Water Balloon topic

Threads related to water balloon launchers.
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joannaardway
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Post by joannaardway » Wed Mar 15, 2006 2:33 pm

After looking over lots of water balloon launcher designs I have put together a pretty complete design - It has yet to see paper, but it should work.

I'm designing some electric circuitry for the Cerberus - this will perform several purposes - it will act as a trigger mechanism, a precise timer to open and close the solenoid valve, and a safety mechanism.

The trigger mechanism is timed based on the likely psi in the tank. The valve shuts to minimise pressure loss.

With a well timed solenoid valve, it should be possible to get a high powered and a lower powered shot per pressure tank.

Because each tank can be fired twice, the circuitry needs to remember how many shots have been taken with each tank, to time it correctly. Once two shots have been fired, it lights an LED to tell me to recharge that tank.

The design might be changed to use a solenoid valve per tank, but I suspect that I can manage with the one and some reed switches so the circuitry knows which tank I have connected up (the higher pressure tank will need a shorter solenoid opening time).
If I had three valves, I wouldn't need to switch the tanks myself, but the circuit would be more complicated (and the launcher more expensive)

The two shot per tank system will allow me to fire six shots before requiring a recharge - which is pretty impressive.

I have largely designed the breech loading system. I believe that a semi-auto system would be too difficult to design and make, so it will be loaded one round at a time.

The safety mechanism is fairly simple in concept but not necessarily circuitry.

Due to various switches and logic gates, the circuit will not open the soleniod valve unless all four of the below apply:
  1. a "round" (a short length of PVC that fits into the breech with the water ballon in it) is loaded.
  2. the breech is shut.
  3. the round has been changed since the last shot. (It can't define between rounds, but at the very least the breech must have opened and the round removed before the circuit resets)
  4. the pressure tank selected hasn't run out.
It will use rechargable 9V batteries to cut down on battery costs.

What do people think so far?

It's going to be very advanced and probably costly, but it will outclass almost all other water balloon launchers.

It will see quite a lot of use, but will be a bit heavy to lug around with a main weapon as it will be closing on a metre in length (weight unknown)
Last edited by joannaardway on Wed Mar 15, 2006 2:52 pm, edited 1 time in total.
Reason: Some mistakes
"Over the hills and far away, she prays he will return one day. As sure as the rivers reach the seas, back in his arms again she'll be." - Over the Hills and far away, Gary Moore

"So many people have come and gone, their faces fade as the years go by. Yet I still recall as I wander on, as clear as the sun in the summer sky" - More than a feeling, Boston

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joannaardway
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Post by joannaardway » Wed Mar 15, 2006 5:54 pm

How accurate is the spudtech air launcher model for a water balloon launcher?

I've been running a few figures through it roughly based on my plans and various figures are coming out which translate roughly to figures in the range quoted for the Douchenator water balloon launcher (a bit higher for the high pressure tank).

What sort of range is the Douchenator safe for use in? It would be good to know before I make it so I can customise it earlier rather than later. Also if I am to use the two-shot per tank idea, I'll need to factor this in.
"Over the hills and far away, she prays he will return one day. As sure as the rivers reach the seas, back in his arms again she'll be." - Over the Hills and far away, Gary Moore

"So many people have come and gone, their faces fade as the years go by. Yet I still recall as I wander on, as clear as the sun in the summer sky" - More than a feeling, Boston

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DX
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Post by DX » Wed Mar 15, 2006 11:06 pm

Applying the word "Safe" for the Douchenator can mean many things. The farthest range that doesn't hurt on impact? The highest pressure that doesn't hurt on impact? The pressure behind a shot is much more important for safety than how far it goes. Being hit at 500ft would not hurt at all because much of the velocity has been lost due to air resistance. In this case, more range = safer because more range = slower velocity. As for pressure, anything under 70 PSI at 100ft out does not hurt. Under 90 PSI at 150ft out does not hurt. At more than 150ft out, the PSI doesn't matter as much. This is assuming that the launcher is aimed like an RPG and not like a mortar. If used in a mortar-like fashion, any pressure at any range is safe.
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joannaardway
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Post by joannaardway » Thu Mar 16, 2006 3:54 pm

Well, the Cerberus is designed around the principle of a sniper rifle rather than an rocket launcher - being based on the over-under principle, and will use a 2" barrel, meaning that my estimation is that use like a mortar would be less practical.

The higher pressure tank is designed for longer range shots, and the whole thing will need to be well constructed and made from pressure rated PVC to avoid any trouble.

In reality a fair portion of it's use will probably be for target shooting down my street - cans and that sort of stuff. As some of you may have read in various places, I am a excellent shot, and if the Cerberus is accurate enough, the practise will allow me to advance further.

However, it will see use in water wars, but probably less than casual target shooting - something that big will be a little impractical (but definately intimdating) for a full on water war - particularly given the maximum ranges I might possibly be able to fire at in my likely enviroments.


Posts integrated into this one.
Post 2:
I've made a post on spudtech about some of the problems I have foreseen.

I'll get back to you on the results of this one.

The biggest problem was how to close the soleniod valve quickly - I have an idea, but I want to check it first.

Post 3:
I'm designing a station called Soul to help recharge Cerberus.

Normally Cerberus could take 300 pumps to fill - with Soul this will be cut to about a quarter - 75 pumps or thereabouts.

Soul will use a large amount of water during this process, so I'll store some of this for use in other soakers.

I'm also designing Soul so that it can be used a bit like Roland Tower's homemade.
Last edited by joannaardway on Fri Mar 31, 2006 5:00 pm, edited 1 time in total.
"Over the hills and far away, she prays he will return one day. As sure as the rivers reach the seas, back in his arms again she'll be." - Over the Hills and far away, Gary Moore

"So many people have come and gone, their faces fade as the years go by. Yet I still recall as I wander on, as clear as the sun in the summer sky" - More than a feeling, Boston

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joannaardway
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Estimations

Post by joannaardway » Fri Mar 31, 2006 4:55 pm

I realise this is my fourth post in a row, but an edit doesn't flag the topic as having a new post so I'll never get any replies. I've integrated the others toghether. Perhaps a friendly mod would delete the empty posts?

I've been doing various calculations based on Cerberus, such as expected recoil, muzzle velocity, weight, and other similar calculations

Expected recoil: (into shoulder) roughly 1 to 2 inches

Expected recoil: (from the hip) roughly 6 inches

Planned tank pressures:
low pressure:
100 psi for first shot
60 psi for the second shot
high pressure:
125 psi for the first shot
70 psi for the second shot

Expected muzzle velocity: Around 100 m/s on the high pressure tank, maybe 80-90 m/s on the lower pressure tank.

Expected weight: roughly 11 kg

Expected cost (with Soul or an air compressor): £150 - £200. The air compressor is the more expensive option (US equivalent: Around $300 [UK PVC is expensive - at least as near to London as I live {and Cerberus needs expensive electronics}])

Other muzzle velocities:
With a 1" ping-pong ball: More than Mach 1 (recoil minimal)
Last edited by joannaardway on Fri Mar 31, 2006 5:02 pm, edited 1 time in total.
"Over the hills and far away, she prays he will return one day. As sure as the rivers reach the seas, back in his arms again she'll be." - Over the Hills and far away, Gary Moore

"So many people have come and gone, their faces fade as the years go by. Yet I still recall as I wander on, as clear as the sun in the summer sky" - More than a feeling, Boston

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wetmonkey442
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Post by wetmonkey442 » Sat Apr 01, 2006 1:28 pm

Although I am certainly pleased to see you interested in WBL, I must tell you that your estimation of a speed of over the sound barrier for a standard ping pong ball is WAY off. Not only do you need high pressure, but a gigiantic output and a really really long barrel. No person that I know of has ver been able to break the sound barrier with any type of compressedm air pneumatic cannon. There are some rumors that two people have broken the sound barrier using compressed helium. This allowed for the sound barrier to be decreased while the projectile was still inside the barrel since the sound barrier in helium is a less than that of air. Sorry, but a ping pong ball is not going to go mach. It is simply too light. If you perhaps filled it with lead...However, if your compression chamber is more than 1inch the disturbance of the air entering the smaller diameter barrel will stop you from getting anywhere close from the sound barrier.

Sorry if you were banking on producing some sonic booms, however your design seems more than adequate enough for launching water balloons. Please update us with progress status as well as pics.

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joannaardway
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Post by joannaardway » Sat Apr 01, 2006 8:44 pm

Based on the fact that this uses a long barrel, a huge C/B ratio and 125 psi, calcuations say it should be possible.

Ping-pong balls only weigh a couple of grams, and have a decent area, so the forces involved would be capable of this sort of velocity, so are excellent projectiles to accelarate to super sonic speeds. Admittedly, they would slow down very fast, but are far better than other projectiles for this.

Given that a ping-pong ball weighs around a 1/100 th of the balloons I intend to fire, even the most conservative of estimates would see the ping pong ball travel at more than Mach 1.

However reality will envitably prove to be different - so yes, it probably won't, but my calculations say it will - which is what the last post was all about.

Anyway, I posted it more for amusement than anything else.

I now have a predicted fire rate for the Cerberus - assuming a full charge of 6 shots and attempted fast fire (i.e. minimal aiming):

Estimated rate of fire: max. 10 rpm with good weapon drills and a bipod.

(This was estimated by lying down and timing mimed motions)

I was considering a modification that would allow up to 120 rpm, but this would:
1) be more expensive
2) be harder to aim
3) not be much use.
4) use up ammo ridiculously fast.

Maximum period of sustained fire at max rpm: 30 seconds assuming a round in the chamber.
Last edited by joannaardway on Sat Apr 01, 2006 8:48 pm, edited 1 time in total.
"Over the hills and far away, she prays he will return one day. As sure as the rivers reach the seas, back in his arms again she'll be." - Over the Hills and far away, Gary Moore

"So many people have come and gone, their faces fade as the years go by. Yet I still recall as I wander on, as clear as the sun in the summer sky" - More than a feeling, Boston

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wetmonkey442
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Post by wetmonkey442 » Sat Apr 01, 2006 11:05 pm

Sorry, but based on the information you've given us, it's impossible. At 125 psi, the GGDT says that you won't get over 600 fps. Roughly 1200 is needed to reach Mach 1. A ping pong ball weighs 2.7 grams, I'm not sure if you understand this, but heavier projectiles will go faster than lighter ones once they have cleared the barrel. A tennis ball will not go over Mach 1 even in the barrel, if you have 125 psi in the chamber. Of course you haven't told us the size or dimensions of your chamber or even the barrel (although you did tell us the barrel diameter). You might be planning to build a gun 20 feet long. :confused:

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joannaardway
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Post by joannaardway » Sun Apr 02, 2006 10:03 am

I realise it is impossible - I thought my last post made that clear. I have known it to be impossible since before the post in which I mentioned it.

The idea was to show the approximate accuracy of the spudtech calculator program for extreme circumstances, and thus the potential error in the calculations made.

I'm sorry if it wasn't clear - I thought people around here could see this as a joke.
"Over the hills and far away, she prays he will return one day. As sure as the rivers reach the seas, back in his arms again she'll be." - Over the Hills and far away, Gary Moore

"So many people have come and gone, their faces fade as the years go by. Yet I still recall as I wander on, as clear as the sun in the summer sky" - More than a feeling, Boston

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Silence
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Post by Silence » Thu Apr 20, 2006 3:43 am

joannaardway, I think you need to point out that information about your water balloon launcher has been focused on "Plans for the future." Well, either way, I've done so now.

Your idea for a recharging station called "Soul" is a good one. You know how people talk about mounting water guns on pickup trucks and other cars? Well, maybe somebody can rig a system like that onto a go-kart or something and use an engine to charge up a special gun (or in this case, a water balloon launcher).

However, a more cost-effective and environmentally friendly method would be to use so-called "dump charging"--theoretically, a method used by electric vehicle owners to quickly charge their batteries by charging from batteries or a station with high voltage. An even more practical method is to have the station constantly pressurize its own PC, and hook up the water balloon launcher; after the valve is opened, the pressures in each PC will equalize.

If nobody responds to this in a few days, I'll just post this in "Plans for the future." That thread, at least, seems to be heating up ;) .

EDIT: I'm glad that people have stopped explaining the power of combustion here--I most certainly would not use a combustion WBL in a water war, or even just for "recreation."

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joannaardway
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Post by joannaardway » Sun Jul 09, 2006 3:44 pm

To inject a little life back into this topic:

How exactly was the Douchenator's muzzle velocity measured? I normally ask this question on spudgun forums, and I realised I'd never asked about the Douche.
"Over the hills and far away, she prays he will return one day. As sure as the rivers reach the seas, back in his arms again she'll be." - Over the Hills and far away, Gary Moore

"So many people have come and gone, their faces fade as the years go by. Yet I still recall as I wander on, as clear as the sun in the summer sky" - More than a feeling, Boston

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DX
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Post by DX » Sun Jul 09, 2006 5:46 pm

We had to calculate it. We used equations from a Physics textbook, don't remember what they were.
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Post by joannaardway » Sun Jul 09, 2006 7:54 pm

I would recommend re-running the maths through GGDT - the calculations are incredibly complex, more so than most people would believe.

The figures I put into GGDT to get similar results were rather odd - most people can't open a ball valve in 25 ms - I have a spring operated one with a spring that would work as suspension on a challenger tank and that struggles to do 25ms.

Or, I can provide plans to an incredibly simple chrono.
"Over the hills and far away, she prays he will return one day. As sure as the rivers reach the seas, back in his arms again she'll be." - Over the Hills and far away, Gary Moore

"So many people have come and gone, their faces fade as the years go by. Yet I still recall as I wander on, as clear as the sun in the summer sky" - More than a feeling, Boston

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Post by Drenchenator » Sun Jul 09, 2006 8:26 pm

It would be far easier to find the velocity through an experiment. The input data that you would put into a program could not cover all of the possible variables (surface area experiencing drag, density of the projectile, and others) that would exist. Water balloons are also, by definition, not solid projectiles, but a mix of a solid (rubber) and a liquid (water).

If I were trying to measure the "muzzle" velocity of a projectile without a chronograph, I would use a video camera and a yardstick (you could get a more accurate reading by increasing the frame rate of the camera though). You could attach the yardstick to the end of the barrel to measure the distance from the barrel after the projectile is shot. Then all that you need to do is record a video of the gun firing and count the number of frames that it takes the projectile to go 1 yard.

Divide the numbers of frames by the frame rate to find the time that it takes for the projectile to travel a yard. Then, by definition, v=dx/dt (velocity equals the change in distance over change in time). So, divide the number of frames by 3 feet (1 yard) and you get velocity of the projectile in feet per second.

This is velocity is not the exact muzzle velocity, but one that should be very close. This the average velocity over an interval of 1 yard, which should be close enough to not really make a difference.

EDIT

It is far more accurate to measure these kind of statistics. The basic physics equations that they tell you in elementary physics don't come anywhere close to the ones from physics with calculus.

Ben and I always like to measure statistics, and not estimate or use math to find them. It's fine to use a lot of equations and things during the design phase, not after something is built and ready to use. That is what the design phase is for. After the thing is built, you can measure the statistics in direct manners. For example, after Ben's SuperCAP was built, we wanted to measure the output of it. So, we got a stop watch and measured the approximate amount of water in the gun. We then shot the gun, and divided the capacity by the time to get the average output over that interval.

Again, it is far better to measure statistics after the gun is built than to "estimate" them, either with math or guesses. If you can get an accurate reading, then why choose not to?
Last edited by Drenchenator on Sun Jul 09, 2006 8:43 pm, edited 1 time in total.
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joannaardway
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Post by joannaardway » Mon Jul 10, 2006 11:08 am

There are other ways of measuring. Video is a bit edgy - exposure times blur the projectile flight.

Take a sound recording (preferably digital) of you shooting at a target a few metres off. If you have the right programs you can measure the time between shot sound and impact sound.

Speed = Distance/time

If you don't have the programs, then if you can upload the sound as a file, I've got a program that I can analyse it with to give you a figure to 3 d.p.
"Over the hills and far away, she prays he will return one day. As sure as the rivers reach the seas, back in his arms again she'll be." - Over the Hills and far away, Gary Moore

"So many people have come and gone, their faces fade as the years go by. Yet I still recall as I wander on, as clear as the sun in the summer sky" - More than a feeling, Boston

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