Water rockets - What's on the board
| On the edge of the field, there are 2 'observing stations': a tripod with a board
onto which you tape a sheet of paper. There is a plumb line so that you can
align the edge of the sheet with vertical. On it, there is a PVC tube, which pivots on
a nail and is held with a cork.
When there is a launch, observers follow the bottle by looking through the PVC tube, and leave the tube at the highest point. Draw a line along the tube and number it. After 5 or so launches, remove the sheets and bring them to the board. Then, on the board, I do the following (6) steps: |
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It shows that there is a sweet spot: too much water and it is harder to lift
all that weight off the ground, too little and you have no mass to expel and make you go.
| On this day, a height of 112 feet was reached with 1/2 cup of water (in a 1-liter bottle at 60 psi). | ||