It is the purpose of this article to provide for the acquisition, construction, improvement, extension, maintenance and operation of a public airport and related facilities in a prudent and economical manner, and this article shall be liberally construed as giving to the authority full and complete power reasonably required to give effect to the purposes hereof. The provisions of this article are in addition to and not in derogation of any power existing in the county commission of a county under any Constitutional or statutory provisions which it may now have, or may hereafter acquire.