IS-3 Prototype Penetration Testing

"Resilience of main hull components

Part	Thickness (mm)	Plate Angle (deg)	Shell type		Angle	Impact velocity	Range (m)	Damage type
			Caliber	Type
Upper front plate	120	60	88	AP	0	965	350	No penetration
Upper front plate	120	60	122	AP	0	758	690	No penetration
Side with spaced armour	85/16	60/35	88	AP	90	982	150	No penetration
Side without spaced armour	85	60	88	AP	90	983	159	Limit of dangerous penetration
Side with spaced armour	85/16	60/35	75	Subcaliber	60	1051	100	No penetration
Side (upper belt)	100	0	75	AP	45	905	500	No penetration
Side (upper belt)	100	0	75	AP	60	720	1600	Penetration
Side (rear part)	60	0	75	AP	35	780	1500	Limit of rear plate
Bottom with spaced armour	20/30	60	75	AP	35	607	2200	Only spaced armour is penetrated
Bottom with spaced armour	20/30	60	75	AP	35	660	1900	Same

Resilience of main turret components

Part	Thickness (mm)	Angle of plate	Shell type		Impact velocity (m/s)	Range (m)	Damage type
			Caliber	Type
Turret front	175	Sphere	88	AP	967	350	Penetration less than shell caliber
2nd belt	120	51	88	AP	900	1000	Penetration within +/- 15 degrees of normal
3rd belt	90-100	58	88	AP	900	1000
4th belt	175	15	88	AP	900	1000
2nd belt	120	51	88	AP	965	350	Penetration within +/- 30 degrees of normal
3rd belt	90-100	58	88	AP	966	350
4th belt	175	15	88	AP	975	300

1. Replace the sides of the hull with a single bent 75 mm thick plate of medium hardness with a 45 mm high hardness screen in the middle part, according to the attached diagram.