Supercannon II mk. 2

Build a homemade water gun or water balloon launcher and tell us about it.
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SSCBen
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Supercannon II mk. 2

Post by SSCBen » Sun May 31, 2009 9:40 pm

I'm planning a revision to the original Supercannon II design. The design will remain fundamentally the same aside from some changes to improve safety, reduce cost, and simplify construction.

Only pressure rated fittings will be used. This means that the reducers will be replaced by a 4 inch coupler and a reducing bushing. The assembly on the back end will be replaced by a 4 inch cap with the necessary components attached directly through the cap and pipe through tapped threads. With the bulky assembly on the back gone I'll increase the length of the chamber a bit. The piston assembly will be reinforced to prevent bending and leaks.

Ultimately I'd like a water gun that could be practical for amusement, tests, and potentially water wars. Last year we discussed the possibility of using a water gun much like Supercannon II with HPA. I discounted the possibility because even a large HPA tank would not provide for many shots, however, as I already have the HPA tank and have no intention of using it for Nerf any longer, I see no reason not to try.

With this revision a new guide will be made. I'm hoping to make a video of the construction process as well to post on Youtube. Perhaps this will bring more people into the hobby.

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cantab
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Re: Supercannon II mk. 2

Post by cantab » Sun May 31, 2009 10:03 pm

If you're using HPA, could you use it through a regulator, and then the entire length of the PC could be occupied by water? That would allow you to use a shorter pressure chamber, making for a physically shorter gun.
I work on Windows. My toolbox is Linux.
Arsenal:
Super Soaker: XP215, 2xXP220, Liquidator, Aquashock Secret Strike M(odded), Arctic Blast M, CPS1200, CPS2100, SC Power Pak, 3l aquapack, 1.5l aquapack
Water Warriors: Jet, Sting Ray M, Shark, Argon M, Tiger Shark, PulseMaster
Others: Waterbolt, The Blaster, Storm 500, Shield Blaster 2000, generic PR gun, generic backpack piston pumper (broken), 3l garden sprayer M, 10l water carrier:

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SSCBen
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Re: Supercannon II mk. 2

Post by SSCBen » Sun May 31, 2009 10:56 pm

cantab wrote:If you're using HPA, could you use it through a regulator, and then the entire length of the PC could be occupied by water? That would allow you to use a shorter pressure chamber, making for a physically shorter gun.
That'd be the idea for a water gun dedicated to that task. Here I'm looking for a multi-purpose gun.

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Silence
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Re: Supercannon II mk. 2

Post by Silence » Mon Jun 01, 2009 3:07 am

cantab, my concern with that idea is that air would need to be flowing through the regulator as you fire. Regulators aren't very high in flow since they're generally tiny and diameter and the valve is often only cracked open. (By the way, joannaardway once pointed me to this great visualization of how regulators work.)

Using an all-metal assembly, liquid propane could work well here. Its vapor pressure is about 150 PSI at room temperature, and it should vaporize quickly enough.

Ben, any reason you've decided to tap threads for the Schrader/etc. valves? I remember you used to discourage that practice for safety issues.

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Vickers303
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Re: Supercannon II mk. 2

Post by Vickers303 » Mon Jun 01, 2009 8:09 pm

From my experience, tapping threads instead of assembling the connectors for the air intake valve would reduce costs by about twenty or so dollars. If the thread is made right, there isn't much danger of air leakage or worse. Teflon is a very good friend here (your best friend is your brain :D ).

Would there be any drastic improvements to range (like breaking 100 feet or something)? That would make an awesome video. But what kind of sucks is that no matter how big or powerful the gun is, there's always a human limit. A forty pound gun is great if it can shoot up to forty yards (or miles, or whatever), but there isn't any point to making it if you can't carry it. Eh. Philosophy. ;)
Why isn't there a water gun armored vehicle yet?

Arsenal: Modded Supercannon, Backpack-modified Piston Gun, WBL, Storm 300 Pistol, and a whole slew of defunct soakers in the garage.

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C-A_99
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Re: Supercannon II mk. 2

Post by C-A_99 » Mon Jun 01, 2009 9:54 pm

I think only fire hoses can hit 100'. Its all physical limitations; more range requires exponential increases to diameter and pressure.

One issue here with any kind of HPA. The air needs to be released after each shot (either completely released, if you're ram-rodding the piston and refilling, or released to a low enough pressure to pump in) and then new air added. The regulator would have to be turned off when filling or re-pumping, then back on to add in more air.

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Silence
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Re: Supercannon II mk. 2

Post by Silence » Tue Jun 02, 2009 12:31 am

The MOARC shot 80 or 90 feet, according to its creator. And Supercannon II itself can top 80 feet with glycerin and pressure substantially over 100 PSI. Scaling everything up is the challenge, but with enough time and money, anything's possible. Take a look at Pumpkin Chunkin' to see how extreme some (spud gun) builders get.

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SSCBen
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Re: Supercannon II mk. 2

Post by SSCBen » Tue Jun 02, 2009 3:32 am

Silence wrote:Ben, any reason you've decided to tap threads for the Schrader/etc. valves? I remember you used to discourage that practice for safety issues.
I was stupid to discourage taping. Taping is perfectly fine if you tap into a doubly thick area like the overlap between a fitting and the pipe. And as Vickers said, it can save a lot of money and has practical purposes as well.
Silence wrote:cantab, my concern with that idea is that air would need to be flowing through the regulator as you fire. Regulators aren't very high in flow since they're generally tiny and diameter and the valve is often only cracked open. (By the way, joannaardway once pointed me to this great visualization of how regulators work.)
I've thought about this a bit in preparation for testing. I'd have to run some numbers or tests to see precisely under what circumstances a regulator would be problematic, but I'd imagine with 1/4" NPT threads a regulator is fine for most reasonable flows. Of course, the point of a Supercannon is to be unreasonable... and consequently the regulator on my father's air compressor may be inadequate for high flow tests.
C-A_99 wrote:One issue here with any kind of HPA. The air needs to be released after each shot (either completely released, if you're ram-rodding the piston and refilling, or released to a low enough pressure to pump in) and then new air added. The regulator would have to be turned off when filling or re-pumping, then back on to add in more air.
Right. I was thinking about adding a WBL to make use of the leftover air. That would help somewhat with the reloading issues too. There'd also definitely be a lot of valves to switch... maybe a single special valve with the right logic could do it.
Last edited by SSCBen on Tue Jun 02, 2009 9:27 pm, edited 1 time in total.

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Silence
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Re: Supercannon II mk. 2

Post by Silence » Tue Jun 02, 2009 4:24 am

Interesting, McMaster-Carr doesn't publish flow rates for any of their regulators, it seems. You'd want to shoot for 60 gallons per minute to match Supercannon II with its nozzle on. (I was going to link to a calculation on Wolfram Alpha, but this page already had the converted output values.)

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SSCBen
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Re: Supercannon II mk. 2

Post by SSCBen » Tue Jun 02, 2009 11:14 pm

McMaster-Carr does publish flow rates in scfm which means "standard cubic feet per minute." I can't remember the exact details of what standard here means (it's on one of the pages), but I assume this number is all that is needed. One 1/4" regulator (4956K11) gives a flow rate of 70 scfm at 100 psi, which is 33 L/s or 524 gpm, hopefully more than adequate.

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cantab
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Re: Supercannon II mk. 2

Post by cantab » Wed Jun 03, 2009 1:54 am

C-A_99 wrote:I think only fire hoses can hit 100'. Its all physical limitations; more range requires exponential increases to diameter and pressure.
Well, you probably COULD build something that would do 100 feet. But:

* It might be too heavy to carry, and require mounting on a trolley.
* It would be expensive.
* It would GUZZLE water. You get to the point where even if you could carry the gun, you couldn't carry enough water. It's fine with something like the MOARC, but no good when there's not a handy body of water nearby.
I work on Windows. My toolbox is Linux.
Arsenal:
Super Soaker: XP215, 2xXP220, Liquidator, Aquashock Secret Strike M(odded), Arctic Blast M, CPS1200, CPS2100, SC Power Pak, 3l aquapack, 1.5l aquapack
Water Warriors: Jet, Sting Ray M, Shark, Argon M, Tiger Shark, PulseMaster
Others: Waterbolt, The Blaster, Storm 500, Shield Blaster 2000, generic PR gun, generic backpack piston pumper (broken), 3l garden sprayer M, 10l water carrier:

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Silence
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Re: Supercannon II mk. 2

Post by Silence » Wed Jun 03, 2009 2:00 am

Ben: Yep, I see the SCFM column now. The regulator you pointed out looks great: you're covered in terms of output and, above all, it's cheap.

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SSCBen
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Re: Supercannon II mk. 2

Post by SSCBen » Wed Jun 17, 2009 1:26 am

I've been busy and consequently haven't had many opportunities to work on this project. Working nearly full time and spending much of the remainder of my free time learning analytical methods for PDEs doesn't leave much for other things.

The plan is to not only make this water gun, but also make a video series documenting the building process. This will put the project on hold until I have access to reasonably good video equipment. I do have a digital camera that shoots 30 fps at a good resolution, however, the video mode is crippled by the lack of sound and its inability to shoot longer than 20 or so seconds.

I'll use the time until then to plan the video and construction guide. I'll post outlines in a day or two after they are finished.

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adronl
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Re: Supercannon II mk. 2

Post by adronl » Sun Jun 28, 2009 11:36 pm

If you want I could help you out a bit on that. I can tell you what happens to the piston after you fire it about 60 times with a coupler or I can show you pictures.

Make sure you do not use vasoline, petroleum jelly or any other petroleum based lubricants. It will decrease the life of the piston severly especially when using a coupler. As far as I can tell you may be able to completely ruin a piston cup this way.

You could decrease the cost much more by loosing all of the parts used on the air side and replacing them with a high pressure schrader valve. Some are rubber but what you would want is metal most are rated for comfortable operating pressure of 150 psi. The ones I use bolt together from the outside so no tapping and if it leaks because it is not tight enough it can be adjusted tighter from the outside. You can buy them at an auto parts store or go to a tire shop. If you continue to use the air pressure method currently used you still need a shut off valve to recharge your gun.

If you want a continuous air flow you can put a locking air nozzle on your air storage tank. Want to get more expensive and crazy go to wal-mart get a 12 volt slime brand air pump there should be one that goes up to 300 psi. Then get a 12 volt solar pannel I am sure you can figure out the rest.
Last edited by adronl on Sun Jun 28, 2009 11:44 pm, edited 1 time in total.

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Silence
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Re: Supercannon II mk. 2

Post by Silence » Mon Jun 29, 2009 12:25 am

As far as I know, a complete valve setup is preferred over the Schrader valve in order to drain the tank quickly and with minimum noise.

Locked