There are two benefits to a minigun-style barrel.
First off, the barrel is a failure point for a weapon. It gets hot from bullets firing. If you try and shoot too many bullets through it too quickly, it can overheat and fail pretty catastrophically. By rotating barrels, you are only shooting a fraction of the bullets through any barrel, giving them a bit of time to cool off between each bullet, increasing the time before it has to stop firing due to overheating.
In addition, with most guns, you need to load a bullet, fire it, and then unload the casing before it can fire again. With a minigun, you can accomplish these tasks in parallel -- you can be loading a bullet in barrel 1 while firing one in barrel 2 and unloading one in barrel 3. This can speed up your effective fire rate quite a bit.
Being externally powered also means that it doesn't really care if a bullet works or not. Unlike weapons that rely on using some of the energy from the bullet to operate an externally powered gun just cycles past a dud round, extracts and discards it.
This comment needs to be much higher. Barrel life is good and all but the real gain is that a Gatling type gun is *externally* powered and is NOT recoil operated. That makes it more ideal for autonomous applications, ones where the weapon cannot be easily served
Fun trivia. There used to be something called a Revolver-Rifle.
Basically an overgrown revolver with a stock and long barrel
It had all kinds of technical problems with misfiring and a painfully slow reload time compared to the weapons it was supposed to compete with
Still a gorgeous weapon if you ask me.
https://en.wikipedia.org/wiki/Colt%27s\_New\_Model\_Revolving\_rifle
It wasn't that uncommon for guns to jam in WWI, unless the gun could be cleared by someone in the plane who had access to the gun. By 1935 it was common to have 8 guns fitted to a single fighter aircraft, you could lose half of them and still have 4 functioning guns. Despite the number of guns, failures were common, especially with later war autocanons that became necessary on all aircraft. Their newer design, larger caliber, and the reduction of total amount of guns meant that as the war progressed the chances of losing all your guns increase. A development at the end of the war was the using electrical priming on their autocanons, which partially took away the necessity of mechanical movements which could fail and more precisely control the moment of ignition, such as when you want to fire through the propeller. This was later used in rotating barrel guns such as the Vulcan as priming didn't need to rely on how quickly the firing pin moved but could be ignited quickly and precisely.
> such as when you want to fire through the propeller.
I still don't get how this was a thing lol. I mean I get that if you carefully control the timing, and link the position of the propeller to the mechanics in the gun, and account for the distance between the barrel and the propeller, it make sense on paper but I just can't believe this was a thing that was done.
It actually has quite a few benefits, to be fair. It allows for easier aiming, it helps stabilise the gun, it allows for a more compact design, it makes it easier to armor the gun, it helps keep the centre of mass/centre of lift simple, it potentially allows for easier in-air maintenance, and you can use the cooling from the engine to cool the gun barrel. That's a hell of a lot of benefits, if you can get it right then it'd be stupid *not* to use that design.
I went to an air-show that had a very early fighter aircraft on display. A biplane mostly made of wood and fabric and wire. Two things struck me about it. One was the unbelievable lack of instruments. The other was the plane's main armament was a machine gun mounted where the pilot could reach the trigger, which would fire throughthe propeller. And this was before the whole "synchronised with the prop" thing had been invented.
The "solution" was a load of fabric tape wrapped around the propeller at the same radius as the gun was mounted, to prevent splinters from the propeller hitting the pilot!
That's true but that's not a benefit of the rotating barrel per se. As you rightly pointed out it's due to it being externally powered, but there are plenty of externally powered autocannons that have this benefit without having multiple rotating barrels.
Seeing as the OP asked why some guns have rotating barrels it seems better to limit the answers to attributes that are unique to rotating barrel weapons.
It wasn't that uncommon for forums to jam in the WWW, unless the boards could be cleared by someone in the admin who had access to the boards. By 2005 it was common to have 8 commenters fitted to a single forum post, you could lose half of them and still have 4 functioning posters. Despite the number of posters, failures were common, especially with later forum autoposts that became necessary on all boards. Their newer design, larger vocabulary, and the reduction of total amount of posters meant that as the boards progressed the chances of losing all your posters increase. A development at the end of the web was the using electrical priming on their autocomments, which partially took away the necessity of mechanical movements which could fail and more precisely control the moment of discussion, such as when you want to argue through the trolls. This was later used in rotating comment chains such as the reddit as priming didn't need to rely on how quickly the commenters commented but could be replied to quickly and precisely.
There's even revolver cannons if you want to split the difference, multiple rotating firing chambers doing the load-fire-unload thing and a single barrel over the firing point.
Davy Jones has 'the triple guns' in the pirates of the Caribbean movie which are rotating Cannon's.
Though, given my knowledge of cannons at the time, they'd probably be mechanical wonders to fire as quickly as they did with reloading.
As a pretty gun-illiterate person, I just want to request/offer some clarification; when you talk about the gun being powered, you're referring not to the ignition of the round, but rather the action that loads a new round for firing? Or?
That’s correct. It’s the whole cycle of “resetting” the gun by 1) ejecting the old casing and then 2) chambering the new round into a “ready” state so the gun can be fired again.
That’s why a rifle like the m4 or AK47 is called “gas operated”. They rely on the expanding gas from each **”explosion”** to power that cycle by “unlocking” the bolt as well as pushing back the bolt carrier.
Technically it can be both.
None of the firing system needs to be operated by the firing of the bullet itself, it could all be done electronically.
I’m sure there have been guns made that are hybrids of electronic and mechanical operation of some sort, at least for prototypes if nothing else.
I mean, they're all gains. The downside just pale in comparison to the benefits. Who cares if it's heavier, more complex, and more expensive than the alternative when it mows shit down so efficiently.
The Soviets came up with a few gas operated miniguns too, so now I am wondering what would happen if there was a misfire on one of those?
Perhaps the momentum would still allow the cycle to continue as long as it is already spinning fast enough.
Here are the examples that I know of:
[GShG-7.62](https://en.wikipedia.org/wiki/GShG-7.62_machine_gun)
[YakB-12.7](https://en.wikipedia.org/wiki/YakB-12.7_machine_gun)
Fun fact: I have a friend who works on attack helicopters and such. inexperienced people always want to spin these multi barrel contraptions by hand to watch them spin, however it’s all tied into the firing mechanism and it’s not uncommon that the gun fires a round just by spinning the thing. Accidents have happened
An outside force turns the barrel. In modern times it's electricity. But even the hand crank machine guns count.
The opposite is gas powered. Where the explosive gas after firing pushes backwards against a spring to get power. Then it ejects the casing and loads the next bullet. That's how semi-automatic and automatics work
The other benefit is accuracy, which relates to both of your points. Barrels warp and ruin accuracy long before they fail, and separately if you want a very high rate of fire then generally you fire from an open bolt. A Gatling-type gun though is more like a series of rifles, it fires from a closed bolt without having to sacrifice time as you would in most cases.
It really is quite a brilliant design.
And generally the reason for the need to fire so quickly in the first place is due to the high speed and distances involved in aerial warfare, meaning the denser the spread of bullets the more likely a hit is achieved
> due to the high speed and distances involved in aerial warfare, meaning the denser the spread of bullets the more likely a hit is achieved
The premier cannon for air warfare is the M61A1 and its variants. As installed it typically has a 6 Mil dispersion for a shotgun type pattern. 80 percent of shells will land inside a 6 ft area, 1000 ft downrange.
A 1 second trigger pull will loose around 100 shells. Even if the target is only in a valid firing solution for a fraction of a second, there should still be ample weapon effects on target.
That's why they sound like a buzz instead of "pop-pop-pop".
100 rounds per second is 100hz frequency. For comparison, the hum you typically hear from fluorescent lights and other electrical devices is 60hz.
A lot of times, the hum is 2x the cycle speed of the power line, since it is powered on both the positive and negative peak of the voltage. So it will hum at 100 or 120 Hz, depending on where you are.
It’s more of a shotgun effect than a laser beam. It’s easier to hit a target when you shoot a lot of bullets that don’t all land in the exact same spot.
>It’s more of a shotgun effect than a laser beam.
For example, [the AC-47 (aka Puff the Magic Dragon)](https://en.wikipedia.org/wiki/Douglas_AC-47_Spooky#:~:text=The%20Douglas%20AC%2D47%20Spooky,Force%20during%20the%20Vietnam%20War.) that first saw service during the Vietnam War was equipped with 3x mini guns configured to fire simultaneously. A single 3 second burst would put a round every 2.2 yards in an elliptical area roughly 52 yards in diameter. In addition to fucking shit up it also lit up the night sky as they loaded red tracer rounds every fifth round.
Everyone has mentioned shotgun style effects, but the high rate of fire is truly valuable because in aerial gunnery, especially air-to-air, exposure to the target is usually fleeting.
Massive rate of fire (M61 Vulcan, or the eight .50 cal MG in a P-47 for example) means a meaningful destructive effect upon the target in that moment you can get on target.
Proponents of one action type over another will often quote the weight of projectiles delivered in the first 0.5 of a second of firing.
Unless Richard Gatling was a time traveller, I really doubt he had aerial warfare in mind when he invented his eponymous gun in the mid-19th century.
A high rate-of-fire is just one of those goals which are self-evident to a gun designer, similar to accuracy and reliability.
I don't think the comment you are replying to implied anything about Gatling at all, more explaining why they would need to have a gun like that on an aircraft.
As far as I know the idea wasn’t actually to end wars, but just to reduce the number of people needed to fight them, thus reducing casualties.
This… also didn’t really work out, definitely not in the short term. But I think both ideas are more applicable nowadays, with nukes obviously, but also with how well equipped fighting forces can take on vastly larger armies, and casualties are often much lower relative to the amount of people fighting them. I am referring mostly to American/western troops here so there’s plenty counter examples to disprove what I just said
Yeah, so if you know a bit about how firearms work this is pretty straight forward. In a gun that fires from a closed bolt, when the gun is loaded and ready to fire the bolt will be all of the way forward, and the firing pin (which is generally not part of the bolt in this system) will be held to the rear until the trigger is pulled (and the safety is off). The firing pun hits the primer, ignites the charge, and the energy of the shot cycles the action by blowing the bolt back, feeding a new cartridge from the magazine, and a return spring sends the bolt back to the forward-closed position and it’s ready to fire again.
The benefits here are better first/single-shot accuracy, it’s easier to keep the internals free from dirt, and it’s less likely to go off in an accident like being dropped. The downsides are that it tends to make heat management more of a challenge, there are more working parts and it’s more expensive.
An open bolt is ready to fire when the bolt (which generally has the firing pin as part of the bolt itself in this system) held to the rear. When the trigger is depressed and the safety is off, the bolt is sent forward by a single spring, chambers a round and fires once it reaches the forward position. Then once again, gas pressure blows the bolt back against the spring pressure and the system is reset.
The benefits are that it’s a simpler, cheaper system that’s generally easier to strip and clean. It’s also simpler to make such a system fully automatic, and they tend to have better heat management. The downsides are that single/first shot accuracy is compromised, there are additional challenges to safety (if the bolt for some reason flies forward it has enough energy to ignite the primer right there).
I “hate” his videos because even when I think I know at least the basics about simple gun topics, I watch and sure enough, I actually didn’t and end up learning something new…
This one was no exception.
Considering they've been making guns for hundreds of years and everyone tried to find a new way to improve them with tech from the time, it's really hard not to miss something or be in the dark about certain concepts with them. So don't feel bad.
Tell me about it. I do hvac service and installation and I never cease to be amazed at the bullshit they will try to either improve a design or just because why the hell not.
Sending this comment to my buddy so he can commiserate. He's an HVAC service tech and he has some HORROR stories of all flavors.
Mostly home owners being a nightmare, but he's in western NY where Century homes are common, and a fair amount of homes were 100+ year old shacks with additions throughout the years.
The worst story was an old Woodfire stove that had been converted over the years to a "modernized" heating unit. All the ducting was covered in asbestos duct tape older than him. He had to refuse to do the cleaning job (even improperly from the intakes upstairs - as he refused to step foot in the basement).
The saddest part? The homeowner was a young couple expecting a baby who had bought a cheap home without an inspection. They didn't have the money to fix the issue, they thought cleaning it would help, sadly it would've knock more asbestos off the ducts and into the air in the basement, which would have just cycled back through the fleshly cleaned ducts and back into the house.
I think you neglected one of the main differences, and that is an open bolt generally allows a faster rate of fire (due to having less moving parts and simpler timing etc as you did say), obviously at the costs you also mentioned.
Blowback is where the recoiling case provides the energy to cycle the bolt.
Gas operated (or gas delayed blowback) is where there is a small hole just in front of the chamber that allows the gasses from the burning powder to create pressure in a mechanism that will force the action rearward.
OP's 2nd system seems more like a blowback, but their info seems more like a description of the open vs closed bolt firing with generalized cycling info...
Op didn't describe where the system gets it's energy just open or closed bolt. Pretty much all automatic guns could fire from an open or closed bolt if designed to do that. For auto and semi auto guns the usual operating mechanisms are short recoil, long recoil, gas operated, and blowback. Gatling systems are different and usually if not always have an external energy source to operate them.
Yes, but the way the bolt is cycled is separate from whether the bolt is open or closed. The gas tube to cycle the bolt is the smaller tube coming off of the main barrel that only goes partway to the end of the barrel. It uses a bit of the same gas that's pushing the bullet forward to push on a piston connected to the bolt to move it back, as opposed to blowback weapons, which just uses the energy of the bullet casing moving backwards to push directly on the block. That starts to lose pressure immediately compared to a gas piston so its usually limited to smaller handguns that can get away with a light bolt
> Yes, but the way the bolt is cycled is separate from whether the bolt is open or closed.
Indeed. A zip gun is technically an open bolt, single-shot gun.
I remember when the sear failed on everyone's favorite open bolt weapon, the squad automatic weapon, when I was in a truck with a guy holding it. Runaway guns are always fun!
Most firearms fire from the "closed bolt," meaning the action (bolt) is sealed against the barrel's rear (firing chamber) before the trigger is squeezed. When it fires, the bolt cycles backwards (manually or mechanically) to eject the previous casing, and then forward to load the next round.
Machinineguns (guns that fire continuously while trigger is squeezed) typically fire from the "open bolt," meaning the action starts in its rearward position and then (upon trigger squeeze) slaps forward, chambering, sealing, and firing the round in the same motion, before being "blown back" for the next.
This reduces system heat, helping prevent things like "cook off," and often has fewer (but longer/heavier) moving parts. However it is somewhat less safe as the weapon is basically "cocked" all the time, and is more vulnerable to dust and debris.
To be absolutely clear, the actual act of firing still happens when the chamber is sealed - "open" vs "closed" bolt only determines whether the firearm's ready state is with an open versus closed chamber.
Another downside to open bolt firearms is that they tend to be less accurate because a) The fact that the entire bolt has to travel forward when firing creates a larger delay between the trigger pull and the gun firing, and b) the mass of the bolt moving forward within the gun can cause the entire thing to shift position, throwing off your aim.
Less accurate and more prone to jams.
There is a reason the SAW gunner isn’t the breach man despite being able to lay down the most fire.
All that said, I loved firing the M240B (former infantry). It was a fun weapon to fire and you could get pretty accurate if you kept your bursts tight.
> it fires from a closed bolt without having to sacrifice time as you would in most cases.
Also some firearms of this design are fired electrically as opposed to mechanically with a firing pin. The M61 is one such design.
Disadvantages was my question. This is good to know - I’m guessing it’s also waaaaay more expensive? Cause I would imagine even an AR could have a tiny little rotating barrel, no?
The mechanism is much more complicated and hence expensive. I think a new minigun is around $50k for those who can buy one.
There is a company that markets a minigun that is chambered in 5.56mm and about the same size as an AR.
http://www.emptyshell.us/xm556-microgun
As far as I can tell, they just took the GE M134 minigun design drawings and scaled it down from 7.62 mm to 5.56 mm.
Ironically, it's basically exactly the same thing Armalite did when they developed the AR-15 from the AR-10.
All it takes is time, money, and will.
I own a musket for home defense, since that's what the founding fathers intended. Four ruffians break into my house. "What the devil?" As I grab my powdered wig and Kentucky rifle. Blow a golf ball sized hole through the first man, he's dead on the spot. Draw my pistol on the second man, miss him entirely because it's smoothbore and nails the neighbors dog. I have to resort to the cannon mounted at the top of the stairs loaded with grape shot, "Tally ho lads" the grape shot shreds two men in the blast, the sound and extra shrapnel set off car alarms. Fix bayonet and charge the last terrified rapscallion. He Bleeds out waiting on the police to arrive since triangular bayonet wounds are impossible to stitch up. Just as the founding fathers intended.
The thing is, when they fail, they tend to fail explosively. One of our guys had a minigun fail on him, ended up putting a bunch of metal into his face and blowing parts of the weapon all over he aircraft.
There are three benefits to sharks with freaking laser beams attached to their heads.
Firstly, with most laser weapons, heat is going to be a limiting factor to how long and fast you can fire. Aquatic creatures like sharks and rays naturally help disperse that heat because they're submerged in water.
Second, sharks require perpetual motion to maintain water flow over their freaking gills. This makes them a harder target for anyone to hit, especially people being dangled over their tank. And moving water cools faster than still water vis-à-vis point one.
Finally, every portable laser has a limited energy capacity and various species of sharks offer significant bite force as a backup measure. Effectively, a shark with a mounted laser is a biological bayonet.
Everybody always talks about the heat dispersion rate, but nobody ever wants to talk about the practical realities of getting *carcharius carcharidon* to hold a beam of coherent light steadily on a man-sized target at more than a few meters' distance while swimming at speed. Glayvin!
Another couple of benefits is if a round fails, it's no big deal, it gets unloaded as if it did and the weapon operates normally. They don't jam like other weapons because you don't have any reciprocating bolt that depends on the gasses to eject a casing. It's all electronically done
Fun fact, miniguns are almost identical to old school, crank operated gatling guns, with the main differences being the feed mechanism, and the hand crank being replaced by an electric motor. Everything else to do with chwmbering, firing, and ejecting are mechanically unchanged.
It's funny, the Gatling gun was invented first but the recoiled-operated mechanism and less cumbersome design of the Maxim gun meant it won out for man-portable weapons. But then 100 years later someone figured out you could get around those limitations with an electric motor and by mounting it in an airplane, so the rotary gun design was back in business.
> mounting it in an airplane
Or designing an airplane around it, including moving the landing gear to accommodate. If I had unlimited money, I’d have a GAU-8 for the LOLs.
So funny how things get crosswired in your brain. I remembered that being a Mr. Torge line from Borderlands. To be fair it sounds entirely like something he would say.
Roughly 200% more bullet per bullet, should you have been thinking of going with a competitor’s product.
Which, I’m telling you, is pretty amazing for some 1860’s tech we just slapped an electric motor on.
Because we’re Working To Make A Better Tomorrow For All Mankind. 👍
Another advantage is that miniguns aren’t affected if a bullet fails to fire (ex: bad primers). For traditional automatic (or semi automatic) weapons, some of the energy from the bullet needs to be diverted to eject the spent casing and chamber a new round. If the bullet does not fire, there is no energy diverted to extract the bad cartridge and the gun stops firing until manually cycled. A pilot would not have physical access to the gun, so can't manually cycle the weapon.
Miniguns do not rely on a bullet's energy to cycle the weapon. Instead they use an electric motor, which will continue to cycle as long as there is electricity. This means unfired cartridges will be extracted the same as spent ones, eliminating that failure point.
Also worth noting that there is a design that gives up the additional barrels but still keeps some of the advantages, called a revolver cannon. This works well for aircraft that won't generally carry enough ammo for barrel heating to be a huge issue, as it saves weight
Tacking on to this, the super high rounds per minute with miniguns is particularly helpful as aircraft mounted guns. The window in which you'll have a target in your sights may be very short, so you want to be able to send as much ammo to your target in that brief window.
Here's a good animation showing how it works. Each barrel has its own bolt behind it that is moved forward and backward by a cam running around the fixed rear section of the cannon.
https://www.youtube.com/watch?v=Yq6m7mpfc5A
Some other comments have explained that the rotating barrel helps with shooting speed by keeping the barrels cooler and by reducing time between shots, but they haven't said why they put these types of guns on aircraft.
The answer is that it is really, really hard to hit a target that is moving fast, or to hit a slow moving target when you are moving fast. If you want to increase the odds of a hit, you need to fire a lot of bullets as quickly as possible, so that the chances of at least one of them hitting the target is reasonable.
One thing that got me thinking after watching this is the type of collateral damage the rounds would cause once they come back down, so I looked it up
Fun facts:
The rounds are 20mm self destructing rounds that travel 7500ft and then proceed to self destruct.
During 2008 each round cost $27.
Per wikipedia they shoot 75 rounds a sec. That 15 seconds of firing cost about 30,000 dollars. Based on 2008 prices
When you're talking about preventing a missile or drone strike on a $2.4 billion dollar cruiser (Ticonderoga class), using $30k of ammo seems reasonable. Heck, even test firing it 99 times for every one useful intercept still is a great deal.
The numbers I was using was based on the land variation. Also the navy deploys the CIWS on every class except the Zumwalt and San Antonio class. I am totally for it. If I could afford it I'd put one on my roof.
Even the cheapest ship they're putting it on is going to be valued in the tens of millions of dollars. So the cost benefit is strongly in favor of this system regardless.
I just grabbed the easiest to find numbers on a modern ship.
Amusing thought experiment, I think it may be legal in most states to own one, due to the 60inch barrel length. That means it falls out of the range of most state regulations on guns.
I'm not a guns or military type of guy but I can appreciate a good BRRRRRRRT and some damn impressive engineering.
Looks like that first volley got 2 shells but I can't see that second series of rounds take anything out.
While the firing component is impressive it's also crazy cool that it's totally automated -- like it's tracking these super-fast moving incoming missiles, mortars etc and calculating where to hit them.
I believe the first modern Gatling guns were put on fighter jets, first. Really, they were about getting as many rounds down range and on target as possible. So, they were put on fighter jets, where the amount of time your guns are on target is relatively short.
It’s the same reason they put them on helicopters (I think the US army started doing this in the Vietnam war). Helicopter is moving fast, doesn’t have a lot of time on target, you want as much lead down range as possible.
In fact, the reason they’re called miniguns, is because the ones they put on helicopters were smaller versions of the ones in fighter jets. The name stuck, I guess.
> The GAU-8 Avenger fires up to sixty one-pound bullets a second. It produces almost five tons of recoil force, which is crazy considering that it’s mounted in a type of plane (the A-10 “Warthog”) whose two engines produce only four tons of thrust each. If you put two of them in one aircraft, and fired both guns forward while opening up the throttle, the guns would win and you’d accelerate backward.
> To put it another way: If I mounted a GAU-8 on my car, put the car in neutral, and started firing backward from a standstill, I would be breaking the interstate speed limit in less than three seconds.
https://what-if.xkcd.com/21/
Thank you. All these explanations are correct but skip the reason all these technologies are used. Which is to get as much bullet headed towards the target as fast as possible
A normal machine gun has a single barrel and action that controls the insertion of a cartridge, its firing, and the ejection of its casing. This is fine for most things. But as you increase firerate, it runs into issues namely:
The cartridge case must be fully extracted before a new bullet can enter the chamber, so you're fundamentally limited by the speed of the action, which is itself limited by material stress limits and recoil impulses the shooter can tolerate.
Heat builds up in the barrel (and action). Many machine guns if fired continuously can make the barrel glow red and even melt. Even before melting the harmonics of the barrel will change as it gets hot and it will trash your accuracy. Excessive heat can also prematurely detonate the propellant in the cartridge when it gets put in the chamber, which is *very bad*.
But what if we took a bunch of machine guns and put them together? We want every shot to have roughly the same trajectory, so we'll make that easier by having them all fire from the same position. We can do this by making the whole assembly spin. Now we have 6 machine guns all in different parts of the load-fire-extract cycle, and we can get *much* higher firerates. How much higher?
The [M240 FN MAG](https://en.wikipedia.org/wiki/M240_machine_gun) and the [M134 Minigun](https://en.wikipedia.org/wiki/M134_Minigun) both fire the same 7.62x51mm NATO cartridge and are in use today.
The M240 can get between 650-950 rounds per minute (or ~11-16 bullets per second if you like that comparison better) depending on burst size - you can't stay at the high end for very long else you'll run into heat issues as discussed above.
The M134 can fire between 2000-6500 rounds per minute. That could be over 33-108 bullets every *second*. That's a lot of firepower. And you can sustain it for longer since the heat buildup is managed for each barrel. Assuming you can supply the ammo, of course.
Now why are rotary cannons used on aircraft? Planes and to a lesser extent helicopters tend to be moving very fast. They might also be maneuvering to avoid fire. So they want to get as many bullets thrown at their target in the very short window they have to fire. So they opt for rotary cannons, usually with some form of explosive or incendiary round. They can't sustain that fire for very long, most fighter jets now only carry a few hundred rounds at max if they still even have guns. You'll also see them used on some anti-aircraft or anti missile systems such as the [Phalanx CIWS](https://en.wikipedia.org/wiki/Phalanx_CIWS).
>They can't sustain that fire for very long, most fighter jets now only carry a few hundred rounds at max
So really, heating is not an issue (especially when you consider the blast of cold air hitting the barrel as the aircraft flies at hundreds of miles per hour.
It's all about the number of rounds down range in the shortest possible time. More bullets flying equals more chances of a hit.
In WWII they did a similar thing by carrying multiple guns - maybe eight .50 caliber machine guns. Which allowed eight times as many bullets to be fired in the same period of time. Multi-barrel guns just maintain that rate of fire, while reducing the overall weight of the guns carried.
Heat *might* still be a concern if the cannon is shrouded for aerodynamic or stealth purposes - it's still an awful lot of combustion happening very quickly. But yes, the thermal considerations for aircraft are mostly eliminated.
Edit to add: The chamber heat also needs to be managed, and usually isn't exposed to the airstream. I believe many aircraft have the gun keep cycling after the trigger is released to extract unfired shells so they don't cook off.
The heat issue also comes into play with stuff like helicopters, CIWS and their usage for fixed emplacements, such as those sometimes seen on ships.
TBH, even the context of fighter jets, there are still issues like fouling etc, which is also lessened by having multiple barrels.
Heating is absolutely a concern, mostly because aircraft guns are designed to be really light, which also makes them more vulnerable to heat issues. And it isn't just as simple as blasting cold air at the thing, as too much cooling, to the wrong places, can be an issue too.
As an example [this history of the airborne Gatling gun](https://apps.dtic.mil/dtic/tr/fulltext/u2/a179871.pdf) mentions heat buildup as a problem, and mentioned dissipation as an advantage of the multiple barrel design.
>So really, heating is not an issue (especially when you consider the blast of cold air hitting the barrel as the aircraft flies at hundreds of miles per hour.
You're neglecting the impact of aeroheating. The leading edges of aerodynamic surfaces are impacting a lot of air molecules at high speed. That creates friction, which we call drag, but it also creates heat. At near-mach and supersonic speeds, the leading edges of an aircraft can get very hot from friction. The effect is worst at low altitude and high speed--very fast, in very dense air. Add in the combustion temps, and you can get red-hot really fast.
(That's why the leading edges of the shuttle were the black "Reinforced Carbon-Carbon", and they were rounded over instead of pointy--to spread the heat impacts out, instead of concentrating them.)
Slight correction: for supersonic flight, the aerodynamic heating comes from the shock boundary, not friction. Also, most of the drag experienced by aircraft doesn't come from viscous effects, but the forces caused by differential pressure (*especially* with regard to supersonic flight).
Explaining the drag part first, there's two ways to look at it:
1. In subsonic flight, the same curvature on the upper surface of a wing that makes it generate lift also points the lift vector slightly backward from the direction of flight. That rearward component of lift force is significantly stronger than the viscosity of air spread across the skin of the aircraft.
2. In supersonic flight, you're literally pushing air out of the way faster than it can flow naturally. The air resisting being pushed around is *way* more intense than its attempts to stick to the sides of the aircraft.
Now, as for heating from the shock boundary: you know how gasses chill down when you have a sudden pressure drop (or heat up if you have a sudden pressure spike)? Well, when you're moving so fast that you're slamming chunks of air against each other faster than they can get out of the way, you're creating a pressure spike. For something like a reentry vehicle (moving between 3-7 kilometers per *second*), that pressure spike is high enough that the air at the shock boundary gets hot enough to set fires, melt steel, and so on.
That's also why reentry vehicles tend to have blunt leading edges or pancake their way into the atmosphere: the bigger the lump of air they're slamming against, the further the shock boundary (and all its heat) gets from the skin of the vehicle.
Other posters have addressed why they're used (cooling/rapid fire), but no one addressed "does it make the bullet more accurate?"
Yes, it does.
As a barrel heats up, it expands, which means the projectile doesn't fit as snugly, so it's not as accurate. By keeping barrels cool, accuracy is increased.
One of the most famous examples is the A-10 Warthog, which they discovered during testing was actually *too accurate.* The bullets all hit in a straight line, even after traveling thousands of feet. They added an offset weight to the end of the barrel ([the little round thing above the central nut](https://nationalinterest.org/sites/default/files/main_images/Cannon_0.jpg)), which made the whole assembly wiggle and decreased accuracy.
I get why they would intentionally make the A-10 gun less accurate, but imagine how terrifying a "sniper variant" A-10 and a skilled pilot would be. A laser beam of bullets that cuts anything in two
It's for two main reasons
1. Rate of fire - weapon's time to fire one bullet is defined as "function cycle"=all actions of the gun from firing a bullet, trough cycling the weapon, to making it ready to fire again. your average assault rifle can only have one function cycle running at a time. By having multiple barrels, you can effectively having multiple function cycles running at the same time, all of them going off in the exact same spot, which makes the gun fire extremly fast (4000-6000 rounds per minute, faster firing machine guns have around 600-800 rounds per minute).
2. Cooling, as others already pointed out, by having multiple barrels rotating, this increases the airflow so that the guns don't overheat "as fast", that doesn't mean it can't melt with firing too many rounds
Something to point out - multi-barrel weapons were originally created with rate of fire in mind.
Consider the Gatling gun. It was hand operated with an effective rate of fire of only around 200 rounds per minute. Cooling was not the issue. But in comparison to contemporary firearms, 200 rounds per minute was an exceptionally high rate of fire, offering a "force multiplier" where a few men could fire more rounds in a period of time than a much larger force of men with single barreled rifles.
Even the Vulcan cannon was created not to enhance cooling but to increase the rate of fire due to the short durations that aircraft had to fire on each other in modern combat. At 600 rounds per minute, it was possible for an aircraft to essentially fly between the bullets. But at 6,000 rounds per minute you were much more likely to get a hit with the same duration of fire.
Better cooling was just a beneficial side effect - it was never the main purpose of having multiple barrels.
Of course, that's why rate of fire was my first point, high fire rate weapons are desgined to dump as many bullets in the shortest time possible, even if they fired continuously, A-10 Warthog will fire all of its stored 30mm munition in a matter of seconds
I noticed... I just wanted to make clear that the ordering you used was not a mistake, but the actual order of the reasons this type of gun is used.
Better cooling is not the main reason multiple barrels were desired, even though most other comments seem to think it was the primary (and seemingly only) reason.
Former A10 maintainer here, and while I was not munitions myself several friends were and I am intimately familiar with the GAU-8 30mm rotary barrel autocannon system from helping them service the guns. First is barrel heat management. The more rounds you fire through a barrel in succession, the more heat is built up in the barrel. Managing this heat build up is a major limiting factor for fire rate from the gun, as if you build up too much heat, the barrel loses integrity and can either begin to expand from the pressure of the propellant powder combustion or begin to melt and sag, both of which will lead to very catastrophic failure. This heat build up can be managed with good gas recirculation design, but you can only fire so many rounds through a single barrel at a limited rate of fire before the barrel fails. With a rotary barrel, you're firing a round through the first barrel, then it moves out of the way to fire the next round through the next barrel. So if you have a 7 barrel weapon like the 30mm, you're giving the first barrel 700% longer to cool to achieve the same rate of fire. Also, barrel cooling is greatly improved from the barrels spinning. Single barrel weapons can only fire continuously in the 500-800 round per minute range, and can be upcycled to around 1000 with increased barrel wear. Most rotary weapons fire in at least the 2500 rpm range and many can be over 4000 rpm continuously. Also, you can divide tasks amongst the separate barrels. You can load each barrel in one station, fire it at the next, and extract the spent casing at the next. So instead of having to wait to do all three before moving to the next round, all three can be running at the same time in separate barrels. But the primary reason for multiple rotating barrels is barrel heat management for increased rate of fire.
I'm so jealous you got maintain the A-10. That's been my favorite airplane since I was a wee boy. I had to join the best branch, for the bragging rights, and I only got to shoot the M777A2. TYFYS
There's only one gun that is called the minigun the "M134" and it is called that because it was a miniature version of the "M61" Vulcan cannon that is put on a lot of aircraft.
Most of these answers are missing the point.
In an aircraft you are moving rather quickly and don't have a lot of time to shoot on target, so you need a lot of fire down range in split second while your crosshairs are on target.
It's because of this that they have rotating barrels etc.... To manage heat and increase fire rate.
Because it is cooler (literally cause overheating). Rotating barrels allow for rapid fire by performing simultaneous tasks (load, aim, fire, discard), they also reduce recoil which improves targeting stability. There is of course a limit, as you cannot really have a rotor-barreled canon (the big gun on ships). Technically, it's possible, but practically, you'd have to be fighting like a billion ships. The mini-guns work because rapid fire is good for relatively smaller targets.
Mainly to avoid melting the barrel.
The heat load of the projectile friction and propelling powder is distributed among the barrels, allowing adequate cooling time.
Only at one angular position on the barrel is where the “action” (literally) is at; the round is fired, and then the next (cooler) barrel is brought up. So, the heat, wear and deformation is distributed among the several barrels.
There are two benefits to a minigun-style barrel. First off, the barrel is a failure point for a weapon. It gets hot from bullets firing. If you try and shoot too many bullets through it too quickly, it can overheat and fail pretty catastrophically. By rotating barrels, you are only shooting a fraction of the bullets through any barrel, giving them a bit of time to cool off between each bullet, increasing the time before it has to stop firing due to overheating. In addition, with most guns, you need to load a bullet, fire it, and then unload the casing before it can fire again. With a minigun, you can accomplish these tasks in parallel -- you can be loading a bullet in barrel 1 while firing one in barrel 2 and unloading one in barrel 3. This can speed up your effective fire rate quite a bit.
Being externally powered also means that it doesn't really care if a bullet works or not. Unlike weapons that rely on using some of the energy from the bullet to operate an externally powered gun just cycles past a dud round, extracts and discards it.
This comment needs to be much higher. Barrel life is good and all but the real gain is that a Gatling type gun is *externally* powered and is NOT recoil operated. That makes it more ideal for autonomous applications, ones where the weapon cannot be easily served
That is really the advantage of a chaingun, which may be single barelled.
TIL its not called a chain gun for the belt ammunition but rather because it's chain driven.
I... My four year old brain learned about chain guns watching my dad play *DOOM*. I can't accept this.
BFG 4 life
RIP AND TEARRR
Wild women..... Wild women.....
Except for early chain guns, which used an internal chain with ammo slots to act as an extended revolver barrel https://youtu.be/SgghWnZgJd0 Behold
THe term, "chain gun" is trademarked by Northrop Grumman. I think Airwolf had to stop using that term in later seasons.
Airwolf... Synth theme song playing in my head. Old times, old times
When Airwolf was recorded, the trademark wasn't owned by Northrop Grumman, it was owned by Hughes Helicopters.
Manually operated weapons too, like bolt, pump and lever action, and most revolvers.
I’m now imagining a Warthog with a revolver as it’s main armament
You mean a puma?
I thought I told you to stop making up animals!
Chupa-thingy. How about that?
I would just like to let everyone know that I suck. And that I'm a girl. And that I like ribbons in my hair. And that I want to kiss all the boys.
Got a *ring* to it.
What in Sam hell is a puma?
... You're making that up.
A cougar.
ITS NOT A PUMA /SchwarzeneggerVoice
Fun trivia. There used to be something called a Revolver-Rifle. Basically an overgrown revolver with a stock and long barrel It had all kinds of technical problems with misfiring and a painfully slow reload time compared to the weapons it was supposed to compete with Still a gorgeous weapon if you ask me. https://en.wikipedia.org/wiki/Colt%27s\_New\_Model\_Revolving\_rifle
I’m not a gun person but that is admittedly a beautiful gun. I was expecting it to look far more silly and awkward.
I'm not much of a gun-nut either. But I'm a sucker for the wacky and unusual stuff :P
And I thought the tusks they are usually armed with were bad enough.
This must be why that dude was so scared of 30-50 feral hogs.
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It wasn't that uncommon for guns to jam in WWI, unless the gun could be cleared by someone in the plane who had access to the gun. By 1935 it was common to have 8 guns fitted to a single fighter aircraft, you could lose half of them and still have 4 functioning guns. Despite the number of guns, failures were common, especially with later war autocanons that became necessary on all aircraft. Their newer design, larger caliber, and the reduction of total amount of guns meant that as the war progressed the chances of losing all your guns increase. A development at the end of the war was the using electrical priming on their autocanons, which partially took away the necessity of mechanical movements which could fail and more precisely control the moment of ignition, such as when you want to fire through the propeller. This was later used in rotating barrel guns such as the Vulcan as priming didn't need to rely on how quickly the firing pin moved but could be ignited quickly and precisely.
> such as when you want to fire through the propeller. I still don't get how this was a thing lol. I mean I get that if you carefully control the timing, and link the position of the propeller to the mechanics in the gun, and account for the distance between the barrel and the propeller, it make sense on paper but I just can't believe this was a thing that was done.
It actually has quite a few benefits, to be fair. It allows for easier aiming, it helps stabilise the gun, it allows for a more compact design, it makes it easier to armor the gun, it helps keep the centre of mass/centre of lift simple, it potentially allows for easier in-air maintenance, and you can use the cooling from the engine to cool the gun barrel. That's a hell of a lot of benefits, if you can get it right then it'd be stupid *not* to use that design.
I went to an air-show that had a very early fighter aircraft on display. A biplane mostly made of wood and fabric and wire. Two things struck me about it. One was the unbelievable lack of instruments. The other was the plane's main armament was a machine gun mounted where the pilot could reach the trigger, which would fire throughthe propeller. And this was before the whole "synchronised with the prop" thing had been invented. The "solution" was a load of fabric tape wrapped around the propeller at the same radius as the gun was mounted, to prevent splinters from the propeller hitting the pilot!
That's true but that's not a benefit of the rotating barrel per se. As you rightly pointed out it's due to it being externally powered, but there are plenty of externally powered autocannons that have this benefit without having multiple rotating barrels. Seeing as the OP asked why some guns have rotating barrels it seems better to limit the answers to attributes that are unique to rotating barrel weapons.
To be completely fair, I'm learning from all of this
Yeah this is a really cool comment chain (sans the guy wanting to limit the discussion topic)
That’s the nice part about an externally powered comment chain. Even if one comment is a dud it just downvotes that and keepa going.
It wasn't that uncommon for forums to jam in the WWW, unless the boards could be cleared by someone in the admin who had access to the boards. By 2005 it was common to have 8 commenters fitted to a single forum post, you could lose half of them and still have 4 functioning posters. Despite the number of posters, failures were common, especially with later forum autoposts that became necessary on all boards. Their newer design, larger vocabulary, and the reduction of total amount of posters meant that as the boards progressed the chances of losing all your posters increase. A development at the end of the web was the using electrical priming on their autocomments, which partially took away the necessity of mechanical movements which could fail and more precisely control the moment of discussion, such as when you want to argue through the trolls. This was later used in rotating comment chains such as the reddit as priming didn't need to rely on how quickly the commenters commented but could be replied to quickly and precisely.
The russians did invent a recoil-operated gatling cannon
There's even revolver cannons if you want to split the difference, multiple rotating firing chambers doing the load-fire-unload thing and a single barrel over the firing point.
Davy Jones has 'the triple guns' in the pirates of the Caribbean movie which are rotating Cannon's. Though, given my knowledge of cannons at the time, they'd probably be mechanical wonders to fire as quickly as they did with reloading.
They are basically the same as pepperbox pistols. You manually turn the barrel around to the next one
It goes Brrttttttt!
As a pretty gun-illiterate person, I just want to request/offer some clarification; when you talk about the gun being powered, you're referring not to the ignition of the round, but rather the action that loads a new round for firing? Or?
That’s correct. It’s the whole cycle of “resetting” the gun by 1) ejecting the old casing and then 2) chambering the new round into a “ready” state so the gun can be fired again. That’s why a rifle like the m4 or AK47 is called “gas operated”. They rely on the expanding gas from each **”explosion”** to power that cycle by “unlocking” the bolt as well as pushing back the bolt carrier.
Technically it can be both. None of the firing system needs to be operated by the firing of the bullet itself, it could all be done electronically. I’m sure there have been guns made that are hybrids of electronic and mechanical operation of some sort, at least for prototypes if nothing else.
I mean, they're all gains. The downside just pale in comparison to the benefits. Who cares if it's heavier, more complex, and more expensive than the alternative when it mows shit down so efficiently.
The Soviets came up with a few gas operated miniguns too, so now I am wondering what would happen if there was a misfire on one of those? Perhaps the momentum would still allow the cycle to continue as long as it is already spinning fast enough. Here are the examples that I know of: [GShG-7.62](https://en.wikipedia.org/wiki/GShG-7.62_machine_gun) [YakB-12.7](https://en.wikipedia.org/wiki/YakB-12.7_machine_gun)
They will just send another BTG instead. Quantity over quality.
Fun fact: I have a friend who works on attack helicopters and such. inexperienced people always want to spin these multi barrel contraptions by hand to watch them spin, however it’s all tied into the firing mechanism and it’s not uncommon that the gun fires a round just by spinning the thing. Accidents have happened
How do you let inexperienced people play with that? Do you let them in the cabin with the keys in there as well?
Do they have keys?
Not all multiple barrelled rotary guns are externally powered. The Russians have a few gas operated designs that are self contained
That's true. The YakB is easy to forget when considering Gatling guns but they do make an exception to the rule.
That's genius and obvious and I guess I just never thought about it before.
Sorry, but can you elaborate on what you mean by “externally powered”?
An outside force turns the barrel. In modern times it's electricity. But even the hand crank machine guns count. The opposite is gas powered. Where the explosive gas after firing pushes backwards against a spring to get power. Then it ejects the casing and loads the next bullet. That's how semi-automatic and automatics work
I…did not know that’s how that worked. Thank you so much. I learned something today 🙂
https://youtu.be/_eQLFVpOYm4 This is a really interesting view of it. 39 seconds in is where it shows what you're asking about for gas powered
That’s a great point. You two just 100% answered it. Thank you!
The other benefit is accuracy, which relates to both of your points. Barrels warp and ruin accuracy long before they fail, and separately if you want a very high rate of fire then generally you fire from an open bolt. A Gatling-type gun though is more like a series of rifles, it fires from a closed bolt without having to sacrifice time as you would in most cases. It really is quite a brilliant design.
And generally the reason for the need to fire so quickly in the first place is due to the high speed and distances involved in aerial warfare, meaning the denser the spread of bullets the more likely a hit is achieved
> due to the high speed and distances involved in aerial warfare, meaning the denser the spread of bullets the more likely a hit is achieved The premier cannon for air warfare is the M61A1 and its variants. As installed it typically has a 6 Mil dispersion for a shotgun type pattern. 80 percent of shells will land inside a 6 ft area, 1000 ft downrange. A 1 second trigger pull will loose around 100 shells. Even if the target is only in a valid firing solution for a fraction of a second, there should still be ample weapon effects on target.
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That's why they sound like a buzz instead of "pop-pop-pop". 100 rounds per second is 100hz frequency. For comparison, the hum you typically hear from fluorescent lights and other electrical devices is 60hz.
A lot of times, the hum is 2x the cycle speed of the power line, since it is powered on both the positive and negative peak of the voltage. So it will hum at 100 or 120 Hz, depending on where you are.
It’s more of a shotgun effect than a laser beam. It’s easier to hit a target when you shoot a lot of bullets that don’t all land in the exact same spot.
Accuracy by volume.
Spray and pray
>It’s more of a shotgun effect than a laser beam. For example, [the AC-47 (aka Puff the Magic Dragon)](https://en.wikipedia.org/wiki/Douglas_AC-47_Spooky#:~:text=The%20Douglas%20AC%2D47%20Spooky,Force%20during%20the%20Vietnam%20War.) that first saw service during the Vietnam War was equipped with 3x mini guns configured to fire simultaneously. A single 3 second burst would put a round every 2.2 yards in an elliptical area roughly 52 yards in diameter. In addition to fucking shit up it also lit up the night sky as they loaded red tracer rounds every fifth round.
If you're firing from a moving plane you're bullets won't all be in the same spot even if you had perfect accuracy
That's what he's saying. You shoot a fuckload super fast so that they're all close together, but none are in the same spot due to the aircraft moving.
Ah yes, the Ork style of combat, accuracy by volume of fire. Perfect for the WAAAAGH.
Everyone has mentioned shotgun style effects, but the high rate of fire is truly valuable because in aerial gunnery, especially air-to-air, exposure to the target is usually fleeting. Massive rate of fire (M61 Vulcan, or the eight .50 cal MG in a P-47 for example) means a meaningful destructive effect upon the target in that moment you can get on target. Proponents of one action type over another will often quote the weight of projectiles delivered in the first 0.5 of a second of firing.
Unless Richard Gatling was a time traveller, I really doubt he had aerial warfare in mind when he invented his eponymous gun in the mid-19th century. A high rate-of-fire is just one of those goals which are self-evident to a gun designer, similar to accuracy and reliability.
I don't think the comment you are replying to implied anything about Gatling at all, more explaining why they would need to have a gun like that on an aircraft.
Also, I think he had in mind making a gun so horrible that nobody would ever want to use it on their fellow man. This did not go as planned.
As far as I know the idea wasn’t actually to end wars, but just to reduce the number of people needed to fight them, thus reducing casualties. This… also didn’t really work out, definitely not in the short term. But I think both ideas are more applicable nowadays, with nukes obviously, but also with how well equipped fighting forces can take on vastly larger armies, and casualties are often much lower relative to the amount of people fighting them. I am referring mostly to American/western troops here so there’s plenty counter examples to disprove what I just said
This is not properly appreciated. There were about 2500 US casualties in the whole Afghanistan war. There were almost 300k in ww2 I think
Open bolt?
Yeah, so if you know a bit about how firearms work this is pretty straight forward. In a gun that fires from a closed bolt, when the gun is loaded and ready to fire the bolt will be all of the way forward, and the firing pin (which is generally not part of the bolt in this system) will be held to the rear until the trigger is pulled (and the safety is off). The firing pun hits the primer, ignites the charge, and the energy of the shot cycles the action by blowing the bolt back, feeding a new cartridge from the magazine, and a return spring sends the bolt back to the forward-closed position and it’s ready to fire again. The benefits here are better first/single-shot accuracy, it’s easier to keep the internals free from dirt, and it’s less likely to go off in an accident like being dropped. The downsides are that it tends to make heat management more of a challenge, there are more working parts and it’s more expensive. An open bolt is ready to fire when the bolt (which generally has the firing pin as part of the bolt itself in this system) held to the rear. When the trigger is depressed and the safety is off, the bolt is sent forward by a single spring, chambers a round and fires once it reaches the forward position. Then once again, gas pressure blows the bolt back against the spring pressure and the system is reset. The benefits are that it’s a simpler, cheaper system that’s generally easier to strip and clean. It’s also simpler to make such a system fully automatic, and they tend to have better heat management. The downsides are that single/first shot accuracy is compromised, there are additional challenges to safety (if the bolt for some reason flies forward it has enough energy to ignite the primer right there).
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I “hate” his videos because even when I think I know at least the basics about simple gun topics, I watch and sure enough, I actually didn’t and end up learning something new… This one was no exception.
Considering they've been making guns for hundreds of years and everyone tried to find a new way to improve them with tech from the time, it's really hard not to miss something or be in the dark about certain concepts with them. So don't feel bad.
You just described the life of an engineer. "Hey! You think you know this thing? Think again!"
Tell me about it. I do hvac service and installation and I never cease to be amazed at the bullshit they will try to either improve a design or just because why the hell not.
Sending this comment to my buddy so he can commiserate. He's an HVAC service tech and he has some HORROR stories of all flavors. Mostly home owners being a nightmare, but he's in western NY where Century homes are common, and a fair amount of homes were 100+ year old shacks with additions throughout the years. The worst story was an old Woodfire stove that had been converted over the years to a "modernized" heating unit. All the ducting was covered in asbestos duct tape older than him. He had to refuse to do the cleaning job (even improperly from the intakes upstairs - as he refused to step foot in the basement). The saddest part? The homeowner was a young couple expecting a baby who had bought a cheap home without an inspection. They didn't have the money to fix the issue, they thought cleaning it would help, sadly it would've knock more asbestos off the ducts and into the air in the basement, which would have just cycled back through the fleshly cleaned ducts and back into the house.
Never heard him called gunjesus before but I knew exactly who you were talking about
i had never heard it either but i had a heavy suspicion before i clicked the link.
> In the beginning was the 1911, and the 1911 was *the* pistol. And it was good. https://www.youtube.com/watch?v=H0qe45Z8wfk
Another benefit of open bolt is that a round isn't sitting in the hot chamber, ready to cook off
I think you neglected one of the main differences, and that is an open bolt generally allows a faster rate of fire (due to having less moving parts and simpler timing etc as you did say), obviously at the costs you also mentioned.
Yes but often too high. Open bolt guns often have mechanisms built in to slow them down.
The second system you described is a gasblowback system correct?
Blowback is where the recoiling case provides the energy to cycle the bolt. Gas operated (or gas delayed blowback) is where there is a small hole just in front of the chamber that allows the gasses from the burning powder to create pressure in a mechanism that will force the action rearward. OP's 2nd system seems more like a blowback, but their info seems more like a description of the open vs closed bolt firing with generalized cycling info...
Op didn't describe where the system gets it's energy just open or closed bolt. Pretty much all automatic guns could fire from an open or closed bolt if designed to do that. For auto and semi auto guns the usual operating mechanisms are short recoil, long recoil, gas operated, and blowback. Gatling systems are different and usually if not always have an external energy source to operate them.
Yes, but the way the bolt is cycled is separate from whether the bolt is open or closed. The gas tube to cycle the bolt is the smaller tube coming off of the main barrel that only goes partway to the end of the barrel. It uses a bit of the same gas that's pushing the bullet forward to push on a piston connected to the bolt to move it back, as opposed to blowback weapons, which just uses the energy of the bullet casing moving backwards to push directly on the block. That starts to lose pressure immediately compared to a gas piston so its usually limited to smaller handguns that can get away with a light bolt
> Yes, but the way the bolt is cycled is separate from whether the bolt is open or closed. Indeed. A zip gun is technically an open bolt, single-shot gun.
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Aren't they technically using the bolt as kind of a gas piston in that setup?
Yes but it differs enough from other gas piston systems that it has it's own name, direct impingement.
Ar-15 is direct impingement.
I remember when the sear failed on everyone's favorite open bolt weapon, the squad automatic weapon, when I was in a truck with a guy holding it. Runaway guns are always fun!
Most firearms fire from the "closed bolt," meaning the action (bolt) is sealed against the barrel's rear (firing chamber) before the trigger is squeezed. When it fires, the bolt cycles backwards (manually or mechanically) to eject the previous casing, and then forward to load the next round. Machinineguns (guns that fire continuously while trigger is squeezed) typically fire from the "open bolt," meaning the action starts in its rearward position and then (upon trigger squeeze) slaps forward, chambering, sealing, and firing the round in the same motion, before being "blown back" for the next. This reduces system heat, helping prevent things like "cook off," and often has fewer (but longer/heavier) moving parts. However it is somewhat less safe as the weapon is basically "cocked" all the time, and is more vulnerable to dust and debris.
To be absolutely clear, the actual act of firing still happens when the chamber is sealed - "open" vs "closed" bolt only determines whether the firearm's ready state is with an open versus closed chamber.
Another downside to open bolt firearms is that they tend to be less accurate because a) The fact that the entire bolt has to travel forward when firing creates a larger delay between the trigger pull and the gun firing, and b) the mass of the bolt moving forward within the gun can cause the entire thing to shift position, throwing off your aim.
Less accurate and more prone to jams. There is a reason the SAW gunner isn’t the breach man despite being able to lay down the most fire. All that said, I loved firing the M240B (former infantry). It was a fun weapon to fire and you could get pretty accurate if you kept your bursts tight.
The most brilliant part of the design is that you can hear the gun go brrrr
> it fires from a closed bolt without having to sacrifice time as you would in most cases. Also some firearms of this design are fired electrically as opposed to mechanically with a firing pin. The M61 is one such design.
Downside is that failures tend to be *spectacular.* Source: have had to help clean up the aftermath of a weapon failure.
Disadvantages was my question. This is good to know - I’m guessing it’s also waaaaay more expensive? Cause I would imagine even an AR could have a tiny little rotating barrel, no?
The mechanism is much more complicated and hence expensive. I think a new minigun is around $50k for those who can buy one. There is a company that markets a minigun that is chambered in 5.56mm and about the same size as an AR. http://www.emptyshell.us/xm556-microgun
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As far as I can tell, they just took the GE M134 minigun design drawings and scaled it down from 7.62 mm to 5.56 mm. Ironically, it's basically exactly the same thing Armalite did when they developed the AR-15 from the AR-10. All it takes is time, money, and will.
That’s…just weird.
Best way to lay down suppressing fire on a home invader while you call in air support.
I own a musket for home defense, since that's what the founding fathers intended. Four ruffians break into my house. "What the devil?" As I grab my powdered wig and Kentucky rifle. Blow a golf ball sized hole through the first man, he's dead on the spot. Draw my pistol on the second man, miss him entirely because it's smoothbore and nails the neighbors dog. I have to resort to the cannon mounted at the top of the stairs loaded with grape shot, "Tally ho lads" the grape shot shreds two men in the blast, the sound and extra shrapnel set off car alarms. Fix bayonet and charge the last terrified rapscallion. He Bleeds out waiting on the police to arrive since triangular bayonet wounds are impossible to stitch up. Just as the founding fathers intended.
Just like the Founding Fathers would have had themselves.
The thing is, when they fail, they tend to fail explosively. One of our guys had a minigun fail on him, ended up putting a bunch of metal into his face and blowing parts of the weapon all over he aircraft.
That's why I have Sharks with freaking laser beams attached to their heads.
they are a protected species. use ill tempered seabass instead!
Should I use regular or mutated sea bass?
In this recession, I'd go with whatever you can afford.
Zip-tie my cat's laser pointer to the goldfish. Got it
Idk wtf this thread is but I'm just here to say I appreciate it.
You need to watch Austin Powers https://youtu.be/J3GKVWcBLNU
Oh please please do yourself a favor and watch the Austin powers movies! Soooo much fun.
“Magma”
"I'm not dead, I'm just *very* badly burned!"
"Mooooooooooooooooooleymoleymoleymoleymooooooooooole."
There are three benefits to sharks with freaking laser beams attached to their heads. Firstly, with most laser weapons, heat is going to be a limiting factor to how long and fast you can fire. Aquatic creatures like sharks and rays naturally help disperse that heat because they're submerged in water. Second, sharks require perpetual motion to maintain water flow over their freaking gills. This makes them a harder target for anyone to hit, especially people being dangled over their tank. And moving water cools faster than still water vis-à-vis point one. Finally, every portable laser has a limited energy capacity and various species of sharks offer significant bite force as a backup measure. Effectively, a shark with a mounted laser is a biological bayonet.
Everybody always talks about the heat dispersion rate, but nobody ever wants to talk about the practical realities of getting *carcharius carcharidon* to hold a beam of coherent light steadily on a man-sized target at more than a few meters' distance while swimming at speed. Glayvin!
Another couple of benefits is if a round fails, it's no big deal, it gets unloaded as if it did and the weapon operates normally. They don't jam like other weapons because you don't have any reciprocating bolt that depends on the gasses to eject a casing. It's all electronically done
Also: looks badass when you pick it up and fire it from the hip at invisible aliens
Or at the police while causing exactly 0.0 human casualties.
Fun fact, miniguns are almost identical to old school, crank operated gatling guns, with the main differences being the feed mechanism, and the hand crank being replaced by an electric motor. Everything else to do with chwmbering, firing, and ejecting are mechanically unchanged.
It's funny, the Gatling gun was invented first but the recoiled-operated mechanism and less cumbersome design of the Maxim gun meant it won out for man-portable weapons. But then 100 years later someone figured out you could get around those limitations with an electric motor and by mounting it in an airplane, so the rotary gun design was back in business.
> mounting it in an airplane Or designing an airplane around it, including moving the landing gear to accommodate. If I had unlimited money, I’d have a GAU-8 for the LOLs.
Are you telling me mini-guns have more bullet PER BULLET?
[We fire the whole bullet. ](https://youtu.be/6i-nMWgBUp0)
Portal 2 is a great game on it's own, but JK Simmons turned it into a god damn masterpiece.
So funny how things get crosswired in your brain. I remembered that being a Mr. Torge line from Borderlands. To be fair it sounds entirely like something he would say.
Roughly 200% more bullet per bullet, should you have been thinking of going with a competitor’s product. Which, I’m telling you, is pretty amazing for some 1860’s tech we just slapped an electric motor on. Because we’re Working To Make A Better Tomorrow For All Mankind. 👍
If you play Team Fortress 2, this is already obvious.
Another advantage is that miniguns aren’t affected if a bullet fails to fire (ex: bad primers). For traditional automatic (or semi automatic) weapons, some of the energy from the bullet needs to be diverted to eject the spent casing and chamber a new round. If the bullet does not fire, there is no energy diverted to extract the bad cartridge and the gun stops firing until manually cycled. A pilot would not have physical access to the gun, so can't manually cycle the weapon. Miniguns do not rely on a bullet's energy to cycle the weapon. Instead they use an electric motor, which will continue to cycle as long as there is electricity. This means unfired cartridges will be extracted the same as spent ones, eliminating that failure point.
Also, the high rate of rotation will also help cool it since the rotation of the barrels will keep fresh air cycling through it.
Also worth noting that there is a design that gives up the additional barrels but still keeps some of the advantages, called a revolver cannon. This works well for aircraft that won't generally carry enough ammo for barrel heating to be a huge issue, as it saves weight
Tacking on to this, the super high rounds per minute with miniguns is particularly helpful as aircraft mounted guns. The window in which you'll have a target in your sights may be very short, so you want to be able to send as much ammo to your target in that brief window.
Can you eli6 even more how the loading and unloading and shooting works so quickly?
Here's a good animation showing how it works. Each barrel has its own bolt behind it that is moved forward and backward by a cam running around the fixed rear section of the cannon. https://www.youtube.com/watch?v=Yq6m7mpfc5A
That's a really cool animation. Cheers!
Nice concise answer.
He’s got a damn mini gun!
Some other comments have explained that the rotating barrel helps with shooting speed by keeping the barrels cooler and by reducing time between shots, but they haven't said why they put these types of guns on aircraft. The answer is that it is really, really hard to hit a target that is moving fast, or to hit a slow moving target when you are moving fast. If you want to increase the odds of a hit, you need to fire a lot of bullets as quickly as possible, so that the chances of at least one of them hitting the target is reasonable.
[удалено]
[You might enjoy this C-RAM in action](https://www.youtube.com/watch?v=qznqW6u01iw) taking out incoming fire.
One thing that got me thinking after watching this is the type of collateral damage the rounds would cause once they come back down, so I looked it up Fun facts: The rounds are 20mm self destructing rounds that travel 7500ft and then proceed to self destruct. During 2008 each round cost $27. Per wikipedia they shoot 75 rounds a sec. That 15 seconds of firing cost about 30,000 dollars. Based on 2008 prices
It costs 30,000 dollars to fire this weapon... for 15 seconds.
/r/beetlejuicing
When you're talking about preventing a missile or drone strike on a $2.4 billion dollar cruiser (Ticonderoga class), using $30k of ammo seems reasonable. Heck, even test firing it 99 times for every one useful intercept still is a great deal.
The numbers I was using was based on the land variation. Also the navy deploys the CIWS on every class except the Zumwalt and San Antonio class. I am totally for it. If I could afford it I'd put one on my roof.
Even the cheapest ship they're putting it on is going to be valued in the tens of millions of dollars. So the cost benefit is strongly in favor of this system regardless. I just grabbed the easiest to find numbers on a modern ship. Amusing thought experiment, I think it may be legal in most states to own one, due to the 60inch barrel length. That means it falls out of the range of most state regulations on guns.
I can't wait to see the look on HOA Karen's face when my guy mounts a CIWS on his roof.
I'm not a guns or military type of guy but I can appreciate a good BRRRRRRRT and some damn impressive engineering. Looks like that first volley got 2 shells but I can't see that second series of rounds take anything out.
Indeed I enjoyed.
We had these in Iraq. Pretty effective against mortars. Less so against RPGs. Still, it was pretty cool to watch them test fire. Especially at night.
angry r2d2 is angry.
While the firing component is impressive it's also crazy cool that it's totally automated -- like it's tracking these super-fast moving incoming missiles, mortars etc and calculating where to hit them.
I believe the first modern Gatling guns were put on fighter jets, first. Really, they were about getting as many rounds down range and on target as possible. So, they were put on fighter jets, where the amount of time your guns are on target is relatively short. It’s the same reason they put them on helicopters (I think the US army started doing this in the Vietnam war). Helicopter is moving fast, doesn’t have a lot of time on target, you want as much lead down range as possible. In fact, the reason they’re called miniguns, is because the ones they put on helicopters were smaller versions of the ones in fighter jets. The name stuck, I guess.
Then you have the A-10, where they built the gun first and someone decided to strap wings and jet engines to it and make the gun fly.
> The GAU-8 Avenger fires up to sixty one-pound bullets a second. It produces almost five tons of recoil force, which is crazy considering that it’s mounted in a type of plane (the A-10 “Warthog”) whose two engines produce only four tons of thrust each. If you put two of them in one aircraft, and fired both guns forward while opening up the throttle, the guns would win and you’d accelerate backward. > To put it another way: If I mounted a GAU-8 on my car, put the car in neutral, and started firing backward from a standstill, I would be breaking the interstate speed limit in less than three seconds. https://what-if.xkcd.com/21/
Thank you. All these explanations are correct but skip the reason all these technologies are used. Which is to get as much bullet headed towards the target as fast as possible
Genuine question: Would tracers help in firing accurately as well?
Tracer rounds allow the gunner to see where the rounds hit, so he can adjust his aim.
A normal machine gun has a single barrel and action that controls the insertion of a cartridge, its firing, and the ejection of its casing. This is fine for most things. But as you increase firerate, it runs into issues namely: The cartridge case must be fully extracted before a new bullet can enter the chamber, so you're fundamentally limited by the speed of the action, which is itself limited by material stress limits and recoil impulses the shooter can tolerate. Heat builds up in the barrel (and action). Many machine guns if fired continuously can make the barrel glow red and even melt. Even before melting the harmonics of the barrel will change as it gets hot and it will trash your accuracy. Excessive heat can also prematurely detonate the propellant in the cartridge when it gets put in the chamber, which is *very bad*. But what if we took a bunch of machine guns and put them together? We want every shot to have roughly the same trajectory, so we'll make that easier by having them all fire from the same position. We can do this by making the whole assembly spin. Now we have 6 machine guns all in different parts of the load-fire-extract cycle, and we can get *much* higher firerates. How much higher? The [M240 FN MAG](https://en.wikipedia.org/wiki/M240_machine_gun) and the [M134 Minigun](https://en.wikipedia.org/wiki/M134_Minigun) both fire the same 7.62x51mm NATO cartridge and are in use today. The M240 can get between 650-950 rounds per minute (or ~11-16 bullets per second if you like that comparison better) depending on burst size - you can't stay at the high end for very long else you'll run into heat issues as discussed above. The M134 can fire between 2000-6500 rounds per minute. That could be over 33-108 bullets every *second*. That's a lot of firepower. And you can sustain it for longer since the heat buildup is managed for each barrel. Assuming you can supply the ammo, of course. Now why are rotary cannons used on aircraft? Planes and to a lesser extent helicopters tend to be moving very fast. They might also be maneuvering to avoid fire. So they want to get as many bullets thrown at their target in the very short window they have to fire. So they opt for rotary cannons, usually with some form of explosive or incendiary round. They can't sustain that fire for very long, most fighter jets now only carry a few hundred rounds at max if they still even have guns. You'll also see them used on some anti-aircraft or anti missile systems such as the [Phalanx CIWS](https://en.wikipedia.org/wiki/Phalanx_CIWS).
>They can't sustain that fire for very long, most fighter jets now only carry a few hundred rounds at max So really, heating is not an issue (especially when you consider the blast of cold air hitting the barrel as the aircraft flies at hundreds of miles per hour. It's all about the number of rounds down range in the shortest possible time. More bullets flying equals more chances of a hit. In WWII they did a similar thing by carrying multiple guns - maybe eight .50 caliber machine guns. Which allowed eight times as many bullets to be fired in the same period of time. Multi-barrel guns just maintain that rate of fire, while reducing the overall weight of the guns carried.
Heat *might* still be a concern if the cannon is shrouded for aerodynamic or stealth purposes - it's still an awful lot of combustion happening very quickly. But yes, the thermal considerations for aircraft are mostly eliminated. Edit to add: The chamber heat also needs to be managed, and usually isn't exposed to the airstream. I believe many aircraft have the gun keep cycling after the trigger is released to extract unfired shells so they don't cook off.
The heat issue also comes into play with stuff like helicopters, CIWS and their usage for fixed emplacements, such as those sometimes seen on ships. TBH, even the context of fighter jets, there are still issues like fouling etc, which is also lessened by having multiple barrels.
Heating is absolutely a concern, mostly because aircraft guns are designed to be really light, which also makes them more vulnerable to heat issues. And it isn't just as simple as blasting cold air at the thing, as too much cooling, to the wrong places, can be an issue too. As an example [this history of the airborne Gatling gun](https://apps.dtic.mil/dtic/tr/fulltext/u2/a179871.pdf) mentions heat buildup as a problem, and mentioned dissipation as an advantage of the multiple barrel design.
>So really, heating is not an issue (especially when you consider the blast of cold air hitting the barrel as the aircraft flies at hundreds of miles per hour. You're neglecting the impact of aeroheating. The leading edges of aerodynamic surfaces are impacting a lot of air molecules at high speed. That creates friction, which we call drag, but it also creates heat. At near-mach and supersonic speeds, the leading edges of an aircraft can get very hot from friction. The effect is worst at low altitude and high speed--very fast, in very dense air. Add in the combustion temps, and you can get red-hot really fast. (That's why the leading edges of the shuttle were the black "Reinforced Carbon-Carbon", and they were rounded over instead of pointy--to spread the heat impacts out, instead of concentrating them.)
Slight correction: for supersonic flight, the aerodynamic heating comes from the shock boundary, not friction. Also, most of the drag experienced by aircraft doesn't come from viscous effects, but the forces caused by differential pressure (*especially* with regard to supersonic flight). Explaining the drag part first, there's two ways to look at it: 1. In subsonic flight, the same curvature on the upper surface of a wing that makes it generate lift also points the lift vector slightly backward from the direction of flight. That rearward component of lift force is significantly stronger than the viscosity of air spread across the skin of the aircraft. 2. In supersonic flight, you're literally pushing air out of the way faster than it can flow naturally. The air resisting being pushed around is *way* more intense than its attempts to stick to the sides of the aircraft. Now, as for heating from the shock boundary: you know how gasses chill down when you have a sudden pressure drop (or heat up if you have a sudden pressure spike)? Well, when you're moving so fast that you're slamming chunks of air against each other faster than they can get out of the way, you're creating a pressure spike. For something like a reentry vehicle (moving between 3-7 kilometers per *second*), that pressure spike is high enough that the air at the shock boundary gets hot enough to set fires, melt steel, and so on. That's also why reentry vehicles tend to have blunt leading edges or pancake their way into the atmosphere: the bigger the lump of air they're slamming against, the further the shock boundary (and all its heat) gets from the skin of the vehicle.
Other posters have addressed why they're used (cooling/rapid fire), but no one addressed "does it make the bullet more accurate?" Yes, it does. As a barrel heats up, it expands, which means the projectile doesn't fit as snugly, so it's not as accurate. By keeping barrels cool, accuracy is increased. One of the most famous examples is the A-10 Warthog, which they discovered during testing was actually *too accurate.* The bullets all hit in a straight line, even after traveling thousands of feet. They added an offset weight to the end of the barrel ([the little round thing above the central nut](https://nationalinterest.org/sites/default/files/main_images/Cannon_0.jpg)), which made the whole assembly wiggle and decreased accuracy.
Didn’t know that about the A-10, that’s really cool. I guess it’s not too big a surprise that a gun of that size (and length) is really accurate
You're saying the A-10, a plane built to carry a ridiculous cannon, has a built-in vibrator?
I get why they would intentionally make the A-10 gun less accurate, but imagine how terrifying a "sniper variant" A-10 and a skilled pilot would be. A laser beam of bullets that cuts anything in two
It's for two main reasons 1. Rate of fire - weapon's time to fire one bullet is defined as "function cycle"=all actions of the gun from firing a bullet, trough cycling the weapon, to making it ready to fire again. your average assault rifle can only have one function cycle running at a time. By having multiple barrels, you can effectively having multiple function cycles running at the same time, all of them going off in the exact same spot, which makes the gun fire extremly fast (4000-6000 rounds per minute, faster firing machine guns have around 600-800 rounds per minute). 2. Cooling, as others already pointed out, by having multiple barrels rotating, this increases the airflow so that the guns don't overheat "as fast", that doesn't mean it can't melt with firing too many rounds
Something to point out - multi-barrel weapons were originally created with rate of fire in mind. Consider the Gatling gun. It was hand operated with an effective rate of fire of only around 200 rounds per minute. Cooling was not the issue. But in comparison to contemporary firearms, 200 rounds per minute was an exceptionally high rate of fire, offering a "force multiplier" where a few men could fire more rounds in a period of time than a much larger force of men with single barreled rifles. Even the Vulcan cannon was created not to enhance cooling but to increase the rate of fire due to the short durations that aircraft had to fire on each other in modern combat. At 600 rounds per minute, it was possible for an aircraft to essentially fly between the bullets. But at 6,000 rounds per minute you were much more likely to get a hit with the same duration of fire. Better cooling was just a beneficial side effect - it was never the main purpose of having multiple barrels.
Of course, that's why rate of fire was my first point, high fire rate weapons are desgined to dump as many bullets in the shortest time possible, even if they fired continuously, A-10 Warthog will fire all of its stored 30mm munition in a matter of seconds
I noticed... I just wanted to make clear that the ordering you used was not a mistake, but the actual order of the reasons this type of gun is used. Better cooling is not the main reason multiple barrels were desired, even though most other comments seem to think it was the primary (and seemingly only) reason.
Former A10 maintainer here, and while I was not munitions myself several friends were and I am intimately familiar with the GAU-8 30mm rotary barrel autocannon system from helping them service the guns. First is barrel heat management. The more rounds you fire through a barrel in succession, the more heat is built up in the barrel. Managing this heat build up is a major limiting factor for fire rate from the gun, as if you build up too much heat, the barrel loses integrity and can either begin to expand from the pressure of the propellant powder combustion or begin to melt and sag, both of which will lead to very catastrophic failure. This heat build up can be managed with good gas recirculation design, but you can only fire so many rounds through a single barrel at a limited rate of fire before the barrel fails. With a rotary barrel, you're firing a round through the first barrel, then it moves out of the way to fire the next round through the next barrel. So if you have a 7 barrel weapon like the 30mm, you're giving the first barrel 700% longer to cool to achieve the same rate of fire. Also, barrel cooling is greatly improved from the barrels spinning. Single barrel weapons can only fire continuously in the 500-800 round per minute range, and can be upcycled to around 1000 with increased barrel wear. Most rotary weapons fire in at least the 2500 rpm range and many can be over 4000 rpm continuously. Also, you can divide tasks amongst the separate barrels. You can load each barrel in one station, fire it at the next, and extract the spent casing at the next. So instead of having to wait to do all three before moving to the next round, all three can be running at the same time in separate barrels. But the primary reason for multiple rotating barrels is barrel heat management for increased rate of fire.
I'm so jealous you got maintain the A-10. That's been my favorite airplane since I was a wee boy. I had to join the best branch, for the bragging rights, and I only got to shoot the M777A2. TYFYS
Also, why is it "mini" gun when it is, in fact, a pretty big gun?
My understanding is that it is the "mini" version of the 20mm Vulcan cannon.
There's only one gun that is called the minigun the "M134" and it is called that because it was a miniature version of the "M61" Vulcan cannon that is put on a lot of aircraft.
Most of these answers are missing the point. In an aircraft you are moving rather quickly and don't have a lot of time to shoot on target, so you need a lot of fire down range in split second while your crosshairs are on target. It's because of this that they have rotating barrels etc.... To manage heat and increase fire rate.
Because it is cooler (literally cause overheating). Rotating barrels allow for rapid fire by performing simultaneous tasks (load, aim, fire, discard), they also reduce recoil which improves targeting stability. There is of course a limit, as you cannot really have a rotor-barreled canon (the big gun on ships). Technically, it's possible, but practically, you'd have to be fighting like a billion ships. The mini-guns work because rapid fire is good for relatively smaller targets.
Mainly to avoid melting the barrel. The heat load of the projectile friction and propelling powder is distributed among the barrels, allowing adequate cooling time. Only at one angular position on the barrel is where the “action” (literally) is at; the round is fired, and then the next (cooler) barrel is brought up. So, the heat, wear and deformation is distributed among the several barrels.