Tank Guns and Ammunition

[Damian]

re: Tank Guns: Photo & Dicussion thread..

Polish article about new german lightweight Rh 120LLR L/47 for light tanks, universal paltforms, tank destroyers, wheel tank destroyers, etc





The most important dates in english:

1. Rh 120LLR L/47 was developed for light tanks, universal paltforms, tank destroyers, wheel tank destroyers, etc
It has the same baistic like Rh120 L44, but use JCB interfejs for progrmed munitions (like DM11)
Its using material and technology originally developed for 140mm Rh guns.
Barrel life time is:
- 800-1400 for trening munitions (sabot/HEAT)
- 600 for DM63
- 200 for DM53
efficiency muzzle brake is between 44%(DM53) and 55%
the recoil is reduced from 650-700kN to only 250kN, and recoil impulse from 28-29kNs to 21kNs.

2. For combat platform with weight about <20t. Rheinmettal developed diffrent gun: Rh 105SB cal 105mm whit recoil only 180kN and recoil impulse 16 kNs. Ammo using in that 105mm gun can penetrate 560mm RHA for 2000m.


3. Rest dates is in the table - transating criteria in tabela for up to down:
Kaliber[mm] - Caliber
Długość lufy[mm] - barrel lenght
Masy [kg] - mass (weight):
- całkowita (tottal)
- lufy (barrel)
- zespołu zamka ( closing gun - I havent propoer word in english)
- zespołu odrzutowego (recoil system)
Objętość komory nabojowej [dm3] - (volume of the chamber for cartridges)
Prędkość początkowa pocisku [m/s] - (V exit)
Długość odrzutu [mm] - (recoil lenght)
Maksymlana siła odrzutu [kN] (recoil strenght)
Maksymlany impuls odrzutu [kNs] (recoil impulse)
Maksymlane ciśnienie gazów [MPa] (maximum gas pressure)

So thin gun can't be used on ~20 tons heavy platforms? Well it is less impressive than XM360 that can be used on such lightweight platforms, is a bit longer and have it's own dedicated MBT version XM360E1.

 

[militarysta]

re: Tank Guns: Photo & Dicussion thread..

So thin gun can't be used on ~20 tons heavy platforms? Well it is less impressive than XM360 that can be used on such lightweight platforms, is a bit longer and have it's own dedicated MBT version XM360E1.

No, Rh120LLR L/47 can be use on 20-25t heavy platforms, but gun is not only probem - ammo store, and others, so germans claim that 120mm guns are optimum for ~25 tons and more platforms, and for lighter then 20tons platforms is desingnated Rh 105SB 105mm. And in article is sentense that not recoil or recoil impulse is a problem (or gun mass) but the whole "suporting sytsem" for gun - FCS, turret, ammo store, etc And for that reson they did so distinction

In facte they did distinction:
20 and more (whit optimum from 25t) Rh120LLR L/47
less then 20 (15-20) Rh 105SB 105mm.

But, Rh120LLR L/47 was developed for...15t. and more platorms when only 4t. is for whole armed part (gun, FSC, ammo) so gun weight must be lower then 2000kg (like in Rh120LLR L/47 ), but in that case scenario only 20 pieces of 120mm ammo can be takes (it ~500kg) etc.

 

[Damian]

re: Tank Guns: Photo & Dicussion thread..

Ah, so this clarify some things. Thank You.

 

[methos]

re: Tank Guns: Photo & Dicussion thread..

Interessting militarysta. It says max. chamber pessure is 670 MPa, but Rolf Hilmes wrote that it is 710 MPa.

Also interessting is the part about the autofrettagering (first page in the center column): It says "1100 MPa i 800 MPa" there, this is 110,000 bar and 8,000 bar... can you please translate this sentence? About what gun is this (L/44, L/55, L/47 LLR, 105 mm SB)?

 

[militarysta]

re: Tank Guns: Photo & Dicussion thread..

can you please translate this sentence?

OK:

Also interessting is the part about the autofrettagering (first page in the center column): It says "1100 MPa i 800 MPa" there, this is 110,000 bar and 8,000 bar... can you please translate this sentence? About what gun is this (L/44, L/55, L/47 LLR, 105 mm SB)?

OK:
This part is about technology during production Rh120LLR L/47 barrel when is using double autofrettagering whit presure 1100 MPa and 800 MPa what allow to use new and better ammo whit highter chamber pressure.

And on the second page it mentions "560 mm RHA" on the second page, for which round? Is this for the new 105 mm smoothbore ammunition or some 120 mm round?

It's for Rh105SB but...not for new round - it's for some older then 2004 105mm APFSDS round use in 105mm, but unfortunatly there is no designation name in tekst. And then in mention in tekst taht it's no "the last word" and now (in 2004) Rheinmettal WM is working on new 105mm APFSDS whit DM53 penetrator tehnology and DM63 properant charge whit better performance then this "560mm RHA" elier mentioned in tekst.

Interessting militarysta. It says max. chamber pessure is 670 MPa, but Rolf Hilmes wrote that it is 710 MPa.

Yes, it's some discrepancy -I'll check in my papers about that.

For 5min You will have PM whit factory Strv.121/122 instruction

 

[Damian]

re: Tank Guns: Photo & Dicussion thread..

For 5min You will have PM whit factory Strv.121/122 instruction

Can You send me it too?

 

[militarysta]

re: Tank Guns: Photo & Dicussion thread..

Can You send me it too?

ok - PMzzzzz

 

[Damian]

re: Tank Guns: Photo & Dicussion thread..

Many thanks.

 

[hest]

re: Tank Guns: Photo & Dicussion thread..

I don't want to be rude, but dates for Rh are not very good. In fact they are far far from truth:



DM53 from L-55 have about 30% bigger MJ on gun exit -so it will be cira about 15.3MJ

How official is this ? Figures for RH/L44 and RH/55 (9MJ and 12.6MJ) came from official sources. As I understood (I may be wrong), that is the maximum potential energy projectile can have (potential which depends on pressure, caliber and lenght).

In any way my figures are valid to make relative comparison (but not specific ??)

 

[Damian]

re: Tank Guns: Photo & Dicussion thread..

How official is this ? Figures for RH/L44 and RH/55 (9MJ and 12.6MJ) came from official sources. As I understood (I may be wrong), that is the maximum potential energy projectile can have (potential which depends on pressure, caliber and lenght).

In any way my figures are valid to make relative comparison (but not specific ??)

Table with data used by Militarysta was made by Polish institute that is developing APFSDS ammunition and was unsing official avaiable data from other allied countries sources.

 

[militarysta]

re: Tank Guns: Photo & Dicussion thread..

How official is this ? Figures for RH/L44 and RH/55 (9MJ and 12.6MJ) came from official sources. As I understood (I may be wrong), that is the maximum potential energy projectile can have (potential which depends on pressure, caliber and lenght).

In any way my figures are valid to make relative comparison (but not specific ??)

Very offcial:
http://www.witu.mil.pl/www/witu_pl.htm
in "Biuletyn Naukowy" ---> "Zeszyty PTU"

This value from WITU pdfs are most realible sources in my opinnion becouse:
1) those pdfs had been writing by professional tank, armour and arment developers
2) most of them are Master's theses and doctoral (PHD's) work
3) WITU is very good institute and have strong relevant from Polish Army and...German Industry.

 

[hest]

re: Tank Guns: Photo & Dicussion thread..

Very offcial:
http://www.witu.mil.pl/www/witu_pl.htm
in "Biuletyn Naukowy" ---> "Zeszyty PTU"

This value from WITU pdfs are most realible sources in my opinnion becouse:
1) those pdfs had been writing by professional tank, armour and arment developers
2) most of them are Master's theses and doctoral (PHD's) work
3) WITU is very good institute and have strong relevant from Polish Army and...German Industry.

Ok, so I assume the other figures are sort of "average" or based on old data (what is the criteria ??)

I am interested in potential performance of guns.

So even without specific data, it can be concluded that:
RH-L/44<2a46-m<RH-l/55

Besides, I do not think it is possible for RH-L55 to achieve more than 15MJ.

Maximum performance which can be achieved with those calibers is initial velocity of 2000m/s (close to 20MJ). This is armament of next generation tanks, 2a82.

 

[methos]

re: Tank Guns: Photo & Dicussion thread..

How official is this ? Figures for RH/L44 and RH/55 (9MJ and 12.6MJ) came from official sources. As I understood (I may be wrong), that is the maximum potential energy projectile can have (potential which depends on pressure, caliber and lenght).

In any way my figures are valid to make relative comparison (but not specific ??)

This is not the maximum potential energy... it is from the used rounds. Weight and velocity are known, rest is very simple math.

Maximum performance which can be achieved with those calibers is initial velocity of 2000m/s (close to 20MJ). This is armament of next generation tanks, 2a82.

20 MJ are not realsitic for the 2A82. Maybe in the wet dreams of some fanboys, but not in reality. For reaching 20 MJ they would need to pack more powder into the chamber as the Swiss did on their 140 mm gun prototype... this is not possible due to physical limitations.
Muzzle velocity is not equivalent with muzzle energy. To bring a 6 kg projectile to 2,000 m/s you will need 12 MJ... this is achievable with the Rh 120 L55 and current generation propellant.

So even without specific data, it can be concluded that:
RH-L/44<2a46-m<RH-l/55

No. The current pressure limit of the 2A46M-x series of guns is significantly below that of the Rh 120 L/44. The 2A46M-x tank guns are slightly longer, but this is needed to compensate the low pressure limitations. The best known 125 mm APFSDS have an energy output of 10.18 MJ, which is below the energy output of 120 mm DM43/KEW-A1 and about the same as M829A1.
We do not know if the Russians did field any new KE ammunition after 1991, but the rounds fielded prior 1991 are all inferior to the latest two generations of 120 mm APFSDS for the Rh 120 L/44 (M256) tank gun.

 

[Akim]

re: Tank Guns: Photo & Dicussion thread..

No. The current pressure limit of the 2A46M-x series of guns is significantly below that of the Rh 120 L/44. The 2A46M-x tank guns are slightly longer, but this is needed to compensate the low pressure limitations. The best known 125 mm APFSDS have an energy output of 10.18 MJ, which is below the energy output of 120 mm DM43/KEW-A1 and about the same as M829A1.
We do not know if the Russians did field any new KE ammunition after 1991, but the rounds fielded prior 1991 are all inferior to the latest two generations of 120 mm APFSDS for the Rh 120 L/44 (M256) tank gun.

Both cannons not substantially differ from each other. Nor in the output given, of any rounds. Yes, the German cannon is hardly better, but at the present level, tanks can resist to each other.
On the whole level of Leo-2А4 to the correspond level of BM Bulat and Т-72B2.

 

[methos]

re: Tank Guns: Photo & Dicussion thread..

Not exactly. Was the autoloader modified on Bulat/T-72B2 to increase penetrator length? Afaik only the T-90A (and probably the T-84) can use 700+ mm long APFSDS.

 

[Akim]

re: Tank Guns: Photo & Dicussion thread..

Not exactly. Was the autoloader modified on Bulat/T-72B2 to increase penetrator length? Afaik only the T-90A (and probably the T-84) can use 700+ mm long APFSDS.

One gun 2A46M(KBA3) is used in all types of tanks .
And we already it is said that lengthening of core, compensated by speed.
Besides ML of tank of BM Bulat, allows to use long APFSDS.
KMDB - 125 mm KBA3 tank gun

 

[Damian]

re: Tank Guns: Photo & Dicussion thread..

And we already it is said that lengthening of core, compensated by speed.

The problem with most types of APFSDS ammunition for T-xx tanks is that it's use of ring sabot, that forces designers to use big fins that reduce velocity quickly, besides this lighter penetrator that flies faster does not mean better or comparable penetration. Sometimes slower penetrator, that also much slowly lost it's velocity and thus kinetic energy, that is also longer, migh achieve better penetration.

 

[methos]

re: Tank Guns: Photo & Dicussion thread..

One gun 2A46M(KBA3) is used in all types of tanks .

And we already it is said that lengthening of core, compensated by speed.

No! There is a optimum velocity for impact:

Penetration performance is not linear. If you have a 100 m/s higher muzzle velocity than the difference will be more than 100 mm RHA perforation at a velocity of 1,100 m/s instead of 1,000 m/s, but the difference between 1,500 m/s and 1,600 m/s is less than 50 mm perforation into RHA!
You try to ignore various factors relevant for armour penetration and focus on a single factor (the velocity) like many people from the former Soviet Union do... simply because this favours their tank. U.S. Americans tend to say "length is the only thing that matters", because their rounds are longer.
But in reality armour penetration is depending on a combination of multiple factors. And one of this factors is the weight per area (which means length, diameter and density of penetrator) another point is velocity (drop of velocity due to fricition and drag, muzzle velocity)... trying to focus on a single thing will lead nowhere. If length wouldn't matter, why did the Soviet increase length of their penetrators? Why did the U.S. do so? Why the Germans? Because they all are dumb? No!


Next thing is the following: 120 mm DM43 from the Rh 120 L/44 is faster than current Soviet-legacy ammunition and longer than any ammunition which is compatible with the standard T-72 autoloader.

 

[Akim]

re: Tank Guns: Photo & Dicussion thread..

No! There is a optimum velocity for impact:

Penetration performance is not linear. If you have a 100 m/s higher muzzle velocity than the difference will be more than 100 mm RHA perforation at a velocity of 1,100 m/s instead of 1,000 m/s, but the difference between 1,500 m/s and 1,600 m/s is less than 50 mm perforation into RHA!
You try to ignore various factors relevant for armour penetration and focus on a single factor (the velocity) like many people from the former Soviet Union do... simply because this favours their tank. U.S. Americans tend to say "length is the only thing that matters", because their rounds are longer.
But in reality armour penetration is depending on a combination of multiple factors. And one of this factors is the weight per area (which means length, diameter and density of penetrator) another point is velocity (drop of velocity due to fricition and drag, muzzle velocity)... trying to focus on a single thing will lead nowhere. If length wouldn't matter, why did the Soviet increase length of their penetrators? Why did the U.S. do so? Why the Germans? Because they all are dumb? No!


Next thing is the following: 120 mm DM43 from the Rh 120 L/44 is faster than current Soviet-legacy ammunition and longer than any ammunition which is compatible with the standard T-72 autoloader.

I said really, that "soviet" school leaned only against speed. Balance of combinations goes also .
DM43A1:
Length of dense core: 574 mm
3BM- 42
Length of dense core 574 mm

And speed for them is identical a 1700 m/s. Muzzle energy at the German cannon hardly more, (12(Ger) /11.8 (Rus) MJ) but it is unimportant.

And the Russian and Ukrainian shells of 90th are comparable with DM53.

 

[methos]

re: Tank Guns: Photo & Dicussion thread..

No. DM33 has a 570 mm core and a 640 mm long sub-projectile. DM43 has a 690 mm long sub-projectile and an unknown core length (but likely 600+ mm). 3BM-42 has a 570 mm long sub-projectile and only 420 mm core.

These modern shells are comparable, but cannot be used in the T-72 autoloader. This is what I said.