Meanwhile, random topic change from Ukraine matters - let's head back to the '80s
PART 1/2
I have recently stumbled at this very decent T-55 upgrades article by people who clearly know how it all works:
http://opisybroni.pl/t-55am-merida/
I am not sure if Google Translate will do, so let me roughly translate fragments that are of meaning to me (and honestly, I should have translate it all!):
Quote:
In order to increase protection, the T-55AM tank was given a passive additional up-armouring in the upper hull, sides and bottom.
(...)
Additional armor weighting 800 kg (...) consisted of: welded additional plate of actual 30mm thickness, behind which there were four 5mm thick steel plates, placed inbeetwen from each other every 23mm. The spaces between them were filled with polyurethane providing an additional armour structure. The angle placement of main plate of 30mm thickness resulted in doubling its effective armor capacity against direct hits. Angle placement of further 5mm plates increased protection for each to 15mm.
(...)
Such placement resulted in such an effect, that in case of direct frontal hit the armour penetrator - after making way through 30mm plate was meeting further plates of further 45mm thickness.
(...)
Thus, against kinetic penetrator munitions (monoblocks 100mm, SABOT, APFSDS etc.) the armor of the upgraded area has improved from 200mm to circa 305mm of steel armor. In case of a HEAT round hit, thanks to several layers as well as filling between those responsible for disrupting shaped charge effect reached the effective protection of 450mm equivalent of steel armor.
(...)
Real thickness of the additional armor was 150mm, what summed up with real thickness of original armor let to the increase of real armor from 100mm to 250mm - and effective one from 200mm to about 500mm.
Additional up-armoring of the turret was designed comparably. (...)
Placing and shapes of external up-armoring, its structure and the main armor of the turret (the latter one of effective armor of 235mm). In the areas up-armored the addons and base frontal armor provided a total effective armor efficiency of 400mm - against kinetic rounds - and circa 450-460mm against shaped charges.
However, in the frontal areas of the turret right by the gun sleeve and PKT co-axial machinegun window the total efficiency was diminished to about 305mm of steel armor efficiency against all sorts of rounds.
For the better protection of the sides, the T-55AM was supplied with side skirt rubber armor of 10mm thickness. Field testing proved that thanks to said upgrade there was a reduction of penetrating effect on the main armor - depending on the type of shaped charge round - starting from 27% (artillery round 3BK5M, 100mm calibre) to 48% (PG-7VM RPG round)
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Actually it is worth to note what the authors write at the end - where they compare the armor protection to western weapons of the ERA, still falsely assuling that TOW penetration capability was at 600mm which we today know - is false:
Quote:
A similar situation regarded the shaped charge munitions, which by the time the modernization was underway reached a penetration of 600mm, resulting in obsolescence of the urmor upgrades against such threats, as the protection against such threats allowed protection of only up to 450mm.
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Summary:
- Effective protection of T-55AM - including polish T-55 "Merida" upgrade - should be actually higher than it currently is;
- One needs to think what to do with a gun sleeve area that was an obvious weak spot in protection;
- Current T-55 Merida in-game effective protection is:
Steel hull: 28cm
Steel turret: 33cm
Anti-HEAT hull: 33cm
Anti-HEAT turret: 35cm
Thus, probably should be:
Steel hull: 30cm
Steel turret: 35cm (this includes the weakspot, otherwise about 40cm)
Anti-HEAT hull: 45cm
Anti-HEAT turret: 45cm or about 40cm (including the weak spot?)
- What could be done with side armor? Increase anti-HEAT to about ~17cm to increase the work of angled shots with those rubber skirts?
- Said update was quite universal - it should probably be applied not only to Merida, but all other T-55AM upgrades, mostly the DDR one and Czech Kladivo program;
- The general idea is that it seems upgraded T-55s had the possibility to actually fend off TOW strikes (mean standard TOW, not I-TOW or TOW-2). I believe it should be reflected in the game, but not without taking the weakspot into account;
- Note on the side: about 650 polish T-55s were brought up to this standard, but formally only three divisions were listed with this tank. In other words, even in 1989 the T-55M and T-55U should technically still be available for Poland as line tanks, not just reserve ones as they are now;