gorf

Through the black line Leo's turret can be easily penetrated with automatic canon

I meant thickness exactly after the weakened zone:

According to T-80A drawing the weakest zone is about 53 cm (after the cavity for coax machine gun). Then it rises to over meter in corners. So there are two advantages of Western scheme: a) the frontal thickness is constant (ie. there is no overarmouring or underarmouring) the angle of filler to perpendicular plane is lower what makes ceramics more effective (I guess that's why the ceramic filler in Russian tanks is so complicated). The avdantages of Russian scheme are mented by Harkonnen already.

I did not intend that green line is exactly 30 grad. If compare with blue looks like 26-27. But at 30 grad should not be a serious difference either. There is nothing holy in 30 grad. It is only technology, not the design. Lecrlerc is not a classical western design and only some similarities. Leclerc is somewhere in the middle between the BE and the Abrams

Т-90С is same style with old Russian, just welded. BE has completelly different design from Abrams/Leo. It has some similarities with Leclerc and K2.

As far as I know the opposite sides of parallelogram are equal in length.

All three green lines have exactly the same length

80% is the certified penetration. Avarage penetration is some 10-15% higher: about 340 mm. Also 105 mm gun allows higher chamber pressure than 100 mm (Vo = 1455 m/s compare to 1375 m/s in 100 mm). T-72A and T-80 glacises were same in that time anyway (50-105-60).

They got M111 and 367 mm is length of M111.

Hetz were captured by Syrians in M48 tanks at Sultan Yakub and passed to Russians. Russians tested them on T-72A. Glacis was penetrated and thats why 17 mm HSS plate was added. Hetz is 367 mm long. Cheers.

M111 aka DM23 was able to penetrate the glacis of T-72A but failed to penetrate the turret. M833 (~450 mm) was considerably supperior to M111 (~ 360 mm). Here are KE protection estimates from Russian books and booklets for Glacis/Turret: T-72: 305/380-410 T-72M: 335/380-410 T-72M1: 400/380-410 T-72C: 485/540 Cheers.

My bet, M829A3, 3BM-32M and especially M829A1 are overestimated.

TPD-K1 was stabilised in the verstical plane, 1K13 was not stabilised at all.

KE protection of front was quite same. Frontal HEAT protection of T tanks was slightly better, on the other hand Chieftain had somewhat better HEAT protection of flanks. T tanks had advantage in gun penetration, but it was compensated by much better post penetration survivability of Chieftain. T-64B had advantage in FSC whic would give advantage on flat terrain, but in hilly terrian gun elevation and depression angles could be more important. and so on and so on.

My point is that Chieftain was comparable with T tanks.

T-72M had better glacis compare to T-64. Turret KE protection was quite same, only HEAT somewhat inferior. Same guns, FCS was better than T-64A, but worse than T-64B. It is always important. In 1973 Centurions with safer ammunition stowage and electric turret/gun drive performed better than better armoured M60A1s. They were installed only in late 70-es. Those are very usefill things in war.

All aspects? Chriftain had comparable front armour, better HEAT protection of flanks due to skirts, safer electric turret drive, much more safe ammo stowage, was equipped with smoke launchers, had better gun elevation/depression angles. Chieftrain performed quite equally vs. T-72M in Iran-Iraq war.

Chieftain.

AFAIK T-72S continued to use T-72A turret, just K1 ERA was added.

That's exactly the reason why it had success

IR work in range 04-1.2 mkm, while thermals in 7.6-14 mkm. active IRs need searchlights and work at 800 m max, passive don't need a searchlight and their range can reach 1.5 km. Range of thermals is 2-5 km, thermals also can see through fog, rain, smoke. [Edited by gorf (27 Nov 2004).]

T-72 had active IR, Mk1 had passive IR, Mk2 got thermals, T-80U - passive IR.

Still it does not explain TWO TIMES difference. I don't know much composite matterials with TE vs HEAT two times higher than vs KE. In that case glacis of M1A1 is weaker...

Lets suppose your estimates are correct, but to what they relate? To hull, turret, which side of hull and turret? Due to wedge shaped of Merk turret protection can varry a lot. Also Mk3 estimates are extremelly doubtful - impossible that KE and HEAT protections vary two times! IMO KE protection is underestimated, while HEAT overestimated. On contrary, you HAVE TO go with shell inside the cannon. Israeli tanks go with HEAT shell, since it is universal.