Optimum dimensions of a Rubens Tube?
There are several Instructables posted for Rubens Tubes, and I have seen a few elsewhere.
I'd like to make one myself, for demonstration purposes, but I'm wondering if there is an optimum set of dimensions?
I have seen diameters from about 2-10cm, and lengths from about 80cm to 2m.
And what diameter holes should I drill?
If it makes a difference, I'll be fuelling it with mains natural gas (methane) in a school lab.
(And, while I'm here, what would be a good rescued speaker to drive it? An old PC speaker?)