T-72s in Chechnya, From Armour Magazine

Paul_L · Post by **Paul_L** » 17 Nov 2001 09:17

<BLOCKQUOTE>quote:<HR>Originally posted by Sanjay: So Paul, how does the Indian 120mm FSAPDS compare to British Tungsten rounds and the German DM-33 ? At first glance, the round seems superior to the L-23 UK FSAPDS round and equal to the DM-33 - is this correct ? <HR></BLOCKQUOTE> Yes its superior to the L-23 which does an estimated 450mm @ 0° @ 2km range.But the DM-33 is better , @ 2km its 550mm @ 0° compared to the estimated 470-510mm for the Indian ammo. This is because the ammo is longer [Est 54cm compared to 47cm] and has less V drop [ 60m/s/km compared to 80m/s/km] so its long range perfomance is much better [ Est 475mm @ 4km compared to 380-430mm for the Indian round] <BLOCKQUOTE>quote:<HR> Paul, another poser - based on what is known about the Indian 105mm FSAPDS round, how does it compare with its contemporary rounds made in the 1980s ? <HR></BLOCKQUOTE>Its compareble to the Original French 105mm APFSDS round OFL-105 G1 and the German 105mm DM-33/M-111 Hetz round ...these are all 1st generation APFSDS.Vic the 125mm gun is not as powerful as the 120mm gun compare the following.125mm smooth bore gun can fire a 7.3kg projectile +sabot @1550m/s and a 7.2kg projectile +sabot @1650m/s and 7kg projectile +sabot @1700m/s and a 6kg projectile +sabot @1800m/sAuto loader limits projectile length to 70cm 120mm rifled gun from about the same time period can fire a 8kg projectile +sabot @ 1550m/s a 8.5kg projectile +sabot @ 1538m/sThere are no length limits on ammo and since the 120mm gun is narrower the sabot is less mass, thus even more mass to the inflight projectile and ultimately the penetrator its self.The L-27 [Charm-3] gets higher velocity for the same projectile mass but uses more advance propellant and a higher pressure gun.By comparsion the Rheinmetall 120mm smooth bore gets 8.2kg @ 1573-1588m/s 8.1kg @ 1680-1690m/s More advanced DM-53 & M-829A2/3 get even higher velocities for the same overall projectile /sabot mass but these feature more advanced propellant technology.Also theres the issue of ammo flexablity. You could backfit the 120 or 125mm penetrator to a 105mm sabot to improve the penetration with a loss in the MV and increases Vdrop due to larger rounds but it would offer a small advantage over the existing 105 APFSDS at range. [roughly] muzzle 47±7cm @ 0° & 49±7cm @ 60° 1000m 43±6cm @ 0° & 44±7cm @ 60° 2000m 38±6cm @ 0° & 40±6cm @ 60° 3000m 34±5cm @ 0° & 35±5cm @ 60° 4000m 29±5cm @ 0° & 31±5cm @ 60°So triple heavy target penetration should be around 3km range.If the projected longer 120mm projectile [L/d 35:1] was matted to the 105mm gun it should achieve the following penetration [ roughly] muzzle 59± 9cm @ 0° & 62± 9cm @ 60°° 1000m 54± 8cm @ 0° & 57± 8cm @ 60° 2000m 49± 8cm @ 0° & 52± 8cm @ 60° 3000m 44± 8cm @ 0° & 47± 8cm @ 60° 4000m 39± 8cm @ 0° & 42± 8cm @ 60°Now this could theoretically be done with longer and longer 120mm ammo matted to the 105mm sabot but the auto loader limits could prevent the same ammo going to 125mm gun.

JCage · Post by **JCage** » 17 Nov 2001 12:55

Paul,No actually its the other way around in the west, 0° refers to a vertical plate while 60° refers to a sharply sloped plate. Then how does sloped armour work?The APFSDS penetration being greater if the armour is sloped...isnt that contradictory?Regards, nitin

Sanjay · Post by **Sanjay** » 17 Nov 2001 20:20

Thanks Paul. So the Indian FSAPDS round is superior to the L-23 and DM-23 ? Is the M-111 the round used in Lebanon by the Israelis ? About lengthened penetrators, take a look at this:125mm FSAPDS with long penetrator is listed as a new product. A 125mm FSAPDS round is also listed under products under production. This seems to indicate that India is doing exactly what Paul suggested. <A HREF="http://www.mod.nic.in/product&supp/welcome.html" TARGET=_blank>http://www.mod.nic.in/product&supp/welcome.html</A> Look under the Ordnance Factories. Scroll down as it is at the end of the page.

JCage · Post by **JCage** » 17 Nov 2001 21:52

<BLOCKQUOTE>quote:<HR>Originally posted by Sanjay: [QB]Thanks Paul.Is the M-111 the round used in Lebanon by the Israelis ?[/b]<HR></BLOCKQUOTE>yes.Tho' whether it was a wonder weapon against the syrians isnt exactly clear.Regards, nitin

JCage · Post by **JCage** » 17 Nov 2001 21:54

<BLOCKQUOTE>quote:<HR>Originally posted by Sanjay: [QB]Thanks Paul.Is the M-111 the round used in Lebanon by the Israelis ?[/b]<HR></BLOCKQUOTE>yes.Tho' whether it was a wonder weapon against the syrians isnt exactly clear.Regards, nitin

Sanjay · Post by **Sanjay** » 17 Nov 2001 22:14

Nitin, What's the uncertainty about the M-111 against the Syrians ? AFAIK, some T-72s had their frontal armour penetrated at 2000 metres in Lebanon.Also, we now have the very real possibility that India has lengthened the penetrator of the 125mm round. What're the implications ?

Raj Malhotra · Post by **Raj Malhotra** » 17 Nov 2001 23:13

is there any info which engine is going to be used for the latest (124) batch of arjun tanks?is it Mtu- 873 or Mtu-883the BR site says 873 but now the subsequent 883 has also been around for a decade and widely exported and offered.

JCage · Post by **JCage** » 18 Nov 2001 00:31

<BLOCKQUOTE>quote:<HR>Originally posted by Sanjay: Nitin, What's the uncertainty about the M-111 against the Syrians ? AFAIK, some T-72s had their frontal armour penetrated at 2000 metres in Lebanon.Also, we now have the very real possibility that India has lengthened the penetrator of the 125mm round. What're the implications ?<HR></BLOCKQUOTE> Darn,that lik aint opening for me. I should have been clearer. The M111 105mm apfsds reportedly does 39 cm at 1 km so T72A at 250mm frontal is indeed toast. However,what i meant was that the accounts of the battle are all mucked up. Its unclear as to which variant of the T72 they did actually knock off-the T72M1(claimed by the israelis)-but the syrians didnt have them...or simpler T72 base variants. Anyways,tank designations apart.. There was one "encounter" in which the T72's(syrian 82nd brigade) were attacked from 3 sides by the merkavas and nagmash's(Modified m113's with tow's). 9 T72's fell to the Merkavas with M111's and another 3 to the nagmash/with tow atgms. The israelis said that the M111 worked wonders. The syrians later claimed that the tanks were hit from the side and not frontally..etc.So to summarize,could the M111 do it?Yeah,i guess so... But whether it got a chance to do it as the israelis claimed ..at extreme range is unclear.Perhaps paul can tell us more.Regarding the 125mmm with longer penetrator,it has to be if we follow pauls premise. That the end result is that velocity drop at longer ranges acts less on penetration and increases the perfromance at longer ranges. it seems a lot is going on...

regards, nitin

JCage · Post by **JCage** » 18 Nov 2001 01:12

IMHO,The reasons for the this latest

125mm apfsds..1.This is a logical development of the "new" 125mm AFSDS currently in service/production.2.At ranges greater than 1.5/2km the performance wasnt good enough against the perceived threat.In fact if we go by the figures,neither side has the ability to punch thru the frontal armour at 2km and beyond.We may claim that we field the most powerful-confirmed gun/ammo combination-the 120mm( the chinese 125M DU/Enhanced Tungsten not being confirmed).By the figures even this may not go to 77mm RHA equivalent vs APFSDS-the maximum AlKhalid +ERA figure at 1.5km ++ Hence the need for better APFSDS ammo.3.Why engage at longer ranges?I feel with the acquisition of better FCS and TI sights a/c the T-XX fleet the IA tankers can reasonably expect to be able to engage the enemy at much longer ranges than previously possible and hence even the ammo needs to be a performer.All the desert storm type tech advances are percolating to the IA and affecting its doctrine too.

regards, nitin

Paul_L · Post by **Paul_L** » 18 Nov 2001 03:38

<BLOCKQUOTE>quote:<HR>Originally posted by nitin: Paul,No actually its the other way around in the west, 0° refers to a vertical plate while 60° refers to a sharply sloped plate. Then how does sloped armour work?The APFSDS penetration being greater if the armour is sloped...isnt that contradictory?Regards, nitin<HR></BLOCKQUOTE>Yes I know this is not simple. Up until the 80s all penetrators -when striking slanted armor - penetrated less than vertical plates. This was in part to do with the fact that they used hard steel and tungsten carbide. These metals tend to shatter if forced laterally when striking a target. Since most projectiles slide on impacting slanted armor they would risk shattering the tip, there by penetrating less.These effects are also controled by the nose design of the penetrator .. the flatter the tip the less the slip. So most modern APFSDS penetrators feature flat tips underneath an aluminum ballistic cap thats designed to strip away on impact [ and thus not effect penetration].In addition research has shown that these effects of the nose tip design are limited to the first 2 projectile diameters. After this much has been eroded away they offer no difference in penetration from a flat tip. Now logically the longer the rod [ higher L/d] , proportionally the less the effect that nose shape has on penetration at all!What was also discovered in research was that long rod penetrators [ any thing much more than 5:1 L/d]. tend to 'turn' into the armor when it penetrates slanted plates. So in the 80s the combination of the above makes long rod APFSDS, made with blunt tips and heavy metal tungsten & DU alloys of medium hardness , much better penetrators of slanted armor. Slanted armor does still have some advantages in deflecting the kinetic energy of impact away from the vehicle and ricoching some types of projectiles.But generally if you look at most western tanks designed from the 1980s on they have much less slope than previous generation tanks.It is of interest to note in resent research , that medium lenght penetrators [ ~ 5:1 L/d] striking layerd targets of ceramics and steel show no difference between slanted and vertical penetration.If the target had be all metal the slanted penetration would have been less.While other studies of steel long rod penetrators striking sharply sloped layered armor show more resistance to penetration at angle when the proportion of the ceramic in the layers was increased.But there is maybe a more basic reason for these sloped turrets. If you compare a boxy turret to a sharply sloped turret it appears that they take up less volume. The Russian tanks all achieve turret volumes of 1.8-2.0 m^3 while a chieftain turret which is only sloped in the front is 3.5m^3 and the more boxy western turrets are 4-5m^3. So it seems - generally speacking] you can get away with smaller turrets if their sharply sloped. The smaller the turret the more armor thickness you can mount for the same turret mass. So the turrets on the Russian tanks weigh about 11-12 tons while the same turrets on the modern boxy western tanks are 16-23tons.T-72gOn the issue of the Israeli M-111 Vs T-72 , I understood the Syrian T-72s were the 'G' model which has glacis plate like the original T-74 which offers about 34cm KE resistance to 30mm diameter APFSDS [M-111]. The front turret is 28cm thick cast armor that resists at about 90% of RHA or 25cm . But this is set back at angle so from straight on the armor around gun [ 0.5m]is ~ 24-26cm while the armor thickens as you move towards the 'corners' of the turret where the LOS thickness is ~ 44-45cm thick [ 20-22cm @ 60-64°]. When struck by 30mm diameter APFSDS thats x 0.9 [cast]x 0.98 [t/d]x 0.98 [Lateral confinement].This results in ~ 38cm KE resistance to APFSDS. The upper front turret of this tank is 5cm Cast armor @ 75-80° [20cm KE resistance] and the lower front hull is ~ 10cm @ 60° , again about 20cm KE resistance.So even a 105mm APDS could penetrate 1/2 of this target from 1-2km range. Russian NII Stali website claims the T-72 is “cast armor 380mm KE 410mm HEAT” and the “glacis is combined with glass reinforced plastic (GRP) 335mm KE 450mm HEAT .

JCage · Post by **JCage** » 18 Nov 2001 10:00

superb post!1.Ok by increasing the L/D ratio,in effect the length,one can get away without changing the pentrator tip shape to get bettr penetration...i'd say that saves on research and then the machining/casting efforts.

2.So,slanted armour still works if you have a lot of ceramics in the armour?Is this what the leo 2a6 does?3.ref: The volume skimping and hence armour piling on- does this justify the fact that slanted armour is more susceptible to penetration. I mean can we pack on so much armour that it really makes a difference where it counts. That is will even the "increased" armour thickness compensate for the fact that it is now slanted and hence more susceptible to long rods??? 4.OK,sloped armour,lesser turret volume--->can achieve the same/better armour thickness with lesser armour--->reducing turret weight in the bargain.By redesigning/sloping the turret they may be able to pile on more kanchan for more armour thickness...or save some weight by getting the neeeded armour thickness / retaining whats there with less kanchan .If they do the latter,then they can add more ERA. Sanjays post about 15 tons of Kanchan and upto 6 tons of ERA may well be achievable and more...or a least thats thats what they intend to do.Regards, nitin

Sanjay · Post by **Sanjay** » 18 Nov 2001 21:09

Considering the Arjun's weight - largely due to Kanchan - and German influence in the Arjun design ( much more than DRDO lets on ), I wonder if assessments of Arjun armour needs to be re-evaluated ? Kraus-Maffei was a prime consultant. Given size and weight similarities and given that India did rely on German help, is it possible that Arjun's armour is more equal to that of a Leopard-2 ? Also bear in mind possibilities that concepts - where applicable - of T-72 armour may have been incorporated.I saw the figures put out earlier, but I have problems given that close collaboration with the Germans. In fact, some cynics have dubbed Arjun as Leopard-2(I) !As an aside, Jane's has rather poor information on the Arjun. I once knew the guy who supplied them with most of the stuff and it's somewhat dated. In fact, Jane's information is largely based on press reports.As I said, Arjun's extra 13-15 metric tons are largely due to the armour. Also, General Sharma's comments cannot be ignored. The threat was seen to be TOW-2+ and 125mm FSAPDS fired from the Khalid. This we've discussed.This is the published information on the chassis of Arjun:"The chassis is fabricated from rolled homogenous armour plate using advanced welding technique. Frontal armour is of Kanchan composite sandwitched between armour plates." URL=http://www.drdo.org//pub/jun98/combat.htmNitin, what was the date of the Arjun's weight estimate of 61.5 tons ? In 1993, the thing weighed 56.5. If its weight increased to 61.5, could that mean additional armour ?I'll throw a curve at everyone here when I say that apparently, the 120mm FSAPDS ammunition is supposed to be able to penetrate Al-Khalid frontal armour at 2-3km -IDR July 1993. It could well be that we've underestimated something.For those interested in the thinking of the Indian armoured corps, it is instructive to note that the competitor for India's follow on tank order in the late 1970s was the Chieftan ( the Leopard-2 was the guiding force behind the Arjun ). The Chieftan lost hands down to the T-72.In 1989-90, India evaluated a small batch of T-80 tanks ( there is even a rumour that they were kept ) and rejected them.The T-90 seems to have been chosen because of its similarity to T-72 and because Avadi would need little modification to convert to T-90 production.Finally, when considering the performance merits of armour, we have to consider crew training. It is clear that the Indian tank crews are very well trained and understand their equipment well.

JCage · Post by **JCage** » 18 Nov 2001 23:11

Sanjay, sending you a mail. UBB is rejecting my efforts to post!

regards, nitin

Raj Malhotra · Post by **Raj Malhotra** » 19 Nov 2001 01:43

Sanjay the higher weight need not necessarily be only due to additional armour protection. IIRC Russians tanks like t-72 have very low internal volume around 12m^3 compared to western tanks 21m^3 which means more armour is required to give same level of protection. A t-72 with equivalent protection to Arjun should weight something like 43-49 tons (shades of T-90).The weight of 61.5 as nitin would have obviously told you is as per CAG. Probably the difference is due to “combat” i.e. fully laden weight. The requirement of protection from top attack has come in later so I wonder whether this 61.5 includes or excludes ERA.Lastly the tank that has successfully combined the Soviet and western philosophies is Le clerc whose designs came a decade later to Leo-2 on which Arjun is based. Principally the idea is use autoloader to give lower profile and hence lower volume and similarly more powerful engine with smaller size was used. (Does the more efficient gun stabilizer of western tanks also occupy more space?)If you want to compare the efficiency of the design and protection of Arjun then it should be against T-90 (which is advanced T-72) rather than vanilla T-72.In this context only, I asked the question relating to Mtu-838, 873 and 883, as the volume of 883 power pack is almost 1/3rd of 838 that Arjun is using. So to that extent the article of Week made sense.Inspite of using T-72 for decades the DRDO does not seem to have used the clever design of t-72 in Arjun (why? Or am I wrong). The reason could be that T-72 and Arjun project was running side by side and lessons learnt from t-72 could not be applied to Arjun.Things like drop tanks and gun launched ATGMs have not been (known?) to have not been incorporated in the design of Arjun. incidentally what is the internal volume of Le clerc?

Sanjay · Post by **Sanjay** » 19 Nov 2001 04:10

Raj, First of all, a rifled gun was specified because of HESH. HESH rounds are considered important for destroying fortifications. That ruled out missiles being fired from the gun. Also, remember that the Arjun development started before the T-90 was conceived. You are correct about the engine being overly large. As I understand things they were seeking a more modern version but then negotiations were put on a back burner when our dear army became entranced with the T-72S and then the T-90! The Arjun's combat weight in 1993 was 56.5 tons. The 61.5 tons didn't include ERA. Finally, the army specified a 4 man crew. The drop tanks are not an issue as there is provision for them on all Indian tanks. The truth is India should have accepted the tank and got 2-3 regiments inducted quickly and then worked out improvements for a Mk.2. What happened is that the army delayed and delayed and delayed and kept insisting on all modifications before induction and still insisting on a Mk.2. The Arjun could have been inducted in 1994-95. India has inducted far worse. What's more we've inducted far worse gone to war and defeated allegedly far better ! Funny that.

Paul_L · Post by **Paul_L** » 19 Nov 2001 04:40

Lecler is reported to be ~ 17.5 m ³ volume while LEO-2 is ~ 19.5 m ³ and M-1A1 is ~ 23 m ³ . I estiamte the Chinese type 85 [similar to Type-90] is ~ 12m ³BTW Nitin the LEO-2A5 is the same as the LEO-2A4 turret with slightly more advanced ceramic in the sandwich layers[JANES]. the wedge armor is hollow,and pics reveal it to be 25-32mm thick armor arranged at ~ 70° mounted 400-800mm from the front turret armor. A german LEO-2 tanker told me its a series of 5 plates of mostly steel , but given the Desinroth designs the armor probably includes 'perforated plates' and 'interlayers'. ...Theres even speculation that Titanium plates might be used.The armor mass applied to the wedge armor looks like ~ 200mm of additional steel mass.What appears to happen is that the wedge armor destablises any penetrating APFSDS so they tumble over the very long distance inbetween the wedge and the main armor leading to a large yawed impact possibly 2-6°. For a 30:1 L/d penetrator that could result in a penetration loss in the ~25% region, but the results depend on the projectile accuracy. poor projecitles may lose as much as ~40% while very accurate projectile could lose only ~5% of its penetration.

Sanjay · Post by **Sanjay** » 19 Nov 2001 04:50

Paul, Nitin and I are cooking up are real treat on the Arjun for your consideration ! Suffice it to say that something is probably awry with the estimates for Arjun armour protection.

Paul_L · Post by **Paul_L** » 19 Nov 2001 04:54

<BLOCKQUOTE>quote:<HR>Originally posted by Sanjay: Paul, Nitin and I are cooking up are real treat on the Arjun for your consideration ! Suffice it to say that something is probably awry with the estimates for Arjun armour protection.<HR></BLOCKQUOTE>sounds good , armor thickness and vehicle volumes would help alot.

Sanjay · Post by **Sanjay** » 19 Nov 2001 05:06

Paul, we're doing our best. We're also sending you the maximum background possible on the trials of the Kanchan itself. Trials began in 1987. The volume calculations are somewhat difficult. Arjun is big, but not as big as thought.

Guest · Post by **Guest** » 19 Nov 2001 05:12

Sanjay, Can you post the info on the forum too? Thanks

Paul_L · Post by **Paul_L** » 19 Nov 2001 05:28

OK heres my updated take on the Type 90 [Al Khalid] armor , along with the usual provisos on the approximate nature of estimates.Turret front Armor mass : Its assumed the same internal volume as the Type 85 tanks and the armor mass is a increase over the Type 85s weight or 49 over 41.7 metric tons for a 18% increase in mass. The T-85 front turret armor mass is 31.8cm steel x 1.18= 37.5cm steel armor mass plus the similar increase over the side and rear turrets +7-8 cm steel , for a 45cm steel mass over a ~65cm LOS thickness with 43cm LOS insert. That’s ~ 5.2 g/cm ³ leading to an assumed insert density of 3.9g/ cm ³ or Alumina [ 97%] . If this is true the inserts are 43cm thick [LOS] AD-97,while the steel is HY-120 RHA . The effective resistance should be…… RHA = 22 cm x 1/1 [Te] x 0.96 /0.98[t/d] = 21.1 / 21.6 cm & 22cm AD-92 = 43 cm x 1.0 /1.54 [Te] x 0.9/0.94 [t/d] = 38.7 / 40.4cm & 66.2cm multipliers HEAT x 1.2 [layers] and KE x 1.2 [confinement] x 0.8 [Lc] x 1.05 [backing] KE resistance should look like [21.1 / 21.6 + 38.7 / 40.4] x 1.2 x 0.8 = 57.4cm /59.5cm KE HEAT resistance should look like [22 + 66.2cm] x 1.2 = 105.6cm HEATFront turret armor looks like 57.4cm [2.5cm APFSDS] 59.5cm [2cm APFSDS] and 105.6 cm HEAT resistance when the reported resistance is 645mm KE . Pakistan discovered that Chinese had overrated penetration estimates by 94-90% , since the same rating system would be used to assess armor resistance, it could be that the 645mm quoted figure is actually 606mm-580mm. From a 30° off angle the turret should offer ~ 53-55cm KE resistance to a 25mm-20mm diameter APFSDS. Norinco Type A ERA is some times mounted on the turret that’s similar to Kontakt ERA . This should add 15mm x 1.7 = 25mm or 17±8mm ÷ Cos 30° = + 2cm ±1cm KE resistance & 15 ± 5cm HEAT, but the coverage is only ~ 2/3 of the profile , and should bring the front turret armor up to ~ 59±2cm [2.5cm APFSDS] ~61±2cm [2cm APFSDS] and ~116cm ±10cm HEAT . Upper front turret accounts for about 1/5 of the turret profile and looks like 48-50 mm HY-120 @ ~ 80° or ~31 cm KE and 31 cm HEAT armor.ERA is also included sometimes in the array , Norinco Type A ERA at normal impact should offer 15mm x 1.7 = 25mm or 17±8mm ÷ Cos 80° , this should boost the armor by ~ 13±6cm KE & 39±17cm HEAT to about 41±9cm KE and 57±26cm . Hull The Type-85 hull has an armor mass of 127.8 mm steel ÷ 0.37 ~ 345mm armor mass , while the lower hull is only 8cm @ 50° = LOS thickness ÷ 0.64 or 13cm LOS armor. Thus the average hull armor mass is ~24cm steel, times the mass increase from Type 85-III to Type 90 which is 18% , this equals ~ 28cm armor mass .The front hull thickness looks like ~47 @ 35 or 45cm @ 45° for a LOS of 57-64cm . That’s 28/60 = 3.66g/cc average density on the glacis and , which in turn suggests a layered structure with say 1/3 RHA[HY-120] plus 2/3 Steltexolite, leading to the following figures……RHA 20cm x 1.05[Te] + 0.96/0.98 [t/d] = 20.2/20.6 cm KE & 21cm HEAT 40cm STEF [0.41 / 0.6] Te x 0.9/0.94 [ T/d] = 14.8/15.4 cm KE & 24cm HEAT Multiples = x 1.2 HEAT [ layering] & x 1.2 [Confinment] x 1.05 [backing] KE= [20.2/20.6 + 14.8/15.4 cm ] x 1.05 x 1.2 = 43.6cm [3cm APFSDS] & 45.4cm [2cm APFSDS] HEAT = [21 cm + 24cm ] x 1.2= 54cm HEAT. Norinco Type A ERA is available that should boost the glacis armor by 15mm x 1.7 = 25mm or 17±8mm ÷ Cos 35-45° , this should boost the armor by ~ 2-3cm±1cm KE & 18-20cm ±8cm HEAT, but the coverage is only ~ 2/3 of the profile , thus the effective resistance for the hull should be ~ 45-47±2cm KE & 67± 13cm HEAT. So you can see that the 120mm APFSDS -as it is can -penetrate a good deal of this AL Khalid frontal armor from straight on at 2-3km range .

Paul_L · Post by **Paul_L** » 19 Nov 2001 12:27

<BLOCKQUOTE>quote:<HR>Originally posted by nitin: We may claim that we field the most powerful-confirmed gun/ammo combination-the 120mm( the chinese 125M DU/Enhanced Tungsten not being confirmed).<HR></BLOCKQUOTE> If as Janes reports the Pak use DU 105mm rounds then it follows they could easly mate this penetrator to a sabot and mount it in there 125mm gun. The Chinese are reported to be doing something like this for their enhanced 125mm gun. <A HREF="http://janes.com/regional_news/asia_pac ... _1_n.shtml" TARGET=_blank>http://janes.com/regional_news/asia_pac ... n.shtml</A>

Raj Malhotra · Post by **Raj Malhotra** » 19 Nov 2001 17:06

<BLOCKQUOTE>quote:<HR>Originally posted by Sanjay: The volume calculations are somewhat difficult. Arjun is big, but not as big as thought.<HR></BLOCKQUOTE>the internal "fighting compartment" volume of arjun may be less than Leo-2 as it is supposed to be adjusted for ergonomics of Indian soldiers.

Raj Malhotra · Post by **Raj Malhotra** » 19 Nov 2001 17:13

<BLOCKQUOTE>quote:<HR>Originally posted by Paul Lakowski: So you can see that the 120mm APFSDS -as it is can -penetrate a good deal of this AL Khalid frontal armor from straight on at 2-3km range .<HR></BLOCKQUOTE>Indian APFSDS?

JCage · Post by **JCage** » 19 Nov 2001 18:27

Raj, yes!look at the figures on the 2nd page of this thread.

Nandai · Post by **Nandai** » 19 Nov 2001 18:38

Paul, could you, without using to much math and technical terms explain the advantages and disadvantages of using a smoothbore gun versus a rifled gun. As most western countries, as well as the Soviets/Russians have gone for a smoothbore gun, there have to be some clear advantage is using them.

Bishwa · Post by **Bishwa** » 20 Nov 2001 02:02

explain the advantages and disadvantages of using a smoothbore gun versus a rifled gun.A rifled gun gives you accuracy but has more wear and tear. It also allows you to fire HESH.A smooth bore gives you better range and allows you to fire missiles from the gun itself.

Rudra · Post by **Rudra** » 20 Nov 2001 02:07

how does a typical non-HESH Ru or Nato tank support a infantry-heavy slow advance in rugged terrain or deal with fire from built up bunkers or towns like on densely populated punjab or jammu border ?Do HEAT rounds have any utility against buildings ? the us army seems to use a 155mm type of short barrel demolition gun to knock down fortified sites ? even a huge seige mortar with FAE mounted on a arjun chassis might be worthwhile ?

Paul_L · Post by **Paul_L** » 20 Nov 2001 03:12

SInce there are no rifling in a smoothbore gun their is less friction, therefore for the same ratio of charge mass to projectile- Sabot mass, you get higher velocity.In theory the barrels of the smooth bore gun last longer , also due to the reduced amount of friction.I've heard about the increased accuracy of rifle bore guns , but looking at the figures from JANES ammo hand books there is no disernable difference in the 'mil' error distances between APFSDS fired from rifle bore guns and smooth bore guns. It seems to be more a function of the ammo design.Yes you can fire full calibre shells more accurately.I guess this means HESH HEAT & HE, but smooth bore versions of the HEAT & HE usually get higher velocities so their more accurate at shorter range and less so at longer range. HESH must hit in a narrow velocity window so extra speed is out of the question.I think NATO gun policy was driven by the AT needs and AP was considered less important. The fact that some of these countries are now trying to developed FS HE shows a renewed focus on this area. If you expect to fight alot of infantry especially in buildings and bunkers I think HESH & HE is the way to go!

Sanjay · Post by **Sanjay** » 20 Nov 2001 03:55

To add to Paul's comments. Please do not try to transpose the European or Middle Eastern battlefields entirely to the subcontinent. The fortifications are a real problem for any attacker along the India-Pak frontier. HESH is nothing short of devastating against them. That's also why 105mm LFG units have a substantial HESH stock. Armoured units in the India-Pakistan theatre are not going to only face good tanks with tough and highly trained crews, but swarms of well trained infantry with excellent anti-tank weapons and, in the case of the Pakistani armour, Indian artillery is improving and will achieve a huge margin of superiority in years to come and will be a nightmare to contend with.

Rudra · Post by **Rudra** » 20 Nov 2001 05:03

Shalav · Post by **Shalav** » 20 Nov 2001 05:22

<BLOCKQUOTE>quote:<HR>Originally posted by Paul Lakowski: HESH must hit in a narrow velocity window so extra speed is out of the question.<HR></BLOCKQUOTE> Correct me if I am wrong, but I understand the principle behind the HESH would be spalling. If so, how would velocity matter? Doesn't the principle behind HESH mean that spalling is a function of the warhead charge rather than warhead velocity, cause even at extreme ranges the charge on a HESH warhead would still be as potent as it was at shorter ranges, not so with a APFSDS warhead which basically depends on transfer of kinetic energy to the target. Or is my understanding all wrong?

Paul_L · Post by **Paul_L** » 20 Nov 2001 07:16

<BLOCKQUOTE>quote:<HR>Originally posted by Shalav: Correct me if I am wrong, but I understand the principle behind the HESH would be spalling. If so, how would velocity matter? Doesn't the principle behind HESH mean that spalling is a function of the warhead charge rather than warhead velocity, cause even at extreme ranges the charge on a HESH warhead would still be as potent as it was at shorter ranges, not so with a APFSDS warhead which basically depends on transfer of kinetic energy to the target. Or is my understanding all wrong?

<HR></BLOCKQUOTE> No not entirely but it is better explained by my good friend Andrew Jaremkow on TankNet...Follow the link below. <A HREF="http://63.99.108.76/ubb/Forum3/HTML/000208.html" TARGET=_blank>http://63.99.108.76/ubb/Forum3/HTML/000208.html</A>

Nandai · Post by **Nandai** » 21 Nov 2001 04:16

Paul, havent Sweden developed a 120mm HE round for the new Leopard 2 tanks, I think I have read something about such a round in swedish army magazines. Would such a round be as good as a HESH round against a bunker, or some other fortified target.

Sanjay · Post by **Sanjay** » 22 Nov 2001 03:49

Paul, Arjun - volume calculations can be based on this:1) Arjun is roughly as long, slightly wider and marginally shorter than Leopard-22) It weighs 3 tons more.

Paul_L · Post by **Paul_L** » 22 Nov 2001 08:46

<BLOCKQUOTE>quote:<HR>Originally posted by Nandai: Paul, havent Sweden developed a 120mm HE round for the new Leopard 2 tanks, I think I have read something about such a round in swedish army magazines. Would such a round be as good as a HESH round against a bunker, or some other fortified target.<HR></BLOCKQUOTE>Since most HE rounds rely on blast fragmentation then I doubt they'd be any good as bunker busters.

Paul_L · Post by **Paul_L** » 22 Nov 2001 10:03

<BLOCKQUOTE>quote:<HR>Originally posted by Sanjay: Paul, Arjun - volume calculations can be based on this:1) Arjun is roughly as long, slightly wider and marginally shorter than Leopard-22) It weighs 3 tons more.<HR></BLOCKQUOTE>I pefer to compare to a known tank armor thickness than something like the LEO-2 , because this is German in design philosiophy. For example the LEO-1 the turret armor is twice as thick as the hull armor , I made an assumption that the LEO-2 armor is the same.I would rather work from Chieftain since it I suspect this was as much an influence on the Indians as anything.Chieftain is 17.1m^3 volume and fields a 120mm gun . JANES A&A 1995/96 reports it has a [empty ] weight of 53,500kg [55,000kg combat].LEO-2 is exactly the same weight as the chieftain so that makes the Arjun 56,500kg [empty] and 58,000kg [combat], does that sound right?Chieftain is 7.5m long [hull];3.5m wide [over skirts] and 1.92m high [total height minus MG and ground clearance 2.43-0.51]. Journal of Military Ordnance Vol 10 # 4 , reports the following : Width 3.85m and height [same as above 2.32 - 0.45]1.87m.There is now hull length but the overall length is 10.19m . Greehill Military books has a tank book [Battle Tanks] the 'provisional' drawing that suggests the hull length is 71% of this length or 7.25m.Those provisional figures suggest the Arjun is 1.03 times the chieftains outer dimensions or 17.6m^3 volume.Its weight is [58/53.5] 1.08 times the chieftain mass but the volume adjustment would bring this down to 1.05 times the Chieftains armor mass.Does any one have any scale drawings of 'real' Arjuns to improve on these figures.

Peeyoosh · Post by **Peeyoosh** » 22 Nov 2001 15:01

SanjayThe engineer in me can see how HESH would work against concrete bunkers, but wouldn't simple measure like sandbags around the walls take away from the efectiveness which relies so heavily on the hard non -yielding surface being available to shape the charge?Finally - has anyone evaluated simple skirts of green bamboo as defence against both HESH and sabot based rod type penetrators?Peeyoosh

Sanjay · Post by **Sanjay** » 22 Nov 2001 18:39

Apparently such measures don't work. I guess the fact you're dealing with Reinforced Concrete as opposed to armour has something to do with it. Also, while the sandbags may absorb something, the exterior will still be compromised. In addition, you can't look at it in terms of a single round being fired at a bunker. It will be hit repeatedly. A bunker doesn't move so many hits can be obtained.Furthermore, you're forgetting plunging fire - use of the tank guns as artillery.Let's put it this way, the some defences along the Western border can usually survive a direct hit from a 155mm HE shell plunging. These same defences will not stand up to a 105mm HESH.Paul, Here are the best dimesions I have available for Arjun: Dimensions Overall length {with gun forward) 10.638 m Overall height {with gun rear) 9.546 m Overall height {with AD gun mount) 3.03 m(Turret roof: 2.32 m) Overall width 3.864 m Combat weight 58.5 tons <A HREF="http://www.drdo.org/products/mbt.htm" TARGET=_blank>http://www.drdo.org/products/mbt.htm</A>I'd say two things: 1) Kraus Maffei was a prime consultant on the Arjun, hence influence cannot be ruled out. Cynics refered to Arjun as Leopard-2(I)! 2) The Chieftan itself was evaluated by India in the 1970s and rejected. That's when the T-72 was selected. The Leopard-2 was unavailable, but was seen as the best tank on which to base the Arjun.I'm not saying that you're wrong, but I'm saying that we have to look at both.

Paul_L · Post by **Paul_L** » 23 Nov 2001 00:17

<BLOCKQUOTE>quote:<HR>Originally posted by Sanjay: Paul, Here are the best dimesions I have available for Arjun: Dimensions Overall length {with gun forward) 10.638 m Overall height {with gun rear) 9.546 m Overall height {with AD gun mount) 3.03 m(Turret roof: 2.32 m) Overall width 3.864 m Combat weight 58.5 tons <A HREF="http://www.drdo.org/products/mbt.htm" TARGET=_blank>http://www.drdo.org/products/mbt.htm</A>I'd say two things: 1) Kraus Maffei was a prime consultant on the Arjun, hence influence cannot be ruled out. Cynics refered to Arjun as Leopard-2(I)! 2) The Chieftan itself was evaluated by India in the 1970s and rejected. That's when the T-72 was selected. The Leopard-2 was unavailable, but was seen as the best tank on which to base the Arjun.I'm not saying that you're wrong, but I'm saying that we have to look at both.<HR></BLOCKQUOTE> Dimensions look similar to what we have. As to Chieftain...most armies rejected it due to poor mobility, why did the Indians reject it?As to LEO-2 , have suspected this for some time. Arjun is reported to feature Kanchan armor in only the turret and side hull. The front hull is only spaced armor and the bottom plate looks like 11-12cm @ 70° or 33-35cm. Problem is thats all I work out for on the armor mass for the lower hull.Is the lower hull just a single RHA plate???