Tanks guns and ammunition.

[Renegade334]

Dunno if that has been posted here before, but the YouTube algorithm has struck again.

 

 

The APFSDS model wasn't specified, only that it is a 120mm sabot.

The failure seen here apparently stems from a destruction of the fin assembly, which also resulted in tip detachment from the long rod's main section.

 

 

[SH_MM]

Seems like it is being fired from a Nexter 120 mm gun without MRS.

[BkktMkkt]

some update

105mm m900 m833 m774 m735

m900 - penetrator length 603 mm, volume 206344,9906mm³ (density 18,6/~3,830kg/real 3,830kg)
m833 - penetrator length 427 mm, volume 196634,2908mm³ (density 18,6/~3,657kg/real 3,668kg)
m774 - penetrator length 345 mm, volume 178942,0578mm³ (density 18,6/~3,328kg/real 3,364kg)
m735 - core length 309,5 mm, volume 119354,6819mm³ (density 18,5/~2,208kg/real 2,210kg)

[Bronezhilet]

21 hours ago, BkktMkkt said:

some update

105mm m900 m833 m774 m735

m900 - penetrator length 603 mm, volume 206344,9906mm³ (density 18,6/~3,830kg/real 3,830kg)
m833 - penetrator length 427 mm, volume 196634,2908mm³ (density 18,6/~3,657kg/real 3,668kg)
m774 - penetrator length 345 mm, volume 178942,0578mm³ (density 18,6/~3,328kg/real 3,364kg)
m735 - core length 309,5 mm, volume 119354,6819mm³ (density 18,7/~2,231kg/real ?)

Nice work!

Are you willing to share your models with me? I'm interested in doing some CFD simulations on them.

[Domus Acipenseris]

This site deal with APFSDS.  Lots of graphs and info.

 

http://www.longrods.ch/start.html

[Ramlaen]

 

[Ramlaen]

30x113 and 30x173 proximity fuze

 

 

[LoooSeR]

Any info on how far proximity fuze can "sense"?

[Ramlaen]

6 hours ago, LoooSeR said:

Any info on how far proximity fuze can "sense"?

 

Not that I am aware of, aiui it is based on the SAGM fuze that was being developed for 40mm grenades.

 

https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2012/armaments/Tuesday14032sande.pdf

https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2015/smallarms/17332_Gilbert.pdf

[Ramlaen]

https://www.facebook.com/18IN3BCT4ID/posts/229367245891559

[Ramlaen]

Finally a picture of ELOS.

 

 

[Zach9889]

Does anyone have an idea of what the KE-W A4 is, referenced in the press release linked below?

 

 https://www.dsca.mil/press-media/major-arms-sales/egypt-120mm-tank-rounds

[Ramlaen]

48 minutes ago, Zach9889 said:

Does anyone have an idea of what the KE-W A4 is, referenced in the press release linked below?

 

 https://www.dsca.mil/press-media/major-arms-sales/egypt-120mm-tank-rounds

 

https://www.thedefensepost.com/2018/09/18/egypt-cleared-60500-tank-rounds-general-dynamics/amp/

The M831A1 and M865 120mm rounds are used for target practice while the A4 Armor-Piercing Fin-Stabilized Discarding Sabot with Tracer (APFSDS-T) rounds are specifically modeled for the Abrams M1A1 and M1A2 tanks’ 120mm M256 main gun.

The A4 variant is a fifth-generation projectile that utilizes an updated blend of propellant to maintain consistent muzzle velocities across operational temperatures from extreme cold through extreme heat, according to the U.S. Army.

The new munitions will replace Egypt’s older model 120MM KE-W, KE-W Al, and KE-W A2 ammunition.

[Zach9889]

Thanks, more curious as to if there are any clues as to what the projectile is. AFAIK the A1 is a licenced DM43. From Ramlaen's excerpt, the details regarding the temperature insensitive propellant is reminiscent of the DM63.

[TWMSR]

KEW - tungsten variant of M829A1

KEW-A1 - variant of DM 43

KEW-A2 - tungsten variant of M829A2

KEW-A3 - probably tungsten variant of M829A3 (ever seen?)

KE-T /AKE-T/KEW-A4 (?) - tungsten variant of M829A4

[Clan_Ghost_Bear]

@TWMSR

 

The KEW-A3 is an update of the KEW-A2 with SCDB propellant:

https://web.archive.org/web/20150813130631/http://defmunintl.com/KEW_A3.html

[SH_MM]

Yes, the KEW-A3 already used a TIPS, i.e. Rheinmetall's SCDB propellant. Given that Defense Munitions International (the short-lived Rheinmetall-GD joint-venture for tank ammo) doesn't seem to exist anymore, GD might have opted to use its own propellant instead.

 

KEW-A4 doesn't use the M829A3/A4 penetrator. They are from different manufacturers; the KEW series is from GD, the M829A3 is from Northrop-Grumman gun/ammo business (formerly ATK). Northrop-Grumman has advertised an export round known as KE-T (Kinetic Energy Tungsten, a tungsten version of M829A3), but nobody is known to have purchased that.

[Lord_James]

Is it more efficient mass wise to have a gun with a longer barrel and lower pressures, or a shorter barrel and higher pressures? The 75mm PaK 42 seems to be about 1 ton by itself, while the similar 77mm HV is 1.5 tons (don’t have a source for the QF 17 lb without carriage). 

[Toxn]

13 hours ago, Lord_James said:

Is it more efficient mass wise to have a gun with a longer barrel and lower pressures, or a shorter barrel and higher pressures? The 75mm PaK 42 seems to be about 1 ton by itself, while the similar 77mm HV is 1.5 tons (don’t have a source for the QF 17 lb without carriage). 

That's a really interesting question! Which I'm deeply unqualified to answer 

 

Anyway, the equation for hoop stress is Pd/2t under the thin-wall assumption, which seems to indicate a linear relationship between pressure and wall thickness. The relationship between pressure and velocity is a bit more complicated, but running the numbers on test barrels (a 75mm L/40 gun running at 375MPa, and a 75mm L/30 running at 500 MPa) seems to show a similar relationship in terms of the length needed.

 

The terms thus appear to cancel out, at least for the calibre range you were referring to: a high-pressure gun, having the same performance as a low-pressure one, will weigh about the same.

 

Here the obvious problem is that cannons are not thin-walled, which means that you need to do integration and constant-finding to get a good answer. Now, without wanting to touch that particular mess at all, my gut feeling is that the higher the pressure the thicker the walls need to be relative to lower-pressure tubes. Which probably leads, in turn, to lower-pressure guns being lighter than higher-pressure ones for the same level of performance. The functional constraint then becomes about length and tube stiffness, which starts to become a significant factor as your low-pressure potato cannon scales up in velocity.

 

Extrapolating, then: a low-pressure gun is great if you can get away with it, being lighter than a high-pressure one of the same performance (which is probably why things like the low-pressure 90mm guns are built the way they are). In fact, as a designer you should probably look for the lowest-possible pressure to run a gun at so long as it fits within the maximum dimensions that you're allowed.

 

Unfortunately, if you're looking at slinging an energetic (read: AP or APFSDS) shell, then this also implies that you're doomed to chase after higher and higher pressures (and thus relatively heavier guns) simply to keep within reasonable size and stiffness constraints.

[Lord_James]

9 hours ago, Toxn said:

That's a really interesting question! Which I'm deeply unqualified to answer 

 

Anyway, the equation for hoop stress is Pd/2t under the thin-wall assumption, which seems to indicate a linear relationship between pressure and wall thickness. The relationship between pressure and velocity is a bit more complicated, but running the numbers on test barrels (a 75mm L/40 gun running at 375MPa, and a 75mm L/30 running at 500 MPa) seems to show a similar relationship in terms of the length needed.

 

The terms thus appear to cancel out, at least for the calibre range you were referring to: a high-pressure gun, having the same performance as a low-pressure one, will weigh about the same.

 

Here the obvious problem is that cannons are not thin-walled, which means that you need to do integration and constant-finding to get a good answer. Now, without wanting to touch that particular mess at all, my gut feeling is that the higher the pressure the thicker the walls need to be relative to lower-pressure tubes. Which probably leads, in turn, to lower-pressure guns being lighter than higher-pressure ones for the same level of performance. The functional constraint then becomes about length and tube stiffness, which starts to become a significant factor as your low-pressure potato cannon scales up in velocity.

 

Extrapolating, then: a low-pressure gun is great if you can get away with it, being lighter than a high-pressure one of the same performance (which is probably why things like the low-pressure 90mm guns are built the way they are). In fact, as a designer you should probably look for the lowest-possible pressure to run a gun at so long as it fits within the maximum dimensions that you're allowed.

 

Unfortunately, if you're looking at slinging an energetic (read: AP or APFSDS) shell, then this also implies that you're doomed to chase after higher and higher pressures (and thus relatively heavier guns) simply to keep within reasonable size and stiffness constraints.

I’m sure there are diminishing returns on such things when bore caliber scales up, and barrel length will most definitely get excessive if you want a low pressure / high velocity 120 (I’m tempted to see how low a pressure you can achieve with a 120mm L/70 while still being a viable sabot shooter). Barrel droop will probably kill any guns this long, though, without reinforcing, which negates the light weight I’m going for. 

[Atokara]

On 11/1/2021 at 10:53 AM, Lord_James said:

Is it more efficient mass wise to have a gun with a longer barrel and lower pressures, or a shorter barrel and higher pressures? The 75mm PaK 42 seems to be about 1 ton by itself, while the similar 77mm HV is 1.5 tons (don’t have a source for the QF 17 lb without carriage). 

If anything it's more of a cost issue rather than a weight issue. The Japanese developed their domestic 120mm with a higher pressure and better recoil system than the Rheinmetall 120mm while also shaving off 450kg in weight. They also scrapped plans for an L/55 upgrade for it after they decided that the performance was satisfactory until the jump to 130mm+ cannons, so similar performance to other L/55s can be implied. Such develops should be expected with 3-4 decades of metallurgy and machining advancement, but that also means higher costs. The thing about the Rheinmetall 120mm is Germany's MIC is primarily  held up by export sales. Their primary focus is creating a desirable product for their customers. A drop in barrel upgrade for existing platforms is a lot cheaper and opens up the market a lot more than a completely redesigned cannon. 

[SH_MM]

17 hours ago, Atokara said:

If anything it's more of a cost issue rather than a weight issue. The Japanese developed their domestic 120mm with a higher pressure and better recoil system than the Rheinmetall 120mm while also shaving off 450kg in weight. They also scrapped plans for an L/55 upgrade for it after they decided that the performance was satisfactory until the jump to 130mm+ cannons, so similar performance to other L/55s can be implied. Such develops should be expected with 3-4 decades of metallurgy and machining advancement, but that also means higher costs. The thing about the Rheinmetall 120mm is Germany's MIC is primarily  held up by export sales. Their primary focus is creating a desirable product for their customers. A drop in barrel upgrade for existing platforms is a lot cheaper and opens up the market a lot more than a completely redesigned cannon. 

 

Rheinmetall is offering a the widest range of 120 mm smoothbore gun of all manufacturers, including completely redesigned cannon. Aside of the standard L/44 and L/55 guns, the L/44A1, the L/55A1, the L/47LR and the L/47LLR are currently offered. The latter two provide more performance than the original L/44 gun (both by having slightly longer barrels and by supporting higher pressures), while being lighter and having a reduced recoil impulse.

 

However for Leopard 2 users, there is little gain in adopting the L/47LR or L/47LLR over something like the L/44A1 or L/55A1. The weight difference isn't really worth redesigning the turret, while improved performance can already be achieved with a change to the L/44A1 or L/55A1 gun at a lower cost.

 

Assuming that Japan's domestic 120 mm gun meets equals the performance of a L/55 or even a L/55A1 is a bit of stretch; them changing plans to adopt the L/55 might be solely related to their reference targets against which their gun might have already provided satisfactory results.

[Lord_James]

Hmmmm, I just had a very weird idea, but it will have to wait until tomorrow for me to flesh it out.

[Gun Ready]

On 9/17/2021 at 3:55 PM, Ramlaen said:

 

Haven't read or seen anything von Rheinmatalls 130 mm gun and ammo! It is pretty quiet with them!

[Lord_James]

21 hours ago, Lord_James said:

Hmmmm, I just had a very weird idea, but it will have to wait until tomorrow for me to flesh it out.

 

Since you like weird ideas @Toxn, I'll @ you specifically  

 

So, with more modern APFSDS having smaller fins that the bourrelet fins of old, couldn't the bore size be reduced for many AP slingers? Reducing the bore diameter (down to roughly 90-95% of the fin diameter, but not to where the fins interact with the tube) might reduce the weight of the barrel, assuming it stays the same thickness, and would definitely reduce the mass of the carrying sabot, meaning more energy towards the penetrator. This might also mean savings to the weight of propellant needed to get a round up to a particular energy, or increase the energy of an already powerful round without increasing the propellant or chamber size. It might be possible to get a 105mm (or less) gun with a thicker barrel and larger chamber that your normal L7A or M68, but slinging full size 120mm (or larger, if the fins fit) sabots at targets. This gun might be somewhat lighter than the 120's, but I don't think by too much. 

 

I'm going to assume I'm not the first person to come up with this, and that there must be problems associated with doing something like this. I'm going to guess there are barrel droop and vibration problems, thought these might be less so than a normally designed gun because I specifically stated that the barrel stays the same thickness as the original gun (read: 120mm L/44) to cope with the (assumed) higher pressures of the larger parent gun. There's also the fact that the HE shells you will want to sling at infantry are also less effective, unless you make the HE abnormally long, which might also have hidden consequences like strange shrapnel dispersion or tumbling or something else you don't want. I'm disregarding HEAT due to it falling out of favor based on greater ERA usage across many combat vehicles, but it's problems would be similar to the HE shell. 

 

Any thoughts from anybody? I'm always open to being corrected and learning real world experience.