Patent ID: 7500423

Claim:
A method of calculating in near real-time two possible angles of elevation of a projectile and associated times of flight so that the projectile can be made to act at a desired point, c h a r a c t e r i s e d in that the azimuth angle of a vertical plane, the XZ plane, in which the launching direction of the projectile lies, is determined in a prior-art manner, for instance by direct measuring the direction to a target on which the projectile is to act, the origin is fixed at the starting point of the projectile and the X axis is fixed to be parallel to the horizontal plane, the angle of elevation and the time of flight are calculated in a process which is divided into two main parts, a calculation part and a logic part, where the calculation part, starting from the diameter (d), mass (m), air drag coefficient (C d ) and launching speed (V launch ) of the projectile, discretely timed calculates projectile positions and associated times of flight in a trajectory, and where the logic part, starting from a maximum inaccuracy in the logic part (acc), a lower limit of the desired height (lh), the horizontal distance to the target (x p ) and the relative height to the target (z p ), sets a first direction of elevation (α launch ), monitors the calculation of projectile positions and time of flight, and interrupts the calculation either, when the projectile lies within a circle of acceptance with the desired point at the centre and with the radius equal to half the value of the inaccuracy (acc) of the logic part and determines the current values of direction of elevation and time of flight as a solution, or when a calculated projectile position lies outside a predetermined boundary condition, and after that, until two solutions have been found, sets a second direction of elevation.