A pop-pop boat is a toy with a very simple steam engine without moving parts, typically powered by a candle or vegetable oil burner
SAHAYA toy steam power boat, runs on candle, fuel flame. Description: scientific toys steamer, early edge education toy, tin boat - lenth 16 cm, width 12 cm, height 5 cm (approx). Function: how does it do that- when the water in the coil boils, the steam expands. This pushes the water out of the tubes. The reaction pushes the boat forward. As the steam continues to expand, it encounters the section of tubing that used to be full of water. This tubing is cold, and the steam condenses back into water. This causes a vacuum to form, which pulls more water back into the tubes. You would expect that the moving back into the tubing would cause the boat to go backwards. However, the doesn't get very far before it hits the end of the tube (the two streams of in the two tubes meet each other in the coil). Any motion caused being sucked into the tubes is reversed by the water hitting the front of the tube (the coil) and pushing the boat forward again. As you saw when you put your finger near the tubes, this back and forth motion is fairly rapid, and the comparatively heavy boat never actually moves backwards at all. These are India on hand-operated presses, from tin plated steel. Hand-painted. They make a wonderfully loud "putt-putt-putt" sound as the steam around a bathtub, swimming pool or pond. Please : product batch being different so the colors & pattern may have a little difference from pics shown, these are fancy utility items. Analyze & read description, size & measurement details.