 Although officially led by Chaplin, Cockerell had considerable involvement in the ongoing design process.Saunders-Roe determined that, in addition to more theoretical work, a test programme involving a large-scale radio-controlled model would be necessary to provide sufficient data to make progress, and produced a proposal to this effect on 4 September 1958.In October 1958, the second stage of the contract was awarded, enabling advanced research into the development of the proposed air cushion and the corresponding principles, such as intake design, directional stability, and control; design studies were also performed for various sizes of hovercraft, ranging from 70-ton to 15,000-ton craft.