That's right! As soon as I import the footage, you'll get to see the Douche in action! It sounds much like a gun being shot, not surprising from a 5 foot long hunk of PVC under 80 PSI of pressure. The footage and all future movies will be hosted offline, in order to save webspace. Look for it to be posted tomorrow!

Here it is in all it's glory. When you watch it, please remember that the ball we were shooting is going much faster than we anticipated so all you see is the cup we use for wadding. The video may take a while to load. Hope you enjoy it.

Nice! I love seeing a cannon in action, and that thing really looks great. How are your results with an actual water balloon? Mine are less than desirable, so it will be interesting to see what kind of performance somebody could get with good wadding.

80-100ft with 70 PSI. The speed you flip the valve and the weight of the object make a huge difference.

We can get up to 200ft with a tennis ball at 70 PSI.

Our Douche can hold more PSI [easily over 150], but it takes a lot more effort to put more than 70 in. We've reached 90 PSI after lots of pumping, but in a war, up to 70 would be the most practical.

Looks... FAST!!! That thing has GOT to hurt! I love it B)

Glad you like it. We'll be getting more footage of it. Hopefully something that shows the object we're shooting.

What you need is to have the camera point down the barrel and take footage at high frame rate, then slow it down.

Hopefully not blowing the camera to peices... :huh:

See if your camera has a framerate option. If so, put it on the highest setting and then you can speed it up if you want. B)

By point it down the barrle I meant put it on top of the barrel, and point it where the barrel is pointing.

Oh, yes. DOWN the barrel, not down the barrel :lol:
That would allow you too see the balloon for more time.

We got more, much better footage today! 250 ft of range with a water balloon, over 300 ft with a tennis ball. We also shot a lacrosse ball, and it is GONE, maybe shot over the whole lot!

You'll really like this stuff, just need time to import and edit. B)

Woh. You should seriously go to some store and buy some cheap glass vases or whatever. Put one 100 ft. away, roll camera, BANG. I don't know if it's accurate enough though. How far away can you hit a target?

We did some calculations. With a tennis ball we got 336 feet high at 141 MPH which is a lot better than we had thought. Also we think that we shot a water balloon 800+ feet at the goffle but we're still not entirely sure on the accuracy fo the calculations. We found that having more than one water balloon or ball in the tank at once can actually increase the range by as much as 100 feet. We got some really good video and we plan to post it as soon as possible.

If it works better with more weight, that's a sign that you aren't using all the energy. Put a longer barrel on it! Might as well put a male adapter on it so you can swap barrels (one for range, one for shot gun like with 4-5 ballons in it maybe?).

The barrel is long as it is. It's about 5'6" so adding more length is probably not a good idea. I like it the way it is now. It works very well.

We've been able to shoot up to 6 tennis balls, all reaching the same height and falling in the same area. We've tested up to 3 water balloons too, and could probably use more. 9 tennis balls could fit in the barrel, the only reason we haven't tried is because we don't have 9! The barrel is already several feet long, making it longer would be impractical.

Keep in mind that the stats are from 70-90 PSI. With a ton more effort, we could get 100, 110, 120. Just 10 PSI more makes a giant difference. But then again it takes a shitload of effort to get that high.

I'm designing a WBL that is designed to simulater a LAW, so it will be a small, one shot deal.

Funny, how big is your chamber? I have a 2" by 2' chamber and I can reach 125 PSI (what I normally fire at), in about 20-25 seconds. I'm using a stand up bike pump.

I don't see how this can be battle practical. First, you can't possibly be accurate at 250ft let alone 800ft. Second, If you fire it too close with to much pressure and you hit someone, You will be sued. It's too much hassle to make sure you are at the proper range to keep this thing safe, and on top of that there is always the possibility of pvc exploding in your face. Saftey is the main reason why I don't build a wbl. Even if I did build one the fact that you must pressurize it with a bike pump isn't at all apeling to me and it limit's me to a certian extent. So unless you can convince me it's safe, I will never build a Wbl for battle purposes.

We play with friends, whom wouldn't sue us if they got hurt, which wouldn't happen in the first place. Douchenators are our long-range artillery, banned from being fired from 100ft away or less. You would be suprised about how accurate one can be from 800 ft. It doesn't matter much because we can load multiple water balloons in the barrel and they will all hit near the same spot.

PVC doesn't explode in your face. "Explode" is a description used only by those whom have not ventured that deeply into Tech. When there is an overload of air, an air leak will develop, about 9 out of every 10 times. The other 1 is if the pipe was poorly glued, or if the seal wasn't good. In that case something may shoot off, like a pc, but never shards or pieces of pipe. On a water balloon launcher, the barrel or pc could shoot off, but they shouldn't hurt anyone if A: You hold a WBL correctly, and B: Are being careless. Again, having parts shoot off is very rare and often preventable.

The reason it is hard for us to achieve high pressure is probably the bike pumps. They are good, stand up types, but likely not powerful enough. $20 explains why we got them.

^I think you mean careful, not careless :huh:

Can't PVC rupture when it is pressurized above its max PSI rating? This wouldn't matter in WBL's, but I think that's where people get the "exploding in your face". If you put an aiming device that had marks for various ranges, you could probably hit a target accuratly at 500 ft. You would just need to spend 2-3 hours measuring distances and at what angle you need to paint the launcher to hit the target.

Well, one way to make it explode would be to rapidly mix water and dry ice in the PC...lots of water and dry ice... In theory, a rabid enough introduction if pressure results in an explosion...that's why bombs don't leak when you hit the fuse...

Uh... I think the idea here was to NOT have the PVC explode on you. I suppose if for some reason you WANTED to, you could make a water weapon out of PVC that would explode, like as a grenade, although that would probably kill or severly injure somebody (what ever happened to promoting fun, safe water warfare?).

Or you can spend 5 minutes using Physics to calculate the angles. Shooting a launcher follows normal parabolic projectile motion. Several formulas are applicable, giving whatever stats are desired.

And of course PVC could rupture over the max ratings, but that's why there are max ratings, and pretty conservative ratings at that. 3" pipe can take 260 PSI, which I don't think I'll be able to pump in anytime soon. Anything smaller than 3" takes more, reaching 600 PSI with half inch pipe. And I'm not quite sure why you want it rupturing in the first place...

Oh yeah. I saw a simulator on a Spud site that calculated ranges. I was thinking of streams of water, which have a lot of drag and cannot be measured accuratly very easily.

Ah! Here we go: http://galileo.phys.virginia.edu/classes/1.../jarapplet.html

Nice! That site confirms our ~800 ft range. The site calculations put the range in meters at 250, our initial calculations put it at 245. Fisix rox! [but not in school]

What velocities was it shooting at? And how much does a water balloon weigh? :huh:

The velocity was 63 m/s [141 MPH]. A water balloon doesn't weigh much, maybe a few kilograms? Our angle was around 60, 70, 80 degrees, usually 70. I thought it was closer to 45 until I viewed the footage again.

Well, since this is so accurate, you could easily make an aiming guide. You could make a flat wide stick that stood vertically with holes in it (plus a fixed point on the end of the WBL) for various ranges (calculated by the computer), each hole when aimed through pointing the WBL at a specific angle. They have things like that on rocket/grenade launchers, I think. :huh:

How can it be practical? Half the time your not even loaded, and they run like hell anyway. I'm almost possitive I could come with in 5-10 feet of the target I'm shooting at. Remember, you are in control of safety. If you prime, glue, and use it correctly it will not "kill" anyone. I'm taking Physics in High School right now, and I can prove that getting hit by a water balloon shot by the Douchenator will not hurt anyone. It'll be nothing more than if someone threw it at you.

Dux, the angle in the video is 70-80 degrees because the angle was set so that you could see the water balloon in the air. Each time I fired it it was at or around 45 degrees.

*Bump*

New video. Quality is bad so you don't always see the water balloon flying through the air. I'l get a better quality movie up tomorrow. It may take a while to load.

These ranges are interesting, but I do not believe you when you say that it can shoot 800 feet or more. And yes, to "validate" this opinion, I already took Physics two years ago and passed with an A easily. It was actually Algebra Based Physics, the local equivalent which is basically the same thing plus some Algebra review and lots of trigonometry (essentially more curriculum in the same time). Next semester I am taking AP Physics, so it looks like I'll be getting even more validation then! :P

Of course, if you use a high pressure large volume pressure chamber, a large barrel, and a fast valve, I would believe you. However, given that your design's barrel is shorter than the pressure chamber and you use a ball valve, I don't believe those ranges.

I would hate for you to shoot this at someone from 800 feet and then see how they feel once they get shot (if they are still alive). From my understanding of projectile motion (which I will admit is somewhat fuzzy, but very intact), the energy used to shoot the projectile up is equal to the energy used as the projectile falls. The projectile looses velocity as it moves up and away from the barrel, and it gains velocity as it falls and moves away from the barrel. The power of the shot at 800 feet should be equal to the force the projectile gets from gravity and the force left after drag from the gun. That should be a lot of force, at least enough to be dangerous. Then again, you did write "OUCH" in your video, so you may know that..

I would love to see the reasoning behind this actually, so please explain because I could easily have forgotten something.

What I am beginning to do now is take the range to inches of 30 shots and make an evaluation of the range based upon mean and standard deviation. This will remove all doubt that a water gun or water balloon launcher can shoot over a certain range. Water gun ranges easily will follow the standard normal distribution, allowing one to make a much more in-depth evaluation. Take statistics if you would like to learn how to do this work, or alternatively read about statistics. I have seen several good websites and I bought a great statistics book for reference at a used book store for less than $5. I was looking for a good Fluid Mechanics/Dynamics book, but I only found a book on pipe fitting for plumbers and some neat math books. The pipe fitting book has a load of repair options and I think I will write an article outlining the most useful methods.

What? The barrel is twice as long as the PC.

Also, believe me, I doubt this thing will hurt anyone. I'll even test it on myself if I have to prove to you guys it won't hurt. I'm not trying to convince everyone to build a douchenator. The Ball valve is fine. It's like flicking a swtich. I don't believe the ranges either but it's been confirmed on two different methods.

I really don't see why people are so critical over this thing.

Ben/Doom, the Douchenator we use now has a pc twice the size of the original one, and the barrel is like 3 times the length of the new pc. This thing has the power to do 800. We initially did calculations in meters per second, since all Physics should be done with SI units, and it came out to 245m. 200m and 50m are easy to picture for track runners. The open lot we fired in is very close to a 200 plus a 50. I was almost thinking about sprinting a 2 and timing it, then sprinting the length of the lot and timing that. It should be similar plus 7 seconds for the 50. 800ft sounds lofty, but it really isn't that long.

And despite the fact that I suck at Physics, we followed the correct formulas and did them correctly. I think our margin of error was +/- .30 of a second, which could change the results by several ft.

Hmm, I never thought I would ever have to see Normal Distribution, SD, or Z-scores ever again. Same for Projectile Motion math. Yet here are 2 places where they apply very well. I hate math overall, but it might be worth the effort to figure out a max range for any given water gun. How could the tests factor in everything you can do to increase range? [big/small k-mods, k-mod+nozzle mod, integration+k+nozzle, etc.]

You're forgeting about air resistance. The initial velocity would be higher than the final velocity. You should have someone stand at the end of the lot and see if they can see where the water balloon landed, then measure the distance using a ten foot string or something.

Good to know that the new WBL is improved. I really was thinking of what appeared on the website. The videos only show the barrel, so I couldn't have known.

I am not saying that these tests will increase range. I am only saying that a more in-depth statistical study will be more useful to determine if range is lower or higher. That can be useful. You could perform a Z-test on your calculator easily to compare similar ranges of water guns. You could even calculate how likely a water gun will shoot a distance.

Accuracy is also a big goal of ours, so I think that 30 trials would be good. That's the minimum for the Z distribution apparently. After shooting a water gun 60 times for a test, you really learn to stop once you get a substantial amount of data.

Then again, you might have been referring to the projectile motion equations. If you used those simple equations they gave you, I wouldn't be surprised if the range appeared elevated. I remember trying out a water-gun-like set of data to see how off the equation would be because it doesn't factor in drag. Simply put, it was nothing close! Drag/air-resistance affects water jets more, so that was really expected.

Those equations don't factor in air resistance, which is exactly why I never really used them. I've used a few of those equations in Calculus, but it really wasn't very useful. You could easily fashion an equation to include air resistance, in fact, I remember the teacher said a thing or two about that, but also said that you needed to know about derivatives to use them. Of course, I know plenty about that crap now, so I think I might look for some information on air resistance in projectile motion.

A quick Google search found something that looks like air resistance factored in: http://math.fullerton.edu/mathews/n2003/Pr...eMotionMod.html Looks fairly straightforward for someone with derivative Calculus knowledge (if you consider implicit double-derivatives fairly straightforward that is). I skimmed over the page and if you don't have derivative Calculus knowledge and would like to factor in drag/air-resistance, you better start reading now. I could explain a thing or two if you have questions, but I would suggest checking out a used book store and picking up a book on Calculus if you do not have one.

Fun stuff... that's no sarcasm either. Things are really only fun when they are useful.

Why shoudn't we be so "critical"? We don't want to hurt anyone while using this thing, so we want to be sure it's safe before building anything. Hit yourself from say 100 ft at what you would call average psi and convince me this won't hurt anyone.

Sorry, I agree with Duxburian on this. You don't know what you're talking about until you build one. First time your pressurize it and fire it, you'll forget everything you were worrying about. There are obvious risks, but if you're smart, use liberal amounts of primer and glue, and don't pressurize it past 100 PSI, then you'll have tons of fun. Also- I found this pretty useful tool for figuring out ditances and power: Gas Gun Design Tool (GGDT)

New video, Better quality. You can actually see the objects being fired.

Good, because this is the week I finally get rid of that dial-up. As soon as it's gone I will take a look at this video. B)