Constant pressure homemade

Build a homemade water gun or water balloon launcher and tell us about it.
Locked
User avatar
SSCBen
Posts: 6449
Joined: Sat Mar 22, 2003 1:00 pm

Constant pressure homemade

Post by SSCBen » Fri Jul 21, 2006 12:45 am

Today I took the time to finish up what most people call a CPH - a constant pressure homemade.

This isn't anything new, rather, it's something I should have done a long time ago. I built this water gun in 2004 just to be the first one to do it. It had a lot of problems actually, and still does a bit. Luckily, I've worked most of the bugs out of the CPS system.

For those unfamiliar with this water gun, it uses rubber tubing to duplicate the same CPS system used in the CPS 2000, CPS 2500, CPS 3000, among other water guns. The water gun is easily more powerful than a CPS 2000.

The chamber has been changed so that it is easier to assemble. There are several problems however, mainly involving the fact that an easier to assemble chamber also is easier for the inner layer of tubing to "pop out" of. More changes are definitely in store to remedy that problem. I also believe the clearance between the inner and outer layers of tubing reduces power after my testing. I also did not add the 8 or so layers of bike tube I did two years ago, so power definitely is less this time around.

The PC case has been finalized. A lot of people said this water gun looks more like a manufactured water gun, and now they'll probably say it even more.

We tested the water gun, mainly to see if it worked as well as it did before. Our video work obviously wasn't the best (the tilt is one thing), and we need to increase the resolution. It's the first time we've done this. Better videos will be taken in the future.

The nozzle also was replaced with a pipe nipple, for reasons obvious in this video: http://www.sscentral.org/video/mvi_0093.avi

Image of the completed water gun: http://www.sscentral.org/images/img_0091.jpg

More videos:

http://www.sscentral.org/video/mvi_0096.avi
http://www.sscentral.org/video/mvi_0098.avi

For all of the people who would like to make one of these, yes, a guide is in the works. These water guns are really easy to build and you get back all the effort in how well it works. :)

User avatar
joannaardway
Posts: 855
Joined: Mon Feb 20, 2006 10:04 pm

Post by joannaardway » Fri Jul 21, 2006 9:56 am

Nice. I'm designing ultra-laminar CPS designs at the moment.

My next trick is to actually make one...
"Over the hills and far away, she prays he will return one day. As sure as the rivers reach the seas, back in his arms again she'll be." - Over the Hills and far away, Gary Moore

"So many people have come and gone, their faces fade as the years go by. Yet I still recall as I wander on, as clear as the sun in the summer sky" - More than a feeling, Boston

User avatar
Silence
Posts: 3825
Joined: Sun Apr 09, 2006 9:01 pm

Post by Silence » Fri Jul 21, 2006 5:03 pm

The way the casing fits over the tee is beautifully done. I'm assuming you didn't glue the 4" (or what I think is 4") PVC to the endcap for ease of maintenance.

The performance appears tremendous! Have you measured the approximate stream speed yet using any of the new formulas? The water in what is probably a very large PC empties in an incredibly small amount of time (unless the videos don't show the entire PC being shot), and it's just amazing. I'm assuming those shots (the water, not the video shots) were riot blasts, given the output and the turbulence...

User avatar
SSCBen
Posts: 6449
Joined: Sat Mar 22, 2003 1:00 pm

Post by SSCBen » Fri Jul 21, 2006 5:33 pm

You are correct about the case. The case isn't glued together. It pops apart easily when I want it to. That's one of the strengths of that design. I also really like how it came together - the ergonomics are excellent. For those who can't wait for the guide, all that's inside of the case is this (and a modified PC): http://www.sscentral.org/images/dscn0190.jpg

The pipe is 4 inch too. 3 inch would have been too small. The PC actually rattles around a bit in there before it is full, so I am considering putting something like a towel in there to soften the noise.

If you're referring to the first video, that was a humorous error. If you watch closely, you can see the nozzle fly off after a split second of a water stream shot out. Consider it an outtake.

The other two videos use a threaded pipe nipple as opposed to non-threaded pipe as I had originally used.

The stream actually is quite laminar as you can see in this still frame:

Image

There's literally only one frame of turbulent flow in this video, and it's due to the air in the nozzle being blown out:

Image

User avatar
Silence
Posts: 3825
Joined: Sun Apr 09, 2006 9:01 pm

Post by Silence » Fri Jul 21, 2006 8:53 pm

Then there must be even more speed than I had expected if the PC emptied so quickly without a riot blast (but everything went out nearly immediately when the nozzle blew out).

I think I finally understand why you put in the pipe nipple afterwards in an effort to prevent a nozzle from popping out. However, I don't think I understand the system very well; could you get some pictures up? Exactly what is a pipe nipple, and where is it in the soaker?

User avatar
SSCBen
Posts: 6449
Joined: Sat Mar 22, 2003 1:00 pm

Post by SSCBen » Fri Jul 21, 2006 9:08 pm

Pipe nipple: http://www.mooseindustrialsurplus.com/i ... 0_3431.jpg

I essentially just used one of these instead of a solvent welded PVC assembly which would have taken time to cure in place of everything after the ball valve. Nothing complicated, just a quick solution. ;)

I can get an image if you'd want one, but I think you'll understand after you see what a pipe nipple is.

User avatar
Silence
Posts: 3825
Joined: Sun Apr 09, 2006 9:01 pm

Post by Silence » Fri Jul 21, 2006 10:31 pm

Okay, so let me guess again: the original male adapter used as the nozzle selector blew off for reasons unknown to me, and since you didn't have another on hand, you improvised and put this together using a pipe nipple and a female adapter.

How much range did this get? I recall the last one was supposed to get around 60 feet, although that might not have been the original CPH you're referring to. If this has less power, then I can't imagine how fast the stream from a CPH with 8 layers of inner tubing will go. This just makes me want to make any homemade, and now I might go clean the disgusting 3" PVC scrap I found before our 8 relatives show up for the weekend...

User avatar
Drenchenator
Posts: 807
Joined: Fri Jun 18, 2004 12:00 pm

Post by Drenchenator » Sat Jul 22, 2006 2:01 pm

This is the same one as before. After a lot of use, he just replaced the rubber bladder with a new piece of latex rubber tubing. Before, this gun was able to shoot at least 60 feet legitimately (measured). This was because the chamber was so thick (two latex rubber tubes and many layers of bike tubes). Now, it can only shoot about 50 to 52 feet, but the chamber is not nearly as thick as before.
The Drenchenator, also known as Lt. Col. Drench.

Locked