Interior Ballistics Calculator

The calculator estimates the achievable muzzle velocity of projectiles fired from smooth-bore tank cannons with a given caliber, projectile travel length, and given charge and projectile mass. The model was developed from a large pool of test data with 120 and 140 mm smooth-bore cannons.

Definitions:

Sebert Factor	The Sebert factor defines the amount of propellant mass flowing together with the bullet through the barrel. Depending on caliber and propellent type it is a value between 0.43 und 0.48.
Projectile Travel Length	The distance, traveled by the projectile, until it leaves the barrel

Boundaries of the input parameters:

	Caliber	118 to 142 mm
	Projectile travel length	4 to 7 m
	Max. gas pressure	4000 to 6500 bar
	Charge mass	7 to 17.5 kg - depending on caliber
	Projectile mass	5.8 to 19.8 kg - depending on caliber
	Sebert factor	0.43 to 0.48

Input Values:

	Caliber		mm
	Projectile travel length		m
	Max. gas pressure		bar
	Charge mass		kg
	Projectile mass		kg
	Sebert factor

Generic Examples:

Caliber	120mm	120mm	130mm	140mm
Tube type	L44	L55	L51	L47
Projectile travel length (m)	4.74	6.04	5.87	5.71
Max. gas pressure (bar)	5500	5500	5500	5500
Charge mass (kg)	8.9	8.9	12.5	16.5
Projectile mass (kg)	8.3	8.3	11	14
Sebert factor	0.43	0.43	0.44	0.45

Muzzle velocity (km/s)	1.679	1.762	1.693	1.686