The British adopted "effective ceiling", meaning the altitude at which a gun could deliver a series of shells against a moving target; this could be constrained by maximum fuse running time as well as the gun's capability. By the late 1930s the British definition was "that height at which a directly approaching target at 400 mph (=643.6 km/h) can be engaged for 20 seconds before the gun reaches 70 degrees elevation". However, effective ceiling for heavy AA guns was affected by non-ballistic factors: COUNT 4
QSN1 What term is used to describe the altitude for a gun to shoot shells against a target that is moving? ANS1 "effective ceiling" QSN2 Who adopted the use of the term, effective ceiling? ANS2 The British QSN3 Along with other factors, how long must a target be engaged to have effective ceiling? ANS3 for 20 seconds QSN4 What affected the effective ceiling for heavy AA guns? ANS4 non-ballistic factors