T-80U Armor Estimate

Preliminary notes:

The maximum thickness of the T-80U front turret armor is reported to be 815mm thick reaching ~920mm near the gun in the "weakened zone". The insert is probably similar in size to the T-90 with ~380mm LOS insert thickness suggested.

The turret is cast with almost half insert which is probably AD-90 mounted on STEF. The KE value of this combo is probably (0.9+0.41)/2 = 0.65 and HEAT value of (1.5+0.55)/2=1.025. Thus the effectiveness is 0.78 KE and 1.02 HEAT around the front turret and 0.66 KE and 0.775 HEAT around the rest of the turret. In other words the 815mm front turret LOS thickness translates into 0.78 x 815 or 64cm KE resistance while the mantle reaches ~83cm and the sloping walls reach 56cm KE resistance. However the 'free edge effect' should reduce the KE values below these figures, the area near the gun would go down 0.6 to 50cm KE, while the 815mm section should be ~0.9 x 64cm or 57cm, and the main walls would be ~ 0.95 times 56cm or 53cm. So the weakened area is around 50-51cm while the main walls are 53-57cm KE. The HEAT values should be 720-815 x 1.02 or ~73-83cm along the main walls.

Kontakt-5 coverage seems to be about 60%.

Upper front turret is 5cm cast plus 5cm STEF at ~77-78.

Glacis is 235mm thick with three steel plates of varing hardness and one layer of STEF. If we assume all plates are 5cm with one of the steel plates semi-hardened steel and the STEF is 5.5cm thick, - The steel would equal 10 + 5 x 1.34 or 16.7cm plus the STEF, which has a KE resistance of 0.41 and HEAT value of 0.55, thus the total resistance is 18.9cm KE and 19.7cm HEAT @ 67 or 49.7cm KE and 52cm HEAT .But a 3cm hard steel plate was added in the 80s boosting the KE resistance by 1.34 x 3 0.38; or 60cm KE & 63cm HEAT. With K-5 thats 782cm KE & 108 5cm HEAT.

Lower hull is 8-10cm at 64 = LOS thickness of 0.438 or 17-23cm KE armor, plus a rubber flap that hangs from the hull nose and provides a basic spaced armor for HEAT warheads. Since the rubber flap is likely to slide against the penetrating HEAT Jet it probably offers about 7-9cm plus the effect of standoff [6cm HEAT] for a total of about 30-38cm HEAT armor. The additional KE resistance is maybe +1cm due to projectile deflection or yaw.

Now to the figures.

Front armor diagram

  ~80-90cm LOS cast mantle x 0.6-0.71 = 54-56cm KE & 80-90cm HEAT
  81.5cm LOS x 0.78 [Cast/STEF/AD-90] = 64cm x ~0.91 = 57cm plus K-5 = 722cm KE
81.5cm LOS x 1.02 [Cast/STEF/AD-90] = 83cm plus K-5 = 1284cm HEAT
  70-72cm LOS x 0.78 [Cast/STEF/AD-90] = 56cm x 0.951 = 53 plus K-5 = 712cm KE2
70-72cm LOS x 1.02 [Cast/STEF/AD-90] = 72cm plus K-5 = 1184cm HEAT2
  44-48cm LOS x 0.66 [Steel/STB] = 29-32cm KE plus K-5 where present = 486cm KE
44-48cm LOS x 0.77 [Steel/STB] = 34-37cm HEAT plus K-5 where present = 7016cm HEAT
  [10 + 8 x 1.34 + 5.5 x 0.41] / 0.383 = ~60cm KE plus K-5 = 782cm KE
[10 + 8 x 1.3 + 5.5 x 0.55] / 0.383 = ~63cm HEAT plus K-5 = 1084cm HEAT
  18-24cm KE and 30-38cm HEAT
Side turret ranges from 40-60cm thick near front thinning to ~ 15-20cm around back. This is probably half and half cast/STEF thus the KE armor is 0.66 while the HEAT armor is 0.77. The effective KE armor ranges from 40cm narrowing quickly to 26cm and 10-13cm around back. The HEAT armor ranges from 46-31cm near the front down to 15-12cm Around back. In the side and rear turret are mounted external storage boxes ~50cm thick that will offer a modicum of spaced armor, this may amount to an additonal ~13-15cm HEAT armor. Additionally K-5 is mounted around the front side of the turret.
The side hull is 6cm thick rolled steel but the lower side hull around the wheels is probably only 2cm thick; side skirts add 25 mm thick reinforced rubber [with steel?] plate plus 60cm airgap increasing the HEAT armor by about 15-17cm against 2nd gen and 26-28cm against 1st gen warheads. This rubber skirting is unlikely to add more than 1cm to the KE side armor, due to deflection. The fuel tanks along the sponsons should add 65cm x 0.1 KE and 0.3 HEAT or an additional 6-7cm KE and ~ 20cm HEAT armor. Over the front half of the side hull NERA is mounted which probably adds ~30cm HEAT and a couple of cm KE resistance.
The rear armor is unlikely to be more than 4cm but fuel tanks mounted there could offer 0.1 to 0.15 Te resistance to APFSDS and 0.34 resistance to HEAT. The HEAT armor would range from 3-4cm to as much as 18cm additional HEAT armor.

1 - adjustment for free-edge effect
2 - a substantial portion of this projection on the right side of T-80U is not covered by ERA due to mounting of L-4 IR searchlight; an area both on the left and right is not covered on T-80UK because of Shtora emitters. In these areas, instead of K-5 assume additional <1cm KE and ~5cm HEAT protection. T-80U(M) is free from this disadvantage.
3 - adjustment for LOS due to angle

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with major contributions by Paul Lakowski.