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June 8

Xylocopa pubescens carpenter bee.

I recorded sounds emitted from a nest of Xylocopa pubescens carpenter bee.

Any information concerning the exact nature of these sounds will be appreciated. Etan J. Tal^(talk) 19:44, 8 June 2019 (UTC)[reply]

sounds like squeaking, produces by friction, this friction being caused by the movement of the bee Gem fr (talk) 20:41, 8 June 2019 (UTC)[reply]

Mechanics of gas powered rotary cannons

There is a lot of material about the mechanics of electrically powered rotary cannons (e.g. Minigun), but i can't really find any information about gas powered ones (e.g. GSh-6-30). How do they actually, mechanically work? Do they have some sort of gas piston, that cycles the weapon in discrete steps for every single shot, similar to standard machine guns? Do they have a gas turbine, that just sets the barrels in motion like an electric motor does? Something else?

I can only find find sources saying something like "the russian gatlings are gas powered, so they fire faster." But why do they? --178.4.77.247 (talk) 20:45, 8 June 2019 (UTC)[reply]

They're gas operated. Gas from the fired barrel is tapped off and works a piston in the cylinder on the side of the frame. This piston has a rack and pinion gear on it, which drives through a short radial shaft to another pinion, which works the radially-toothed ring gear you can see here. That drives the barrel frame around. The piston also cocks the action. A further ring gear and pinion (parallel teeth), also visible here, drives the feed. You can also see the piston return spring here, which is a twisted wire helix. They're prone to failures and the multiple wires keep the action working even if one strand fails.

Compared to the US weapons, the drive is more powerful and so it accelerates to full firing rate more quickly (useful for air combat). However it's too powerful, there's insufficient damping or end stops, and it shakes airframes to bits. The naval mounts are much more robust and survive by sheer Soviet brute force. What it really needs is a gas valve which would reduce the power once up to speed. Andy Dingley (talk) 21:09, 8 June 2019 (UTC)[reply]

Thanks a lot! This is much more information than i've found through Google. I would suggest to also put it onto the GSh-6-30 article.

If i may risk some speculation, could my idea of a turbine powered gatling possibly work? It should solve the problem of the piston hammering the mount. Also, like with electric motors, as the barrels spin freely they should be able to eject some misfired catridges without stopping the gun. But i guess it might need a kickstart to get the ROF high enough to sustain operation. --178.4.77.247 (talk) 22:00, 8 June 2019 (UTC)[reply]

Turbines are naturally best for low torques at high speeds – which isn't what a firearm needs, at least not for starting. The piston mechanism (which is used in every gas-operated weapon) is a better impedance match (ratio of force or torque and speed) to what's needed here. But it's a bit crude for secondary effects, such as the vibration. No doubt it met someone's Five Year Plan, and that's the Soviet way. Andy Dingley (talk) 23:00, 8 June 2019 (UTC)[reply]