Water Cannon

Problem: Friction

How to get water from source to target (fire) over long range through air.

The water stream from a hose tends to break up into ever smaller droplets due to turbulent mixing and friction. The turbulence is introduced either at the nozzle or through friction with air. Once the stream starts to break up the tendency is to break up even faster as the total surface area of the stream increases (many droplets of small size have more area than few of large size).

I thought about this for a few minutes and have an idea or two.

Solution Candidate 1:

We need to reduce the effects of the mixing of air and water in the stream. One way to do this is by "pelletizing" the water by freezing so that the size of the droplets is fixed.

Problem I With Candidate 1:

To difficult and costly to freeze large quantities water on demand.

Launch: Ice shell is both preceded and followed by liquid water
Flight: Ice shell acts as wind screen to protect liquid water behind it against breakup by air friction

Solution Candidate 1A:

Rather than freezing all the water of the stream into pellets suppose we get a bit more selective. Suppose that instead we only freeze "shells" of water shaped like the front surfaces of cannon shells. We need to freeze just enough of the water to act as a wind screen For the liquid water behind it.

Problem I With Candidate 1A:

The shells would be more fragile than a solid shot of equivalent volume and would not survive the pressures needed for launch.

Solution For Problem I With Candidate 1A:

There would be water in the launcher both behind and ahead of any given shell. Since water is incompressible the water ahead of the shell would support it during launch.

Problem II With Solution Candidate 1A:

How to build the ice shells rapidly as needed. This is much easier to solve than trying to freeze all the water. I have a few ideas...

Page first created Saturday, February 17, 2001
Page last modified Friday, November 22, 2002 11:55 AM
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