Several things affect noise. The most common is how much water is in the boiler. Shake out as much water as you can before priming. You need water in the straws, but only droplets in the boiler, which flash to steam quickly.Also, moving the candle a little forward or backward can change loudness. I find tea candles too weak for good sound. Sometimes an engine gets louder after a minute of running. Slater
re: why don't the straw part inside the engine melt? Good question. I think it's partly because the water in the tubes keeps them from getting too hot; partly becuause the heat from the candle goes mostly up and away from that part of the engine; and partly because the epoxy around the straw ends helps them keep their form. Slater
@RTdeluxe i saw a video that explained how water is a great heat conductor. so if you heat one part the whole mass of water will heat up with it, therefor making it much harder to come to very hot temp.
Are you using a tea candle (don't). Look at the troubleshooting section. Also, people's second engine almost always works better than the first. follow directions very carefully. Slater
reducing the diameter of the hole increases the speed/volume ratio, so it goes faster, but it also increases the friction, so it makes it slower. The smaller the diameter, the more the friction increases, so there will be a point in which making the hole smaller will increase the friction so much, that speed will be less.
Yes, if you look about 3 minutes in, I sketch a graph that indicates a point where it becomes counterproductive to restrict the end. You can verify this by experimenting.
Exactly. In this case, doing the math is not a good option, there is too much variability in the water and the coefficient of friction. It is far better to do this by experimentation.
The physics does not work. You do not gain energy by making a nozzle smaller. The thrust is determined by the mass of water multipled by the speed. Reducing the flow causing higher speed actually reduces thrust since you are adding resistance
I did not say that you gained energy by making the nozzle smaller; I said that you gain speed. I think it's more about load matching to the speed of the boat. You see the same idea in rocket engines. Of course, if you take it to the extreme and restrict the opening too far--past the point of diminishing returns--then the engine performance would be reduced. You have to find the sweet spot.
