[intellec7]

Instead of using the Tilt servo's angle as a direct input into the trajectory equation, you should use trigonometry. You know how high the target is and you know how high the camera is. tan(tilt_angle )= (height_target - height_camera)/ distance

so

distance = (height_target - height_camera) / tan(tilt_angle)

Then look into the trajectory equations for a projectile launched at constant V at an angle. It involves decomposing the angled velocity into a horizontal velocity (which never changes throughout the trajectory) and a vertical velocity (which changes due to gravity).