Large Model Tornado Built for The Weather Channel's New Science Series

cameron's picture
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Model tornado built for The Weather Channel series "3 Scientists Walk into a Bar."
Model tornado built for The Weather Channel series "3 Scientists Walk into a Bar."

It's only a few days until the premiere of “Three Scientists Walk into a Bar” on The Weather Channel. One of the episodes that will be airing next Sunday night (barring any last-minute schedule changes) features the model tornado I mentioned in the previous post. It was one of the coolest things I did while helping with the show and I wanted to share a few details about it.

Model tornado prototype testing.I had built a small model tornado when I was about 11 years old and already understood the basics of what was needed. But Travis wanted something big, like gymnasium-sized BIG, so we had our work cut out for us. We studied models built by others and set up the test rig you see in the photo to the left. One of the goals for the build was maximum visibility of the funnel, so we started out trying fans on the floor. A few times, a funnel would start to form, but it just wouldn't stay together. The circular airflow wasn't consistent enough to maintain it.Initial model tornado construction.

We decided on a design using 6 PVC pipes which would hang from an upper platform. The pipes would be capped on the lower end and would hold electric leaf blowers on the upper end. Yes, 6 electric leaf blowers! Holes along one side of each up pipe would direct the airflow horizontally and we could rotate each pipe to align the airflow with the other pipes.

Preparing to lift the model tornado platform for the first time.The upper platform is made up of two halves to form an 8-foot diameter disc. We had to get the platform suspended in order to mount the legs, which were made up of 10-foot long 4x4 posts with large casters. The Harbor Freight Gantry Crane made this possible, but just barely.

In the center of the platform is the large fan which provides our updraft. We started out with a standard shop fan and soon found that it just wasn't strong enough to pull an updraft at the height we needed. We lucked out by finding a used 1.5HP industrial fan and things started coming together.Planning sketches of the model tornado's platform.

The funnel was still very inconsistent. It would appear for a few seconds, then randomly breakup for no apparent reason. What was happening was air being pulled up through the main fan was just circling back around the platform and being pulled right back into the fan. In other words, our baffle wasn't large enough. We solved this by adding a chimney of sorts around the main fan. This increased the negative pressure provided by the main fan and the more powerful updraft helped maintain the funnel.

Finally, we got it! The model tornado works!It was a difficult build because so much of it was trial and error and it was stressful because of our tight schedule. But to see this thing in action is pretty awesome. I'm really proud of what we did and think it's going to make a great episode.

I hope you'll watch the show this coming Sunday night on The Weather Channel.

Cameron B. Prince
Tesla Universe Webmaster

Comments (2)

trackergd's picture

In your initial trials without the chimney the industrial fan was "short cycling" so what you ended up creating was a "ducted fan" which seems to better simulate the violent updraft. Pretty neat design and it looks like you worked out the bugs pretty well. Have you received any feedback on how your simulation parameters compare against funnel formation analysis reported by storm chase team probes and radar data? I have used dry ice in water to create a "fog" in creating a funnel (on a very small scale using a computer fan), however it looks like you have water on the floor creating the funnel? Again, great job!

cameron's picture

Thanks man! I am not sure what the network did as far as scientific data is concerned. They didn’t keep me in the loop much on that end. Maybe that will be mentioned on the show. We tried all sorts of things to provide the visible element (fog machines, dry ice in cold, warm and boiling water, etc.). At the end of the day, it worked best by busting the dry ice into small pieces and pouring it into a mound centered below the main fan.

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