My new CPH

Killer 7 · Post by **Killer 7** » Sun Apr 13, 2008 3:22 am

I have been working on a new CPH for about two weeks now. I have made some excellent progress. It is a high output, high flow gun with plenty of power, And unfortunately I have not completed it yet. The working part of the gun functions, but I still have to mount the PC, and make a pump handle, and support. The PC case is 4" drainpipe about 3' long. The CPS chamber is in total about 3/8" thick, and made in two layers, and 18" long. The tubing from the hose barb th\o the nozzle is all 3/4" or larger to increase flow significantly. The nozzle sizes are; 1/8", 1/4", 3/8", 1/2", 5/8", and riot blast(3/4") no nozzle. I t uses a standard 1/2" pump with a 16" pump stroke. The backpack I made for it holds 2.5 ga. If my math is anywhere near close the PC should hold upwards of a gallon when full( this gun will be heavy). I have only fired it twice, and forgot to take ranges on the two shots, they were spectacular though. It has the biggest riot blast I have seen. Of course that excludes the Photo of Ben's Super Cannon 2. I will post pictures tomorrow if I have the time after I get back from doing the final assembly of the gun. Overall it is a pretty sadistic piece of water weaponry. As for range I do not know what to expect, but I am hoping for 60' or more.

Drenchenator · Post by **Drenchenator** » Sun Apr 13, 2008 3:29 am

Sounds great! From your description, the gun seems to be a monster of a homemade. And a gallon of PC capacity is unheard of! But your design definitely goes along with it. I await photos and statistics.

Silence · Post by **Silence** » Sun Apr 13, 2008 3:44 am

Congratulations on applying all the basic concepts - large capacity and large bore for increased flow. Your design definitely has solid potential. However, I would look to upgrade the rubber bladder in the future - with layering, you should be able to get LRT greater than 3/8" in thickness. Plus Ben may be able to get thick LRT wholesale, which would definitely help.

CROC · Post by **CROC** » Sun Apr 13, 2008 12:00 pm

Wouldn't this have like 2 PC fills before having to go for a reload? That seems a bit low, if you ask me.

Killer 7 · Post by **Killer 7** » Sun Apr 13, 2008 2:04 pm

I do plan on making the chamber a little thicker in the fuure if I can, but with the way I was layering it it is way too difficult to put on layers of near equal size. So I had to settle for 3/8" for now
Yes it does seem to have a low resivoir to PC ratio, but a larger resivoir would just make everything heavier. Plus I also do not plan on using the larger nozzles or riot blast very often, but it is nice to have that option should the need arise. I will also have very good shot time on a few of the smaller nozzles.like 1/8", and1/4".

Silence · Post by **Silence** » Sun Apr 13, 2008 2:58 pm

I've seen and used commercial water guns with ratios like that - the XP 270, for example. In fact, I would say it's the PC + reservoir capacity that matters, since you can fill the PC and then fill the reservoir again.

The PC holds water as well as the reservoir does.

Drenchenator · Post by **Drenchenator** » Sun Apr 13, 2008 2:59 pm

It may only get 2.5 full pressure chambers per full reservoir, but you have to think of how large the chamber is. It's 128 ounces! I don't know about you, but I'm sure that's a lot. The reservoir is more or less reserve water; you can only use water in the chamber--and from this this gun shines.

You can also say that it would take about 48 to 50 pumps to fill the chamber, which does seem like a lot. If you take the pump and chamber volume into account, it's not really. The pump volume is 80 mL, more than twice the conventional 32 mL. So, in a sense, the gun doesn't get low numbers in some stats, but to truly carry that much water in the chamber, it's doesn't need good numbers in those stats: It just needs to have a large pressure chamber.

Killer 7 · Post by **Killer 7** » Sun Apr 13, 2008 9:08 pm

My dad and I finished building the supports for everything, and the gun looks phenomenal. But when I tested it I found that the Bladder is inflating from the rear, and moving foreward, so I have to take it apart, and flip it around so it starts inflating from the front and moves to the rear. Pictures will follow soon.

CROC · Post by **CROC** » Tue Apr 15, 2008 2:02 am

I agree that 128 oz. is a lot of water. If only you could fire it all at once, it would be incredible. Now, 3 full tank shots is still very little. The capacity is actually large, so it could last for quite a while. That is too heavy (I think) to carry with your arms alone. You would want a backpack on this gun for a reservoir.

Killer 7 · Post by **Killer 7** » Sun Apr 20, 2008 1:24 am

Hi guys, sorry it took so long for me to get the pictures, but I hope You enjoy.
All nozzles shown shoot past 55' . The first picture is 3/8", the second is 1/2", and the third is the 5/8" nozzle. I can't wait to use this in a battle.

Killer 7 · Post by **Killer 7** » Thu May 01, 2008 4:03 am

I took some ranges on my gun (finally). Here were the results. All measurements were to the end puddle.
1/8" 45'
1/4" 58'
3/8" 62'
1/2" 59'
5/8" 55'
It was a little windy the day I took these.

I am looking for some tubing to thicken the chamber a bit, but I do not want to use bike tubes, or colossus it with more LRT.
I was looking into pure gum tubing, or Buna-N tubing. Because they come in sizes that would fit easily over my chamber.
Does anyone know if pure gum tubing, or Buna-n tubing would work in a CPS chamber?

Silence · Post by **Silence** » Thu May 01, 2008 10:38 pm

If pure gum is the same as natural rubber, it will work. Buna-N is a synthetic that was designed as a tire alternative in World War II - it holds a good seal for O-rings, and it's much tougher, but the elasticity is nonexistent relative to rubber.

SSCBen · Post by **SSCBen** » Fri May 02, 2008 10:48 pm

I remember posting something about trying other rubbers a few years ago and no one had any real thoughts about it. I didn't go further, but now would be a good time to.

The problem with rubbers is that they're not all made the same. You need something that's elastic and can return to the original shape. I'm not sure if pure gum rubber has the returning properties of latex. Buna-N should be a lot less elastic, and without elasticity the bladders will be less constant in pressure. Butyl (the rubber in bike tires) should be okay from what I've seen, but it doesn't expand anywhere as much as latex (and McMaster-Carr doesn't sell it).

This rubber comparison chart might help: http://www.mcmaster.com/param/html/tubi ... erials.htm

Since no one's done anything with rubbers other than latex or butyl, experimentation is all I can recommend. I don't know if other rubbers would work well.

Silence · Post by **Silence** » Fri May 02, 2008 11:42 pm

There's not much of a demand for durable, chemical-resistant elastic tubing, so I doubt there's been much research into latex alternatives. Everything I've seen was designed for tires and seals, which are far more prevalent and expensive than rubber tubing.

Ben, do you know butyl's spring constant per cross-sectional area (from slicing a sheet)? I think it has a much higher spring constant, but I may be wrong.

SSCBen · Post by **SSCBen** » Sat May 03, 2008 12:16 am

Rubber doesn't follow Hooke's law from what I've read. If you were looking for some spring constants and couldn't find any that's probably why. I just tried to find some using Google to no avail.

I remember looking for books on the properties of rubber elasticity because that knowledge is necessary to make some sort of pressure function, but I couldn't find anything here at College Park. Maybe I used the wrong search terms. I think I'll investigate again.

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