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John Kettler

Tunguska Armament Revisited! Does CMBS have it wrong?

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Remember the question I raised before about how many cannon there were on the Tunguska? Two vs. four. My understanding is that CMBS models 2, but that's a problem. Why? Army Guide says the Tunguska has 2 x 2A-38M 30 mm guns, each of which is a twin gun mount. 4 x 30 mm guns, not 2 x 30 mm guns. That particular page is straight from the 2A-38M manufacturer's, KBP, site. I suspect this will have all kinds of interesting in-game effects.

 

Regards,

 

John Kettler

 

 

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2A38M is a single unit, not two separate guns.  Likewise GSH-30 is not treated as two separate guns, but one gun with high RoF.  Tunguska has 2x 2A38M, not 4x 2A38M.

Edited by akd

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akd,

 

I understand that point, but it's not what the product description says at all.  Perhaps, then, the manufacturer needs to revisit its choice of phrasing used in its marketing materials? In any event, this is a very nice vid someone whose handle is TulaKirill put together showing the entire range of light cannon produced by KBP, with the 2A-38M appearing at 4:22. From that pic it is clear that weapon has staggered barrels, whereas the GSh-30 (0:28), as fitted to the Su-25/FROGFOOT, has them even. There also appears to be confusion about nomenclature, for multiple sites refer not to the GSh-30, but to the GSh-30-2 and directly assign to to the above CAS aircraft.

 

https://www.youtube.com/user/TulaKirill

 

Regards,

 

John Kettler

Edited by John Kettler

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Umm, it has4 barrels. Two per side. One barrel per side has a velocity sensor for feedback to the fcs. There is a ring for that, and one is set back, no doubt to ease feeding and extraction issues. 

 

Why is there a question about it only having 2 barrels?

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You can like, literally see there are only two guns on a Tung...

I thought that too, for a while. Look close. The orientation of the twin barrels is a staggered over/under which are stacked right on top of each other.

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c3k,

 

I think the staggered barrels have nothing to do feed and extraction and everything to do with accuracy wrecking muzzle blast interference between succeeding shots as the barrels alternate firing at very high ROF. I think the MV on the 2A-38M (960 m/sec) is driving this. ROF is 2500 rpm. Battleships had trigger time limiters to prevent adjacent guns in a turret from firing at the same time for precisely that reason. GSh-30 MV is 870 m/sec, considerably lower. ROF is 3000 rpm.

 

Apocal,

 

Judging by what you said, you didn't watch the vid I provided in my #3. At 4:22 you can see the 2A-38M with no shroud or housing. When you do, you will find it quite easy to count the barrels for yourself. It's an odd looking weapon, but that's how they built it. They undoubtedly had a reason for doing it that way. Russian gun designers are about as pragmatic as they come. 

 

gunnersman,

 

You have no idea how many times I've gone back and forth with myself over this. It helps enormously to have a photo of the cannon by itself in figuring out such matters.

 

Regards,

 

John Kettler

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I thought that too, for a while. Look close. The orientation of the twin barrels is a staggered over/under which are stacked right on top of each other.

 

 

Apocal,

 

Judging by what you said, you didn't watch the vid I provided in my #3. At 4:22 you can see the 2A-38M with no shroud or housing. When you do, you will find it quite easy to count the barrels for yourself. It's an odd looking weapon, but that's how they built it. They undoubtedly had a reason for doing it that way. Russian gun designers are about as pragmatic as they come.

 

Multiple barrels don't mean multiple guns, guys.

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Apocal,

 

It's very hard to tell what it is when much of the weapon isn't visible. Nor does it help that such designs as the 2A-38M are wildly uncommon in the West. Here, if you see two barrels, it usually means two separate guns, as seen here in a helpful shot of an Oerlikon twin 20 mm mount.

 

http://en.wikipedia.org/wiki/Oerlikon_20_mm_cannon#mediaviewer/File:HMCS_Haida_Hamilton_Ontario_14.jpg

Likewise, you have the loosely comparable (similar in caliber if not MV, 881 m/sec, to the 2A-38M) Bofors Twin 40 of WW II fame.

 

http://www.ussslater.org/tour/weapons/40mm/images/40mm_5.jpg

 

Note how closely the barrels are spaced, yet each barrel unambiguously has its own breech assembly and ammo chute in which to place the ammo clips. Had someone figured out how to alternately feed ammo to one barrel, then the other, from the same common ammo supply, then you'd have the functional equivalent of the 2A-38M. Obviously, the engineering differences go deeper than that, but what I've shown suffices at the conceptual level. 

 

Regards,

 

John Kettler 

Edited by John Kettler

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Apocal,

 

It's very hard to tell what it is when much of the weapon isn't visible. Nor does it help that such designs as the 2A-38M are wildly uncommon in the West.

 

There is a picture of the gun in your first link, top-most and to the right, then a shot of their installation on the Tung. And we've had multi-barrel designs since the Vulcan. Even used them in air defense vehicles.

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Apocal,

 

The Russian 2-barrel scheme isn't the same as a Gatling gun, which is what the Vulcan is. The GSh-23 and GSh-30 operate on entirely different firing principles, of which the first big one is that they are linear, not rotary, systems. The way the GShs work is via the revolutionary Gast principle, which dates back to WW I. Two barrels and two actions joined together. When Barrel 1 fires, the recoil forces load and fire Barrel 2, which then does the same for Barrel 1 and so on. 1600 rpm from the 7.92 mm Gast gun!

 

Regards,

 

John Kettler

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The quote below is from the same website the information about the cannon came from:

 

"The vehicle belt-fed cannons fire a 30mm unified round. The twin barrel cannon pattern provides for a rate of fire of 5,000 rds/min."

 

2S16 Tunguska

 

That may be some exaggeration for marketing purposes. But you will need more than two barrels to get that ROF.

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Apocal,

 

The Russian 2-barrel scheme isn't the same as a Gatling gun, which is what the Vulcan is.

 

I'm aware of how it works. I'm just saying that multi-barrel guns have been a common thing for over a half century now.

Edited by Apocal

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