The most likely is an underestimated muzzle velocity, as it is very unlikely that the ammunition performance of standard armor-piercing projectiles would increase the penetration to such an extent.Īn example from the table is the German 7.5-cm KwK 37 L/24. about 20% or more) than the theoretically calculated penetration values.įluctuations of a few percent may easily be due to different qualities of the armor plates or deviations in the test procedure, but such a positive excursion of this magnitude leads to at least one of the underlying parameters or assumptions being incorrect. It is much more likely that the muzzle velocities are overrated and the ammunition was of inferior design and quality.Īnother indirect evidence of suspicious muzzle velocities stems from the relatively rare cases in which the historical test result is significantly higher (i.e. The worse test values for the Allied guns cannot simply be attributed to the German tests with poor test armor or their obvious inability to measure 1,000 meters and an angle of 30 degrees. Both guns are shorter than the 8.8 cm KwK 36 L/56 of the Tiger I in their actual and caliber-related length, have a similar propellant and projectile mass ratio and should nevertheless have higher muzzle velocities. American Pershing tank with 90mm M3 L/51 gun from the RAC Tank Museum.Įxamples from the table are the US 90mm M3 L/51 and the Soviet 85mm ZiS-S-53 L/54.6. This is all the more true if the combat reports are based on the test results and the respective country has a mixed record in the production of high-quality armor plates. If the actual penetration values for the weapons with shorter barrels are about 20% below the expected theoretical penetration force and the ratio of propellant to projectile mass is comparable to that of other guns in the class, this serious evidence suggests that the deviation is more due to an incorrectly reported muzzle velocity than to mysteriously hard armor plates in the firing tests. In this case, the additional muzzle velocity can only be attributed to the quantity and quality of the propellant used in the shell. Historical test results vs calculated values (1,000 m at 30°): It is interesting to note that for some weapons of similar caliber, the stated muzzle velocity is higher, although the respective weapon has a shorter caliber barrel length than comparable weapons. The table provides further evidence that some stated muzzle velocities must be inaccurate.Īs already mentioned, the muzzle velocity is largely dependent on the ratio of propellant, projectile mass and barrel length. This matter is much more complex and problematic than the actual calculation of the penetration figures !Įven with the best available information and computer power, our calculated muzzle velocities and the resulting calculated penetration value will never be more accurate or consistent than the data from direct historical test results. the greater the tolerances, the more gases escape at the sides of the projectile, which can drastically reduce the muzzle velocity and increase the instability of the projectile) and the effects of the barrel rifling (this determines the rotation of the projectile, which affects the forces on the projectile and its acceleration time). Knowledge of the chemical composition of the propellant and chemical combustion efficiency, ammunition design and amount of propellant used, the significant variations in the force behind the projectile (the force on the projectile changes as it is accelerated along the barrel by the increase in chamber volume and expanding gases), the friction in the barrel, exact projectile mass, exact barrel length, gun breach and barrel tolerances at the production (e.g.
Tank buster ww2 plus#
In order to accurately calculate the muzzle velocity, where plus or minus 1% must not be exceeded, the following should be considered: However, the breech chamber pressure values are only available for some weapons and these are not more reliable or consistent than muzzle velocity or direct penetration measurements. These are the dominating factors which determine the muzzle velocity and give an approximate value. To do this, the pressure inside the breech chamber must be determined and the acceleration of the projectile must be calculated over the length of the barrel. One could initially be of the opinion that the calculation of the muzzle velocity is a relatively simple matter.