Just playing Call of Duty and noticed the death machine spins and I always wondered why.
In: Engineering
Aiming for the 5yo answer, though many here are great.
Think like an old clothes washer. The dial turns around.
Load water
Wash
Empty water
Same deal for gatling guns. They could have a single barrel. Imagine it going in its circle. Load-fire-empty.
Now just add more barrels so that it can have more shots per minute. (Or multiple shots every circle)
Not every machine gun with rotating barrels is a Gattling gun. The Gattling gun was the crank operated machine gun used in the mid 1800’s to early 1900’s. Modern rotary guns have their own names and models.
As others have mentioned, only gatling guns have to spin to shoot. While heat dissipation and the rate of fire are affected by the rotation, they aren’t really the reason why a gatling gun spins.
Modern gatling guns were developed as faster jet aircraft required a greater volume of fire to hit a target. Gatling guns allow for a greater rate of fire to produce the volume needed. The reason they spin, however, is the rotation allows multiple concurrent cycles of operation within the same weapon.
The standard cycle of operation for a gun is feeding, chambering, locking, firing, unlocking, extracting, ejecting, cocking. In a machine gun, all of these steps must happen in order and the entire cycle must be completed in its entirety for every round that is fired.
The rotation of a gatling gun allows for multiple cycles of operation – one cycle per barrel – to happen concurrently. As the gun (an M61 Vulcan in my head) rotates, a different step of the cycle of operations happens at a specific position. There are six breech bolts in an M61 – one per barrel – that rotate along a cam path machined into the housing of the gun.
Feeding happens at about the 4 o’clock position, when a round is fed into the gun in front of a breech bolt. As the gun rotates, the cam path drives the breech bolt forward, chambering the round and locking at about the 2 o’clock position. Firing happens at about the 12 o’clock position. As rotation continues, the cam path drives the breech bolt back, extracting the brass at about the 10 o’clock position. Then, the brass is ejected at the 8 o clock position.
Because there is a separate barrel and breech bolt at each point, all five of those steps happen simultaneously. On each rotation, each barrel completes a full cycle of operation in its entirety; which also means that on each rotation, the gun completes six individual cycles of operation concurrently.
Because it’s how they work?
Boom, one barrel, reload, cooling time, boom, next barrel reload cooling time..
Then do this really fast.
This depends entirely on the gun.
“Gatling Gun” refers specifically to a series of similar guns designed by Richard Jordan Gatling, from 1861 to the late 1890s. These all had a group of barells that rotated around a single hub. The guns in question were a development of breech loaded Bolt Action rifles that had seen some success in Europe in the mid 1800’s.
In a loose sense it also refers to modern guns with a similar configuration.
Gatling’s innovation was that, instead of the bolt being unlocked, drawn back by hand, the cartridge replaced manualy, the bolt reengaged, and the hammer and firing pin then cocked,…. all those tasks were done mechanically by a series of cams. The cartridges were dropped into the ejection port by gravity, and as one barell rotated to the bottom the bolt was retracted and the spent brass casing dropped, again by gravity.
This can be seen in [this video.](https://youtu.be/ZoMe8hV6uFM)
They were basically just a series of bolt action rifles arranged in a circle. In this way 2 or 3 men could produce the same rate of fire as an entire squad with manual rifles. However it isn’t considered fully automatic since it required the gunner to hand crank it over to fire.
Gatling’s design suffered some major drawbacks. It was subject to friction, making it difficult to turn over. It could easily be jammed by a stray cartridge or broken parts of the mechanism, and there wasn’t an easy way to clear a jam. It was extremely heavy, as much as a moderate sized cannon, which required a cannon cart, making it very exposed for the gun crew. It was difficult to take apart to clean, repair, and maintain. Most importantly recoil forces from firing caused major wear on the parts supporting the barrels which could cause a breakdown at exactly the wrong time.
Automatic fire in single barell can be achieved in several ways.
Certain semiautomic breech loaded, bolt action weapons appeared in the later half of the 1800’s. However these types still required the operator to perform one or more steps such as cocking the hammer or replacing the spent cartridge. (These need to be distinguished from revolver style weapons where the cartridges are permanently held and not extracted and the entire breech block rotates.)
The most successful semiautomatics at that time used a design where the barrel itself could slide back and forward and recoil was absorbed by a spring. The recoil of the heavy barrel itself then pushed the mechanism that unlocked and withdrew the bolt.
In 1884 Hiram Stevens Maxim successfully demonstrated a prototype fully automatic machine gun. Maxim’s machine gun used a sliding barell to push a spring pendulum which extracted the spent cartridge, ejected it, cocked the hammer, engaged a new cartridge, then closed the bolt and finally released the hammer.
An animation can be seen in [this video.](https://youtu.be/hiFGKWPSaas)
Maxim’s gun rendered Gatling guns obsolete. They weighed 1/5 as much, were more reliable and had a better rate of fire. Maxim guns were belt-fed instead of gravity fed which meant they could sustain fire for much longer. Changing them belt took a few seconds. They could be crewed by only two men, and a single man could keep the fire going for quite a while if he had a few spare open buckets of ammo.
One of it’s drawbacks is that friction and hot gases could, after a few tens of rounds, heat the single barrel so hot that it would weakened and warp, damage the rifling, and possibly explode from becoming too soft. To counteract this production models had a water filled jacket that kept the barrel from overheating by simply boiling the water, a cumbers
This is a problem that was only partially solved with new high heat resisting steels in the 1930s and 40s. The German MG-42 used in WW2 was notorious and highly feared for it’s extremely high rate of fire of about 1100-1200 rounds per minute. However at this rate a few seconds of sustained fire wpuld burn several hundred rounds and make the breech visibly dull red hot. To counteract this the barrel was designed to be quickly removed and replaced with a single locking lever. An innovative feature found on many post WW2 automatic rifles.
Just changing an overheated barell on guns mounted on aircraft is out of the question. The introduction of jet engines meant a fighter jet would close on it’s target in a short time and the time within the effective range of guns would be 2-5 seconds.
This means an extremely high rate of fire was needed. Basically, saturate the area where you think the target will be in a few seconds, with as many rounds as possible in as short a time as you can.
Worse, wings on jet fighters needed to be thin which made it impractical to mount half a dozen large heavy MG’s and their magazine and feed belts there. A single fuselage mounted gun with a ridiculously high fire rate was needed, which also wouldn’t suffer catastrophic barrel failure after a single burst.
Enter the ghost of Richard Gatling. The idea was to combine several machine guns into a single rotating chasis and feed them from a single large magazine and single belt, and mount it all on the fuselage.
While Gatling’s original guns weren’t belt fed and were only capable of 200-300 rounds per minute. With modern technology and materials, and a belt feed, that could be increased by a factor of 20x.
It turns out explosions are hot. Lots of explosions in short order will deform or even melt a barrel. If you want lots of explosions quickly you either need some way to cool the barrel (water-cooling the barrel was the standard solution early on) or you need multiple barrels. Spinning those barrels helps cool them a bit, but also lets you stage the action. So while one barrel is being fired the next is being loaded, the previous is having the casing extracted, etc, and each barrel has a longer period in which to cool down before another round gets fired through it.
This video is not ELI5, but has a pretty in-depth look into how the modern miniguns work.
I’ll attempt an actual ELI5 answer:
A Gatling gun is actually several guns glued together. The ammo has to go into each gun. The guns are turned around in a circle so the ammo can go into each gun.
For an in depth, non-ELI5 answer, check out Forgotten Weapons video about the modern version of a Gatling gun: the M134 minigun: https://youtu.be/rIlwHT4IdRc
Also side note: you referred to “machine guns”and Gatling guns as though they are the same when they aren’t really. (To commenters: don’t get super pedantic on me) A typical “machine gun” is something like an M249, M60, or PKM with a single barrel and the bolt cycles forward and back using the gas from the firing shot. A minigun has multiple barrels and is electrically driven rather than gas operated.
2 reason:
1: what everyone else says. multi barrels = multi loading, letting you load much much faster than single barrel, as you need to clear the chamber before firing again. in multi barrel design you dont need to immediately clear it, just cycle to the next and fire.
2. when you have 1 barrel, all your bullets are going to come out of there. when you are shooting the amount of lead a vulcan is, at the insane rof of 6k+ rounds per min, you are going to destroy/warp the barrel regardless of what alloy you use. but when you have 6 barrels. instead of shooting 24,000 rounds down 1 barrel, you are splitting it to 4,000 round per barrel. greatly prolonging the life expectancy of the gun. Because unlike games, changing the barrel is a pretty tedious task.
Because it has multiple barrels. This allows it to shoot faster than one barrel. At a ELI5 level they strapped 6 guns together so it shoots 6x faster than a normal machine gun.
But it’s not literally 6 whole guns. As the barrels rotate they get a bullet loaded and then rotate into a position where they get fired by a single trigger. This is faster than having one barrel because it takes a little bit of time to load and unload a barrel so by having six you can do it faster
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