The various Crusader and Centaur anti-aircraft tanks were the products of a long and tortuous development process over which time the enormous complexity of the problem of dealing with aerial targets emerged. In contrast to ground targets, aircraft could appear unexpectedly from any direction and complete an attack in mere seconds, while their relative velocity would increase and decrease exponentially as approached and exited the target area. This in turn necessitated a turret control system that could switch direction onto a new target almost instantly, while retaining fine control at both the minimum and maximum engagement velocities. It would also need to be controllable in traverse and elevation characteristics simultaneously. What would eventually emerge after much consequent delay was an effective equipment that found itself being deployed after the Luftwaffe had already been reduced to its weakest.