Machine Guns and Cannons (Ground, Vehicle, and Aircraft Mounted Weapons)

[dy031101]

BTW, the tank-mounted version of the 125mm is the 2A46. 2A45 is the towed gun.

I tried looking up the number for the 2A45 because I expect the figure for the 2A46 to be based on the assumption that an autoloader is present whereas maybe the one for the towed gun might be more in line with the "no autoloader" scenario.

[Weaver]

BTW, the tank-mounted version of the 125mm is the 2A46. 2A45 is the towed gun.

I tried looking up the number for the 2A45 because I expect the figure for the 2A46 to be based on the assumption that an autoloader is present whereas maybe the one for the towed gun might be more in line with the "no autoloader" scenario.

Ah I see. And yet oddly enough, they both give similar figures. Of course, the towed gun has seven crew, so at least two of them could be loading, one with the shell and one with the charge, which would give a higher rate.

[dy031101]

Ah I see. And yet oddly enough, they both give similar figures. Of course, the towed gun has seven crew, so at least two of them could be loading, one with the shell and one with the charge, which would give a higher rate.

I see your point.  

Dang.

But yeah, I suppose the new ammos alone would indeed worth the replacement effort.

[rickshaw]

Separate cased ammunition as against what in naval parlance is referred to as "QF" or "Quick-firing" ammunition (fixed ammunition [ie the round is permanently fixed to the case of the ammunition to form a single unitary piece of ammunition] ) are much slower to load, particularly in a tank where there is usually only one human loader to do both jobs - load the round and the propellant case.

I understand that experience with the Chieftain/Challenger contradicts that, however much it may seem intuitive. The difference seems to be the awkwardness of handling the long, heavy fixed 120mm round in a confined space as opposed to the "handiness" of the separate projectile and charge.

You're answered your own point I think.  Of course it should be remembered that Chieftain/Challenger use bagged charges, not cased ones.   ASIUI, bagged charges are indeed a great deal easier to load than cased rounds inside a turret.  They also allow, unlike with fixed rounds, "lap loading" to be safely accomplished (the loader has a shell on his lap, ready to load.  With cased rounds and in particular combustible cased rounds, this is strictly a huge no-no.  If a flashback/fire/penetration occurs, the cased round can burn.  There have been several deaths that I know of in US Army tanks where loaders were allowed to "lap load" on the range and when a flashback occurred, the round on their laps burnt [note, didn't quite explode just burnt really, really, really fast].  In a Chieftain/Challenger all he's holding on his lap is a shell, with a very thick case or its an inert APFSDS dart, so its a lot harder to ignite.  The bagged charge is still held in the charge locker, which is water-jacketed. ). 

[rickshaw]

I understand that experience with the Chieftain/Challenger contradicts that, however much it may seem intuitive. The difference seems to be the awkwardness of handling the long, heavy fixed 120mm round in a confined space as opposed to the "handiness" of the separate projectile and charge.

I was playing with a hypothetical replacement of an old 122mm tank gun with a new 125mm gun.

If we are talking about just a simple gun replacement (no new turret), would it have precluded the installation of a matching autoloader?

The hypothetical tank's age aside, if we go without the autoloader then, would the replacement have been worthwhile?

No replacement is "simple" as the British Army has found with the 120mm smoothbore replacing the 120mm rifled guns in Challengers.  Basically they found they'd need a new turret.  It would cheaper and easier than trying to adopt the existing one to accept completely different rounds.  The 122mm is a very different beast to the 125mm.   Anyway, the JS-III was a piece of crap by all accounts.  The Soviets were glad to get rid of them and replaced them basically with the vehicle the JS-III was meant to replace - the JS-II.

[Weaver]

Separate cased ammunition as against what in naval parlance is referred to as "QF" or "Quick-firing" ammunition (fixed ammunition [ie the round is permanently fixed to the case of the ammunition to form a single unitary piece of ammunition] ) are much slower to load, particularly in a tank where there is usually only one human loader to do both jobs - load the round and the propellant case.

I understand that experience with the Chieftain/Challenger contradicts that, however much it may seem intuitive. The difference seems to be the awkwardness of handling the long, heavy fixed 120mm round in a confined space as opposed to the "handiness" of the separate projectile and charge.

You're answered your own point I think.  Of course it should be remembered that Chieftain/Challenger use bagged charges, not cased ones.   ASIUI, bagged charges are indeed a great deal easier to load than cased rounds inside a turret.  They also allow, unlike with fixed rounds, "lap loading" to be safely accomplished (the loader has a shell on his lap, ready to load.  With cased rounds and in particular combustible cased rounds, this is strictly a huge no-no.  If a flashback/fire/penetration occurs, the cased round can burn.  There have been several deaths that I know of in US Army tanks where loaders were allowed to "lap load" on the range and when a flashback occurred, the round on their laps burnt [note, didn't quite explode just burnt really, really, really fast].  In a Chieftain/Challenger all he's holding on his lap is a shell, with a very thick case or its an inert APFSDS dart, so its a lot harder to ignite.  The bagged charge is still held in the charge locker, which is water-jacketed. ). 

As I understand it, the Chally charges are a mixture of bagged and rigid combustible cased. The high velocity charges for APFSDS are cased and the ones for HESH and WP are bagged.

[dy031101]

Seeing there having been several experiments and acceptance of BMP-3-type armament suites by some countries, could an autoloading IFV turret armed with a 90mm DEFA F1 or Cockerill Mk.3 have been made cheap and simple enough to appeal to customers that already operate those guns?  Or was the two-man crew of the existing turret not really that bad?

[dy031101]

What's the high-explosive power of the 76mm gun M1?  The only thing I ever managed to find was that it underperformed when compared to the 75mm gun, but I want to compare it with smaller guns reputed to fire good HE shells, in my case the 45mm gun used to arm the T-26 light tank.

[dy031101]

Looking for (real, projected, and probable derivative) tank guns used by late-WWII American and German heavy tank projects (105mm~128mm range), I have a few questions:

1. do they use seperated projectiles and propellant cases?

2. what other factors contributed to those prototype tanks being large (eight road wheels per side, those American prototypes) and heavy?

[sagallacci]

regarding end of WWII big guns - The German 128 gun in the JagdTiger had a two-piece round. The earlier 128 Flak gun had a fixed round, but that proved to be a heavy and awkward item to manually maneuver around inside a vehicle.
The various big guns were really big, and needed big and heavy vehicles to handle them, and were also heavily armored. So, they tended to be really, really big.

Modern weapons of similar calibre have the advantage of better metallurgy and more clever ammo, so don't need to have such long cases and bulky chambers and breeches.

[dy031101]

Upon further browsing over the internet I found a lot of mentions that mass-produced Russian heavy tanks all have a low rate of fire (a commonly-cited figure being "two rounds per minute") with their main gun.  The figure for the Western counterparts were more scarcely-mentioned: M103 is said to have attained five rounds per minute (no mention for the Conqueror, but since I'm under the impression that the guns are the same, I'd figure that the Conqueror can do as well).  Only with the Chieftain tank did I find a figure at eight rounds per minute.

What about the various Soviet prototypes armed with a 130mm gun?  Is the Chieftain indeed the first tank to have a big gun with relatively easily-handled shells?

Anyway, the JS-III was a piece of crap by all accounts.  The Soviets were glad to get rid of them and replaced them basically with the vehicle the JS-III was meant to replace - the JS-II.

Speaking of which, it appears that IS-2 (including the derivative ISU-122) and IS-3 weren't really noted for gun accuracy.  Is it because of bad fire control or some weakness with their gun?

[rickshaw]

regarding end of WWII big guns - The German 128 gun in the JagdTiger had a two-piece round. The earlier 128 Flak gun had a fixed round, but that proved to be a heavy and awkward item to manually maneuver around inside a vehicle.
The various big guns were really big, and needed big and heavy vehicles to handle them, and were also heavily armored. So, they tended to be really, really big.

Modern weapons of similar calibre have the advantage of better metallurgy and more clever ammo, so don't need to have such long cases and bulky chambers and breeches.

Long cases are actually a disadvantage in gun design, particularly tank gun design.   Essentially what is needed is a large surface area to ensure even and continuous burning of the propellant so that lends itself to a short, broad cartridge case.   If coupled with the need to promote fast burning of the propellant to ensure rapid increases in pressure to create very high velocities in a relatively short barrel, again that points to the use of a short, broad chamber and hence cartridge case.  When creating earlier HV guns, such as for naval or AA use, the opposite was believed for many years but in both cases, it was possible to have much longer barrels than tanks could, so a slower, continuous burn of propellant was believed necessary to create high velocities because you had a much longer barrel in which to develop optimum pressure before the round exiting the end.

[kitnut617]

A question, the minigun fires the .30 round, was there ever a .50 made as a minigun ?

[Weaver]

A question, the minigun fires the .30 round, was there ever a .50 made as a minigun ?

Yes, the GECAL .50, available in three and six barrelled versions. The Russians also had the Yak-B four-barrelled gun on the Hind, which fired their 12.7 x 108mm round.

[Maverick]

At the other end of the scale, there was also the GE 'Six-Pack', which was chambered for the 5.56mm round.

Regards,

Mav