Water Launchers

[Silence]

@ m15399: Could you please post a link to that? I'm interested now...I don't know the ideal air to water volume ratio, and that could be important for my understanding of ITWCs. Sure, you could make a short but really wide air compartment, but why not just make it overslung (that's right, it's not underslung, but overslung since the air is on top)?

@ Ben: There really isn't much point in using a hole saw if they are so hard to come by (especially the correct hole sizes, I'd imaging). Cutting the rubber with a cardboard cutter will suffice, and it might be a bit more convenient.

[DX]

In the ITWC, the ideal air/water ratio is 2/3 water, 1/3 air. The gun will still shoot well if it is as high as 3/4 water and as low as 2/5 water. Any higher will produce a short, weak riot blast, and any lower will produce a riot blast mixed with mist. Inside the good ratio range, however, you get the classic giant stream.

Note that these were not derived mathematically. These ratios are from me doing tests and applying logic. If someone else wants to do the math, they are welcome, however, math is my worst subject and I'm not fond of calculating things.

[Silence]

Thanks for the information--while math may have worked, it can overlook certain variables, unlike pure experimental results. Either way, I haven't experimented enough to know what the ratio is, and I don't feel like doing the math, either.

Assuming you're shooting 5 L of water (it's probably more, but oh well), then you'll need an air compartment that stores at least 2.5 L. Maybe a T instead of a 180 degree turn would work--because if one made the air comparment's diamter exactly 3 times the water compartment's diameter, then the air compartment would be only 1/9th the length of the water compartment! Of course, the T and especially the reducer might be clumsy.

[DX]

I think what it is like now will work for now. The next version will have a slanted-inverted T or a slanted backwards L. Depends on how the first ITWC works. Right now it is really comfortable to hold since I made the lengths with that in mind. For now, the air will just float up there until the ratio falls to the point where more water is needed. Using the water balloon launcher pc as a tester, I got 1-4 good shots until the ratio fell too low [repressurizing after each shot].

This thing is going to guzzle water, but since I'm going to be using it sparingly, that won't matter.

[Silence]

I can't wait to see the pictures--even if it's only to see whether the shape is practical or not. It's good to know that it already features good test results, considering it uses relatively new technology.

I am gone for a week starting tomorrow--I'll miss so much !

[Ben]

@ Ben: There really isn't much point in using a hole saw if they are so hard to come by (especially the correct hole sizes, I'd imaging). Cutting the rubber with a cardboard cutter will suffice, and it might be a bit more convenient.

I believe that you're getting the wrong impression. Hole saws are common, in fact, I saw a fairly good selection of them at Wal-Mart today. Larger diameter ones would be harder to come by, but smaller ones are easy to find. I don't use them too often, so they're not on my mind all of the time. More recently I have began to use them to cut seals for a new Nerf gun of mine, which is when I considered their use in Supercannon II

McMaster-Carr's got a good selection online of hole saws, and I intend to order from there. I'll need a hole saw because I need a near perfect seal that would be harder to achieve by cutting rubber with a smaller knife. There also is the fact that I intend on cutting a thicker rubber sheet.

Now onto something else...

I don't think that an inverted L would be the best design either. Right now I am considering a rotated U shaped, with the bottom being the water container. The air will still be on top, and holding won't be so awkward.

Getting tired... more tomorrow.

[Silence]

So, is SuperCannon II supposed to be a PCgH or something like that? I don't see another possible use for a 4" O-ring.

However, even if this O-ring is not intended for a PCgH, I thank you for even accidentally pointing it out. I never truly considered the fact that the O-ring size as used in a PCgH's PC could be hard to come by, but now, I am starting to realize that. If I can't cut out a good O-ring from rubber using a cardboard cutter, I might have to buy a hole saw too !

Yes, that U-shaped method for a WC (IUWC?) is exactly what I have been referring to, though in more easily understandable words. To me, the idea of a heavy, two-foot tower sticking up out of the back of my soaker is slightly disconcerting. EDIT: Needless to say, a U will perform the same function as an inverted T or L--and in fact, if the user is following the 45-degree rule and using an inverted T or L instead of a U, then the water will be at a greater elevation than the air !!!

[m15399]

Why don't you look up the old thread? It is similar to a precharger, but it doesn't use on board pumps.

[Silence]

Thanks for the save, m15399. Sure, I have read through that thread before, but it was slightly rushed. In addition, I hadn't actually been looking for information about whether it used a plunger in the PC or not.

I'm assuming hole saws have a point in the middle that shows you where the center of the circle is. Otherwise, one might have some trouble aligning the OD and the ID circles.

[m15399]

You wouldn't have to make a ring if you didn't want to. You could cut out a circular piece of rubber and screw it onto the front of a large dowel (slightly smaller than pipe) or whatever that would slide along behind the rubber.

[Silence]

Well, if you just screw a circle of rubber on, when you pull the plunger out, the edge of the circle will fall slightly away from the dowel, possibly compromising the seal. That won't work.

[m15399]

If the rubber is thick enough, it won't bend at all. Anything over 1/4" isn't going to bend. Even if it did bend, you could put a large washer between the screwhead and the rubber to keep it from bending too much.

[Ben]

Hole saws do put a hole in the exact center of the circle. I believe they do so for stability while drilling, but the holes do have other uses.

I don't intend to create a rubber O-ring by drilling twice. That would be counter-productive and more expensive than simply buying a correct sized O-ring and trying to make it seal correctly. I intend on drilling two or more seals and using some big washers or something similar to separate them and keep them straight. m15399 thinks very much like I do.

[Silence]

Hmm...a large metal washer would actually work quite effectively. I haven't seen any that have a 4" OD and a 1/4" ID, but I assume they exist, so that should be entirely possible.

[DX]

Interesting, now we have 5 unique water cannon/launcher designs:

ITWC
MS ITWC
Super Cannon I
Super Cannon II
PCgH
MT
IT41

Yeah, we've made a lot of abbreviations, but then again I wouldn't want to type out "Multi-Shot Inverted-T Water Cannon" every time I wanted to refer to that gun, for example.