Rubens Flame-Tube

Last Saturday morning I spent 4 hours making a Rubens Tube at the Makerspace while the crew from Pumping Station: One was shooting footage for their documentary entitled The Rebirth of the Maker Movement. Here is the first lighting of the tube:
Milwaukee Makerspace: We play with fire
A Rubens Tube is a pretty flashy piece of physics demo gear that uses fire to show the acoustic standing wave pattern inside an organ-pipe like tube fitted with a loudspeaker at one end. The 48” long, 2.5” diameter tube is filled with propane, which escapes through a series of 50 0.043” diameter holes spaced by 0.9 inches all along the length of the tube. Once the tube is full of propane (with absolutely no air), the 50 propane jets are lit with a striker or match, and all 50 flames have an identical height of 2 or 3 inches. When sound is played though the speaker at one end of the tube, the flame height is modulated by the acoustic pressure from the speaker. When a single tone (sine wave) at a resonance frequency of the system is played though the speaker, the heights of the flames map out the sinusoidal shape along the length of the tube. Playing music with dynamics or signing through the speaker is especially dramatic. I need to spend a few more hours fitting the Rubens Tube with a speaker at the other end and adding an additional propane inlet.