Super Soaker Central

Regardless of whether force or pressure determines water gun performance - I'm thinking it's pressure - I hope to build a hybrid cannon soon. We've been doing some landscaping and renovation, which has meant a couple trips to Lowes already - and more are likely on the way.

For those who haven't caught on to the jargon in the thread title, let me explain:
> PCgH (Pre-Charger Homemade) - it can be a pre-charger type of APH. You can fill the pressure chamber with air beforehand (through the Schrader valve) and then use the gun normally afterwards, for less dropoff. That said, most of the time I'll probably just leave it uncharged for greater water capacity.
> WC (Water Cannon) - it can also be a water cannon. Fill the PC with water, then pressurize with air through the Schrader valve. That's the main purpose of the Schrader valve - it's not necessarily there to turn the APH into a PCgH.
> Hybrid - the weapon acts both as a regular air pressure water gun and as a water cannon.
> Sidearm - this is actually going to be a fairly lightweight and specialized gun. It's more of a sidearm meant for greater distance than it is a primary weapon, since it is going to take a bit to pressurize, either through the pump or through the Schrader valve.

The priorities, in order:
> high range (So I'm focusing on pressure, which is safe with a small tube, and on flow coefficient)
> small size/light weight
> high volume/shot time
(Which pretty much means that I'm not looking for any volume or shot time. This gun doesn't really need to suit the BPF in my sig, because it's not designed as a primary weapon.)

Some dimensions and parts I've been considering:
> The water gun will have a 2" diameter PC. The piston will either use an O-ring or a cup seal like what Ben used in SuperCannon II. Any input on which one tiameter pump. I told you, this is a specialized gun, and it o use? Either option will require an order online, from McMaster-Carr or oringsusa or something. My dad's had good experiences with McMaster-Carr though, and they have fast shipping.
> The PC will probably be between 12" and 18" in length. Not too small, not too large. It's going to be small in height and length, so it can probably be holstered or something as a sidearm. The problem is that unless I change the configuration (not really a problem), the grip will be in the back, and the ball valve in the front. I don't want my hands more than 20" apart, at least when firing.
> A 3/8" or even a 1/4" pump. It will certainly take a while to fill and pressurize the PC, but so what - it's not meant for regular fighting.
> A Schrader valve will be attached to the back of the PC, perhaps with a small ball valve or something to quickly release the pressure. In fact, at the pressures the pump can reach, it might not even be worth it to use the Schrader valve. But the valve's just there as an option for pre-charging and in case I want even higher pressures. An air coupler might also be considered for future use. Oh, and hooking up a bicycle foot pump will tell me what pressures I can attain with the onboard pump, although I won't use it like that in battle - just for stats.
> The "barrel" will probably be 1", 1.25", or 1.5" in diameter. Flow coefficient is fairly important here, but we don't really know what a good size is. SuperCannon II had a strong coefficient for its nozzle with 1.5" tubing, but I don't know whether or not a smaller diameter will suffice. Smaller ball valves will certainly be easier to turn.
> Nozzles will probably include sweeper nozzles, which I've sourced online but haven't ordered, a fire hose nozzle like SuperCannon II's (if I use 1.5" tubing), and metal pipe nipples with the inner seal filed off. 1/4" and 3/8" sizes should be common for pipe nipples and perhaps even sweeper nozzles, although I could try using endcaps for different sizes.
> This design will actually use a backpack, even though I've been sworn against them. I wouldn't normally use a single-shot sidearm unless I'm traveling heavy anyway. I'm really interested in the solar shower backpack idea that Ben said he picked up from an email.
> The configuration is going to be similar to Ben's CPHs. The PC will be aligned such that the opening is at the front. A tee in the barrel will lead to the ball valve and nozzle at the front. However, the middle of the tee will actually point up, with the second check valve and the pump tube slung over the PC. The pump grip will be a 2" coupler with the inner rim filed off, tracked over the PC (it can slide without the inner rim). The first check valve will be in the back, pointing down, and will serve as a grip.

What there will not be in this design:
> A regular finger trigger or a hand trigger to actuate the ball valve can't be implemented. This design is going for flow coefficient as well as pressure, so I'll need large ball valves, which will require too much force. Also, this is actually one design that I don't want to be overly complex or bulky.
> I'm not using an onboard reservoir, as I mentioned earlier. I could route the pump and second check valve underneath the PC, have the first check valve as a grip, and have a reservoir on top; but then it'll be bulky and top heavy. As a sidearm, this weapon could even be filled and then detached from the backpack to be smaller.

And for self-reference, here's at least some of the stuff I have to order online:
> O-ring(s) and possibly cup seals (I'll need an O-ring for the pump anyway)
> sweeper nozzles/fire hose nozzles/metal pipe nipples if I can't find them locally
> a solar shower
> a ball valve if Lowes doesn't carry the right size
> 1/4" or 3/8" tubing for the pump
> 1/4" or 3/8" check valves unless I build my own, which will require springs from McMaster-Carr
> the rest of the 1/4" or 3/8" fittings

Perhaps I won't reach the goals I'm aiming for with these sizes. But it's going to be an experiment at the very least, and hopefully the hybrid won't perform too badly.

I've also been planning a CPH that's a bit less specialized. But seeing as I have my Orca and several other (not so good) stock guns, I'm fairly set as primary water guns go. Regardless, the CPH would probably involve much smaller flow coefficients, but allowing for a real trigger and a very powerful rubber bladder. It would also have an onboard reservoir. But that's another story.

Can't write much, but all I wanted to say was that solar showers can be more conveniently bought in Wal*Mart or any outdoors store than online. Don't expect to spend more than $5 for one. They make great backpacks.

Thanks for the tip.

Do you think it would be better to use an O-ring or a piston cup seal for the piston? Looking back at the first SuperCannon II thread, you suggest that a cup seal is more reliable than the O-rings that MrPukeOnYourHead used. I believe that, but I just want to see if you've changed your mind after building SuperCannon II. (I doubt it. )

I'm now considering using 3" tubing for the PC. 2" is a bit too small upon further thought, and piston friction could be more of an issue. But I don't know, 2" would hopefully show a bigger difference for the pressure-force debate, and I don't really want to pump up a really large PC with a narrow pump.

2" and 3" Schedule 40 tubing have slightly larger IDs than 2" and 3" - but 4" does not. So I'm wondering whether or not the cup seals will perform well.

EDIT on 4/30, 8:46 PM: I've now even more determined to go with 3" tubing. It'll allow me to have more volume while keeping the PC length down to 12" or so. The problem is that I'll have to get it from McMaster-Carr (likely with killer shipping) or from some local place, maybe Ace Hardware.