Using Maximum Time Of Flight for a projectile from Physics to set the time when a projectile destroys itself

[Saaransh_Vatsa]

In Projectile Mechanics, The Maximum Time of Flight for a Projectile is (2*Velocity)/(Gravitational Acceleration),

For A Launch Speed of 4000cm/s, Maximum Time of flight is around 8 seconds. But since the tanks are always moving, they will never be at maximum range. So a healthy Approximation of 6 seconds can be used.