Waterzooka LR© - Piston Water Gun with Hydraulics

[waterzooka]

I think my drawings are better than my photos, but I wanted show the Waterzooka LR© from beginning to end. If you haven't seen the background on this design, check out later part of this thread. The Best Soaker for River Rafting?

I made a trip to Lowes tonight and picked up a few fittings I didn't already have. I was unable to find a 2" x 1-1/4" Bell Reducer, so I used a 2" coupler with a 2" x 1-1/4" Internal Reducer. Also, my O-Rings for the 3/4" piston should be here tomorrow from McMaster-Carr.

I still have to cut some spacers for the 1-1/4" floating piston. I should be able to finish that tomorrow and I'll post the pics.

The total length is 5'. (What a monster) I can't wait to test the distance.

Some interesting extras:
I tested vegetable oil for the hydraulic fluid and was pleasantly surprised with its lubrication qualities. I think I will be giving up on water proof grease and using vegetable oil for all my pvc piston water guns. My O-Rings seals are extremely tight and require some force. However, when they were lubricated with vegetable oil, the piston moved effortlessly and still maintained a perfect seal. SilentGuy had suggested water for the hydraulic fluid, but due to the self-lubricating qualities of the vegetable oil, I will give it a try first. Worst case scenario, I soak someone and raise their cholesterol.

Also, I attached the end caps and other fittings with 1/4" - 20 Nylon Bolts. Now I will be able to dismantle and change parts, hydraulic fluid, etc. I have built so many water guns in the past and eagerly glued all the fittings together only to find out that I needed to make a small change. And of course that means buying more fittings or pipe and starting over again.

And I did finally figure out how to bleed the hydraulic system - without adding any external connectors or fittings. My floating piston is hollow and has a Nylon bolt at one end. Before I insert the floating piston and attach the nozzle, I will fill the cylinder with vegetable oil, slide in the floating piston and let the vegetable oil seep up through the hole. When all the air is removed, I will insert the bolt and tighten. Then attached the nozzle. In the future, when I need to bleed the system again or replace the hydraulic fluid, I can remove the nozzle and loosen the bolt.

No predictions yet, but I'm hoping for 60 feet!

[SSCBen]

Looks good! I can't wait for the distance test either.

If you can get the distance close but not quite there, let us know because a few nozzle changes might be able to add a few more feet of range. I wouldn't doubt that this water gun would have considerably more force than others, so you might not even need those changes.

If this does work well, consider filing for a patent. I realize that it will cost a lot of money, but people will copy this design ruthlessly once they hear about it if it works. This is a very creative design and it should be protected.

[CAPTAIN Nate]

"No predictions yet, but I'm hoping for 60 feet!"
60 feet! I really hope you get that distance, maybe even more. Anyway, I wish you good luck with this project. Bye!

[Silence]

Sounds great! I can't wait to see how it works...

I just realized that you don't need a ball valve as I suggested for replacing the hydraulic fluid. Just pull out the pump piston . Plus, I don't think it has much (if any) cholesterol...

I would have concerns about using the vegetable oil, except that it probably isn't as bad as other things (like Vaseline, which can eventually degrade rubber). Hopefully you ordered Buna-N rubber O-rings (the material is synthetic, I believe created by German scientists to provide rubber during war), which is fairly noncorrosive.

5' in length! That sounds very impractical, especially with the weight in the front. Definitely try to go for wider diameters in the future or just settle for a smaller pump/fire amount. As I said, if you add a tube to the water source, then a smaller capacity can't be too bad...

Your large nozzles might be slightly more expensive than the norm if they're going to be as wide as the tube for easy access to the bleeding screw, but then again, it would cost a lot to downsize anyway. Whatever.

But as Ben said, the nozzles are a huge factor in the range--and I don't need to explain why. You'll probably want 3-4 threaded endcaps for the most flexibility in nozzle selection, output, and range. (And by the way, did you test various nozzle sizes for range on the Waterzooka's that you're currently selling?)

Anyway, good luck with the design! Especially with a good set of nozzles, there's no way the range on this thing can be less than what I believe to be 65' on the regular Waterzooka. And definitely try to get a patent...I'm sure Ben would know.

[isoaker_com]

Design looks pretty slick and I'd love to hear about the test-firing results. Admittedly, I am a little confused about the benefits of using hydraulics in this case. I presume the idea is to make the small piston that is against the water move more quickly than the large piston the user is compressing in order to gain velocity. Somehow, though, I recall some problem when trying to use a large piston to move a smaller one.

Edit: oh, hold on, you're using a smaller piston to compress the larger one, striving to increase the amount of force applied by the water against the nozzle. Interesting!

Anyhow, good luck with the tests! I also hope that you figure out how to limit the need for lubrication that may end up in the stream flow.

[waterzooka]

Here are some pics of the final assembly.





The results are mixed.
*Hydraulics operated 100%. I could definitely notice the decrease in force needed to operate.
*Maximum range was about 57'. I think nozzle design could help a lot. The standard Waterzooka shoots between 40'-50'.
*The long 3/4" plunger was flexing a lot. A stiffer, stronger plunger shaft would allow me to apply more force.
*The bleed screw in the floating piston worked great. After I poured in the vegetable oil I had to wait a few minutes for all the air bubbles to rise.
*The multiplication of the force was incredible. After the final assembly, I placed my thumb over the nozzle and checked for air/oil leaks. The fittings that were held in place by set screws creak and settled in. I thought the whole thing just might explode. I'll have to attach a pressure gauge to measure.

All in all, I'll say it was a success. I'm not sure if hydraulics are best suited for piston water guns or piston pumps to be used in Air Pressure Homemades or a Constant Pressure Homemades. With my initial test results, the lower force needed to shoot 50' seemed to be the best benefit as the distance was not greatly improved. I calculated the increase of force to be ≈2.27x. I used inside diameters of 1.36" (1-1/4" pvc) and 2.047 (2" pvc). I rely on spreadsheets for math these days, so someone should check my results.


I will have to try larger diameter pvc and the earlier stacked design I started out with. 5' wasn't too bad, but a shorter design would be easier to manage.

One thing for sure, with a hose attachment and a source of water (like a river or lake), you could shoot this gun all day and not get tired.

EDIT:
I forgot I had a pressure gauge for checking engine compression. I tested the standard Waterzooka and the Waterzooka LR. All I could get from the standard piston water gun was 25 psi, however, I was able to consistently achieve 75 psi with the LR. Ben, time for some math and nozzle design?

[SSCBen]

This is great! Just as I expected. For some reason I thought it would be just short of 60 feet.

2.27 sounds correct. I do know from 1 1/4 inch to 2 inch without taking in the true diameter of the pipes is 2.25 times. Just doing the math right now, it's approximatley 2.265 which is about what you had give or take some insignificant thousands' place digits.

Here's most of what you need to know about nozzle design:

- Flat holes drilled in the end of a PVC cap are good for testing, but bad for best range. Conical nozzles are the most readily available nozzle for distance.

- Nozzle orifice sizes also matter a lot and you should test to find approximately the right nozzle orifice diameter. For this, the best thing to do really is to drill a bunch of test caps, thread them on, and test them one by one. You could get a little mathematical to estimate the best nozzle size, but close is significant enough.

Between these two things, you should be able to increase range at least a few feet to get a more efficient system.

You can find small "sweeper" nozzles at most gardening places but I'l afraid that they probably have too small of a hole, even after you drill a larger one:



McMaster-Carr sells nice, but fairly expensive garden hose nozzles. The only problem with these nozzles aside from the price is that the inside is very rough and I'm afraid it creates turbulence. If you have a sand blaster you can smooth out the inside. If you're interested in going this route, part number 7678T1 is what you'd be interested in. This nozzle threads onto 3/4" NPT fittings.

Other than those two options, there's no real way to get a conical nozzle of appropriate size for this water gun unless you machine it somehow, and I have no experience with that.

If the conical nozzles don't seem right, you can just drill a correctly sized hole and still expect an increase in range, but it won't have perfect efficiency. I'd very roughly estimate the ideal nozzle orifice diameter of this water gun to be about 3/8".

Just for those who might be interested in trying this, you would not get an increase in force by using hydraulics in an air pressure water gun because the piston diameter is too small for the air pressure to get a good amount of force anyway. If anything it would complicate the system. This hydraulic idea works best on something that is providing a force to begin with. That does mean that you can apply this idea to the spring water guns everyone talks about.

[waterzooka]

Ben, Thanks for the nozzle ideas.

I was thinking about using 1/2" or 5/8" Nylon bolts and drilling an orifice right down the middle. Then I could drill and tap the PVC cap and insert different sizes. I could use 1/2" or 3/4" length and a jam nut. The length would help with the flow. And the jam nut would allow me to make sure the Nylon bolt was flush with the inside of the cap.

Has any one tried this before.

[SSCBen]

That sounds a little too complicated. I've tapped threads before, but you wouldn't need to in this case. Just get another reducer and a coupler and threaded nozzles will be as easy as drilling a hole in a threaded cap. Of course, if reducers are hard to come by where you live, then that would be potential method.

If you are unfamiliar with the threaded cap nozzles, check out our APH page or ask if you want some more images. I'm afraid that I didn't include as many images as I could have.

[Silence]

Definitely great news! Just remember that you'll be pumping out less water due to the trade-off, so you need to plan for that. Use a really long wooden dowel or something inside the pump shaft when it's in use, or even aluminum, in order to prevent the bending. Who knows, it just might work.

A few tips for the nozzle drilling: Use a powerful drill to drill quickly, eliminating excessive "tapering"; use a chisel, sandpaper or something in order to get rid of the rim on the inside; and use female threaded endcaps instead of male threaded ones. Furthermore, you don't need any more than 3-4 endcaps when testing, even excessively--just work your way up the nozzle sizes and drill through the smaller ones.

[waterzooka]

I'm familiar with reducers. Lowes has a better selection than Home Depot.

The only problem with drilling threaded caps is that they produce a very low aspect ratio. (The ratio of length to width) And when the orifice is larger it becomes more of a problem. Several years ago, I tested a higher aspect ratio with a non-tapered orifice and the result was positive.

Schedule 40 fittings are about .15 wall thickness, so even with a 1/4" orifice, the flow (stream) is not that good. If you take a look at the Water Blaster, They have an extended nozzle to help with the stream. I thought the Nylon Bolts would be a cheaper solution than creating a custom molded or machined cap. I use a drill press for drilling so making the nozzles described in my earlier post would be fairly simple.

By the way - I enlarged the orifice to 5/16" on a standard Waterzooka and I was able to get a little more distance - about 50'-52'. I think 3/8" would be good size and if a get a chance later, I will try it.

[waterzooka]

I tried 3/8" - not much better on either water gun.

Then I tried a 1" length section of hollow threaded rod (Used in electrical lamps, etc) to increase the aspect ratio and it was a better stream, but when I really applied a lot of force the stream broke up.

This nozzle thing is frustrating - I've read all the post regarding this topic and I just wish I could stop off at the corner nozzle store and pick up what I needed.

I will have to try some of the options at McMaster-Carr.

[isoaker_com]

Results are quite impressive to say the least. Out of curiousity, any idea how much vegetable oil ended up pushed out in the stream? This would be my primary concern were such a soaker to end up used in battle. Otherwise, great job and good luck with optimizing the nozzle!

B)

[waterzooka]

During my first test there was no detectable amount of vegetable oil in the stream. I tested this by trying to slide around on the spray left on the sidewalk.

However, on my second test, the sidewalk was slippery - and I know why.

I removed the nozzle to make some changes and decided to bleed the hydraulic system again. (Just to see if it would work) I ended up with 4-5 tablespoons of vegetable oil in front of the floating piston. (The water chamber). I poured it out, but I did not wipe it. There was a fair amount of oil still left.

If I am more careful and clean up after bleeding the system, then it should be okay.

I have to admit, after messing around with vegetable oil, I kind of like the suggestion by SilentGuy to just use water as the hydraulic fluid. I will experiment with different seals to produce a good seal that does not require extra lubrication. I've been thinking about the Seal Cups that Ben suggested. Unfortunately, McMaster-Carr doesn't stock a small size for the 1-1/4" piston.

I wonder how long it took Edison to perfect the light bulb?

[Silence]

I've got a few overly critical questions. Does the use of two diameters give you the same advantage as using a smaller diameter from the start, but with greater capacity since the diameters can be scaled up? If so, then why do you even need a plunger and hydraulic fluid besides whatever you're shooting?

Edison had a huge group of people and I believe spent a year or so testing different materials. And then there was Tesla, who did a much better job by actually inventing the fluorescent lightbulb which is superior. But that's off topic.

I dunno...I think that if you didn't bother to replace the vegetable oil so often and if you cleaned up the excess afterwards, then there wouldn't be a problem. Then again, it's unlikely the lube would go away if it doesn't mix with water. I'll have to see if vegetable oil is bad for natural rubber...

And by the way, are those seals made out of Buna-N rubber? If so, then disregard my concerns related to the degrading rubber.