Sequential PC's

[cantab]

I was thinking about seperate PC guns, and how there is a trade-off between quick pumping and long firing, since they don't work well unless they're quite full (or you prime them).

So I wondered, is there any way to have a gun with multiple PC's fill them each in turn? So when you pump, initially it fills just the first PC, then when the pressure reaches a certain level, that opens a valve to the second allowing you to pump water into it.

I think what might work is for the secondary PC to have two check valves. The outlet is just normal, while the inlet only opens under a certain pressure. A third PC, if present, would then use a slightly higher pressure inlet. Would that work?

The result would be a sort of one-sided CPS. The first few pumps fill the first PC, and then you have full power, further pumping just fills the other PCs. When you shoot you still get dropoff though.

[Silence]

That's possible with pressure release/relief valves, but I don't recommend it. Also, you would want the highest pressure chamber to be filled first.

The end result would be performance exactly equal to the same system with no "pressure inlets". A regular APH would have all its pressure chambers at the same pressure and they'd lose pressure more slowly. In yours, the first chamber would fill to peak pressure. Then the second chamber would fill until its peak pressure (which must be lower than the first chamber's, or the negative pressure gradient would stop water from flowing into the second chamber in the first place).

You also have the problem of the pressure equalizing if all the outlets lead to one barrel (and I'm not sure that they do). Maybe you need check valves, which restrict the flow. In the end, you just end up limiting the pressure in some of the pressure chambers.

People have suggested using ball valves as inlets and outlets for each pressure chamber. It's less complex, but it doesn't really solve the problem since you could just have longer shot time with a large pressure chamber. The "saving pressure for later" concept could be solved with a precharger piston in one pressure chamber. As far as I'm concerned, the APH should be kept a simple design, and if you want to mess with the pressure, it's easier to use rubber or a piston.

[Drenchenator]

All of the extra work for no really performance benefit doesn't sit well with me. I appreciate the idea, but implementing it and building it doesn't seem worth it in my mind. The overall idea of having a few shots ready or having pressure ready can be done more easily with a pre-charger system. I just think it's too complicated when there are simpler, easier to build options at hand.

[Captain Galaxy]

It would basically be a check valve that opens at 50 psi instead of 2. You could probably make a check valve with a stronger spring.

[devvo]

its an interesting idea, why not have two PC's and have a ballvalve on one so you can have short and sweet when you want it and open the valve when you want a long stream. pressure relief valves are complex to adjust without pressure testing equipment, not to mention expensive/

[cantab]

Yeah, one could just use ball valves - but then it's loads of fiddly opening and closing. That would hardly an easy weapon to use.