Main Battle Tanks and Armour Technology

[The Last Stand]

The side turret is 140 mm in the area which is overlapping with the frontal area and only from 90° angle:

Yes, but the NATO targets were standarized somewhere in the 1960/70s. They represent the armour of the T-10 heavy tank at different parts/angles. Modern 105 mm APFSDS can also defeat NATO heavy targets at 5,000 m.

I heard on some other forum that the targets were made to test HEAT rounds and not APFSDS. Any info on that?

Regards,
Keshav

 

[methos]

Also, what's your opinion on the real penetration.

It's performance is rather questionable. Judging by a short modelling with the Lanz-Odermatt equation, penetration might be around 420 mm RHA at 2,000 m against 235 HB steel at 60°. This roughly equals 400 mm RHA with an hardness of 270 HB under the same conditions and only ~350 - 360 mm RHA with an hardness of 270 HB at 2,000 m and 0° impact angle. But for more detailed modelling/estimating many input values remain unknown and can only be estimated.

I hope there really is the new 120 mm APFSDS ammunition mentioned serveral times on this forum, but 650 mm RHA penetration at 2,000 m seems to be rather hard to achieve with the given gun system.

You were correct in stating that the EFC of APFSDS is 3 or 4 times more than the other rounds but the OFB site states that the EFC is 500 and EFC of APFSDS is 1.
So the barrel has an actual life of 500x3 (HESHx3) = 1500 EFC? Is the barrel that strong? Also compare this value of 1500 with the Royal Ordnance L7 and L30 guns as I am unable to get data for them.

Seems a bit wrong.

APFSDS on avarage is 3-4 EFC, and HE, HEAT and HESH on avarage is 1 EFC, so if gun have a life time of 1500 EFC, you can fire 1500 HE/HEAT/HESH and much less APFSDS.

It is depending on the definition. Spielberger said that the Rh 120 has a barrel life of 500 "standard rounds" DM13 (i.e. EFC) and three times the amount of barrel life when firing DM12. EFC means "equivalent full charge", so using the KE ammunition as reference makes sense. But with more types of KE ammunition being introduced (with different EFC values) another type of ammunition had to be chosen for referencing.

If the Indian barrel can fire 500 KE or 1,500 HESH rounds, then it is comparable to modern 120 mm and 125 mm smoothbore guns in this aspect.

 

[Damian]

Waiting for L7 and L30 values on barrel life.

Ok, I figured out I have official document from Polish institute WITU that is specialized in military technology, and this document have such data.

The American M68 105mm rifled gun that is american version of the L7, so should have similiar performance, have service life of 1,000 shots, don't know tough if it is EFC, but as we follow international standads, it is most probably provided in EFC.

As for L30, I didn't find service life in any credible source, Wikipedia says however it's service life is 400 EFC.

 

[The Last Stand]

It's performance is rather questionable. Judging by a short modelling with the Lanz-Odermatt equation, penetration might be around 420 mm RHA at 2,000 m against 235 HB steel at 60°. This roughly equals 400 mm RHA with an hardness of 270 HB under the same conditions and only ~350 - 360 mm RHA with an hardness of 270 HB at 2,000 m and 0° impact angle. But for more detailed modelling/estimating many input values remain unknown and can only be estimated.

I hope there really is the new 120 mm APFSDS ammunition mentioned serveral times on this forum, but 650 mm RHA penetration at 2,000 m seems to be rather hard to achieve with the given gun system.

Thanks Methos. Do you think that there is any scope for improvement of the ammunition? The round is supposed to be 940 mm long, penetrator length is unknown, (Damian knows something about it) and the round is made of Tungsten alloys and the muzzle velocity is around 1650 m/second. I thought this was comparable to contemporary rounds. Any thoughts?

The American M68 105mm rifled gun that is american version of the L7, so should have similiar performance, have service life of 1,000 shots, don't know tough if it is EFC, but as we follow international standads, it is most probably provided in EFC.

As for L30, I didn't find service life in any credible source, Wikipedia says however it's service life is 400 EFC.

Service life is that low? Of course we don't know the real value but I didn't expect that.

Anyway, the L7 has more ammunition types available than any smoothbore gun in service now.

APDS
APERS-T ("Anti-personnel-tracer")
APFSDS: 1,475 m/s
Canister
Dummy
HE: 1,174 m/s
HEAT
HESH: 737 m/s
Smoke-White phosphorus incendiary
Target Practice
Target Practice Discarding Sabot[

Damian, you said that rounds like HEAT are costly for rifled rounds. IIRC, the HEAT rounds of the L7 have some sort of special stabilization. I've been reading up on the Second World war's weapons for the past 1 year now and German scientists in 1943 concluded that using HEAT rounds in rifled guns was a waste of money as the explosives were disturbed due to spin and the penetration was greatly reduced. They switched to smoothbore. :accepted:

Read up on the world's first smoothbore anti-tank guns:

8 cm PAW 600 - Wikipedia, the free encyclopedia
Panzerwurfkanone 10H64 - Wikipedia, the free encyclopedia

The PAW 600 (8H63) was very innovative. It reused mortar cases from the standard infantry mortar! Was ready and issued at the end of the war, didn't see service. The 10H64 used cases from the standard infantry howitzer. Wasn't issued to troops. Both were dirt cheap and the 8H63 had penetration of more than ~140 mm. Overkill for any Allied tank except IS-2. 10H64 could destroy the IS-3 which didn't see service.

Regards,
Keshav

 

[Damian]

Damian, you said that rounds like HEAT are costly for rifled rounds. IIRC, the HEAT rounds of the L7 have some sort of special stabilization. I've been reading up on the Second World war's weapons for the past 1 year now and German scientists in 1943 concluded that using HEAT rounds in rifled guns was a waste of money as the explosives were disturbed due to spin and the penetration was greatly reduced. They switched to smoothbore.

Shaped charge jet, to say it simply "do not like spinning", it disturbs it's strutucre and decrease penetration capabilities. This is why most popular shaped charge ammunition types, are all fin stabilized, be it fired from tank guns, RPG's or ATGM launchers. There is ismiliar problems with APFSDS ammunition, the longer is KE penetrator, the more difficult is to use spin for stabilizing it during flight, so the only option are fins.

These are only two from several reasons why rifled guns as main armament of tanks, are obsolete, there is just no reason to stick with them, unless someone wants to be some huge military hipster.

Oh and by the way, as far as I know, HEAT ammunition for L7, of any type, did not have any "special stabilization", however French 105mm rifled gun, used on AMX-30, had HEAT ammunition called Obus-G that had warhead mounted on ball bearings so it was not spinning, while the projectile shell was normally spin stabilized. Of course it made projectile more complex and probably also expensive.

 

[The Last Stand]

I read about the Obus-G. I got it confused with the L7.

Damian, please reread my former post and see the question I wanted Methos to answer. Can the rounds can be redesigned to achieve better performance? Please don't talk about rifled guns being obsolete. I agree that they are obsolete but we are stuck with the L/52 gun till Arjun Mk.2. Beyond that it is unknown.

Many ammo types are present for the L7. After all, if so many rounds can be designed for a 105 mm rifled gun, why not for a 120 mm gun?

Regards,
Keshav

 

[Damian]

Damian, please reread my former post and see the question I wanted Methos to answer. Can the rounds can be redesigned to achieve better performance?

It is better to just design new ammunition, redesigning existing ammunition, might improve their performance but how much is the question.

Many ammo types are present for the L7. After all, if so many rounds can be designed for a 105 mm rifled gun, why not for a 120 mm gun?

There is no technical obstacle to design so many types of ammunition for 120mm rifled and smoothbore guns, the problems are different armed forces requirements and costs. Besides this, today many types of ammunition can be replaced by single type, for example programmable HE which can act as multipurpose ammunition replacing 4 other types of ammunition.

 

[The Last Stand]

There is ismiliar problems with APFSDS ammunition, the longer is KE penetrator, the more difficult is to use spin for stabilizing it during flight, so the only option are fins.

It is difficult to use spin to stabilize the basic APDS (Armor piercing Discarding Sabot - first used in the 17 pounder) rounds. The tungsten(or maraging steel as in the T-62) cored rounds of the old days (1940-60) were not that long but were so inaccurate that the 17 pounder could not hit a Tiger at more than 500 metres with APDS rounds but the gun was so good that other rounds could reliably hit the Tiger at upto 1500 metres.

The T-62 had a smoothbore gun which made the steel cored APDS notoriously inaccurate - even more than the 17 pounder. The Soviet designers solved this with fins. The round was still in its infancy but it was accurate enough thanks to the unmatched muzzle velocity(for that time) of 1600 m/second . The 2A20 115 mm would now be classified as a good gun with bad rounds.

Regards,
Keshav

 

[The Last Stand]

It is better to just design new ammunition, redesigning existing ammunition, might improve their performance but how much is the question.

Well the current MK1 itself is a redesign of an old ammo which penetrated 400 mm. The MK1 supposedly penetrates over 500 mm. DRDO prefers redesigning since funds for R&D are low when compared to say, the funds allocated for the US DoD.

There is no technical obstacle to design so many types of ammunition for 120mm rifled and smoothbore guns, the problems are different armed forces requirements and costs. Besides this, today many types of ammunition can be replaced by single type, for example programmable HE which can act as multipurpose ammunition replacing 4 other types of ammunition.

The Indian Army loves HESH. It was invaluable in the battles of the 1965 and 71 wars, and destroyed thousands of bunkers. The bunkers have been rebuilt. HESH was specifically requested. So the rifled gun was designed. Programmable HE can be designed by ARDE within 5 years and inducted in 10 years but it will be costly. The HESH does the job much cheaper. Damian, you said that bunkers can be modified to make HESH useless. I support that too. A simple spall liner used in their Chinese tanks can be applied to the inside by the Pakistani army. But they are surely not aware of the fact and are busy building bunkers that can easily be destroyed.
There are no problems with money. If the DRDO makes the Defence minister(who is pro-indigenous and pro-technology) understand, they can get uninterrupted funding. The IA has specific requirements. Otherwise we could have had Programmable HE rounds by now.

Regards,
Keshav

 

[The Last Stand]

@Moderator

Sorry for derailing topic with discussion about ammunition. Is there a separate thread for discussing tank ammunition types, or can I create one?

Regards,
Keshav

 

[pmaitra]

@Moderator

Sorry for derailing topic with discussion about ammunition. Is there a separate thread for discussing tank ammunition types, or can I create one?

Regards,
Keshav

Continue here please. Armour and ammunition go together, because ammunition tries to defeat armour, while armour tries to defeat ammunition. It would be far more convenient to discuss them here.

 

[The Last Stand]

Continue here please. Armour and ammunition go together, because ammunition tries to defeat armour, while armour tries to defeat ammunition. It would be far more convenient to discuss them here.

Thanks.

I have had a big, big doubt for many days. In modern tanks, the guns almost always have Kinetic energy penetrators as primary rounds and High Explosive multi-purpose rounds as secondary. Hollow charge warheads are rarely found today and they are even more rarely used on tanks. Why? Is composite armour extremely effective against HEAT rounds?

AFAIK, HEAT-FS can be just as accurate(compared to APFSDS) and almost always has better penetration. Also I heard that HEAT is becoming nearly useless since most tanks are beginning to field ERA. I also heard that Tandem HEAT warheads are impossible to design for Tank guns and only one such projectile has been designed.

Why not use HEAT rounds instead of APFSDS? HEAT will be 2 or 3 times cheaper, will have lower EFC value and will not require complicated production methods.

Give me your respected opinions on this.

Regards,
Keshav

 

[Damian]

I have had a big, big doubt for many days. In modern tanks, the guns almost always have Kinetic energy penetrators as primary rounds and High Explosive multi-purpose rounds as secondary. Hollow charge warheads are rarely found today and they are even more rarely used on tanks. Why? Is composite armour extremely effective against HEAT rounds?

APFSDS ammunition is used as primary heavy armor defeating ammunition, while HEAT was used in NATO mostly as multipurpose round, but it is slowly replaced by multipurpose programmable HE ammunition.

And yes, composite armor is far more efficent against HEAT warheads than against APFSDS.

AFAIK, HEAT-FS can be just as accurate(compared to APFSDS) and almost always has better penetration. Also I heard that HEAT is becoming nearly useless since most tanks are beginning to field ERA. I also heard that Tandem HEAT warheads are impossible to design for Tank guns and only one such projectile has been designed.

No, HEAT do not have always better penetration, and yes, tank guns fired HEAT is useless against frontal composite armor and ERA.

And wrong, there were developed tandem and even triple warhead HEAT rounds in Soviet Union/Russia, altough it seems that triple warhead was never fielded, not in big number at least.

Why not use HEAT rounds instead of APFSDS? HEAT will be 2 or 3 times cheaper, will have lower EFC value and will not require complicated production methods.

Because it is not as effective as APFSDS. Besides this, shaped charge jet is less dangerous to crew than APFSDS penetrator, simply because SC jet leaves very small hole in armor, jet takes much less material with it to strike crew, and in most cases if ammunition is not hit by it, or is isolated from crew, crew will survive penetration of such jet (of course in case of tank), while in case of APFSDS, especially made from pirophoric DU, their chances are much smaller.

 

[The Last Stand]

Thanks Damian! But I always thought that HEAT was better. Maybe HEAT was superior only in the Second World War. The RPzB 54/1's HEAT warhead weighed 3.3 kg (with rocket motor) and penetrated 200+ mm of RHA. In comparison the APCR (completely unrelated to sabot - I know) round of the 8,8 cm Flak 43 (Tiger Ausf.E's gun on a mount) weighed 7.3 kg and penetrated exactly 171 mm at 30 degrees at 100 metres.

In regards to the earlier post where we discussed about HEAT penetration, hear this. The Koenigstiger (Tiger Ausf.B) fired a HEAT round which penetrated 90 mm at 100 metres and weighed 7.65 kg. In comparison the lighter (by 300 grams) APCR round could penetrate around ~240 mm at 30 degrees at 100 metres.

HEAT rounds hate rifled guns 3 times more than I thought.

Anyway, a HEAT round is under development for the Arjun. The new round will contain a filling of CL-20, the world's most powerful conventional explosive material which was synthesised by the HEMRL at a cost of Rs. 70,000 per kilogram (1288 US dollars - as of this hour) and had already produced 100 kg as of April 2010. (Around 5 kg everyday) They have produced more than adequate quantity now.

CL-20 is 60 times more powerful than RDX.

AFAIK 120 mm HEAT with RDX penetrates around ~250-300 mm. If replaced with CL-20 tandem warhead and Obus-G type ball bearings, penetration could be around ~1200 mm or more. Only thing, mass production will be very costly unless orders of more than 30000 or 40000 are placed. I suppose that one round would require around 3 kg of CL-20. 'Adequate quantity' should be around 2 tonnes. so we can make 670+ warheads now already.

If MoD approves the fielding of this round,

R.I.P - Pakistan tanks.
= :drunk:

Sources: 1) DRDO lab develops powerful explosive ‘CL-20’ - Brahmand.com
2) High Energy Materials Research Laboratory - Wikipedia, the free encyclopedia
3) Press Information Bureau English Releases

 

[Damian]

You are overestimating CL-20. And underestimating RDX and 120mm HEAT rounds.

German/US DM12/M830 120mm HEAT penetrates 600-650mm of RHA while being designed in the late 1970's and fielded in 1979-1980.

A 120mm HEAT round penetrating 1,200mm RHA is nothing more than a fantasy, to penetrate such armor plate you need a calliber of around 150mm.

Oh and by the way, CL-20 was developed in USA. http://en.wikipedia.org/wiki/CL-20

 

[The Last Stand]

You are overestimating CL-20. And underestimating RDX and 120mm HEAT rounds.

German/US DM12/M830 120mm HEAT penetrates 600-650mm of RHA while being designed in the late 1970's and fielded in 1979-1980.

A 120mm HEAT round penetrating 1,200mm RHA is nothing more than a fantasy, to penetrate such armor plate you need a calliber of around 150mm.


Oh and by the way, CL-20 was developed in USA.

I was talking about HEAT rounds fired from the L30. I didn't say that we developed CL-20. Read my post carefully. I said HEMRL 'synthesised' CL-20. Scientists have already stated that CL-20 is 4 times superior to HMX which is 15 times superior to RDX. So CL-20 = 15x4 = 60 times the power of RDX.

Regards,
Keshav

 

[Damian]

I was talking about HEAT rounds fired from the L30.

There are no HEAT rounds for L30 gun.

I didn't say that we developed CL-20. Read my post carefully. I said HEMRL 'synthesised' CL-20. Scientists have already stated that CL-20 is 4 times superior to HMX which is 15 times superior to RDX. So CL-20 = 15x4 = 60 times the power of RDX.

Still does not change a fact that penetration of 1,200mm RHA for a 120mm HEAT round is most probably not achievable. And even 1,200mm RHA does not guarantee you a successfull perforation, there was a friendly fire incident in the gulf war in 1991 when M1A1HA was struck by AGM-114 Hellfire missile in turret front, and it didn't perforate it's armor. AGM-114 penetrates ~1,200mm of RHA.

 

[asianobserve]

A 120mm HEAT round penetrating 1,200mm RHA is nothing more than a fantasy, to penetrate such armor plate you need a calliber of around 150mm.

The Americans had something bigger way back in 1947, the 155mm L/40 T7 rifled tank gun installled on the T-30 Heavy Tank...

The gun can fire both AP and HEAT rounds.

 

[asianobserve]

In 1955 the Americans also put a 155mm Tank Gun on their T-58 project with oscillating turrent (with autoloader)

 

[Damian]

@asianobserve you need to remember that these guns are not even slightly comparable in performance with modern smoothbores, also these in 140mm and 150+mm calliber.

And by the way, it is not T-30 and T-58, because this is Soviet designation system, Americans used T30 and T58, without "-" in designation code. Later to avoid further confusion they changed designation system from T (Testing) to XM (eXperimental Model).