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During an discussion with friends regarding pneumatic cannons, I came up with this gem :). Piston power pneumatic cannon. My friends however, didn't share my excitement regarding this revolution in the potato chucking industry.

The idea is simple: Using the gas laws, we can work out that if the volume of a container is halved, the pressure will double.

  • Step 1. The piston will be push as far as possible into the container (this would require some sort of racket system/locking so you don't get a 100+psi punch).
  • Step 2. The value is opened to release pressure, and fire the projectile.
  • Step 3. The piston is pulled back, opening valves, through which air is drawn.

enter image description here

The potential issues I see are as follows:

  • The strength of the air container
  • The force required to push the piston would be equal to the area of the piston times the force of the air. A lot of force.

Am I missing some critical mechanical failure point? Is this a feasible plan, or is there a reason this is not really done?

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    $\begingroup$ Sounds like any bike pump. $\endgroup$
    – Solar Mike
    Jul 14, 2023 at 17:05
  • $\begingroup$ True. That is basically what I am was thinking. However unlike a bicycle pump, this would release 80-100psi all at once. $\endgroup$
    – Haggis2.0
    Jul 14, 2023 at 17:16
  • $\begingroup$ So add a reservoir a non-return valve and a ball valve… basically a compressor with tank. $\endgroup$
    – Solar Mike
    Jul 14, 2023 at 17:40
  • $\begingroup$ you are describing a pump action pellet gun $\endgroup$
    – jsotola
    Jul 15, 2023 at 20:56

1 Answer 1

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In this picture BRANDT 60mm PNEUMATIC MORTAR you can see a couple of guys with a hand pump for pressurizing the air tank. (That whole page is worth looking at, as is the whole online "museum" of retro-tech)

You write "the valve is opened" as if that is a minor detail :) Actually valve design and control is a critical element of engine design, and was a critical element of steam engine design, so the pneumatic gun designers had a running start.

The second problem I see is that you've got a wide short-throw pump: the force required is proportional to the area of the piston. You'll note that real bicycle pumps are long and narrow. I don't think you'll be able to get enough air at enough pressure to do more than tumble a potato out.

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