Are gas operated rotary guns superior?
Posted by Naskva@reddit | ForgottenWeapons | View on Reddit | 57 comments
This has been bugging me for a bit. Does anyone know why gas operated rotary guns aren't more common? They seem to have some major advantages compared to electrically operated ones, namely reduced weight and lack of spin-up.
Are there maybe some hidden problems with them or could this be a case of electric cannons already being the norm? Perhaps something else?
30 mm
GAU-8: 619.5 lb (281 kg), 3,900 RPM.
GSh-6-30: 149 kg (328 lb), 4-6,000 RPM.
20/23mm
M61A2 Vulcan: 92 kg (202 lb), 6,000 RPM
GSh-6-23: 73–76 kg (161–167 lb), 10,000 RPM
7.62 mm
M134D-H 19 kg (42 lb), 6,000 RPM
GShG-7.62: 19 kg (42 lb), 6,000 RPM
JMHSrowing@reddit
I do believe one of the biggest things I do believe is reliability in regards to ammunition.
A gas operated gun required ammunition to work within certain specifications, where as an externally powered gun doesn’t care if the ammunition even fires at all let alone how much gas pressure it has produced. When you fire so much ammunition very quickly and that burst of fire can be quite important, not having to worry about something like that is quite the boon. It also allows for use of different ammunition without changing as much on the weapon
Naskva@reddit (OP)
I see, hadn't thought of that but it makes complete sense!
Though, wouldn't it be possible to use the rotational inertia to clear any jammed shells? Sorry if it's a dumb question
DerFurz@reddit
It would also be a problem if something on the very first round doesn't work as expected
JMHSrowing@reddit
It’s not dumb at all. It would be theoretically possible but that would be difficult to make reliable with the different variables in pressure/energy in the system.
It would be an additional complexity, especially like how the system would need to regulate itself to not say spit out shells with that inertia when it’s simply not supposed to be firing.
(I’m not quite an expert in these things, so this should probably be taken with a grain of salt)
The electric/hydraulic powered weapon allows for these things to be done relatively simply outside the power source itself which of course is already needed to be present in the majority of applications.
Naskva@reddit (OP)
Fair enough, I'm beginning to see why electric is preferred. Seems like a right pain to make the gas operated ones reliable.
Think I understand now why so many are interested in firearms, looks to be a pretty massive rabbit hole!
HagarTheTolerable@reddit
You feeling ok bro?
petty_brief@reddit
Relax, he's just got really strong beliefs.
PantherX69@reddit
This person who believes, believes especially. What’s so hard to understand?
JMHSrowing@reddit
I wrote this literally several minutes after I woke up
trackerbuddy@reddit
I thought you were very passionate about the subject.
Nyga-@reddit
I do believe he is okay I do believe he was tired
HagarTheTolerable@reddit
Just making sure you weren't having a stroke lol
st00pidQs@reddit
Gotta do wellness checks on the homies
f38stingray@reddit
Besides the better answers already mentioned, there are probably other significant weight factors between guns. Barrel construction might be significantly different, for example, Wikipedia says the GSh-30 (the single barrel version of the Russian 30 mm) has a barrel life of 150 rounds. One source says the GAU-8 has a barrel set life of 21,000 rounds (3,000 rounds per barrel).
It is possible that other components besides the action are built much lighter on Russian guns. I don't have super solid sources for better comparisons, though.
AMRIKA-ARMORY@reddit
Barrel life of 150 rounds…? What?
f38stingray@reddit
Oops, I misread, it is 2,000 rounds using 150 round burst.
Yeah, I was thinking, “that’s only one ammo drum’s worth! Ah well, it kinda tracks.” Anyway, even then a 2k round barrel life with a less powerful round suggests a more lightly-constructed barrel.
AMRIKA-ARMORY@reddit
Okay that makes so much more sense lol.
So, considering that the single-barreled GSh-30 has a rate of fire of 4000-6000 rpm, and one barrel of the GAU-8 has a rate of fire of only 557rpm…I’d say that it’s perfectly fair for the GSh-30 barrel to have only two thirds of the barrel life.
A 150-round burst at 4000+ rpm is insane haha
f38stingray@reddit
The GSh-30-1 has a rate of fire of up to 1,800 rpm, not as bad but yeah still easier than the GAU.
I don't know much about barrel wear physics but I'm guessing that heating/energy dump into the metal is closely-related. It looks like the GAU does about 10% more muzzle energy than the GSh. Even at the original high 4,200 rpm fire rate on the GAU, that'll be 10 rounds per second sustained, versus 25 for the GSh for the slow rate. On balance it looks like about 2.32 times more energy for the GSh per second fired - that's a lot.
The rotary arrangement makes a big difference!
ExtensionConcept2471@reddit
It would be almost (if not) impossible to build a gas operated rotary gun and it would probably be heavier and less reliable than an electric powered one.
GaegeSGuns@reddit
So impossible that it has been done and fielded many times
ExtensionConcept2471@reddit
Show me a gas operated rotary gun?
GaegeSGuns@reddit
Did you actually read the post
AegisofOregon@reddit
I don't know that reducing the weight would be a major consideration in any multi-barrel design. The truck/tank/plane/ship isn't really going to notice an extra 20 pounds of electric drive mechanism.
Petrus_Rock@reddit
A plane or helicopter will notice. You can only lift so much weight. A lighter gun means more other stuff. Like a missile with an additional 20 pounds of high explosives. I’m no explosives expert but that’s a considerable difference.
apeincalifornia@reddit
The fighter jets that carry these weigh 30,000-70,000lbs
Petrus_Rock@reddit
And a Falcon 9 rocket weights 1.2 million pounds yet every gram or ounce is measured. Your point?
apeincalifornia@reddit
Falcon 9: 15,000 lbs of payload, 875,000lbs of fuel, 56,000 empty vehicle weight. Falcon 9s entire purpose is to deliver payload to orbit which is a function of its weight. A fighter jet has a lifespan measured in thousands of hours and does so over hundreds/low thousands of flights. Payload on fighters is extremely variable, and 20-100lbs difference in the weight of the gun is a small amount considering the reliability difference between electric and gas operated. Fighters can shrug off weight. Now a super light dogfighter from the late 40s early 50s like an F-86, Mig 15, Vampire, Panther etc, that weight would be more important. With 30,000-60,000 lbs of thrust and in-air refueling, that weight is negligible. That’s my point smart ass.
Petrus_Rock@reddit
That’s uncalled for. I love learning by being corrected when I’m wrong … assuming people don’t start acting like a jerk or name calling for no reason.
dairyman2049@reddit
Because you started off passive aggressively by saying "your point?".
I love it when someone starts the argument and gets mad about the other party giving them the same energy.
Katzchen12@reddit
Fire rate isn't everything as many of the other commenters have said. In theory the electric driven guns could reach and exceed those fire rates. The main advantage is weight savings and simplicity when it comes to gas rotary's. It also requires nothing extra or any power draw on the platform. These are all relatively minor when considering the application of rotary guns. Most if not all of these guns are operated on platforms that can supply power and the overall weight savings is typically not utilized in the similar application. For example the a-10 can carry a little over 1000 rounds vs the mig-27 at 300 rounds. Both airframes are only slightly comparable in roles and application. To flip this around in the ciws role again after about 3000 rpm you really aren't gaining much more than having to reinforce the mounting and you are probably sacrificing accuracy. If this clears up why its really not a clear one is better than the other and it's more just a preference by the nation.
0x24435345@reddit
Seems mostly answered but if you’re interested in further info there is almost a directly linked case. The GAU-4 (M130) is a self driven version of the M61 Vulcan. It still has an electric starter but other than that it’s gas operated. Additionally, most vulcans aren’t electrically driven. On aircraft they’re hydraulically driven and on CIWS they are pneumatically driven, although that may switch to electrical eventually fire better fire rate control and reliability.
Naskva@reddit (OP)
The more you know, thanks!
IShouldbeNoirPI@reddit
From what i remember reading MI-24 ground crews didn't even load full load of 12,7mm as it had tendency to jam and so why bother carrying that weight both sides.
But it may be also a problem of dust in Afghanistan and it would work more reliably in Europe or over some jungle
MonsieurCatsby@reddit
I forget whether it was the GShG 7.62mm or the YakB 12.7mm, but one (or both) of those guns had a reputation with ground crews for being an absolute dog to service. Once working it worked, but they hated having to service the weapon as retuning it afterwards to get it running again was a nightmare
Brookeofficial221@reddit
Can anyone think of a gas operated gun being mounted in a tank or an aircraft? I can’t. When you want ultimate reliability you use electric.
ExtensionConcept2471@reddit
Most tanks have gas operated guns mounted in various locations!
Petrus_Rock@reddit
I can think of many gas operated guns in tanks but not of any with gas operated rotary guns. But I can think of very few with rotary guns in the first place. Probably a good question for the chieftain.
Plump_Apparatus@reddit
Finding a tank that has a cannon sized( > 20mm) secondary is rare. About the only one I can think of would be the AMX 30 with its 20mm F2.
At least for production tanks. Prototypes you have things like the Serbian T-72M2 with dual 20mm Oerlikon chain-guns, later a single 2A42 30mm. Ukraine demoed the T-72E with a GSh-23, a 23mm dual barrel gast gun. Among some others.
Maybe in the drone-centric future, but in I'd be doubtful. Space and weight on a tank are already at a premium. Rotary cannons are large and heavy, and more importantly consume copious amounts of heavy ammunition.
Petrus_Rock@reddit
The linguistic problem are going to start having here is what “guns” means. Once we start talking about big stuff, the meaning of gun changes. For us gun and (man portable) firearm is the same. For artillery folks and boat people gun ≠ firearm. To them it’s small: firearm, medium: cannon, large: gun.
zeocrash@reddit
I believe the GSh-6-30 used by the Russian navy and also infamously as the gun on the mig 27 is a gas actuated rotary cannon.
zeocrash@reddit
As to why the GHs-6-30 was infamous on the mug-27.
Viktor_Bout@reddit
Reliability is the largest issue. If a shell misfires in an A10 and it's gas operated, it will jam the gun.
If it's electrically operated it will just spit out the unfired round and keep cycling.
You don't have to hinge the reliability of the gun system on the reliability of the ammo.
pookiegonzalez@reddit
The Soviets wanted extreme cold weather reliability (i.e shooting in case the gun was frozen) and a gun system that was independent of the sensitive aircraft electrical systems. Those things already have crazy, electronic-killing recoil so they didn’t want a huge electric motor that could possibly power surge the system on top of that.
henryjonesjr83@reddit
Gas operated means you’re taking energy from the bullet and putting it back in the gun
By definition a chain gun of any kind will shoot harder than an identical gas operated one
ExtensionConcept2471@reddit
Absolute rubbish! The small amount of gas tapped off to cycle the gun makes next to no difference in projectile velocity!
henryjonesjr83@reddit
I was explaining the science.
But you’re correct, the energy difference is minimal
Naskva@reddit (OP)
Interesting, so that's another advantage of gas operated rotary guns?
I'm not really a gun-nut, so my knowledge about the details is limited
B3nny_Th3_L3nny@reddit
it would be a disadvantage for gas operated weapons not an advantage
Reniconix@reddit
Electric guns have max spin rate immediately (or close enough to it), whereas gas guns would require spool time. Getting the barrels spinning takes significant amounts of energy, which to have to balance with actually pushing the bullet down the barrel, too much gas tapped destroys accuracy and effective range (slower bullet leaves the barrel after it's spun out of place). In the length of a normal burst, a gas gun from a dead stop may only shoot 1/4 the amount of bullets that an electric gun did because of spool time. That's a serious flaw when the whole point of rotary guns is high fire rate.
WindstormMD@reddit
The electric operation of the gun is also used in loading/unloading. Many of these guns (especially aircraft mounted ones) retain the spent casings to avoid having the weight balance shift too much from firing, a problem identified on in mid-WWII once armaments exceeded a certain size
RaptorFire22@reddit
P39s were prone to flat spins when out of ammo. Bell kept getting reports of it but couldn't replicate it because Bell engineers always put ballast in the nose where the guns would be. They took the ballast out and sure enough, the aircraft would flat spin.
One-Strategy5717@reddit
An electrically operated rotary gun can be cycled without firing, in order to clear the mechanism, in the case of a misfire/jam.
A gas operated rotary gun would have to be cycled by hand in the case of a misfire/jam, which is kinda hard to do from the cockpit of the plane.
An electrically operated rotary can also have its rate of fire be adjusted with the speed of the motor. In order to do the same with gas operation, you would have to adjust the gas flow, which could have a detrimental effect on reliability.
Rocjahart@reddit
Gas fired guns could be manually charged with a solenoid in case of jam, still not as reliable I bet but a lot lighter.
Fire rate can be adjusted through adjustable gas ports and spring pressure, it's done plenty on ground based machine guns.
Plump_Apparatus@reddit
Not likely a solenoid, as the cocking force requires too much force. The solenoid would be massive.
GSh-6-30 and GSh-6-23 both use pyrotechnic cocking charges, I couldn't say on the little GShG-7.62.
Proarms_shooter@reddit
These are usually not the type of guns where you can easily adjust something on the go. So having the gun electronically controlled is very helpful here
pbchadders@reddit
External power works better in some use cases as any duds are automatically cleared without any intervention, also with most western spec ones being built as external power for multiple generations bureaucratic inertia is a thing.
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