the thing in action with the LED's (Camera doesn't work too well in the dark, it's much brighter in real life):
And some video's:
I am thinking about maybe even making a web interface and having a webcam stream, so that people can fiddle around with the machine over the internet, though have a few other things to work on before that. If you want any other details, let me know
Cheers,
Dan
