Complex sentence: Hawker Aircraft continued to produce designs under its own name as a part of Hawker Siddeley Aircraft, and from 1955, Hawker Siddeley Group, until the name was dropped, along with those of the sister companies, in 1963.
Split into simpler sentences: Hawker Aircraft continued to produce designs under its own name as a part of the Hawker Siddeley Aircraft, from 1955 division of Hawker Siddeley Group. The "Hawker" brand name was dropped, along with those of the sister companies, in 1963.