Simulation of the 125mm 3OF19 HE-FS projectile against single plate armour and spaced armour. Spaced armour is supposed to improve protection against explosives, as the air gap allows for the blast energy to be dissipated before hitting the armour underneath. The total metal weight and thickness is equal for both tests, but with the spaced armour having an air gap of 125mm. Plates are mounted at 60° for all tests. Approximate velocity of the fragments is around 1400 m/s.
Material Properties taken from literature, 3OF19 from wikipedia :
 Air & TNT: https://osf.io/f8awq/download/?versio…
 3OF19 specs: https://en.wikipedia.org/wiki/125_mm_…
To note: The tail assembly and fins have not been modelled as they would have no effect on the penetration. SPH would have been better for this model but I didnt have the time or the computational power to implement it properly.
The T-34E featured spaced armour on the hull and turret, intended to protect against sub-calibre and HEAT munitions, with the simulation showing how it would fair against APCR from the long-barrelled 50mm KwK39 L/60.
The KwK39 offered a higher muzzle velocity than the Panzer III’s previous KwK38 cannon, and its Pzgr.40 Armor-Piercing Composite-Rigid (APCR) projectile provided it with excellent penetration. However, spaced armor can cause shattering of the brittle core. The T-34’s armor has been modelled as 440BHN steel, with the applique plate being 500BHN. The spacing and angling has been approximated from the Warthunder 3D model.
It should be noted that the image of live fire-testing is not of the T-34E, but one of it’s prototypes, using high hardness applique plates but with a closer spacing, and likely not an impact from Pzgr.40, but Soviet APCR.
The MBT-70 was an advanced prototype main battle tank, developed during the 1960s between America and West Germany. Later that decade, the Swedish Strv103 entered service. The simulation shows what would happen if a Slppjr m/66 APDS round impacted the upper plate of the MBT-70 from 800m away. The MBT-70’s spaced armour was intended to protect against “105mm APDS from 800m” but it is likely this referred to L28 APDS (and its equivalents) as it was the standard APDS round for the US and West Germany at the beginning of the project. L28 featured a tungsten carbide core, which is susceptible to shattering against spaced armor.
Slppjr m/66 was the Swedish designation of L52 APDS, which featured a tungsten alloy core and only entered production in the mid-60’s, . This made it a lot tougher than L28, making spaced armor substantially less effective against it. For reference, L52 (Slppjr m/66) can penetrate just over 130mm RHA @60° at this range.
There is varying information on the MBT-70’s armor composition, thickness, and angle, with the simulated layout following the more commonly stated parameters. Its interesting that the 38mm HHA – 127mm gap was used on the Leopard 2K as well.