Micro Gatling Pneumatic

[inonickname]

I'm designing a micro gatling gun. I'll use a cellphone (vibrator) motor to rotate the barrels (8 barrels, about 3.5mm id, 2mm apart). Power source would be from a high pressure portable source (I'd be using a compressor with a onboard tank). Each barrel should have a small extension which actuates a valve as the barrel centers to the chamber. (and closes after the shot). If I can't find a setup to suit that it'll just run continuously (no valve, just have gaps inbetween barrels to exhaust pressure. Power comes from a rechargeable 1/4 aa battery (same width, less length) which can be charged off to aa's after use (about 5-10 minutes. For reloading I'm thinking of a micro vortex style inside the chamber, or a kind of "scoop" on the end of each barrel which picks a bb up from the tray. A small plate seals it at the top to airtight it during firing.

Sounds very hard/impossible I know.. but input welcome. I'll post a few diagrams I drew up tomorrow.

[jackssmirkingrevenge]

Interesting idea, scaling down the design would certainly reduce many of the logistical problems associated with rotary barrel designs. Some thoughts:

Fist of all, I don't think a cellphone motor will quite cut it, I think you need at least one of the ubiquitous mabuchi type motors.

What were you planning on using as ammunition? If it's spherical lead shot, then I would recommnend making a cloud BBMG with multiple barrels. This would allow you to use a constant flow valve, avoid having a reloading mechanism on the barrels and the blocking/unblocking motion of the barrels over the air/ammunition exit would improve your efficiency and power.

Alternatively, you could have a sleeve over each barrel that covers a slot of ammunition to be fed from an external hopper, with the cam alternately opening and closing the sleeve for loading and fiting respectively. On this scale, I think a separate valve would be an unneccesary complication and you can get away with using say a blowgun to provide constant flow. In this case as well the blocking action of the rotating barrels would minimise air loss.

For a small calibre, you're going to need significant pressures for decent power, in the order of several hundred psi at least. An on board compressor and tank isn't quite going to cut it, it would be more realistic to use a HPA/CO₂ bottle feeding through a regulator.

[jimmy101]

To get the vibrator motor to work you are going to need a pretty substantial gear reduction train. That motor probably has nearly zero torque at it's no-load speed, which is something like a couple thousand RPM. Probably better to get a motor with more power and a built in gear train. Something that is going at perhaps 200 RPM. (Check the motors at www.allelectroncs.com)

A vortex chamber requires air flow through the system to "chamber" the next round. If the chamber's outlet is getting opened and closed you might not get a round chambered consistently when the barrel is aligned. A sweeper type mechanism in the chamber coupled to the rotation of the barrels might work better. The sweeper could also seal and unseal the chamber outlet to the barrel. An air tight seal wouldn't be needed (though it would be nice), you just want the leakage to be significantly less than what the air supply system can make up.

If you can seal / unseal the chamber then your air efficiency is going to be much better. Votex's, even with a 120 PSIG source, only operate at something like 15~30 PSIG. If you can open and close the the chamber to barrel connection you might get reasonable performance from a 120 PSIG source since the air supply will be able to keep up much better and you'll have much less pressure drop in the system.

A gattling type gun would be pretty cool, though I'm not sure it'll accomplish much. Vortex and cloud BBMGs already fire about as fast as a modern gattling gun (like a minigun). The advantage of the gattling would be if you can seal and unseal the barrels so you can maintain much higher chamber pressures.

[jackssmirkingrevenge]

The advantage of the gatling would be if you can seal and unseal the barrels so you can maintain much higher chamber pressures.

Not only that but you can control the rate of fire using a rheostat and slowing the rate of fire down means more time during which the "valve" is open and therefore more power

[inonickname]

When I was thinking about reloading mechanisms and the vortex I realised that unless I got a very fast motor the vortex would have a better rof anyway. How much does it hurt a vortex's performance to not have a constant airflow through the barrel, only for a short time? Would it even work consistently?

[jackssmirkingrevenge]

The fact that you're be sacrificing ROF for an increase in internal pressure and therefore indidivual projectile energy would make it a better launcher.

I agree with Jimmy though that the shaft of the rotating barrels should extend into the chamber and maybe be linked to an agititator to provide reliable feeding.

[inonickname]

So if I use an agitator through the bb's, which will then exit the barrel when in the correct position hopefully, will it actually fire or will the barrel not be in place long enough to release the bb's?

[jackssmirkingrevenge]

With BBs leaving the barrel of a BBMG at a rate of tens per second, I think you'll have the opposite problem, ie getting only one BB per barrel

[inonickname]

I've begun construction. Sourced a motor and cut the barrel disks and found the barrels. Barrel disks are made of 4mm perspex. Going well so far, I'll get some pictures up soon.

[Ragnarok]

It's a spam drop. Moderators are being called guys.

EDIT: Irrelevant now, the post I was referring to has seemingly been deleted.

[jrrdw]

A few members got their websites in their sigs, hold off we will see where it goes.

[mikemurph]

Wow, That'll be one heck of a mini!

[Gaderelguitarist]

If this is successful, you better get ready to produce a lot.

I've only seen Gatling airsoft guns priced at over $600 USD, and they tend to be uselessly big and heavy.

[Moonbogg]

It's a spam drop. Moderators are being called guys.

this thread is a spam drop? I don't get it.

I'm trying real hard to not make an immature reference to vibrator motors. I love your idea for a gun. It should be awesome. Let me know if I can do anything to help.

[inonickname]

This is an old idea, I have everything drawn up (on irl paper, whoa?).

I have several detailed images of the firing valve and magazine (one per barrel) though I do not have the resources nor the will to build it. You would need a lot of brass telescoping tubes, motor, rheostat, valves, drill press, holesaws.. a lot of work for a lower rof than a strafer.

I can make some new ones in paint if somebody is really willing to make it.

By the way, I'm lost. Spam drop?