Small bombs, rapid fire

[cantab]

Is there any particular reason to use multiple barrels? In real guns (eg gatling guns) it's to avoid overheating issues, but WBL's don't have that.

[aEx155]

Originally Posted by cantab

Is there any particular reason to use multiple barrels? In real guns (eg gatling guns) it's to avoid overheating issues, but WBL's don't have that.

I think the sole reason to use multiple barrels is to lower the chance of popping balloons. Since the only time they move (in the barrel) is when they're loaded and when they're fired, that leaves very little chance of them breaking.

I'm thinking that you could have a team of 2 - 3 people, one (or two) loading a set of barrels and one firing. That would have the advantage of ROF while keeping balloons safe. Probably you could use some sort of breech system if you wanted to lose the multiple barrels, but that would reduce the ROF.

[Ben]

Multiple barrels are easy to make, relatively cheap, and don't pop balloons. They are also heavier and bulkier.

What I'm thinking of is something that can be held by one person rather than something operated by multiple. Range-wise it'd be able to shoot maybe 200 feet. I might add some simple iron sights to it too to improve accuracy.

Once I find my camera I'll post up a drawing of my concept...

[Silence]

If you try designing a launcher or Nerf gun that uses magazines instead of multiple barrels, you'll find a brick wall when it comes to loading, creating a seal, and firing the balloons without popping them. Sabots don't help too much. Rotating barrels prevent parts from touching the balloons.

[cantab]

There are stock Nerf guns that use magazines. Though of course Nerf darts don't pop.

[CROC]

Oh, but they do cantab, but they do. If enough air goes through a Nerf dart, the top will be forcefully removed from the gun, or the glue will magically wear out, and just the dart head will fly.

[cantab]

Oh yeah...I've actually had that happen, though probably due to crappily glued darts rather than excessive power.

[Silence]

Darts are also too soft in most cases. Many magazine-fed Nerf guns (both commercial and homemade) use complicated shells and ejection systems to make sure the darts aren't crushed. Without shells, you need long springs with low force constants and very tight tolerances.

[aEx155]

Kind of unrelated and related at the same time, but would using CO2 be acceptable here? It's not a water gun, and technically, since there's no chamber to fill (you could make it metal) you wouldn't have to worry about fracture.

Also, cantab's bit about multi-barrel guns having to cool down makes me thing that they would be able to "warm up" after firing, which would reduce the chance of breaking.

I know you could use HPA or bike-pumping really fast, but it was just an odd idea I though about.

[Ben]

CO2 is a bad idea with plastic because the temperature makes the plastic brittle. It's also rather inconsistent unless you have very good equipment. I'd prefer HPA, especially given that they use the same threads and everything.

When I actually get around to making something like this it'll surely start off with PVC pipe but I'd love to get my hands on some CNC equipment and maching something... a simple WBL would be fine to start with.

Though, with CNC equipment I might be able to make a working bolt system, but I'd have to make parts fit together so that there's no seam, which might not be possible.

If I don't post a picture of my idea tomorrow, someone should send me an email to remind me...

[Silence]

HPA expands to maybe 10 to 200 times its compressed volume, depending on the pressure. Propane expands to around 300 times its original volume as a liquid. Carbon dioxide, about 850 times. So there are definite advantages to using liquid gas, plus the vapor pressures are lower than HPA. But vaporization is endothermic and can chill PVC even when deregulated.

Ben, if you *can* use metal for the entire launcher, then you could use propane or carbon dioxide instead and get a massive storage boost.

Originally Posted by aEx

Also, cantab's bit about multi-barrel guns having to cool down makes me thing that they would be able to "warm up" after firing, which would reduce the chance of breaking.

You mean, letting the PVC warm up after being chilled by the passing air? That's probably not a very reliable mechanic and it's pretty risky, if you ask me.