Kilolauncher - is it possible?

Build a homemade water gun or water balloon launcher and tell us about it.
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cantab
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Kilolauncher - is it possible?

Post by cantab » Fri Jun 27, 2008 7:49 pm

Just a simple comment to get some discussion going.

A water balloon launcher with a range of over a kilometre (3200 feet). Would it be possible?

I believe yes, considering what has been done in "punkin chunkin", http://www.punkinchunkin.com/

True, pumpkins are more robust than water bombs, but even they will break if subjected to too much force. The challenges for a WBL will thus be much the same as for a punkin chunker, and the potential designs also the same. (What results have been had with trebuchet WBLs? Has anyone tried a centrifugal design).

I appreciate it would have serious battle practicality issues, since it would almost certainly be huge, slow firing, immobile, and innacurate. But it's more a technical challenge.

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Silence
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Re: Kilolauncher - is it possible?

Post by Silence » Fri Jun 27, 2008 7:55 pm

No way, as far as I'm concerned. According to this page, the terminal velocity of a raindrop varies from 0.2 to 20 miles per hour depending on its size. Every stream turns into rain eventually, which goes nowhere fast.

Edit: Oops. I see you were talking about water balloon launchers, not water guns.

You can counter the effects of acceleration/inertia by having a long barrel in which the balloon slowly accelerates. The problem is the air resistance at that velocity might rip the balloon to shreds anyway, unless you have tiny balloons that haven't really been stretched.

Code: Select all

If fired at a [b]45 degree angle[/b] with [b]no deceleration from drag[/b] at velocity [b]v[/b] for a range of [b]1000 meters[/b]...

vx = v / sqrt(2)
t = d / vx
t = d * sqrt(2) / v

y = 0
y = -5 * t^2 + v * t / sqrt(2)

5 * t = v / sqrt(2)
v = 5 * sqrt(2) * t
v = 5 * sqrt(2) * d * sqrt(2) / v
v^2 = 10 * d
v = sqrt(10 * d)

d = 1000
v = sqrt(10,000)
[b]v = 100 m/s[/b], I think.
After integrating air drag, that number will probably be at least 200 m/s. I'm fairly sure a balloon would rupture at that velocity, at least if it's filled and stretched enough.
Last edited by Silence on Fri Jun 27, 2008 8:21 pm, edited 1 time in total.

aEx155
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Re: Kilolauncher - is it possible?

Post by aEx155 » Fri Jun 27, 2008 10:57 pm

At first, the title made me think you were launching something that weighed a kilo...nevermind.

Technically, if you put the balloon in some sort of housing (imagine a sabot, but it doesn't release the balloon until later), and like SilentGuy said, accelerate slow enough, you might be able to get it to go a kilometer. The problem with that would be finding a way to make something that carries a balloon then releases...

You could always try some other from of water balloon, like those reusable ones I've seen somewhere...

I just want to ask, buut has anyone tried rifling the barrel of WBL? I know it doesn't work in guns, but since were talking about launchers, I though I might put this in.

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cantab
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Re: Kilolauncher - is it possible?

Post by cantab » Fri Jun 27, 2008 11:10 pm

I wouldn't have the balloon travelling in a sabot. Though one might be useful to help in the launcher - but then you have to make sure it doesn't go flying out.

It's certainly reasonable to use a thicker/less inflated than normal balloon, since it'll be falling at a fair speed, so it's going to smash anyway. More troublesome might be the size to use. You don't want a direct hit to be too dangerous, at least not if you want it to be remotely usable in battle. But a smaller projectile will suffer badly from drag.

Yeah, the foam ball types might work. But I'd say that's not really a proper water balloon.

As for methods - well an air cannon is the obvious one, and one of the safer options (since they're firing where you point them if they fire at once). A centrifugal machine would be rather more hazardous. I'm wondering how the forces compare. A huge catapult could work well also.

As for rifling a WBL - well doesn't rifling go hand-in-hand with elongated bullets, as opposed to round musket balls, cannonballs, or indeed water balloons. Though elongate balloons exist
Also large cannons (like tank guns) nowadays have moved back to being smoothbore anyway.
I expect the result of a rifled WBL would be even worse than a gun. The surfaces on the bore would just tear the balloon to shreds. Of course I might be wrong...
If you do want the balloon to spin in flight, fins might be a better approach, like model rockets use. With an elongated balloon that could work - though there's the question of whether it would be rigid enough to hold it's long shape in flight.

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Re: Kilolauncher - is it possible?

Post by aEx155 » Fri Jun 27, 2008 11:25 pm

I wasn't talking about the foam "water balloons". I was think more of those plastic, collapsible water balloons. I remember seeing some on iSoaker, but I can't seem to find them. You could also try making one of those water grenades, which I saw somewhere here.

As for rifling, most people with potato cannons rifle, to increase accuracy. It would probably work with a balloon in a sabot, although I don't think it would do much after I think about it.

EDIT: Found it: http://www.isoaker.com/isc/Armoury/Anal ... iball.html
Last edited by aEx155 on Fri Jun 27, 2008 11:38 pm, edited 1 time in total.

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Specter
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Re: Kilolauncher - is it possible?

Post by Specter » Sat Jun 28, 2008 12:38 am

Those plastic balls are no longer made and would be very hard to find. They were made with the Storm series of water guns made by Jakks Pacific.
I remember seeing them in the store when I got my Storm 600.
My "arsenal": Customizable APH, Storm 600 pistol (still haven't finished fixing this), launcher- Model:AB1.0(Decommissioned), AB1.5, soon AB 1.1(2"rebuild) maybe ill get something else in the future
My site Image My website/forum is back up and running, for the most part after it having been deleted in october

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Silence
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Re: Kilolauncher - is it possible?

Post by Silence » Sat Jun 28, 2008 4:01 am

Water balloons probably aren't stable enough to benefit from rifling. Bullets have high rotational inertia (the metal lies on the edges) and they're well-balanced from front to rear, as well as symmetrical and static across the other two axes.

cantab, all water balloon launchers use sabots of some kind. It's not obvious when you read about the launchers themselves, but they do use sabots. It can range from wadding to tennis ball cans to Pringles cans to the Snake-Eye water balloon shell.

Only pneumatic launchers and firearms scale up easily. Trebuchets become bulky, expensive, and immobile, and they reach a limit of practicality even with near-infinite resources. Punkin Chunkin launchers are better - just extend the barrel and use a larger air tank and you're set.

A centrifuge would have to be huge and be rotating at dangerous, uncontrollable velocities. For all you know the imbalance from the balloon at one end would shake it apart. Given that the period of rotation T = r / v, and a v of 200, even a wheel 400 m in diameter (a quarter mile, or 4 football/soccer field lengths) would have to spin at one rotation per second. Imagine a Ferris wheel spinning 360 degrees in that time. And it's only a fraction of the size you'd need.

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cantab
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Re: Kilolauncher - is it possible?

Post by cantab » Sat Jun 28, 2008 10:22 am

Centrifugal machines work for the pumpkins, I didn't just pluck the idea out of thin air. There was even one built on Scrapheap Challenge, ie in 10 hours out of old junk. You use a counterweight to help the balance. The most difficult bit is getting the release right, or you risk firing at some completely random elevation. And yeah, they are fricking dangerous.

http://www.youtube.com/watch?v=RPA7EiukJTA
The record holding centrifugal machine. Also you get a sense of the scale of the things. The air cannons and centrifugals are actually similar in size.

Trebuchets do scale. Sure, they become huge, but they can launch stuff far. 'Yankee Siege' holds the record. While on Scrapheap Challenge a trebuchet was built from telegraph poles and an iron girder, and using four tons of lead, attempted to throw a Mini! It broke though :-(

But air cannons are probably the best. Though that said, big tanks of high pressure air are basically bombs.

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Re: Kilolauncher - is it possible?

Post by aEx155 » Sat Jun 28, 2008 3:08 pm

cantab wrote:Centrifugal machines work for the pumpkins, I didn't just pluck the idea out of thin air. There was even one built on Scrapheap Challenge, ie in 10 hours out of old junk. You use a counterweight to help the balance. The most difficult bit is getting the release right, or you risk firing at some completely random elevation. And yeah, they are fricking dangerous.

http://www.youtube.com/watch?v=RPA7EiukJTA
The record holding centrifugal machine. Also you get a sense of the scale of the things. The air cannons and centrifugals are actually similar in size.

Trebuchets do scale. Sure, they become huge, but they can launch stuff far. 'Yankee Siege' holds the record. While on Scrapheap Challenge a trebuchet was built from telegraph poles and an iron girder, and using four tons of lead, attempted to throw a Mini! It broke though :-(

But air cannons are probably the best. Though that said, big tanks of high pressure air are basically bombs.
Most of those things launch hard/solid projectiles; things that take a lot of force to break.

We're talking about water balloons here, which take very little (sometimes) to break. If the forces we're putting them through with regular high-efficiency WBLs breaks some balloons, imagine what would happen if we used technology made for a different purpose?

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Silence
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Re: Kilolauncher - is it possible?

Post by Silence » Sat Jun 28, 2008 11:25 pm

Wow. Point taken, cantab. And thanks - that was a cool link. I'm glad I wasn't within a mile of that thing while it was fired.

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cantab
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Re: Kilolauncher - is it possible?

Post by cantab » Sat Jun 28, 2008 11:54 pm

Out of interest - what's the current WBL range record?

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SSCBen
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Re: Kilolauncher - is it possible?

Post by SSCBen » Sun Jun 29, 2008 1:16 am

There's no official record that I know of and no one's claiming the best range. I'm sure the best range is less than 800 feet (~250 meters).

Interesting discussion so far. With a decently sized catapult my Boy Scout troop could launch water balloons several hundred meters with maybe 6 people pulling on a rope. That was at a camporee where the theme had something to do with siege engines. Every troop built one or more siege engines. From what I remember, before the "war" we had a lot of the troops with trebuchets were cocky but they turned out to be either made or operated incorrectly so they didn't work as well as our simple catapult.

I vaguely remember a discussion thread at Spudtech (now defunct but archived) that discussed launching water-filled two-liter bottles with nose cones rather than simple water balloons for longer range. I'll see if I can dig that up...

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Re: Kilolauncher - is it possible?

Post by aEx155 » Sun Jun 29, 2008 3:34 pm

If we're talking about 2L bottles, it be easier to use them as rockets than launching them out of something. I've seen rockets fly pretty far, and considering that I'm using "lower" pressures of 80 PSI (yes, 80 PSI is considered low...) they can definitely go farther...

We could also try using rockets to launch balloons; I saw somewhere online a guy with a simple rocket launcher. He had this story of how a student put an apple on one of the rockets they were launching, and that inspired him to use water balloons. I'm not sure whether or not they would survive the accelerations, but it's an interesting idea to look into...

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cantab
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Re: Kilolauncher - is it possible?

Post by cantab » Sun Jun 29, 2008 4:01 pm

Hmmm... a rocket might be interesting. There was a party where we had water rockets, and they were going up nicely with a mere 45 psi.
I'm also tempted by the idea of a catapult. It would seem simpler than an air cannon - you just need lots of elastic, a really strong frame, and a winch to pull it back. But I imagine aiming is difficult, as is achieving high angle launches.
Also, I suppose a remote control bomber would be the easiest and safest way to achieve the goal.

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