Simplest WBL

Build a homemade water gun or water balloon launcher and tell us about it.
Fredcompany
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Simplest WBL

Post by Fredcompany » Thu Jun 03, 2010 4:12 pm

What is the simplest design for a WBL?
I have a couple of different lengths of PVC, a bike valves and lots of tractor tyre inner.
I also have a couple of other bits.

My water gun reached 27 feet today (I know it's not impressive, but it's better than anyone else's water gun round here, and it fires quite a lot of water - still haven't got the nozzle right.)

Is there anything (preferably a simple WBL) that I could make with the parts I have (i don't mind if it only shoots balloons 20m)?
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C-A_99
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Re: Simplest WBL

Post by C-A_99 » Thu Jun 03, 2010 9:23 pm

The absolute simplest is the 3-man water balloon slingshot you can find in stores and hobby shops online. Not very accurate but it doesn't require pumping and can still get good range. It does, of course, require 3 people to use though.

The simplest pneumatic launcher (air powered) is the Douchenator. In a nutshell, it is a pressure chamber of 3" PVC, reducers to a firing valve (which is usually 1" to 1.5"), and reducers to the 3" barrel. 3" or 4" is strongly recommended for the pressure chamber, but 2" or 3" are acceptable sizes for the barrel depending on the balloons you want to use.

So, you can construct a portable Douchenator, portable meaning it has short PC and barrel lengths. However, you can get better performance with longer PC's and barrels, but in that case, you'll want an over-under setup (where pipe elbows are used so that the PC is under the barrel) unless you don't mind carrying a 7ft long hunk of PVC around, not to mention the risk of it breaking.

For barrel and PC lengths, generally, you want the barrel to be at least twice as long as the PC. This varies depending on your needs and uses, but for a 3ft barrel, you can have 1ft to 2ft of pressure chamber. You don't want the PC to be too long though; it's better to use thicker pipe if you need massive amounts of air.

However, any PC longer than 1' x 3" will take substaintially more time to power up. Anything longer than 2' x 3" is generally completely unecessary. If you need a really portable launcher, you can try something like a 2' x 2" or 3" barrel with a 9" X 3" PC in an over-under setup.

More complicated WBL's feature things like multiple PC's (which require several valves to control if you want consistent shots; the old inline PC setup saves money on valves but does not allow for consistent shots since the pressure and volume changes affect it), and faster loading. Breech loading can be done in several different ways but so far I only know of two launchers that breech load; one made in Australia and one I made. Specifics on how to create the breech I used can be found here but it lacks documentation on the rest of the launcher which means it's not as useful for beginners.

Now, there's one issue I'm concerned of. PVC is not widely available in some parts of the UK, though you seem to be able to find it just fine. Be absolutely sure the pipe you buy for the pressure chamber is rated for pressure; if large home improvement stores don't have it, chances are that small hardware stores do. As for fittings, I'm not as sure on those; most are not pressure rated but have worked just fine for WBL PC's. You'll know a reducing fitting is pressure rated when it's not actually a reducer, but a bushing that requires a coupler to connect. However, finding those bushings and couplers at larger sizes (3") is difficult.

Metric conversions; I don't know what the standards for pipe are in the UK, but 2" is approx. 50mm, 3" is about 76mm, 1" would be about 25mm, and 1.5" would be roughly 38mm. Yes, english units suck but that's a lot of us have got to deal with.

Fredcompany
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Re: Simplest WBL

Post by Fredcompany » Thu Jun 03, 2010 9:36 pm

I've been brought up on metric units, so I don't mind them - but I can still (roughly) visualise in Imperial units.

I just remembered I have some PVC elbows which might fit the PVC I've got.

As for getting PVC, there's a hardware store near me which has practically a small warehouse at the back.
The only problem with PVC in England is the price of the tubing, but the joints are cheaper than copper ones, so they sort of balance out.

What sort of pressure would be about right for a 3 foot long barrel, 2 foot long pressure chamber, for it to shoot 50 feet?
Last edited by Fredcompany on Thu Jun 03, 2010 9:45 pm, edited 1 time in total.
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C-A_99
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Re: Simplest WBL

Post by C-A_99 » Thu Jun 03, 2010 10:50 pm

One thing I forgot to mention is the type of valve you use. There are generally three choices; the piston valve, ball valve, and sprinkler valve. The piston valve has to be built manually and is of course, the most difficult to do. However, it opens at a good speed that definitely won't burst any balloons. The ball valve is the cheapest and easiest, but requires a torque arm to open at a reasonable speed, but is more difficult to aim this way. Even with a torque arm, the valve still opens slowly, meaning that the projectile has escaped when most of the air is just coming out. The sprinkler valve is usually the best option; a common modification is used to improve it's performance and so that it doesn't require electricity.

You may want to go with a modified sprinkler valve and 1'x3" PC; the smaller PC requires less pumping but the fast air release may cause balloons to burst unless you have good sabots. Designing "cradles" on your sabots will greatly reduce the chances of the balloons bursting upon launch. To create a sabot, you need to trim a conically shaped cup (bottom smaller than top) so that it seals in the pipe you're using. There is an article on building good sabots. You don't want to use Pringles' cans because they will scratch up the barrel, have a lot of friction, do not seal well, can be dangerous, and do not cradle the balloon(s) being fired.

Now for range... Most launchers can easily get 300ft of range, while 400ft and 500ft are possible with higher pressures and larger designs. 50ft range for water balloons can be achieved with a good throwing arm, so plan to use your launchers at farther range than that. You can use low pressure levels to stay safe and for targets that aren't too far away. Targets that are farther away should be bomboarded with several water balloons at a time, which is safer. Directly firing at targets farther away means that they may dodge the balloon which may not be accurate enough to hit them.

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martianshark
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Re: Simplest WBL

Post by martianshark » Thu Jun 03, 2010 11:56 pm

Piston valves can't open too fast. There was a page in the homemade section that showed that the mauler valve popped balloons. Also, Havoc is the simplest, not the Douchenator.

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C-A_99
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Re: Simplest WBL

Post by C-A_99 » Fri Jun 04, 2010 2:54 am

This is a piston valve and it opens considerably faster than any ball valve. The Havoc requires elbows, so how is it simpler than the Douchenator? (Not to mention the PC is poorly designed; 2" is a bad choice for PC's and does not perform as well.)

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zeda.beta
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Re: Simplest WBL

Post by zeda.beta » Fri Jun 04, 2010 2:58 am

I would start with a douchenator, because they are the most simple. (Havoc is just a douchenator with a t bend connecting the pc to the barrel.)
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C-A_99
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Re: Simplest WBL

Post by C-A_99 » Fri Jun 04, 2010 4:42 am

The Havoc also has a 2" PC instead of 3", inhibiting performance as I described above.

I personally recommend starting with your own over-under WBL that's pretty much a mash of the two designs. Use a 3" PC that's about 1' to 1.5' long. 1' elbows are recommended so you can stack the barrel on top easily. I recommend a modified sprinkler (solenoid) valve but if those are too expensive, the ball valve with torque arm is your last option. After that you can have a 3" barrel or 2"; I recommend starting out with 3" as it can take a higher variety of munitions. 2" is usually used when you need a breech and it's much easier to build one for 2" barrels. Without a breech, you have to ram-rod your sabots down the barrel, or make it so that they don't seal well and can simply slide down.

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Re: Simplest WBL

Post by Fredcompany » Sun Jun 06, 2010 4:35 pm

What about a version of one of those catapult WBLs but contained in a barrel, so it's more accurate and smaller?
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zeda.beta
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Re: Simplest WBL

Post by zeda.beta » Sun Jun 06, 2010 4:39 pm

Then you have the problem of distance. You might as well throw it if you are using elastic in a tube.
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Fredcompany
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Re: Simplest WBL

Post by Fredcompany » Sun Jun 06, 2010 4:40 pm

good point
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C-A_99
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Re: Simplest WBL

Post by C-A_99 » Sun Jun 06, 2010 8:08 pm

I experimented with a catapult/barrel system before and needless to say, it got less range than my Max-D 2000. In order for this to work, you need something huge and even then I'm still not sure if it could work very well. Spring powered has been considered too as it's used in Nerf and airsoft. Problem is, you need an awfully huge spring to shoot a projectile as large and heavy as a water balloon, especially if there's more than one balloon.

Pneumatics are the tried and true method. =)

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Re: Simplest WBL

Post by cantab » Fri Jun 11, 2010 6:06 pm

Something that hasn't been mentioned yet - how about a sling? Not a slingshot, a sling. Extremely simple, extremely light and portable, and better range than regular throwing. Probably need a bit of practice to get accurate.
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Comrade117
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Re: Simplest WBL

Post by Comrade117 » Fri Jun 11, 2010 6:40 pm

You mean something like this?
http://www.youtube.com/watch?v=NdsrfwvRqTU
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Fredcompany
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Re: Simplest WBL

Post by Fredcompany » Fri Jun 11, 2010 8:37 pm

I've seen that before Comrade.
Cantab, I like that idea...
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