The first Z Batteries were equipped with a single-rocket launcher, the Projector, 3-inch, Mark 1. It was soon found that the rockets did not perform as accurately as the trials had suggested and that the proximity fuses were rarely effective. Therefore, the technique of firing the rockets in large salvos was introduced, and projectors capable of firing an ever-larger number of rockets were developed. The Projector, 3-inch, No 2, Mk 1 was a twin launcher and the No 4 Mk 1 and Mk 2 fired 36 rockets at a time in a "ripple" firing sequence.