File talk:Water rocket.gif

Error in Animation

There is an error in the animation. In the beginning the Bottle is almost full filled with water. Then air is added. You can see the bubbles floating up. When they reach the top the water level sinks. This is not plausible. Water is (almost) incompressible. There should be more air in the bottle in the beginning. When Air is pressed in The water-level should go up (according to the Volume of the bubbles). When the bubbles reach the Tip the water falls back to its initial level. In this whole process the volume of water (and air) in the bottle is constant. The only change is the mass and pressure of the air.

In general I think the water level in the bottle is to high. In my experiments a bottle filled 2/3 with water works best. Greetings. Jahobr (talk) 16:16, 11 February 2011 (UTC)

Agreed. With the ratio of compressed air to water shown in the animation, the rocket would go nowhere. The expansive energy in the air would be used up in a moment. The most common advice I see is half and half air to water, but I would not dispute Jahobr's experimental conclusion that 1 to 2 works well.

I completely disagree with all of the above comments. This animation is 100% accurate.