Potential Successor to APH

[watercrazy007]

Hi guys, this is my first post.

I've been building homemade water guns for over a year in the style of a 2 inch diameter piston water cannon. It gets its air from 3/8 inch air hose wrapped around it so that I can have the cannon ready on standby and take the valve "safety" off whenever I want to fire. For a brief time, I was able to get an 80 ft. (70 ft. effective) range at 150 psi, but have since taken it apart to make it better (and because I made mistakes).

My history aside, you guys have some killer ideas in this forum, and I hope you like mine.

As you know, regular APH water guns have separate tanks for air and water, and you force the water in your pump through one way valves to pressurize air. This results in top heavy setups that you can only hold upright, are not linear, and drop off pressure quickly.

Idea #1 is to put a piston in between the air and the water so it can be moved about, and to move the air chamber to a horizontal position, more resembling a water cannon, and allowing for greater capacity.

Normal APH's drop off pressure quickly because they essentially have small volume of air that start out at normal pressure.

Idea #2 is to pre-pressurize the air and install a pressure regulator similar to SSCBen's CAPH, to where there is the pipe with the piston in it (1''-2'' ID) which compresses air to purely air pipes which wrap around the main pipe (for ergonomics). A key difference is the addition of a ball valve bypass which can be opened to allow air to get around the pressure regulator (if the pressure regulator acts like a check valve, which some do), and then close to allow constant pressure (100+ psi) the other way.

A lot of aspects are similar to a water cannon and many to a CAPH. But what limits a CAPH (sorry, off topic from APH), is the need for external pressurization and replenishing of air. The Idea #2 I told (I'll post many drawings later) does not require extra air, because the system is contained from the bypass.

Idea #3 is to use the same pump for both pressurizing air and water. Instead of the fluid coming in the first check valve and being pushed out the second, the fluid has a choice of two (second check valves), one being sorted exclusively for air and the other only for water. The flow can be redirected into two possible paths: one to the air tank, and the other to the water chamber.

So in total, the water gun would require 2-3 Check Valves (depending on configuration) and 4 ball valves (1 for water flow path, 1 for air flow path, 1 for pressure reducer bypass, and 1 to shoot the water).

Again, I'm going to post a few pictures to make what I'm saying make sense. The packaging is the difficult part. How do you like it? Tell me if it makes sense, if you love it, hate it, or any of that.

Edit: When I said pictures, I meant drawings because this is just a concept. Sorry for the confusion.

[SSCBen]

Great first post. Welcome to WWN.

The APH was designed over 10 years ago, was not originally intended to be a "standard" homemade water gun, and is in need of a major update. Other folks had improvements in mind back then that I was mostly dismissive of as I recall, and in retrospect I was wrong to be so dismissive.

I think it's worth trying to make a simple separate PC design which can be made with components that come only from a hardware store with minimal work. For many people, an APH is the most complicated thing they will have built up to that point. The current standard APH design fits the goal of being simple yet decent fairly well. More advanced designs are of course worth coming up with for the more dedicated, but I'd caution recommending these to someone new to building in general. Your ideas are more advanced.

Idea 1 (pistons) are definitely worth looking at more. There have not been too many piston designs, probably because making a large piston is not alway easy. The piston cups on McMaster-Carr are pretty good, but if I were to redo the Supercannon II design, I'd have a spacer that is the same diameter as the piston cups to help prevent warping of the cups. If I recall correctly, DX says the cups with warp over time.

Idea 2 (using a regulator with a piston water gun, if I understand you correctly) is a great idea. It can be done in a variety of ways, but I don't think anyone has tried any of them. Probably 5 or more years ago I had a design for a CAPH that worked similar to what you propose, but without a ball valve. I used check valves instead. I don't have the design right in front of me, so it might be easiest for you to think about how to do this yourself. You might have a better design than me. I could dig up the design if you're interested, otherwise.

If I recall correctly, there are some issues with these sorts of designs that would be most obvious if you work out the math on paper. (I'm an engineer so I did.) The main problem is that you will have to put in more energy than you get out. In the filling part of the cycle, the pressure is at the level of the air regulator supply, which is higher than that of the regulated pressure. But in the firing part of the cycle, the pressure is at the regulated pressure. Consequently, you don't get perfect efficiency. The efficiency of a standard air pressure water gun is 100% (the pressure you get out is the pressure you pump in), a piston water gun is slightly less due to friction, and the efficiency of this design can be anywhere from very low to very high depending on how it's designed. The math is not particularly complicated (high school level algebra) but it's unfortunately needed to avoid trial and error when designing. If I recall correctly, my goal was to make the efficiency match that of CPS bladders, which is only around 65% according to the data I have. (Little known disadvantage of bladders.)

Another consequence of that is that because of adiabatic compression, you'll slowly increase the temperature and consequently the pressure of the air regulator supply side of the blaster. This basically means that you should add a vent to release some excess pressure every once in a while. Not a major issue, and if you design the blaster to get better efficiency this will be less of a problem anyway.

Idea 3 doesn't seem worthwhile to me. It'll make the design a fair bit more complex for little benefit. You should only need to precharge once before a battle or before each round at worst, and I think a small bike pump would be perfect for this. Just include a schrader valve in the design.

Anyhow, I'm sure we'd all be happy to see your drawings and any photos of your other blasters.

[Drenchenator]

Hi watercrazy007! I appreciate your enthusiasm.

Idea 1 seems like a simple correction to achieve linear flow, and probably would improve the performance noticeably. I think that using an elastic chamber would be a simpler design, though, without having to worry about the dropoff in pressure.

I'm actually somewhat against constant air pressure designs based on my experiences working with Ben on them. I do think they have potential, but the complexity becomes a real issue. There are so many more parts to worry about! Nonetheless your ideas may have some merit in simplifying the operation by combining the concept with an APH-style design. I look forward to your build and results!

The APH was basically designed to be easy to build. There is a design saying in engineering: good, fast, cheap, pick two. It picks fast and cheap. That's not say that the design is not good --- certainly its performance is much better than what you get off a store shelf! --- but its design emphasis was only being easy to build, a good start for beginners. I second your idea that we probably need a successor or at least an update, because the design is rather old at this point and we should know more now, but I do think these 3 designs you describe are more complex and require a lot more parts than the APH, so ultimately they may not be a good successor for the role the APH plays.

Still, I look forward to your pictures and blueprints! Words can only describe so much...

[watercrazy007]

I made Sketchup drawings of two versions of my watergun. Both do not have a pressure regulator drawn in them yet (still figuring how to cost-effectively implement this), but one has a regular pump while the other has the (air/water) pump. Unfortunately, I haven't been able to post the Sketchup files, so I have screenshots. (SIMPLE DESIGN = IDEA 1 Only) (IDEA 3 Obsolete)




Simple Design (Left Side):

Simple Design (Left Side View).png (217.65 KiB) Viewed 21043 times

In this design, the top barrel is the air tank, the middle barrel is the piston chamber, and the small barrel at the bottom is the pump. This is designed to hopefully be far more ergonomic than standard APH's. For the bottom tee, I'm thinking of filing a rubber sheet so that it fits between the pipes, then Gorilla gluing the PVC-Rubber-PVC sandwich for better structural rigidity. There also needs to be a strong brace to hold up the 1 1/2 ID top pipe.




Simple Design (Right Side):

Simple Design (Right Side View).png (242.28 KiB) Viewed 21043 times

The simple design functions as a standard APH, with the exception of the added piston. Water is sucked from the bottom left (just shown as a 1/2'' ID pipe), which can be connected to a gun or backpack mounted water reservoir, and pushed through the side pipe of the gun into the main chamber, pushing the piston, which pushes the air. Once pressurized, (doesn't have to be completely filled), releasing the main valve makes the piston push the water out of the cannon. A Schrader valve which pressurizes/depressurizes the tank is not shown.




Simple Design (FPS View and Front):

Simple Design (FPS View).png (266.42 KiB) Viewed 21043 times

Simple Design (Front View).png (233.71 KiB) Viewed 21043 times

Summary & Comments:
So here are some of the pictures! As I said earlier, I am still working on the water gun with the pressure regulator to make it smaller and more cost effective. This is all supposed to be concepts anyway, and any of you can use any of my ideas and designs at any time. Right now I have no money, so this will be a later project for me.

SSCBen:
In the original post, thanks for pointing out that I can use a check valve instead of a ball valve for the bypass. It's amazing I missed that and I was seriously going to take the unnecessary step of turning on and off the ball valve whenever I wanted to pump. About the adiabatic heating, I suppose a cycle where I put more work in the gas that it takes out would cause an net increase in thermal energy. I also don't want excess heat to reduce the pressure rating of PVC, especially for pressures above 100 psi. Would that thermal energy have enough time to accumulate before being transferred to the water and air?

For the piston efficiency, I've been able to create a 2'' one thanks to Nighthawkinglight on Youtube. With lubrication, It eats away only 2-3 psi in friction. The same type of idea should work on a smaller scale with dremeling and sanding.

I would love to see what you did for your CAPH design, thanks.

Drenchenator: For the Simple Design, I believe I've gone as basic as possible. What do you think? I'll have to calculate price, but it should be super cheap too.


Concept Statistics (Simple Design) (Range and Output Information from homemade 150-75 psi drop-off 2 inch piston cannon)

Length: 32''
Width: 2 1/4'' Shaft; 6'' maximum
Height: 10.5''
Capacity: 463 ml (1 1/2'' x 16''); 824 ml (2'' x 16'') (Customizable)
Pressure: 150-90 psi Max (Pressure Dropoff)
Edit: Output: 85x (Homemade Piston Cannon Shot 1.5L for 0.58 sec)
Pumps to Fill: 15 pumps (1 1/2'' x 16''); 26 pumps (2'' x 16'') (0.546'' x 9.5'' Piston Rod)
Range: 65-70 feet effective range (where most of the water lands with no wind) (80 feet max)
Price (Gun Only): (est. $60.23)


Simple Design with Union

Simple Design with Union.png (232.68 KiB) Viewed 21021 times

[Drenchenator]

I think your simple design is quite minimal. I don't see any major changes you could make to simplify it. Personally, I think a basic homemade CPS design would achieve roughly the same performance with a lot less work and complexity, but I see the value in trying out something newer.

However, I am wary about some of the numbers you are using.

I don't doubt your original range estimate on your previous piston cannon --- it seems reasonably given the performance other people have gotten --- but given that the simple design is hand-pumped, you will not get anywhere close to 150 psig. To pump a 1/2" PVC pump at 150 psig, you will need to use 46 pounds of force. That's a lot! That is substantially higher than what the manufacturers use. You are more likely to achieve around 60 to 70 psig realistically, and your performance will suffer accordingly. That is one of the reasons why I never really cared for the super-high range stuff as it exists now, because it's not the kind of performance the human body can achieve reasonably through pumping.

Your unfilled weight I also think is too low, though I don't have anything to back up that claim (other than experience).

The price seems optimistic given the number of PVC parts you require. Individually PVC parts are cheap, but when you are buying a large variety of fittings and connectors, the price adds up quickly. I would go to a store and inventory and price out what you need to get a true estimate. I may be wrong, but I think you will find that it will cost more that 50 dollars. Since you mentioned having no money, I highly recommend that you price out everything in a spreadsheet before continuing, since for good-fast-cheap you must pick cheap.

[watercrazy007]

Thanks for replying again, Drenchenator:

I definitely agree with the things you are saying. The weight estimate was just a (meh, sounds about right) estimate. If its not close, I'll remove it. While I still believe 46 pounds is attainable, its definitely not for combat. There are some places that sell 3/8 inch pipe (26 pounds force), but then 27 pumps (1 1/2'' x 16'') and 48 pumps (2'' x 16'') would be the figures. I'm wondering if some of the problem could be solved with packaging. Are there some pumps which are easier to pump than others that require the same force? Could you have more leverage on the pump to achieve a greater force? Would increasing the shaft length help?

Price: (All from Lowes Except O-ring, Schrader Valve and Check Valves) Edit: Price is With Union

Gun Assembly
Orbit Black Tunneling kit: $4.87
Sch 40 1 inch Ball Valve: $5.29
Lasco 1 1/2'' x 1'' PVC Bushing $1.32
Lasco 1 1/2'' x 1/2'' Threaded Reducing Tee $1.64
Lasco 1 1/2'' Coupling $0.85
Charlotte Pipe 1 1/2'' x 5' $5.39
Lasco 1 1/2'' x 1/2'' Bushing (x2) $1.76
Lasco 1/2'' Elbow (x3) $1.20
Lasco 1/2'' Threaded Elbow $0.80
Charlotte Pipe 1/2'' x 5' Pipe $2.08
Lasco 1/2'' Tee $0.39
Ebay - B & K 1/2'' Check Valve (x2) $10.56
Lasco 1'' Tee $1.26
Lasco 1'' 45-Deg Elbow $0.98
Lasco 1'' x 1/2'' Bushing $0.77
Home Depot 1/8'' Schrader Valve $3.87
Lasco 1/2'' Schedule 80 Nipple (1' length) $1.45
Lasco 1 1/2'' Cap $0.98
Homeworks Worldwide 1 1/2'' Union $6.68
Charlotte Pipe 1'' x 2' Pipe $2.65

Piston (If it Works TBD)
1'' Plug $0.90
1'' Coupling (May Need to Sand) $0.46
Custom O-ring (5/32 thickness?) $1.00?

Pump Rod
Lasco 1/2'' PVC Elbow $0.40
Madison Mill Wood Poplar Dowel $1.68
Custom 1/2'' O-ring (thickness?) $1.00?

Total: $60.23
Total (With 15% For Taxes, Extra Costs): $69.26

[Drenchenator]

I'm glad that you've priced out the majority of the project. The prices seem reasonable to me, but remember to include some margin for the unplanned too (add a reasonable percent to the overall cost).

There is nothing that you can do about the amount of force, but other aspects may help. The equation is simple: F = P * A, where A = 0.25 * pi * d^2, F is the force, P is the pressure, A is the area, and d is the pump diameter. Based on this equation, the length of the pump rod doesn't matter but the diameter does. You are correct that a smaller diameter pump will reduce the force substantially (notice the power of 2 for diameter, so changing the diameter will change the force a lot). But that will require many more pumps.

Personally, I would not design a gun with anything over 20 pounds of force to pump. 50 seems rather obtainable. But if you believe that you can somehow achieve 50 or so pounds, it would be easier if you have a better grip and engage different muscle groups. For example, a pistol grip pump --- putting a pistol grip or perpendicular rod on the pump --- will give you better leverage and make the high force required more tolerable.

[watercrazy007]

I'm starting to see that the standard version (not shown) is a waste of time. It's more complexity for no benefit. You could almost buy a bike pump and Schrader valve for the money it takes to make the accessories. I've removed it. I've updated the simple version with minor modifications; they should be a slightly smaller (and easier to build) side pipe assembly, a pistol grip pump for better leverage (credit to Drenchenator), and visible 1/2'' Schedule 80 pipe.

Important Edit:
I meant to say the standard version was not was good, but the simple version is the one I'm trying to make excellent.

The statistics are better than we both thought. Like a dummy, I figured an ID of 0.5'' for the pump when Schedule 40 pipe has an ID of 0.622''. I thought in my head Schedule 80 pipe with an ID of 0.546'', while you saw Schedule 40 pipe in the diagram. These errors should now be corrected. The max pump force should be 35 pounds, which is still a lot.

I also updated the pricing.

What do any of you think about servicing? An idea is to use adapters, but you'd have to unthread the tank before you'd be able to get at the adapters. Using a union sounds much easier and would allow easier alignment in construction.

What do you guys think of the design so far? What do you like or dislike? If the max pressure was set at 70 psi, (which would require 17.5 lbs max pumping force) and you were a beginner (building your first homemade), would you prefer to build this or a common APH? What do you think could be done to improve this design so that it may be more favorable?

There is a picture with the union installed.

[watercrazy007]

Here is the complex design, which incorporates constant pressure:

Complex Design

Complex Design 2.png (403.64 KiB) Viewed 21009 times

Its basically the simple design, but with two ways into the pressure chamber. When your pump pushes the piston back, air goes through the PVC check valve. When you fire the water gun, air goes only through the 1/4'' pressure regulator, which you can set the pressure on. The pressure regulator is a PVC to brass threaded connection, using 1/4'' PVC pipe nipples and 1/4'' x 1/2'' PVC Bushings (All Available for a total of $5.00 at PVCFittingsOnline.com)


Range:
The range depends on the pressure set by the regular and the pressure lamination is intended for. As far as I can tell (correct me if I'm wrong), lamination has never been attempted at constant pressures above 100 psi, so it is unknown how far this water gun can shoot.

With good lamination at 70 psi, conventional APH's can make puddles with no wind at 70 feet.

With this water gun, roughly 100 psi can be maintained the entire shot, 125 psi can be maintained half of the shot, and so on.

This water gun may very easily shoot water 80 or more feet.


Price:
The price is similar to the simple design, with the exception of these changes:
PVC 1/2'' x 1/4'' Reducer Bushing
PVC 1/2'' x 1/4'' Threaded Reducer Bushing
PVC 1/4'' x 2'' Nipple (x2) ($5.00 roughly on PVCFittingsOnline.com)
Lasco 1/2'' Tee $0.39
1 1/2'' x 1/2'' Threaded Reducing Tee $1.64
Lasco 1/2'' Elbow $0.40
Lasco 1/2'' Threaded Elbow $0.80
B&K 1/4'' Coupling $3.89
Ebay - 1/4'' 160 psi Inline Pressure Regulator $6.54
Ebay - B&K 1/2'' PVC Check Valve $5.28
(removed) 1 1/2'' Coupling (-)$0.85

Total (of Entire Gun): $83.32

[Drenchenator]

Sorry for taking a while to reply! I didn't have access to my main computer these last few days.

I like the idea of being able to perform maintenance on the internals, but I don't know enough about union adapters to say whether that's a good idea or not. I will say this though. Parts like that are designed for water at lower pressures. You are talking about higher pressures and the union will be in contact with air. That may change the performance. Personally, I think it will just leak air. It's another complexity in an already complex enough build.

If I were a beginner, I would greatly prefer building a regular APH. It's a simple design. There are few parts you need to buy. Ben made pages upon pages of documentation on how to build it with a lot of pictures and diagrams. In the standard APH, all parts are pretty much off the shelf. You just cut them and fasten them together, and that's all. This is a much more complex build, with many different sizes and kinds of pipe and pipe fittings. Beginners will not do it as their first build, but maybe their second or third (after an elastic bladder homemade).

At this point, you are probably wondering why I keep bringing up complexity versus simplicity. Well, I keep doing that because you are trying to position this build as a replacement for the standard APH. The standard APH was designed to be as simple as possible, with as few parts and as few pipe sizes as possible, and as little work as possible. I would not be harping about complexity if you said that this was just a regular build for an experienced builder. This build is great for an experienced builder: it introduces a lot of new cool ideas and tries to achieve a high performance in a hand-pumped package. What's not to love? But it's not a simple design for beginners, unfortunately, and I don't think there is much you can do to position it as such.

The "complex design" introduces more interesting ideas. It would be good for the experienced builder. I don't think the constant air pressure concept has been mastered yet, so this could be a step in the direction. I'm very interested in the results when you build it, especially all the performance characteristics.

Still, 70 feet of range is hard to believe. 80 feet is even harder. I don't think either claim has any basis. I would prefer testing to back those claims up.

The gun's design certainly promotes a more laminated stream, and if you could hand-pump it more than 100 psi it should have a higher range, but neither of those is the issue I am worried about. The issue is that previous piston guns like SuperCannon 2 had an extremely large internal diameter (4 inches in this case), and that creates an enormous capacity for flow. Supercannon 2's flow rate with a nozzle was 4 L/s, and without a nozzle was around 15 L/s (the measurement was tricky in that case since the chamber emptied in 4/15 s, based on video). The internal diameter here is 1.5 inches, 14% of the area that SuperCannon 2 has. Obviously range and flow rate vary based on the nozzle, but max range is correlated with max flow rate. I fear that the max flow rate of this design does not correlate with your projected range estimates, in other words. I would expect the design to achieve at least 60 feet of range (which certainly is excellent!) but anything more than 65 feet would be hard to back up.

[watercrazy007]

Thanks again for responding.

PVC Unions do not leak. Here is a picture of one:

PVC Union.jpg (108.91 KiB) Viewed 20992 times

Basically the threads squeeze a flat PVC surface against the O-ring creating the seal. Although I have no definitive proof to show you yet, I have used a PVC Union to connect my air hose (leading to a brass 1/4'' x 1/2'' reducer bushing to a 1/2'' brass ball valve to a 1/2'' sharkbite fitting to a 1/2'' x 1' PVC reducer bushing to finally the 1' Union) to the 2'' pressure chamber. I have used the water cannon for months under 150 psi (not constant pressure but intermittent) and the union does not leak. I have had problems with Male/Female Adapters leaking and they are a pain to unthread and rethread, but a PVC Union requires no thread sealant, does not leak, and swivels around so alignment is not an issue. Deattachment takes 5 seconds with a Union. If you are especially unsure, PVCFittingsOnline sells the Union I used, which is rated for 225 psi.

Remembering back, I have made a video or at least some pictures of my 2'' piston cannon working. I''ll try to find those, because it has a 1'' Union working in it. The reason I get so excited over range is because the piston cannon was able to get consistent 70 foot puddle ranges anywhere from 105 psi+ max pressure without any lamination. Even if 80 feet is over-the-top right now doesn't mean its not possible with 120+ psi, lamination, and constant pressure given the right design.

Yes, sometimes its harder to find the simpler solution This requires some sort of sanding and more parts, whereas regular APH's do not. I'm not giving up on the idea, but its still maybe too complex.

I still want to keep this thread going for simple ideas.

Do you think it would be a good idea to rename the project and put it in a new thread geared toward experienced builders?
(NOTE: The CAPH successor 'complex design' was not meant to be for beginners)

Oh, and by the way, PVCFittingsOnline sells PVC ball valves for a reasonable price that are far easier to turn than generic PVC ball valves.

[Drenchenator]

The reason I get so excited over range is because the piston cannon was able to get consistent 70 foot puddle ranges anywhere from 105 psi+ max pressure without any lamination. Even if 80 feet is over-the-top right now doesn't mean its not possible with 120+ psi, lamination, and constant pressure given the right design.

I must apologize. I don't think I've explained my point well enough. Pressure and "lamination" are not the only variables that matter. I am doubtful about your projected ranges because the design has a small internal diameter (piston diameter), and that means that it can't achieve a high enough flow rate to get those kind of ranges.

Could you perhaps explain what you mean by "lamination"? I'm not sure we are using the same definition.

I hope this figure I put together explains my overall point better:

range_versus_flow_rate.png (60.69 KiB) Viewed 20980 times

This scatterplot plots the maximum flow rate a gun achieves versus the maximum range it achieves. It's comparing the riot blast output to the maximum range with a nozzle, in other words. Obviously there is a lot of scatter, because there are more variables to consider (and experimental error), but a clear trend emerges. It would take an exponential increase in flow rate to increase the range linearly. That's a lot!

To get a high range you must have a high maximum flow rate. According to the curve fit I put here, you can expect 80 feet of range if you have 240 L/s of flow rate. Obviously that's only an estimate based on this dataset, but I think the number is telling. 80 feet of range is possible (look at a fire truck!) but you need a tremendously thick stream to get it. If the design can't maintain a thick stream, it won't get the range.

How do you get a high output or a thick stream? The gun has to "push out" as much water as quickly as possible. Increasing the piston diameter certainly does that (quadratically, actually). A 1.5 diameter piston only has 14% of the area that a 4 inch piston does, so it can only achieve a fraction of the flow rate that the 4 inch piston would.

Another way to see this is with a control volume analysis of a piston gun. You'll see is that the flow rate Q scales with the piston area to the first power (linearly) and the pressure drop to the one-half power (like a square root). Therefore, increasing the piston area would improve the flow rate much more rapidly that increasing the pressure would.

Here's another way to think of this. As the water stream leaves the nozzle, it starts to break up. It gradually turns into droplets instead of a single stream of water. This breakup process starts on the outside of the stream and gradually works in. If the stream comes from a squirt gun, it's so thin that it breaks up immediately and goes nowhere. But if it's from a fire hose, it's very thick and it takes a long time for the breakup to get to the core. Therefore we should expect high flow rates to protect the stream against breakup. This is overly simplistic (it ignores so much!), but largely true nonetheless.

I still want to keep this thread going for simple ideas.

Do you think it would be a good idea to rename the project and put it in a new thread geared toward experienced builders?
(NOTE: The CAPH successor 'complex design' was not meant to be for beginners)

That's your choice. If you think you should do that then do it.

[watercrazy007]

You've explained your point well enough now. I've looked at irrigation sites and their figures for sprinkler range and flow capacity are a little higher but match close to yours. It is ratio of the areas (conservation of flow) which makes the water go faster and farther and the thickness of the stream (flow rate) which allows the water to not break up, so a 1.5'' diameter pipe should have figures inferior to the testing of my own 2'' cannon, or about a 60' range. Upping the diameter to 2'' should be no problem, and at 85x (10^3.41 ml/sec) I should expect (56 feet - 66 feet) (17-20m) ranges, but since my cannon is 150 psi max, it gives just enough extra square root oomph from the pressure to send the range into 68-70 feet, which is as far as my 2'' piston cannon gave puddles.

When I said no lamination, I meant that I just plopped the 3/8'' Orbit Tunneling Kit Nozzle ahead of the 1'' ball valve and called it good to go. No straws or any other strategies to make more laminar flow were used. If I could get 65-70 foot range without better lamination techniques, then I had hope to get better range.

About your diagram, did SSCBen get a 73 ft range on the riot blast or the 1/2'' nozzle? On his Supercannon II thread (which is what got me into building water guns), he says 73 feet range @ 100 psi, but lists only the output of the 1/2'' nozzle at 100 psi. The riot blast output is measured only at 60 psi, which leads me to believe the 73 ft range was done on the 135X 1/2'' nozzle and not the 500X riot blast. If that is true, then it fits directly above the SuperCAP while having only 1.6 times the flow rate of the 2'' Cannon (albeit for longer that 0.58 sec) and it would be reasonable for the 2'' piston cannon to shoot 70 feet at 150 psi.

[Drenchenator]

Do you have any pictures or videos of your previous build? I would like more details about your original design. The original piston water guns used 2 inch pistons and shot around 45 feet at 130 psi. Granted, this builder did not use any straws or flow conditioners or even a good nozzle. But given that his setup is very similar to yours, I hope you understand my curiosity when you keep mentioning the same design getting 25 feet more than a nearly-identical previous design.

About your diagram, did SSCBen get a 73 ft range on the riot blast or the 1/2'' nozzle? On his Supercannon II thread (which is what got me into building water guns), he says 73 feet range @ 100 psi, but lists only the output of the 1/2'' nozzle at 100 psi. The riot blast output is measured only at 60 psi, which leads me to believe the 73 ft range was done on the 135X 1/2'' nozzle and not the 500X riot blast. If that is true, then it fits directly above the SuperCAP while having only 1.6 times the flow rate of the 2'' Cannon (albeit for longer that 0.58 sec) and it would be reasonable for the 2'' piston cannon to shoot 70 feet at 150 psi.

As I had said, the figure is comparing a gun's maximum possible values of range or flow rate on any nozzle, not just on a single nozzle. For all of the homemades and some of the stock guns, the maximum range was achieved on a different nozzle than what achieved the maximum flow rate. So I plotted the max flow rate (usually the riot blast) against the max range (which never was the riot blast). You can think of the plot this way: the horizontal axis represents the gun's highest flow rate possible (even if it hurts the range), and the vertical axis represents the gun's highest range possible (even if it hurts the output). In each axis, the performance is maximized for that criteria alone.

The point of the plot is to compare a gun's overall max performance, not to compare its performance on a single nozzle. SuperCannon 2 got 73 feet on the 1/2 inch nozzle, and about 20 feet (roughly) on the riot blast. Again, since this plot compares the max values for each gun (not each nozzle), the SuperCannon 2's riot blast output is plotted against its 1/2 inch nozzle range, since the riot blast got the best output and the 1/2 inch nozzle got the best range. I did this for all of the guns, so the comparison is always fair. SuperCAP had a 135X riot blast and 65 feet range with a nozzle. It wouldn't be a fair comparison to move SuperCannon 2's output down from 500X to 135X, since SuperCannon 2's max output was 500X. Again, the point to compare the maximum performance for all nozzles on a gun, not just one nozzle. I don't think you completely understand this plot, so I suggest you look it over more carefully. If you have any more questions about it, I'll be glad to answer them.

[watercrazy007]

It was difficult to find these videos and share it to you, but here they are. One video is of me with the 3/8'' nozzle and the other is with me doing the 1'' riot blast which I call shotgun mode. These videos are from two months ago. I set out to improve my cannon for a party a month ago, only to take it apart and quickly put it together again. I haven't gotten around to rebuilding my water cannon the right way since. I was aiming for the tree in both videos and not doing a range test, but feel free to judge for yourself how far the cannon shot and its output. Here is some information that will help you:

The distance from the nozzle to the tree is 30 feet
The distance from the nozzle to the road is 55 feet
The water volume is roughly 2'' diameter x 29'' length (almost 1.5 L)

Water Cannon with Nozzle - https://www.youtube-nocookie.com/embed/T7pYEHXVeVk
Water Cannon Shotgun Mode - https://www.youtube-nocookie.com/embed/o8F-mGcqc00

I don't know why the other 2'' piston cannons shot 45 feet. I have never seen them. What I do know is that my piston has very low friction using Vasoline (2-3 psi). If you look closely, I have a 1'' PVC Union that I attach the nozzle to. I also attach another section of a union which transitions to a Schrader valve, which is also what I use to indirectly pressurize the air hose. Its clunky but has never leaked for a year. If you pump with a bicycle pump, you hear the piston move at about 2-3 psi on the gauge. If you want pictures of this setup I can send them to you. I cut half the coupling off to make it shorter, but here's the piston design:
https://www.youtube.com/watch?v=BCZGWvieJ7I


My nozzle comes from an Orbit Tunneling Kit, and is specifically designed to attach to 1'' PVC pipe for maximum flow. It is very smooth.
https://www.lowes.com/pd/Orbit-Black-Tu ... it/3386682

As a side note, I can get multiple shots with one of the 1'' ball valves from PVCFittingsOnline. It is far easier to turn than regular ball valves.
http://www.pvcfittingsonline.com/1-delu ... ocket.html

Quote from Tim's POPCAP thread:
....3/8” Forestry Nozzle**** @ 70 PSI:
•Range: 72 feet (75 feet to the last drop)
•Output: 48 oz/sec
•Shot Time: 8 sec

You have the ability to verify this, but his gun uses the same nozzle side with the same output, so the water should be going just as fast. If the stream is smooth, and the complex design's stream should be, then the 2'' piston cannon should shoot 72 feet like the POPCAP.

Edit: (7/27/17) The Orbit Tunneling Kit Nozzle is actually only 1/4'' in diameter.

[marauder]

This is absolutely incredible.

I love your use of PVC unions BTW.

[Drenchenator]

Yeah, those videos are great! I apologize for my negativity here; your performance was just significantly better than I had expected based on previous work. But I can't argue with the videos!

I've been interested in Tim's work, because he seems to design for performance by optimizing often neglected characteristics (like using flow straighteners, etc.). I think we can all benefit from that kind of thinking. Perhaps if you also design with these neglected characteristics in mind, you could achieve 80 feet based on your previous designs as groundwork.

[SSCBen]

Sorry for the delay. I wanted to reply to this thread for a while but have not had much free time lately.

I also don't want excess heat to reduce the pressure rating of PVC, especially for pressures above 100 psi. Would that thermal energy have enough time to accumulate before being transferred to the water and air?

I would not worry about this at all. The difference in densities and heat capacities between the air and PVC mean that the temperature increase of the PVC is going to be small.

With lubrication, It eats away only 2-3 psi in friction. The same type of idea should work on a smaller scale with dremeling and sanding.

I'll have to look into Nighthawkinglight on YouTube as this sounds very good.

What do any of you think about servicing? An idea is to use adapters, but you'd have to unthread the tank before you'd be able to get at the adapters. Using a union sounds much easier and would allow easier alignment in construction.

A union sounds like a good idea for a piston water gun. With that being said, in my piston designs so far I've just assumed that the pressure chamber has a finite lifetime and made the entire thing threaded onto the remainder of the gun. Of course, for something like Supercannon II the entire gun is the pressure chamber, so this may not be a good approach in general.

The range depends on the pressure set by the regular and the pressure lamination is intended for. As far as I can tell (correct me if I'm wrong), lamination has never been attempted at constant pressures above 100 psi, so it is unknown how far this water gun can shoot.

With respect to range, I'd like to mirror Drenchenator's basic point that as range increases, the flow rate required to get that range also increases. Before I looked into the range-to-flow ratio. Read some of that topic for more on the idea. The lower the range, the higher the range-to-flow ratio, in general

It doesn't look like this made it into the thread I just linked to, but back then I did a fair number of runs of my water jet range simulator to look at optimizing range-to-flow ratio for a given range. If I design a water gun that produces a highly coherent jet (my preferred term over "laminated" or what most people say) then I can calibrate the simulator to it and optimize the gun in a few ways (ideal nozzle diameter, ideal pressure, and ideal firing angle).

One recommendation: Don't focus too much on the pressure as a measure of how quickly the jet breaks up. It would be useful to think about the Weber number of the water gun: We = rho * v^2 * d / sigma. rho is liquid density, v is the velocity, d is the nozzle diameter, and sigma is the surface tension. The velocity isn't always easy to measure, especially if your pressure isn't constant, but you can get a good estimate by using a set volume of water and measuring the shot duration and then using the right flow rate formula.

The distance at which the stream "breaks up" (however defined) scales roughly with d * We^(1/3) * Tu^(-1/4) in most of our cases. Tu is a measure of how turbulent the stream is. (Higher is more turbulent, that is, worse.) If either We or Tu gets too high then the relationship I mentioned no longer holds and the breakup distance would tend to plateau.

Do you think it would be a good idea to rename the project and put it in a new thread geared toward experienced builders?

Yes, I think that would be prudent. The APH is definitely not optimal for beginners, but it's not bad. It doesn't require that much work and it works okay. I'm definitely open to improving the design, but it would have to be pretty simple.

Oh, and by the way, PVCFittingsOnline sells PVC ball valves for a reasonable price that are far easier to turn than generic PVC ball valves.

Thanks, this is good to know.

One video is of me with the 3/8'' nozzle and the other is with me doing the 1'' riot blast which I call shotgun mode.

Nice work, your design looks very powerful. Definitely makes me wish I had the time to build something right now...